git/symlinks.c

282 строки
7.9 KiB
C
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Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
#include "cache.h"
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* Returns the length (on a path component basis) of the longest
* common prefix match of 'name_a' and 'name_b'.
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*/
static int longest_path_match(const char *name_a, int len_a,
const char *name_b, int len_b,
int *previous_slash)
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
{
int max_len, match_len = 0, match_len_prev = 0, i = 0;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
max_len = len_a < len_b ? len_a : len_b;
while (i < max_len && name_a[i] == name_b[i]) {
if (name_a[i] == '/') {
match_len_prev = match_len;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
match_len = i;
}
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
i++;
}
/*
* Is 'name_b' a substring of 'name_a', the other way around,
* or is 'name_a' and 'name_b' the exact same string?
*/
if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
(len_a < len_b && name_b[len_a] == '/') ||
(len_a == len_b))) {
match_len_prev = match_len;
match_len = i;
}
*previous_slash = match_len_prev;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
return match_len;
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
}
static struct cache_def default_cache;
static inline void reset_lstat_cache(struct cache_def *cache)
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
{
cache->path[0] = '\0';
cache->len = 0;
cache->flags = 0;
/*
* The track_flags and prefix_len_stat_func members is only
* set by the safeguard rule inside lstat_cache()
*/
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
}
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
#define FL_DIR (1 << 0)
#define FL_NOENT (1 << 1)
#define FL_SYMLINK (1 << 2)
#define FL_LSTATERR (1 << 3)
#define FL_ERR (1 << 4)
#define FL_FULLPATH (1 << 5)
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* Check if name 'name' of length 'len' has a symlink leading
* component, or if the directory exists and is real, or not.
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*
* To speed up the check, some information is allowed to be cached.
* This can be indicated by the 'track_flags' argument, which also can
* be used to indicate that we should check the full path.
*
* The 'prefix_len_stat_func' parameter can be used to set the length
* of the prefix, where the cache should use the stat() function
* instead of the lstat() function to test each path component.
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*/
static int lstat_cache(struct cache_def *cache, const char *name, int len,
int track_flags, int prefix_len_stat_func)
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
{
int match_len, last_slash, last_slash_dir, previous_slash;
int match_flags, ret_flags, save_flags, max_len, ret;
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
struct stat st;
Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
if (cache->track_flags != track_flags ||
cache->prefix_len_stat_func != prefix_len_stat_func) {
/*
* As a safeguard rule we clear the cache if the
* values of track_flags and/or prefix_len_stat_func
* does not match with the last supplied values.
*/
reset_lstat_cache(cache);
cache->track_flags = track_flags;
cache->prefix_len_stat_func = prefix_len_stat_func;
match_len = last_slash = 0;
} else {
/*
* Check to see if we have a match from the cache for
* the 2 "excluding" path types.
*/
match_len = last_slash =
longest_path_match(name, len, cache->path, cache->len,
&previous_slash);
match_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
if (!(track_flags & FL_FULLPATH) && match_len == len)
match_len = last_slash = previous_slash;
if (match_flags && match_len == cache->len)
return match_flags;
/*
* If we now have match_len > 0, we would know that
* the matched part will always be a directory.
*
* Also, if we are tracking directories and 'name' is
* a substring of the cache on a path component basis,
* we can return immediately.
*/
match_flags = track_flags & FL_DIR;
if (match_flags && len == match_len)
return match_flags;
}
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* Okay, no match from the cache so far, so now we have to
* check the rest of the path components.
*/
ret_flags = FL_DIR;
last_slash_dir = last_slash;
max_len = len < PATH_MAX ? len : PATH_MAX;
while (match_len < max_len) {
do {
cache->path[match_len] = name[match_len];
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
match_len++;
} while (match_len < max_len && name[match_len] != '/');
if (match_len >= max_len && !(track_flags & FL_FULLPATH))
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
break;
last_slash = match_len;
cache->path[last_slash] = '\0';
Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
if (last_slash <= prefix_len_stat_func)
ret = stat(cache->path, &st);
else
ret = lstat(cache->path, &st);
if (ret) {
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
ret_flags = FL_LSTATERR;
if (errno == ENOENT)
ret_flags |= FL_NOENT;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
} else if (S_ISDIR(st.st_mode)) {
last_slash_dir = last_slash;
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
continue;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
} else if (S_ISLNK(st.st_mode)) {
ret_flags = FL_SYMLINK;
} else {
ret_flags = FL_ERR;
Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
}
Optimize symlink/directory detection This is the base for making symlink detection in the middle fo a pathname saner and (much) more efficient. Under various loads, we want to verify that the full path leading up to a filename is a real directory tree, and that when we successfully do an 'lstat()' on a filename, we don't get a false positive due to a symlink in the middle of the path that git should have seen as a symlink, not as a normal path component. The 'has_symlink_leading_path()' function already did this, and cached a single level of symlink information, but didn't cache the _lack_ of a symlink, so the normal behaviour was actually the wrong way around, and we ended up doing an 'lstat()' on each path component to check that it was a real directory. This caches the last detected full directory and symlink entries, and speeds up especially deep directory structures a lot by avoiding to lstat() all the directories leading up to each entry in the index. [ This can - and should - probably be extended upon so that we eventually never do a bare 'lstat()' on any path entries at *all* when checking the index, but always check the full path carefully. Right now we do not generally check the whole path for all our normal quick index revalidation. We should also make sure that we're careful about all the invalidation, ie when we remove a link and replace it by a directory we should invalidate the symlink cache if it matches (and vice versa for the directory cache). But regardless, the basic function needs to be sane to do that. The old 'has_symlink_leading_path()' was not capable enough - or indeed the code readable enough - to really do that sanely. So I'm pushing this as not just an optimization, but as a base for further work. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-09 20:21:07 +04:00
break;
Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
}
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* At the end update the cache. Note that max 3 different
* path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
* for the moment!
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*/
save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
cache->path[last_slash] = '\0';
cache->len = last_slash;
cache->flags = save_flags;
} else if ((track_flags & FL_DIR) &&
last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* We have a separate test for the directory case,
* since it could be that we have found a symlink or a
* non-existing directory and the track_flags says
* that we cannot cache this fact, so the cache would
* then have been left empty in this case.
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*
* But if we are allowed to track real directories, we
* can still cache the path components before the last
* one (the found symlink or non-existing component).
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
*/
cache->path[last_slash_dir] = '\0';
cache->len = last_slash_dir;
cache->flags = FL_DIR;
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
} else {
reset_lstat_cache(cache);
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
}
return ret_flags;
}
#define USE_ONLY_LSTAT 0
/*
* Return non-zero if path 'name' has a leading symlink component
*/
int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
{
return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
}
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
/*
* Return non-zero if path 'name' has a leading symlink component
*/
int has_symlink_leading_path(const char *name, int len)
lstat_cache(): more cache effective symlink/directory detection Make the cache functionality more effective. Previously when A/B/C/D was in the cache and A/B/C/E/file.c was called for, there was no match at all from the cache. Now we use the fact that the paths "A", "A/B" and "A/B/C" are already tested, and we only need to do an lstat() call on "A/B/C/E". We only cache/store the last path regardless of its type. Since the cache functionality is always used with alphabetically sorted names (at least it seems so for me), there is no need to store both the last symlink-leading path and the last real-directory path. Note that if the cache is not called with (mostly) alphabetically sorted names, neither the old, nor this new one, would be very effective. Previously, when symlink A/B/C/S was cached/stored in the symlink- leading path, and A/B/C/file.c was called for, it was not easy to use the fact that we already knew that the paths "A", "A/B" and "A/B/C" are real directories. Avoid copying the first path components of the name 2 zillion times when we test new path components. Since we always cache/store the last path, we can copy each component as we test those directly into the cache. Previously we ended up doing a memcpy() for the full path/name right before each lstat() call, and when updating the cache for each time we have tested a new path component. We also use less memory, that is, PATH_MAX bytes less memory on the stack and PATH_MAX bytes less memory on the heap. Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable comments to this patch! Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 18:14:50 +03:00
{
return threaded_has_symlink_leading_path(&default_cache, name, len);
Add has_symlink_leading_path() function. When we are applying a patch that creates a blob at a path, or when we are switching from a branch that does not have a blob at the path to another branch that has one, we need to make sure that there is nothing at the path in the working tree, as such a file is a local modification made by the user that would be lost by the operation. Normally, lstat() on the path and making sure ENOENT is returned is good enough for that purpose. However there is a twist. We may be creating a regular file arch/x86_64/boot/Makefile, while removing an existing symbolic link at arch/x86_64/boot that points at existing ../i386/boot directory that has Makefile in it. We always first check without touching filesystem and then perform the actual operation, so when we verify the new file, arch/x86_64/boot/Makefile, does not exist, we haven't removed the symbolic link arc/x86_64/boot symbolic link yet. lstat() on the file sees through the symbolic link and reports the file is there, which is not what we want. The function has_symlink_leading_path() function takes a path, and sees if any of the leading directory component is a symbolic link. When files in a new directory are created, we tend to process them together because both index and tree are sorted. The function takes advantage of this and allows the caller to cache and reuse which symbolic link on the filesystem caused the function to return true. The calling sequence would be: char last_symlink[PATH_MAX]; *last_symlink = '\0'; for each index entry { if (!lose) continue; if (lstat(it)) if (errno == ENOENT) ; /* happy */ else error; else if (has_symlink_leading_path(it, last_symlink)) ; /* happy */ else error; /* would lose local changes */ unlink_entry(it, last_symlink); } Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 09:11:07 +04:00
}
/*
* Return non-zero if path 'name' has a leading symlink component or
* if some leading path component does not exists.
*/
int has_symlink_or_noent_leading_path(const char *name, int len)
{
struct cache_def *cache = &default_cache; /* FIXME */
return lstat_cache(cache, name, len,
FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
(FL_SYMLINK|FL_NOENT);
}
/*
* Return non-zero if all path components of 'name' exists as a
* directory. If prefix_len > 0, we will test with the stat()
* function instead of the lstat() function for a prefix length of
* 'prefix_len', thus we then allow for symlinks in the prefix part as
* long as those points to real existing directories.
*/
int has_dirs_only_path(const char *name, int len, int prefix_len)
{
struct cache_def *cache = &default_cache; /* FIXME */
return lstat_cache(cache, name, len,
FL_DIR|FL_FULLPATH, prefix_len) &
FL_DIR;
}
static struct removal_def {
char path[PATH_MAX];
int len;
} removal;
static void do_remove_scheduled_dirs(int new_len)
{
while (removal.len > new_len) {
removal.path[removal.len] = '\0';
if (rmdir(removal.path))
break;
do {
removal.len--;
} while (removal.len > new_len &&
removal.path[removal.len] != '/');
}
removal.len = new_len;
}
void schedule_dir_for_removal(const char *name, int len)
{
int match_len, last_slash, i, previous_slash;
match_len = last_slash = i =
longest_path_match(name, len, removal.path, removal.len,
&previous_slash);
/* Find last slash inside 'name' */
while (i < len) {
if (name[i] == '/')
last_slash = i;
i++;
}
/*
* If we are about to go down the directory tree, we check if
* we must first go upwards the tree, such that we then can
* remove possible empty directories as we go upwards.
*/
if (match_len < last_slash && match_len < removal.len)
do_remove_scheduled_dirs(match_len);
/*
* If we go deeper down the directory tree, we only need to
* save the new path components as we go down.
*/
if (match_len < last_slash) {
memcpy(&removal.path[match_len], &name[match_len],
last_slash - match_len);
removal.len = last_slash;
}
}
void remove_scheduled_dirs(void)
{
do_remove_scheduled_dirs(0);
}