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Jeff King 00611d8440 add open_nofollow() helper
Some callers of open() would like to use O_NOFOLLOW, but it is not
available on all platforms. Let's abstract this into a helper function
so we can provide system-specific implementations.

Some light web-searching reveals that we might be able to get something
similar on Windows using FILE_FLAG_OPEN_REPARSE_POINT. I didn't dig into
this further.

For other systems without O_NOFOLLOW or any equivalent, we have two
options for fallback:

  - we can just open anyway, following symlinks; this may have security
    implications (e.g., following untrusted in-tree symlinks)

  - we can determine whether the path is a symlink with lstat().

    This is slower (two syscalls instead of one), but that may be
    acceptable for infrequent uses like looking up .gitattributes files
    (especially because we can get away with a single syscall for the
    common case of ENOENT).

    It's also racy, but should be sufficient for our needs (we are
    worried about in-tree symlinks that we ourselves would have
    previously created). We could make it non-racy at the cost of making
    it even slower, by doing an fstat() on the opened descriptor and
    comparing the dev/ino fields to the original lstat().

This patch implements the lstat() option in its slightly-faster racy
form.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-16 09:41:32 -08:00
Jeff King 6479ea4a8a xrealloc: do not reuse pointer freed by zero-length realloc()
This patch fixes a bug where xrealloc(ptr, 0) can double-free and
corrupt the heap on some platforms (including at least glibc).

The C99 standard says of malloc (section 7.20.3):

  If the size of the space requested is zero, the behavior is
  implementation-defined: either a null pointer is returned, or the
  behavior is as if the size were some nonzero value, except that the
  returned pointer shall not be used to access an object.

So we might get NULL back, or we might get an actual pointer (but we're
not allowed to look at its contents). To simplify our code, our
xmalloc() handles a NULL return by converting it into a single-byte
allocation. That way callers get consistent behavior. This was done way
back in 4e7a2eccc2 (?alloc: do not return NULL when asked for zero
bytes, 2005-12-29).

We also gave xcalloc() and xrealloc() the same treatment. And according
to C99, that is fine; the text above is in a paragraph that applies to
all three. But what happens to the memory we passed to realloc() in such
a case? I.e., if we do:

  ret = realloc(ptr, 0);

and "ptr" is non-NULL, but we get NULL back, is "ptr" still valid? C99
doesn't cover this case specifically, but says (section 7.20.3.4):

  The realloc function deallocates the old object pointed to by ptr and
  returns a pointer to a new object that has the size specified by size.

So "ptr" is now deallocated, and we must only look at "ret". And since
"ret" is NULL, that means we have no allocated object at all. But that's
not quite the whole story. It also says:

  If memory for the new object cannot be allocated, the old object is
  not deallocated and its value is unchanged.
  [...]
  The realloc function returns a pointer to the new object (which may
  have the same value as a pointer to the old object), or a null pointer
  if the new object could not be allocated.

So if we see a NULL return with a non-zero size, we can expect that the
original object _is_ still valid. But with a non-zero size, it's
ambiguous. The NULL return might mean a failure (in which case the
object is valid), or it might mean that we successfully allocated
nothing, and used NULL to represent that.

The glibc manpage for realloc() explicitly says:

  [...]if size is equal to zero, and ptr is not NULL, then the call is
  equivalent to free(ptr).

Likewise, this StackOverflow answer:

  https://stackoverflow.com/a/2135302

claims that C89 gave similar guidance (but I don't have a copy to verify
it). A comment on this answer:

  https://stackoverflow.com/a/2022410

claims that Microsoft's CRT behaves the same.

But our current "retry with 1 byte" code passes the original pointer
again. So on glibc, we effectively free() the pointer and then try to
realloc() it again, which is undefined behavior.

The simplest fix here is to just pass "ret" (which we know to be NULL)
to the follow-up realloc(). But that means that a system which _doesn't_
free the original pointer would leak it. It's not clear if any such
systems exist, and that interpretation of the standard seems unlikely
(I'd expect a system that doesn't deallocate to simply return the
original pointer in this case). But it's easy enough to err on the safe
side, and just never pass a zero size to realloc() at all.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-02 12:18:14 -07:00
brian m. carlson 14570dc67d wrapper: add function to compare strings with different NUL termination
When parsing capabilities for the pack protocol, there are times we'll
want to compare the value of a capability to a NUL-terminated string.
Since the data we're reading will be space-terminated, not
NUL-terminated, we need a function that compares the two strings, but
also checks that they're the same length.  Otherwise, if we used strncmp
to compare these strings, we might accidentally accept a parameter that
was a prefix of the expected value.

Add a function, xstrncmpz, that takes a NUL-terminated string and a
non-NUL-terminated string, plus a length, and compares them, ensuring
that they are the same length.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-05-27 10:07:06 -07:00
Junio C Hamano b660a76d0f Merge branch 'dl/wrapper-fix-indentation'
Coding style fix.

* dl/wrapper-fix-indentation:
  wrapper: indent with tabs
2020-04-22 13:42:47 -07:00
Denton Liu 7cd54d37dc wrapper: indent with tabs
The codebase uses tabs for indentation. Convert an erroneous space
indent into a tab indent.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-28 18:06:51 -07:00
Junio C Hamano 6e12570822 Merge branch 'ah/cleanups'
Miscellaneous code clean-ups.

* ah/cleanups:
  git_mkstemps_mode(): replace magic numbers with computed value
  wrapper: use a loop instead of repetitive statements
  diffcore-break: use a goto instead of a redundant if statement
  commit-graph: remove a duplicate assignment
2019-10-09 14:01:00 +09:00
Jeff King 53d687bf5f git_mkstemps_mode(): replace magic numbers with computed value
The magic number "6" appears several times in the function, and is
related to the size of the "XXXXXX" string we expect to find in the
template. Let's pull that "XXXXXX" into a constant array, whose size we
can get at compile time with ARRAY_SIZE().

Note that we probably can't just change this value, since callers will
be feeding us a certain number of X's, but it hopefully makes the
function itself easier to follow.

While we're here, let's do the same with the "letters" array (which we
_could_ modify if we wanted to include more characters).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-03 09:58:25 +09:00
Alex Henrie 54a80a9ad8 wrapper: use a loop instead of repetitive statements
A check into the history of this code revealed no particular reason for
the code to be written in this way. All popular compilers are capable of
unrolling loops if it benefits performance, and once this code is
replaced with a loop, the magic number 6 used in multiple places in this
function can be replaced with a named constant.

Reviewed-by: Derrick Stolee <stolee@gmail.com>
Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-02 15:04:23 +09:00
Jeff King 9827d4c185 packfile: drop release_pack_memory()
Long ago, in 97bfeb34df (Release pack windows before reporting out of
memory., 2006-12-24), we taught xmalloc() and friends to try unmapping
pack windows when malloc() failed. It's unlikely that his helps a lot in
practice, and it has some downsides. First, the downsides:

  1. It makes xmalloc() not thread-safe. We've worked around this in
     pack-objects.c, which installs its own locking version of the
     try_to_free_routine(). But other threaded code doesn't.

  2. It makes the system as a whole harder to reason about. Functions
     which allocate heap memory under the hood may have farther-reaching
     effects than expected.

That might be worth the tradeoff if there's a benefit. But in practice,
it seems unlikely. We're generally dealing with mmap'd files, so the OS
is going to do a much better job at responding to memory pressure by
dropping individual pages (the exception is systems with NO_MMAP, but
even there the OS can probably respond just as well with swapping).

So the only thing we're really freeing is address space. On 64-bit
systems, we have plenty of that to go around. On 32-bit systems, it
could possibly help. But around the same time we made two other changes:
77ccc5bbd1 (Introduce new config option for mmap limit., 2006-12-23) and
60bb8b1453 (Fully activate the sliding window pack access., 2006-12-23).
Together that means that a 32-bit system should have no more than 256MB
total of packed-git mmaps at one time, split between a few 32MB windows.
It's unlikely we have any address space problems since then, but we
don't have any data since the features were all added at the same time.

Likewise, xmmap() will try to free memory. At first glance, it seems
like we'd need this (when we try to mmap a new window, we might need to
close an old one to save address space on a 32-bit system). But we're
saved again by core.packedGitLimit: if we're going to exceed our 256MB
limit, we'll close an existing window before we even call mmap().

So it seems unlikely that this feature is actually doing anything
useful. And while we don't have reports of it harming anything (probably
because it rarely if ever kicks in), it would be nice to simplify the
system overall. This patch drops the whole try_to_free system from
xmalloc(), as well as the manual pack memory release in xmmap().

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-13 12:21:33 -07:00
Carlo Marcelo Arenas Belón 729a9b558b wrapper: avoid undefined behaviour in macOS
0620b39b3b ("compat: add a mkstemps() compatibility function", 2009-05-31)
included a function based on code from libiberty which would result in
undefined behaviour in platforms where timeval's tv_usec is a 32-bit signed
type as shown by:

wrapper.c:505:31: runtime error: left shift of 594546 by 16 places cannot be represented in type '__darwin_suseconds_t' (aka 'int')

interestingly the version of this code from gcc never had this bug and the
code had a cast that would had prevented the issue (at least in 64-bit
platforms) but was misapplied.

change the cast to uint64_t so it also works in 32-bit platforms.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-19 07:41:31 -07:00
Pranit Bauva e3b1e3bdc0 wrapper: move is_empty_file() and rename it as is_empty_or_missing_file()
is_empty_file() can help to refactor a lot of code. This will be very
helpful in porting "git bisect" to C.

Suggested-by: Torsten Bögershausen <tboegi@web.de>
Mentored-by: Lars Schneider <larsxschneider@gmail.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-02 10:23:02 -08:00
Johannes Schindelin 033abf97fc Replace all die("BUG: ...") calls by BUG() ones
In d8193743e0 (usage.c: add BUG() function, 2017-05-12), a new macro
was introduced to use for reporting bugs instead of die(). It was then
subsequently used to convert one single caller in 588a538ae5
(setup_git_env: convert die("BUG") to BUG(), 2017-05-12).

The cover letter of the patch series containing this patch
(cf 20170513032414.mfrwabt4hovujde2@sigill.intra.peff.net) is not
terribly clear why only one call site was converted, or what the plan
is for other, similar calls to die() to report bugs.

Let's just convert all remaining ones in one fell swoop.

This trick was performed by this invocation:

	sed -i 's/die("BUG: /BUG("/g' $(git grep -l 'die("BUG' \*.c)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-06 19:06:13 +09:00
Brandon Williams eb78e23f22 wrapper: rename 'template' variables
Rename C++ keyword in order to bring the codebase closer to being able
to be compiled with a C++ compiler.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-02-22 10:08:05 -08:00
Simon Ruderich 0a288d1ee9 wrapper.c: consistently quote filenames in error messages
All other error messages in the file use quotes around the file name.

This change removes two translations as "could not write to '%s'" and
"could not close '%s'" are already translated and these two are the only
occurrences without quotes.

Signed-off-by: Simon Ruderich <simon@ruderich.org>
[jc: adjusted tests I noticed were broken by the change]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 11:53:14 +09:00
Jeff King 06f46f237a avoid "write_in_full(fd, buf, len) != len" pattern
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).

So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:

  1. It can do a funny signed/unsigned comparison. If your
     "len" is signed (e.g., a size_t) then the compiler will
     promote the "-1" to its unsigned variant.

     This works out for "!= len" (unless you really were
     trying to write the maximum size_t bytes), but is a
     bug if you check "< len" (an example of which was fixed
     recently in config.c).

     We should avoid promoting the mental model that you
     need to check the length at all, so that new sites are
     not tempted to copy us.

  2. Checking for a negative value is shorter to type,
     especially when the length is an expression.

  3. Linus says so. In d34cf19b89 (Clean up write_in_full()
     users, 2007-01-11), right after the write_in_full()
     semantics were changed, he wrote:

       I really wish every "write_in_full()" user would just
       check against "<0" now, but this fixes the nasty and
       stupid ones.

     Appeals to authority aside, this makes it clear that
     writing it this way does not have an intentional
     benefit. It's a historical curiosity that we never
     bothered to clean up (and which was undoubtedly
     cargo-culted into new sites).

So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).

[1] A careful reader may notice there is one way that
    write_in_full() can return a different value. If we ask
    write() to write N bytes and get a return value that is
    _larger_ than N, we could return a larger total. But
    besides the fact that this would imply a totally broken
    version of write(), it would already invoke undefined
    behavior. Our internal remaining counter is an unsigned
    size_t, which means that subtracting too many byte will
    wrap it around to a very large number. So we'll instantly
    begin reading off the end of the buffer, trying to write
    gigabytes (or petabytes) of data.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Junio C Hamano f31d23a399 Merge branch 'bw/config-h'
Fix configuration codepath to pay proper attention to commondir
that is used in multi-worktree situation, and isolate config API
into its own header file.

* bw/config-h:
  config: don't implicitly use gitdir or commondir
  config: respect commondir
  setup: teach discover_git_directory to respect the commondir
  config: don't include config.h by default
  config: remove git_config_iter
  config: create config.h
2017-06-24 14:28:41 -07:00
Brandon Williams b2141fc1d2 config: don't include config.h by default
Stop including config.h by default in cache.h.  Instead only include
config.h in those files which require use of the config system.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-15 12:56:22 -07:00
Junio C Hamano b9a7d55d93 Merge branch 'nd/fopen-errors'
We often try to open a file for reading whose existence is
optional, and silently ignore errors from open/fopen; report such
errors if they are not due to missing files.

* nd/fopen-errors:
  mingw_fopen: report ENOENT for invalid file names
  mingw: verify that paths are not mistaken for remote nicknames
  log: fix memory leak in open_next_file()
  rerere.c: move error_errno() closer to the source system call
  print errno when reporting a system call error
  wrapper.c: make warn_on_inaccessible() static
  wrapper.c: add and use fopen_or_warn()
  wrapper.c: add and use warn_on_fopen_errors()
  config.mak.uname: set FREAD_READS_DIRECTORIES for Darwin, too
  config.mak.uname: set FREAD_READS_DIRECTORIES for Linux and FreeBSD
  clone: use xfopen() instead of fopen()
  use xfopen() in more places
  git_fopen: fix a sparse 'not declared' warning
2017-06-13 13:47:09 -07:00
Junio C Hamano 93dd544f54 Merge branch 'jc/noent-notdir'
Our code often opens a path to an optional file, to work on its
contents when we can successfully open it.  We can ignore a failure
to open if such an optional file does not exist, but we do want to
report a failure in opening for other reasons (e.g. we got an I/O
error, or the file is there, but we lack the permission to open).

The exact errors we need to ignore are ENOENT (obviously) and
ENOTDIR (less obvious).  Instead of repeating comparison of errno
with these two constants, introduce a helper function to do so.

* jc/noent-notdir:
  treewide: use is_missing_file_error() where ENOENT and ENOTDIR are checked
  compat-util: is_missing_file_error()
2017-06-13 13:47:07 -07:00
Junio C Hamano c7054209d6 treewide: use is_missing_file_error() where ENOENT and ENOTDIR are checked
Using the is_missing_file_error() helper introduced in the previous
step, update all hits from

  $ git grep -e ENOENT --and -e ENOTDIR

There are codepaths that only check ENOENT, and it is possible that
some of them should be checking both.  Updating them is kept out of
this step deliberately, as we do not want to change behaviour in this
step.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-30 09:29:00 +09:00
Nguyễn Thái Ngọc Duy 382fb07f7b wrapper.c: make warn_on_inaccessible() static
After the last patch, this function is not used outside anymore. Keep it
static.

Noticed-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-26 12:33:56 +09:00
Nguyễn Thái Ngọc Duy e9d983f116 wrapper.c: add and use fopen_or_warn()
When fopen() returns NULL, it could be because the given path does not
exist, but it could also be some other errors and the caller has to
check. Add a wrapper so we don't have to repeat the same error check
everywhere.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-26 12:33:56 +09:00
Nguyễn Thái Ngọc Duy 11dc1fcb3f wrapper.c: add and use warn_on_fopen_errors()
In many places, Git warns about an inaccessible file after a fopen()
failed. To discern these cases from other cases where we want to warn
about inaccessible files, introduce a new helper specifically to test
whether fopen() failed because the current user lacks the permission to
open file in question.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-26 12:33:55 +09:00
Junio C Hamano 5938454cbc Merge branch 'dt/xgethostname-nul-termination'
gethostname(2) may not NUL terminate the buffer if hostname does
not fit; unfortunately there is no easy way to see if our buffer
was too small, but at least this will make sure we will not end up
using garbage past the end of the buffer.

* dt/xgethostname-nul-termination:
  xgethostname: handle long hostnames
  use HOST_NAME_MAX to size buffers for gethostname(2)
2017-04-23 22:07:57 -07:00
David Turner 5781a9a270 xgethostname: handle long hostnames
If the full hostname doesn't fit in the buffer supplied to
gethostname, POSIX does not specify whether the buffer will be
null-terminated, so to be safe, we should do it ourselves.  Introduce
new function, xgethostname, which ensures that there is always a \0
at the end of the buffer.

Signed-off-by: David Turner <dturner@twosigma.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-18 19:58:04 -07:00
Ramsay Jones b2d593a779 wrapper.c: remove unused gitmkstemps() function
The last call to the mkstemps() function was removed in commit 659488326
("wrapper.c: delete dead function git_mkstemps()", 22-04-2016). In order
to support platforms without mkstemps(), this functionality was provided,
along with a Makefile build variable (NO_MKSTEMPS), by the gitmkstemps()
function. Remove the dead code, along with the defunct build machinery.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-28 11:54:21 -08:00
Ramsay Jones 34de5e4bb0 wrapper.c: remove unused git_mkstemp() function
The last caller of git_mkstemp() was removed in commit 6fec0a89
("verify_signed_buffer: use tempfile object", 16-06-2016). Since
the introduction of the 'tempfile' APIs, along with git_mkstemp_mode,
it is unlikely that new callers will materialize. Remove the dead
code.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-28 11:54:14 -08:00
Junio C Hamano 2b6456b808 Merge branch 'jk/write-file'
General code clean-up around a helper function to write a
single-liner to a file.

* jk/write-file:
  branch: use write_file_buf instead of write_file
  use write_file_buf where applicable
  write_file: add format attribute
  write_file: add pointer+len variant
  write_file: use xopen
  write_file: drop "gently" form
  branch: use non-gentle write_file for branch description
  am: ignore return value of write_file()
  config: fix bogus fd check when setting up default config
2016-07-19 13:22:23 -07:00
Junio C Hamano 7725bebe21 Merge branch 'sb/submodule-parallel-fetch'
Fix recently introduced codepaths that are involved in parallel
submodule operations, which gave up on reading too early, and
could have wasted CPU while attempting to write under a corner
case condition.

* sb/submodule-parallel-fetch:
  hoist out handle_nonblock function for xread and xwrite
  xwrite: poll on non-blocking FDs
  xread: retry after poll on EAGAIN/EWOULDBLOCK
2016-07-19 13:22:15 -07:00
Eric Wong d751dd11ae hoist out handle_nonblock function for xread and xwrite
At least for me, this improves the readability of xread and
xwrite; hopefully allowing missing "continue" statements to
be spotted more easily.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-11 09:51:45 -07:00
Jeff King 52563d7ecc write_file: add pointer+len variant
There are many callsites which could use write_file, but for
which it is a little awkward because they have a strbuf or
other pointer/len combo. Specifically:

 1. write_file() takes a format string, so we have to use
    "%s" or "%.*s", which are ugly.

 2. Using any form of "%s" does not handle embedded NULs in
    the output. That probably doesn't matter for our
    call-sites, but it's nicer not to have to worry.

 3. It's less efficient; we format into another strbuf
    just to do the write. That's probably not measurably
    slow for our uses, but it's simply inelegant.

We can fix this by providing a helper to write out the
formatted buffer, and just calling it from write_file().

Note that we don't do the usual "complete with a newline"
that write_file does. If the caller has their own buffer,
there's a reasonable chance they're doing something more
complicated than a single line, and they can call
strbuf_complete_line() themselves.

We could go even further and add strbuf_write_file(), but it
doesn't save much:

  -  write_file_buf(path, sb.buf, sb.len);
  +  strbuf_write_file(&sb, path);

It would also be somewhat asymmetric with strbuf_read_file,
which actually returns errors rather than dying (and the
error handling is most of the benefit of write_file() in the
first place).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-08 09:47:29 -07:00
Jeff King ee861e0f78 write_file: use xopen
This simplifies the code a tiny bit, and provides consistent
error messages with other users of xopen().

While we're here, let's also switch to using O_WRONLY. We
know we're only going to open/write/close the file, so
there's no point in asking for O_RDWR.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-08 09:47:29 -07:00
Jeff King ef22318cff write_file: drop "gently" form
There are no callers left of write_file_gently(). Let's drop
it, as it doesn't seem likely for new callers to be added
(since its inception, the only callers who wanted the gentle
form generally just died immediately themselves, and have
since been converted).

While we're there, let's also drop the "int" return from
write_file, as it is never meaningful (in the non-gentle
form, we always either die or return 0).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-08 09:47:29 -07:00
Eric Wong ef1cf0167a xwrite: poll on non-blocking FDs
write(2) can hit the same EAGAIN/EWOULDBLOCK errors as read(2),
so busy-looping on a non-blocking FD is a waste of resources.

Currently, I do not know of a way for this happen:

* the NonBlocking directive in systemd does not apply to stdin,
  stdout, or stderr.

* xinetd provides no way to set the non-blocking flag at all

But theoretically, it's possible a careless C10K HTTP server
could use pipe2(..., O_NONBLOCK) to setup a pipe for
git-http-backend with only the intent to use non-blocking reads;
but accidentally leave non-blocking set on the write end passed
as stdout to git-upload-pack.

Followup-to: 1079c4be0b ("xread: poll on non blocking fds")

Signed-off-by: Eric Wong <e@80x24.org>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-27 08:34:15 -07:00
Eric Wong c22f620205 xread: retry after poll on EAGAIN/EWOULDBLOCK
We should continue to loop after EAGAIN/EWOULDBLOCK as the
intent of xread is to try until there is available data,
EOF, or an unrecoverable error.

Fixes: 1079c4be0b ("xread: poll on non blocking fds")

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-27 08:33:21 -07:00
Junio C Hamano 40cfc95856 Merge branch 'nd/error-errno'
The code for warning_errno/die_errno has been refactored and a new
error_errno() reporting helper is introduced.

* nd/error-errno: (41 commits)
  wrapper.c: use warning_errno()
  vcs-svn: use error_errno()
  upload-pack.c: use error_errno()
  unpack-trees.c: use error_errno()
  transport-helper.c: use error_errno()
  sha1_file.c: use {error,die,warning}_errno()
  server-info.c: use error_errno()
  sequencer.c: use error_errno()
  run-command.c: use error_errno()
  rerere.c: use error_errno() and warning_errno()
  reachable.c: use error_errno()
  mailmap.c: use error_errno()
  ident.c: use warning_errno()
  http.c: use error_errno() and warning_errno()
  grep.c: use error_errno()
  gpg-interface.c: use error_errno()
  fast-import.c: use error_errno()
  entry.c: use error_errno()
  editor.c: use error_errno()
  diff-no-index.c: use error_errno()
  ...
2016-05-17 14:38:28 -07:00
Nguyễn Thái Ngọc Duy 1da045fb9d wrapper.c: use warning_errno()
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-09 12:29:08 -07:00
Nguyễn Thái Ngọc Duy 659488326c wrapper.c: delete dead function git_mkstemps()
Its last call site was replaced by mks_tempfile_ts() in 284098f (diff:
use tempfile module - 2015-08-12) and there's a good chance
mks_tempfile_ts will continue to successfully handle this job. Delete
it.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-22 14:07:55 -07:00
Junio C Hamano 11529ecec9 Merge branch 'jk/tighten-alloc'
Update various codepaths to avoid manually-counted malloc().

* jk/tighten-alloc: (22 commits)
  ewah: convert to REALLOC_ARRAY, etc
  convert ewah/bitmap code to use xmalloc
  diff_populate_gitlink: use a strbuf
  transport_anonymize_url: use xstrfmt
  git-compat-util: drop mempcpy compat code
  sequencer: simplify memory allocation of get_message
  test-path-utils: fix normalize_path_copy output buffer size
  fetch-pack: simplify add_sought_entry
  fast-import: simplify allocation in start_packfile
  write_untracked_extension: use FLEX_ALLOC helper
  prepare_{git,shell}_cmd: use argv_array
  use st_add and st_mult for allocation size computation
  convert trivial cases to FLEX_ARRAY macros
  use xmallocz to avoid size arithmetic
  convert trivial cases to ALLOC_ARRAY
  convert manual allocations to argv_array
  argv-array: add detach function
  add helpers for allocating flex-array structs
  harden REALLOC_ARRAY and xcalloc against size_t overflow
  tree-diff: catch integer overflow in combine_diff_path allocation
  ...
2016-02-26 13:37:16 -08:00
Jeff King e7792a74bc harden REALLOC_ARRAY and xcalloc against size_t overflow
REALLOC_ARRAY inherently involves a multiplication which can
overflow size_t, resulting in a much smaller buffer than we
think we've allocated. We can easily harden it by using
st_mult() to check for overflow.  Likewise, we can add
ALLOC_ARRAY to do the same thing for xmalloc calls.

xcalloc() should already be fine, because it takes the two
factors separately, assuming the system calloc actually
checks for overflow. However, before we even hit the system
calloc(), we do our memory_limit_check, which involves a
multiplication. Let's check for overflow ourselves so that
this limit cannot be bypassed.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-02-22 14:50:32 -08:00
Junio C Hamano da07df3ee3 Merge branch 'js/fopen-harder' into maint
Some codepaths used fopen(3) when opening a fixed path in $GIT_DIR
(e.g. COMMIT_EDITMSG) that is meant to be left after the command is
done.  This however did not work well if the repository is set to
be shared with core.sharedRepository and the umask of the previous
user is tighter.  They have been made to work better by calling
unlink(2) and retrying after fopen(3) fails with EPERM.

* js/fopen-harder:
  Handle more file writes correctly in shared repos
  commit: allow editing the commit message even in shared repos
2016-02-05 14:54:11 -08:00
Junio C Hamano 7a63c9e3da Merge branch 'js/fopen-harder'
Some codepaths used fopen(3) when opening a fixed path in $GIT_DIR
(e.g. COMMIT_EDITMSG) that is meant to be left after the command is
done.  This however did not work well if the repository is set to
be shared with core.sharedRepository and the umask of the previous
user is tighter.  They have been made to work better by calling
unlink(2) and retrying after fopen(3) fails with EPERM.

* js/fopen-harder:
  Handle more file writes correctly in shared repos
  commit: allow editing the commit message even in shared repos
2016-01-20 11:43:35 -08:00
Junio C Hamano 187c0d3d9e Merge branch 'sb/submodule-parallel-fetch'
Add a framework to spawn a group of processes in parallel, and use
it to run "git fetch --recurse-submodules" in parallel.

Rerolled and this seems to be a lot cleaner.  The merge of the
earlier one to 'next' has been reverted.

* sb/submodule-parallel-fetch:
  submodules: allow parallel fetching, add tests and documentation
  fetch_populated_submodules: use new parallel job processing
  run-command: add an asynchronous parallel child processor
  sigchain: add command to pop all common signals
  strbuf: add strbuf_read_once to read without blocking
  xread: poll on non blocking fds
  submodule.c: write "Fetching submodule <foo>" to stderr
2016-01-12 15:16:54 -08:00
Johannes Schindelin 79d7582e32 commit: allow editing the commit message even in shared repos
It was pointed out by Yaroslav Halchenko that the file containing the
commit message is writable only by the owner, which means that we have
to rewrite it from scratch in a shared repository.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-01-07 13:52:55 -08:00
Junio C Hamano 5498c57cdd Merge branch 'jk/ident-loosen-getpwuid'
When getpwuid() on the system returned NULL (e.g. the user is not
in the /etc/passwd file or other uid-to-name mappings), the
codepath to find who the user is to record it in the reflog barfed
and died.  Loosen the check in this codepath, which already accepts
questionable ident string (e.g. host part of the e-mail address is
obviously bogus), and in general when we operate fmt_ident() function
in non-strict mode.

* jk/ident-loosen-getpwuid:
  ident: loosen getpwuid error in non-strict mode
  ident: keep a flag for bogus default_email
  ident: make xgetpwuid_self() a static local helper
2015-12-21 10:59:07 -08:00
Stefan Beller 1079c4be0b xread: poll on non blocking fds
The man page of read(2) says:

  EAGAIN The file descriptor fd refers to a file other than a socket
	 and has been marked nonblocking (O_NONBLOCK), and the read
	 would block.

  EAGAIN or EWOULDBLOCK
	 The file descriptor fd refers to a socket and has been marked
	 nonblocking (O_NONBLOCK), and the read would block.  POSIX.1-2001
	 allows either error to be returned for this case, and does not
	 require these constants to have the same value, so a portable
	 application should check for both possibilities.

If we get an EAGAIN or EWOULDBLOCK the fd must have set O_NONBLOCK.
As the intent of xread is to read as much as possible either until the
fd is EOF or an actual error occurs, we can ease the feeder of the fd
by not spinning the whole time, but rather wait for it politely by not
busy waiting.

We should not care if the call to poll failed, as we're in an infinite
loop and can only get out with the correct read().

Signed-off-by: Stefan Beller <sbeller@google.com>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-12-16 12:06:08 -08:00
Jeff King e850194c83 ident: make xgetpwuid_self() a static local helper
This function is defined in wrapper.c, but nobody besides
ident.c uses it. And nobody is likely to in the future,
either, as anything that cares about the user's name should
be going through the ident code.

Moving it here is a cleanup of the global namespace, but it
will also enable further cleanups inside ident.c.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-12-10 15:38:59 -08:00
Jeff King 7b03c89ebd add xsnprintf helper function
There are a number of places in the code where we call
sprintf(), with the assumption that the output will fit into
the buffer. In many cases this is true (e.g., formatting a
number into a large buffer), but it is hard to tell
immediately from looking at the code. It would be nice if we
had some run-time check to make sure that our assumption is
correct (and to communicate to readers of the code that we
are not blindly calling sprintf, but have actually thought
about this case).

This patch introduces xsnprintf, which behaves just like
snprintf, except that it dies whenever the output is
truncated. This acts as a sort of assert() for these cases,
which can help find places where the assumption is violated
(as opposed to truncating and proceeding, which may just
silently give a wrong answer).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-25 10:18:18 -07:00
Junio C Hamano e7ffa38c6e write_file_v(): do not leave incomplete line at the end
All existing callers to this function use it to produce a text file
or an empty file, and a new callsite that mimick them must end their
payload with a LF.  If they forget to do so, the resulting file will
end with an incomplete line.

Teach write_file_v() to complete the incomplete line, if exists, so
that the callers do not have to.

With this, the caller-side fix in builtin/am.c becomes unnecessary.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-25 12:48:39 -07:00
Junio C Hamano 12d6ce1dba write_file(): drop "fatal" parameter
All callers except three passed 1 for the "fatal" parameter to ask
this function to die upon error, but to a casual reader of the code,
it was not all obvious what that 1 meant.  Instead, split the
function into two based on a common write_file_v() that takes the
flag, introduce write_file_gently() as a new way to attempt creating
a file without dying on error, and make three callers to call it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-24 13:09:02 -07:00