git/merge-ort.c

1574 строки
51 KiB
C

/*
* "Ostensibly Recursive's Twin" merge strategy, or "ort" for short. Meant
* as a drop-in replacement for the "recursive" merge strategy, allowing one
* to replace
*
* git merge [-s recursive]
*
* with
*
* git merge -s ort
*
* Note: git's parser allows the space between '-s' and its argument to be
* missing. (Should I have backronymed "ham", "alsa", "kip", "nap, "alvo",
* "cale", "peedy", or "ins" instead of "ort"?)
*/
#include "cache.h"
#include "merge-ort.h"
#include "alloc.h"
#include "blob.h"
#include "cache-tree.h"
#include "commit.h"
#include "commit-reach.h"
#include "diff.h"
#include "diffcore.h"
#include "dir.h"
#include "object-store.h"
#include "strmap.h"
#include "tree.h"
#include "unpack-trees.h"
#include "xdiff-interface.h"
/*
* We have many arrays of size 3. Whenever we have such an array, the
* indices refer to one of the sides of the three-way merge. This is so
* pervasive that the constants 0, 1, and 2 are used in many places in the
* code (especially in arithmetic operations to find the other side's index
* or to compute a relevant mask), but sometimes these enum names are used
* to aid code clarity.
*
* See also 'filemask' and 'dirmask' in struct conflict_info; the "ith side"
* referred to there is one of these three sides.
*/
enum merge_side {
MERGE_BASE = 0,
MERGE_SIDE1 = 1,
MERGE_SIDE2 = 2
};
struct merge_options_internal {
/*
* paths: primary data structure in all of merge ort.
*
* The keys of paths:
* * are full relative paths from the toplevel of the repository
* (e.g. "drivers/firmware/raspberrypi.c").
* * store all relevant paths in the repo, both directories and
* files (e.g. drivers, drivers/firmware would also be included)
* * these keys serve to intern all the path strings, which allows
* us to do pointer comparison on directory names instead of
* strcmp; we just have to be careful to use the interned strings.
* (Technically paths_to_free may track some strings that were
* removed from froms paths.)
*
* The values of paths:
* * either a pointer to a merged_info, or a conflict_info struct
* * merged_info contains all relevant information for a
* non-conflicted entry.
* * conflict_info contains a merged_info, plus any additional
* information about a conflict such as the higher orders stages
* involved and the names of the paths those came from (handy
* once renames get involved).
* * a path may start "conflicted" (i.e. point to a conflict_info)
* and then a later step (e.g. three-way content merge) determines
* it can be cleanly merged, at which point it'll be marked clean
* and the algorithm will ignore any data outside the contained
* merged_info for that entry
* * If an entry remains conflicted, the merged_info portion of a
* conflict_info will later be filled with whatever version of
* the file should be placed in the working directory (e.g. an
* as-merged-as-possible variation that contains conflict markers).
*/
struct strmap paths;
/*
* conflicted: a subset of keys->values from "paths"
*
* conflicted is basically an optimization between process_entries()
* and record_conflicted_index_entries(); the latter could loop over
* ALL the entries in paths AGAIN and look for the ones that are
* still conflicted, but since process_entries() has to loop over
* all of them, it saves the ones it couldn't resolve in this strmap
* so that record_conflicted_index_entries() can iterate just the
* relevant entries.
*/
struct strmap conflicted;
/*
* paths_to_free: additional list of strings to free
*
* If keys are removed from "paths", they are added to paths_to_free
* to ensure they are later freed. We avoid free'ing immediately since
* other places (e.g. conflict_info.pathnames[]) may still be
* referencing these paths.
*/
struct string_list paths_to_free;
/*
* output: special messages and conflict notices for various paths
*
* This is a map of pathnames (a subset of the keys in "paths" above)
* to strbufs. It gathers various warning/conflict/notice messages
* for later processing.
*/
struct strmap output;
/*
* current_dir_name: temporary var used in collect_merge_info_callback()
*
* Used to set merged_info.directory_name; see documentation for that
* variable and the requirements placed on that field.
*/
const char *current_dir_name;
/* call_depth: recursion level counter for merging merge bases */
int call_depth;
};
struct version_info {
struct object_id oid;
unsigned short mode;
};
struct merged_info {
/* if is_null, ignore result. otherwise result has oid & mode */
struct version_info result;
unsigned is_null:1;
/*
* clean: whether the path in question is cleanly merged.
*
* see conflict_info.merged for more details.
*/
unsigned clean:1;
/*
* basename_offset: offset of basename of path.
*
* perf optimization to avoid recomputing offset of final '/'
* character in pathname (0 if no '/' in pathname).
*/
size_t basename_offset;
/*
* directory_name: containing directory name.
*
* Note that we assume directory_name is constructed such that
* strcmp(dir1_name, dir2_name) == 0 iff dir1_name == dir2_name,
* i.e. string equality is equivalent to pointer equality. For this
* to hold, we have to be careful setting directory_name.
*/
const char *directory_name;
};
struct conflict_info {
/*
* merged: the version of the path that will be written to working tree
*
* WARNING: It is critical to check merged.clean and ensure it is 0
* before reading any conflict_info fields outside of merged.
* Allocated merge_info structs will always have clean set to 1.
* Allocated conflict_info structs will have merged.clean set to 0
* initially. The merged.clean field is how we know if it is safe
* to access other parts of conflict_info besides merged; if a
* conflict_info's merged.clean is changed to 1, the rest of the
* algorithm is not allowed to look at anything outside of the
* merged member anymore.
*/
struct merged_info merged;
/* oids & modes from each of the three trees for this path */
struct version_info stages[3];
/* pathnames for each stage; may differ due to rename detection */
const char *pathnames[3];
/* Whether this path is/was involved in a directory/file conflict */
unsigned df_conflict:1;
/*
* Whether this path is/was involved in a non-content conflict other
* than a directory/file conflict (e.g. rename/rename, rename/delete,
* file location based on possible directory rename).
*/
unsigned path_conflict:1;
/*
* For filemask and dirmask, the ith bit corresponds to whether the
* ith entry is a file (filemask) or a directory (dirmask). Thus,
* filemask & dirmask is always zero, and filemask | dirmask is at
* most 7 but can be less when a path does not appear as either a
* file or a directory on at least one side of history.
*
* Note that these masks are related to enum merge_side, as the ith
* entry corresponds to side i.
*
* These values come from a traverse_trees() call; more info may be
* found looking at tree-walk.h's struct traverse_info,
* particularly the documentation above the "fn" member (note that
* filemask = mask & ~dirmask from that documentation).
*/
unsigned filemask:3;
unsigned dirmask:3;
/*
* Optimization to track which stages match, to avoid the need to
* recompute it in multiple steps. Either 0 or at least 2 bits are
* set; if at least 2 bits are set, their corresponding stages match.
*/
unsigned match_mask:3;
};
/*** Function Grouping: various utility functions ***/
/*
* For the next three macros, see warning for conflict_info.merged.
*
* In each of the below, mi is a struct merged_info*, and ci was defined
* as a struct conflict_info* (but we need to verify ci isn't actually
* pointed at a struct merged_info*).
*
* INITIALIZE_CI: Assign ci to mi but only if it's safe; set to NULL otherwise.
* VERIFY_CI: Ensure that something we assigned to a conflict_info* is one.
* ASSIGN_AND_VERIFY_CI: Similar to VERIFY_CI but do assignment first.
*/
#define INITIALIZE_CI(ci, mi) do { \
(ci) = (!(mi) || (mi)->clean) ? NULL : (struct conflict_info *)(mi); \
} while (0)
#define VERIFY_CI(ci) assert(ci && !ci->merged.clean);
#define ASSIGN_AND_VERIFY_CI(ci, mi) do { \
(ci) = (struct conflict_info *)(mi); \
assert((ci) && !(mi)->clean); \
} while (0)
static void free_strmap_strings(struct strmap *map)
{
struct hashmap_iter iter;
struct strmap_entry *entry;
strmap_for_each_entry(map, &iter, entry) {
free((char*)entry->key);
}
}
static void clear_or_reinit_internal_opts(struct merge_options_internal *opti,
int reinitialize)
{
void (*strmap_func)(struct strmap *, int) =
reinitialize ? strmap_partial_clear : strmap_clear;
/*
* We marked opti->paths with strdup_strings = 0, so that we
* wouldn't have to make another copy of the fullpath created by
* make_traverse_path from setup_path_info(). But, now that we've
* used it and have no other references to these strings, it is time
* to deallocate them.
*/
free_strmap_strings(&opti->paths);
strmap_func(&opti->paths, 1);
/*
* All keys and values in opti->conflicted are a subset of those in
* opti->paths. We don't want to deallocate anything twice, so we
* don't free the keys and we pass 0 for free_values.
*/
strmap_func(&opti->conflicted, 0);
/*
* opti->paths_to_free is similar to opti->paths; we created it with
* strdup_strings = 0 to avoid making _another_ copy of the fullpath
* but now that we've used it and have no other references to these
* strings, it is time to deallocate them. We do so by temporarily
* setting strdup_strings to 1.
*/
opti->paths_to_free.strdup_strings = 1;
string_list_clear(&opti->paths_to_free, 0);
opti->paths_to_free.strdup_strings = 0;
if (!reinitialize) {
struct hashmap_iter iter;
struct strmap_entry *e;
/* Release and free each strbuf found in output */
strmap_for_each_entry(&opti->output, &iter, e) {
struct strbuf *sb = e->value;
strbuf_release(sb);
/*
* While strictly speaking we don't need to free(sb)
* here because we could pass free_values=1 when
* calling strmap_clear() on opti->output, that would
* require strmap_clear to do another
* strmap_for_each_entry() loop, so we just free it
* while we're iterating anyway.
*/
free(sb);
}
strmap_clear(&opti->output, 0);
}
}
static int err(struct merge_options *opt, const char *err, ...)
{
va_list params;
struct strbuf sb = STRBUF_INIT;
strbuf_addstr(&sb, "error: ");
va_start(params, err);
strbuf_vaddf(&sb, err, params);
va_end(params);
error("%s", sb.buf);
strbuf_release(&sb);
return -1;
}
__attribute__((format (printf, 4, 5)))
static void path_msg(struct merge_options *opt,
const char *path,
int omittable_hint, /* skippable under --remerge-diff */
const char *fmt, ...)
{
va_list ap;
struct strbuf *sb = strmap_get(&opt->priv->output, path);
if (!sb) {
sb = xmalloc(sizeof(*sb));
strbuf_init(sb, 0);
strmap_put(&opt->priv->output, path, sb);
}
va_start(ap, fmt);
strbuf_vaddf(sb, fmt, ap);
va_end(ap);
strbuf_addch(sb, '\n');
}
/*** Function Grouping: functions related to collect_merge_info() ***/
static void setup_path_info(struct merge_options *opt,
struct string_list_item *result,
const char *current_dir_name,
int current_dir_name_len,
char *fullpath, /* we'll take over ownership */
struct name_entry *names,
struct name_entry *merged_version,
unsigned is_null, /* boolean */
unsigned df_conflict, /* boolean */
unsigned filemask,
unsigned dirmask,
int resolved /* boolean */)
{
/* result->util is void*, so mi is a convenience typed variable */
struct merged_info *mi;
assert(!is_null || resolved);
assert(!df_conflict || !resolved); /* df_conflict implies !resolved */
assert(resolved == (merged_version != NULL));
mi = xcalloc(1, resolved ? sizeof(struct merged_info) :
sizeof(struct conflict_info));
mi->directory_name = current_dir_name;
mi->basename_offset = current_dir_name_len;
mi->clean = !!resolved;
if (resolved) {
mi->result.mode = merged_version->mode;
oidcpy(&mi->result.oid, &merged_version->oid);
mi->is_null = !!is_null;
} else {
int i;
struct conflict_info *ci;
ASSIGN_AND_VERIFY_CI(ci, mi);
for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
ci->pathnames[i] = fullpath;
ci->stages[i].mode = names[i].mode;
oidcpy(&ci->stages[i].oid, &names[i].oid);
}
ci->filemask = filemask;
ci->dirmask = dirmask;
ci->df_conflict = !!df_conflict;
if (dirmask)
/*
* Assume is_null for now, but if we have entries
* under the directory then when it is complete in
* write_completed_directory() it'll update this.
* Also, for D/F conflicts, we have to handle the
* directory first, then clear this bit and process
* the file to see how it is handled -- that occurs
* near the top of process_entry().
*/
mi->is_null = 1;
}
strmap_put(&opt->priv->paths, fullpath, mi);
result->string = fullpath;
result->util = mi;
}
static int collect_merge_info_callback(int n,
unsigned long mask,
unsigned long dirmask,
struct name_entry *names,
struct traverse_info *info)
{
/*
* n is 3. Always.
* common ancestor (mbase) has mask 1, and stored in index 0 of names
* head of side 1 (side1) has mask 2, and stored in index 1 of names
* head of side 2 (side2) has mask 4, and stored in index 2 of names
*/
struct merge_options *opt = info->data;
struct merge_options_internal *opti = opt->priv;
struct string_list_item pi; /* Path Info */
struct conflict_info *ci; /* typed alias to pi.util (which is void*) */
struct name_entry *p;
size_t len;
char *fullpath;
const char *dirname = opti->current_dir_name;
unsigned filemask = mask & ~dirmask;
unsigned match_mask = 0; /* will be updated below */
unsigned mbase_null = !(mask & 1);
unsigned side1_null = !(mask & 2);
unsigned side2_null = !(mask & 4);
unsigned side1_matches_mbase = (!side1_null && !mbase_null &&
names[0].mode == names[1].mode &&
oideq(&names[0].oid, &names[1].oid));
unsigned side2_matches_mbase = (!side2_null && !mbase_null &&
names[0].mode == names[2].mode &&
oideq(&names[0].oid, &names[2].oid));
unsigned sides_match = (!side1_null && !side2_null &&
names[1].mode == names[2].mode &&
oideq(&names[1].oid, &names[2].oid));
/*
* Note: When a path is a file on one side of history and a directory
* in another, we have a directory/file conflict. In such cases, if
* the conflict doesn't resolve from renames and deletions, then we
* always leave directories where they are and move files out of the
* way. Thus, while struct conflict_info has a df_conflict field to
* track such conflicts, we ignore that field for any directories at
* a path and only pay attention to it for files at the given path.
* The fact that we leave directories were they are also means that
* we do not need to worry about getting additional df_conflict
* information propagated from parent directories down to children
* (unlike, say traverse_trees_recursive() in unpack-trees.c, which
* sets a newinfo.df_conflicts field specifically to propagate it).
*/
unsigned df_conflict = (filemask != 0) && (dirmask != 0);
/* n = 3 is a fundamental assumption. */
if (n != 3)
BUG("Called collect_merge_info_callback wrong");
/*
* A bunch of sanity checks verifying that traverse_trees() calls
* us the way I expect. Could just remove these at some point,
* though maybe they are helpful to future code readers.
*/
assert(mbase_null == is_null_oid(&names[0].oid));
assert(side1_null == is_null_oid(&names[1].oid));
assert(side2_null == is_null_oid(&names[2].oid));
assert(!mbase_null || !side1_null || !side2_null);
assert(mask > 0 && mask < 8);
/* Determine match_mask */
if (side1_matches_mbase)
match_mask = (side2_matches_mbase ? 7 : 3);
else if (side2_matches_mbase)
match_mask = 5;
else if (sides_match)
match_mask = 6;
/*
* Get the name of the relevant filepath, which we'll pass to
* setup_path_info() for tracking.
*/
p = names;
while (!p->mode)
p++;
len = traverse_path_len(info, p->pathlen);
/* +1 in both of the following lines to include the NUL byte */
fullpath = xmalloc(len + 1);
make_traverse_path(fullpath, len + 1, info, p->path, p->pathlen);
/*
* If mbase, side1, and side2 all match, we can resolve early. Even
* if these are trees, there will be no renames or anything
* underneath.
*/
if (side1_matches_mbase && side2_matches_mbase) {
/* mbase, side1, & side2 all match; use mbase as resolution */
setup_path_info(opt, &pi, dirname, info->pathlen, fullpath,
names, names+0, mbase_null, 0,
filemask, dirmask, 1);
return mask;
}
/*
* Record information about the path so we can resolve later in
* process_entries.
*/
setup_path_info(opt, &pi, dirname, info->pathlen, fullpath,
names, NULL, 0, df_conflict, filemask, dirmask, 0);
ci = pi.util;
VERIFY_CI(ci);
ci->match_mask = match_mask;
/* If dirmask, recurse into subdirectories */
if (dirmask) {
struct traverse_info newinfo;
struct tree_desc t[3];
void *buf[3] = {NULL, NULL, NULL};
const char *original_dir_name;
int i, ret;
ci->match_mask &= filemask;
newinfo = *info;
newinfo.prev = info;
newinfo.name = p->path;
newinfo.namelen = p->pathlen;
newinfo.pathlen = st_add3(newinfo.pathlen, p->pathlen, 1);
/*
* If this directory we are about to recurse into cared about
* its parent directory (the current directory) having a D/F
* conflict, then we'd propagate the masks in this way:
* newinfo.df_conflicts |= (mask & ~dirmask);
* But we don't worry about propagating D/F conflicts. (See
* comment near setting of local df_conflict variable near
* the beginning of this function).
*/
for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
if (i == 1 && side1_matches_mbase)
t[1] = t[0];
else if (i == 2 && side2_matches_mbase)
t[2] = t[0];
else if (i == 2 && sides_match)
t[2] = t[1];
else {
const struct object_id *oid = NULL;
if (dirmask & 1)
oid = &names[i].oid;
buf[i] = fill_tree_descriptor(opt->repo,
t + i, oid);
}
dirmask >>= 1;
}
original_dir_name = opti->current_dir_name;
opti->current_dir_name = pi.string;
ret = traverse_trees(NULL, 3, t, &newinfo);
opti->current_dir_name = original_dir_name;
for (i = MERGE_BASE; i <= MERGE_SIDE2; i++)
free(buf[i]);
if (ret < 0)
return -1;
}
return mask;
}
static int collect_merge_info(struct merge_options *opt,
struct tree *merge_base,
struct tree *side1,
struct tree *side2)
{
int ret;
struct tree_desc t[3];
struct traverse_info info;
const char *toplevel_dir_placeholder = "";
opt->priv->current_dir_name = toplevel_dir_placeholder;
setup_traverse_info(&info, toplevel_dir_placeholder);
info.fn = collect_merge_info_callback;
info.data = opt;
info.show_all_errors = 1;
parse_tree(merge_base);
parse_tree(side1);
parse_tree(side2);
init_tree_desc(t + 0, merge_base->buffer, merge_base->size);
init_tree_desc(t + 1, side1->buffer, side1->size);
init_tree_desc(t + 2, side2->buffer, side2->size);
ret = traverse_trees(NULL, 3, t, &info);
return ret;
}
/*** Function Grouping: functions related to threeway content merges ***/
static int handle_content_merge(struct merge_options *opt,
const char *path,
const struct version_info *o,
const struct version_info *a,
const struct version_info *b,
const char *pathnames[3],
const int extra_marker_size,
struct version_info *result)
{
die("Not yet implemented");
}
/*** Function Grouping: functions related to detect_and_process_renames(), ***
*** which are split into directory and regular rename detection sections. ***/
/*** Function Grouping: functions related to directory rename detection ***/
/*** Function Grouping: functions related to regular rename detection ***/
static int detect_and_process_renames(struct merge_options *opt,
struct tree *merge_base,
struct tree *side1,
struct tree *side2)
{
int clean = 1;
/*
* Rename detection works by detecting file similarity. Here we use
* a really easy-to-implement scheme: files are similar IFF they have
* the same filename. Therefore, by this scheme, there are no renames.
*
* TODO: Actually implement a real rename detection scheme.
*/
return clean;
}
/*** Function Grouping: functions related to process_entries() ***/
static int string_list_df_name_compare(const char *one, const char *two)
{
int onelen = strlen(one);
int twolen = strlen(two);
/*
* Here we only care that entries for D/F conflicts are
* adjacent, in particular with the file of the D/F conflict
* appearing before files below the corresponding directory.
* The order of the rest of the list is irrelevant for us.
*
* To achieve this, we sort with df_name_compare and provide
* the mode S_IFDIR so that D/F conflicts will sort correctly.
* We use the mode S_IFDIR for everything else for simplicity,
* since in other cases any changes in their order due to
* sorting cause no problems for us.
*/
int cmp = df_name_compare(one, onelen, S_IFDIR,
two, twolen, S_IFDIR);
/*
* Now that 'foo' and 'foo/bar' compare equal, we have to make sure
* that 'foo' comes before 'foo/bar'.
*/
if (cmp)
return cmp;
return onelen - twolen;
}
struct directory_versions {
/*
* versions: list of (basename -> version_info)
*
* The basenames are in reverse lexicographic order of full pathnames,
* as processed in process_entries(). This puts all entries within
* a directory together, and covers the directory itself after
* everything within it, allowing us to write subtrees before needing
* to record information for the tree itself.
*/
struct string_list versions;
/*
* offsets: list of (full relative path directories -> integer offsets)
*
* Since versions contains basenames from files in multiple different
* directories, we need to know which entries in versions correspond
* to which directories. Values of e.g.
* "" 0
* src 2
* src/moduleA 5
* Would mean that entries 0-1 of versions are files in the toplevel
* directory, entries 2-4 are files under src/, and the remaining
* entries starting at index 5 are files under src/moduleA/.
*/
struct string_list offsets;
/*
* last_directory: directory that previously processed file found in
*
* last_directory starts NULL, but records the directory in which the
* previous file was found within. As soon as
* directory(current_file) != last_directory
* then we need to start updating accounting in versions & offsets.
* Note that last_directory is always the last path in "offsets" (or
* NULL if "offsets" is empty) so this exists just for quick access.
*/
const char *last_directory;
/* last_directory_len: cached computation of strlen(last_directory) */
unsigned last_directory_len;
};
static int tree_entry_order(const void *a_, const void *b_)
{
const struct string_list_item *a = a_;
const struct string_list_item *b = b_;
const struct merged_info *ami = a->util;
const struct merged_info *bmi = b->util;
return base_name_compare(a->string, strlen(a->string), ami->result.mode,
b->string, strlen(b->string), bmi->result.mode);
}
static void write_tree(struct object_id *result_oid,
struct string_list *versions,
unsigned int offset,
size_t hash_size)
{
size_t maxlen = 0, extra;
unsigned int nr = versions->nr - offset;
struct strbuf buf = STRBUF_INIT;
struct string_list relevant_entries = STRING_LIST_INIT_NODUP;
int i;
/*
* We want to sort the last (versions->nr-offset) entries in versions.
* Do so by abusing the string_list API a bit: make another string_list
* that contains just those entries and then sort them.
*
* We won't use relevant_entries again and will let it just pop off the
* stack, so there won't be allocation worries or anything.
*/
relevant_entries.items = versions->items + offset;
relevant_entries.nr = versions->nr - offset;
QSORT(relevant_entries.items, relevant_entries.nr, tree_entry_order);
/* Pre-allocate some space in buf */
extra = hash_size + 8; /* 8: 6 for mode, 1 for space, 1 for NUL char */
for (i = 0; i < nr; i++) {
maxlen += strlen(versions->items[offset+i].string) + extra;
}
strbuf_grow(&buf, maxlen);
/* Write each entry out to buf */
for (i = 0; i < nr; i++) {
struct merged_info *mi = versions->items[offset+i].util;
struct version_info *ri = &mi->result;
strbuf_addf(&buf, "%o %s%c",
ri->mode,
versions->items[offset+i].string, '\0');
strbuf_add(&buf, ri->oid.hash, hash_size);
}
/* Write this object file out, and record in result_oid */
write_object_file(buf.buf, buf.len, tree_type, result_oid);
strbuf_release(&buf);
}
static void record_entry_for_tree(struct directory_versions *dir_metadata,
const char *path,
struct merged_info *mi)
{
const char *basename;
if (mi->is_null)
/* nothing to record */
return;
basename = path + mi->basename_offset;
assert(strchr(basename, '/') == NULL);
string_list_append(&dir_metadata->versions,
basename)->util = &mi->result;
}
static void write_completed_directory(struct merge_options *opt,
const char *new_directory_name,
struct directory_versions *info)
{
const char *prev_dir;
struct merged_info *dir_info = NULL;
unsigned int offset;
/*
* Some explanation of info->versions and info->offsets...
*
* process_entries() iterates over all relevant files AND
* directories in reverse lexicographic order, and calls this
* function. Thus, an example of the paths that process_entries()
* could operate on (along with the directories for those paths
* being shown) is:
*
* xtract.c ""
* tokens.txt ""
* src/moduleB/umm.c src/moduleB
* src/moduleB/stuff.h src/moduleB
* src/moduleB/baz.c src/moduleB
* src/moduleB src
* src/moduleA/foo.c src/moduleA
* src/moduleA/bar.c src/moduleA
* src/moduleA src
* src ""
* Makefile ""
*
* info->versions:
*
* always contains the unprocessed entries and their
* version_info information. For example, after the first five
* entries above, info->versions would be:
*
* xtract.c <xtract.c's version_info>
* token.txt <token.txt's version_info>
* umm.c <src/moduleB/umm.c's version_info>
* stuff.h <src/moduleB/stuff.h's version_info>
* baz.c <src/moduleB/baz.c's version_info>
*
* Once a subdirectory is completed we remove the entries in
* that subdirectory from info->versions, writing it as a tree
* (write_tree()). Thus, as soon as we get to src/moduleB,
* info->versions would be updated to
*
* xtract.c <xtract.c's version_info>
* token.txt <token.txt's version_info>
* moduleB <src/moduleB's version_info>
*
* info->offsets:
*
* helps us track which entries in info->versions correspond to
* which directories. When we are N directories deep (e.g. 4
* for src/modA/submod/subdir/), we have up to N+1 unprocessed
* directories (+1 because of toplevel dir). Corresponding to
* the info->versions example above, after processing five entries
* info->offsets will be:
*
* "" 0
* src/moduleB 2
*
* which is used to know that xtract.c & token.txt are from the
* toplevel dirctory, while umm.c & stuff.h & baz.c are from the
* src/moduleB directory. Again, following the example above,
* once we need to process src/moduleB, then info->offsets is
* updated to
*
* "" 0
* src 2
*
* which says that moduleB (and only moduleB so far) is in the
* src directory.
*
* One unique thing to note about info->offsets here is that
* "src" was not added to info->offsets until there was a path
* (a file OR directory) immediately below src/ that got
* processed.
*
* Since process_entry() just appends new entries to info->versions,
* write_completed_directory() only needs to do work if the next path
* is in a directory that is different than the last directory found
* in info->offsets.
*/
/*
* If we are working with the same directory as the last entry, there
* is no work to do. (See comments above the directory_name member of
* struct merged_info for why we can use pointer comparison instead of
* strcmp here.)
*/
if (new_directory_name == info->last_directory)
return;
/*
* If we are just starting (last_directory is NULL), or last_directory
* is a prefix of the current directory, then we can just update
* info->offsets to record the offset where we started this directory
* and update last_directory to have quick access to it.
*/
if (info->last_directory == NULL ||
!strncmp(new_directory_name, info->last_directory,
info->last_directory_len)) {
uintptr_t offset = info->versions.nr;
info->last_directory = new_directory_name;
info->last_directory_len = strlen(info->last_directory);
/*
* Record the offset into info->versions where we will
* start recording basenames of paths found within
* new_directory_name.
*/
string_list_append(&info->offsets,
info->last_directory)->util = (void*)offset;
return;
}
/*
* The next entry that will be processed will be within
* new_directory_name. Since at this point we know that
* new_directory_name is within a different directory than
* info->last_directory, we have all entries for info->last_directory
* in info->versions and we need to create a tree object for them.
*/
dir_info = strmap_get(&opt->priv->paths, info->last_directory);
assert(dir_info);
offset = (uintptr_t)info->offsets.items[info->offsets.nr-1].util;
if (offset == info->versions.nr) {
/*
* Actually, we don't need to create a tree object in this
* case. Whenever all files within a directory disappear
* during the merge (e.g. unmodified on one side and
* deleted on the other, or files were renamed elsewhere),
* then we get here and the directory itself needs to be
* omitted from its parent tree as well.
*/
dir_info->is_null = 1;
} else {
/*
* Write out the tree to the git object directory, and also
* record the mode and oid in dir_info->result.
*/
dir_info->is_null = 0;
dir_info->result.mode = S_IFDIR;
write_tree(&dir_info->result.oid, &info->versions, offset,
opt->repo->hash_algo->rawsz);
}
/*
* We've now used several entries from info->versions and one entry
* from info->offsets, so we get rid of those values.
*/
info->offsets.nr--;
info->versions.nr = offset;
/*
* Now we've taken care of the completed directory, but we need to
* prepare things since future entries will be in
* new_directory_name. (In particular, process_entry() will be
* appending new entries to info->versions.) So, we need to make
* sure new_directory_name is the last entry in info->offsets.
*/
prev_dir = info->offsets.nr == 0 ? NULL :
info->offsets.items[info->offsets.nr-1].string;
if (new_directory_name != prev_dir) {
uintptr_t c = info->versions.nr;
string_list_append(&info->offsets,
new_directory_name)->util = (void*)c;
}
/* And, of course, we need to update last_directory to match. */
info->last_directory = new_directory_name;
info->last_directory_len = strlen(info->last_directory);
}
/* Per entry merge function */
static void process_entry(struct merge_options *opt,
const char *path,
struct conflict_info *ci,
struct directory_versions *dir_metadata)
{
VERIFY_CI(ci);
assert(ci->filemask >= 0 && ci->filemask <= 7);
/* ci->match_mask == 7 was handled in collect_merge_info_callback() */
assert(ci->match_mask == 0 || ci->match_mask == 3 ||
ci->match_mask == 5 || ci->match_mask == 6);
if (ci->dirmask) {
record_entry_for_tree(dir_metadata, path, &ci->merged);
if (ci->filemask == 0)
/* nothing else to handle */
return;
assert(ci->df_conflict);
}
if (ci->df_conflict) {
die("Not yet implemented.");
}
/*
* NOTE: Below there is a long switch-like if-elseif-elseif... block
* which the code goes through even for the df_conflict cases
* above. Well, it will once we don't die-not-implemented above.
*/
if (ci->match_mask) {
ci->merged.clean = 1;
if (ci->match_mask == 6) {
/* stages[1] == stages[2] */
ci->merged.result.mode = ci->stages[1].mode;
oidcpy(&ci->merged.result.oid, &ci->stages[1].oid);
} else {
/* determine the mask of the side that didn't match */
unsigned int othermask = 7 & ~ci->match_mask;
int side = (othermask == 4) ? 2 : 1;
ci->merged.result.mode = ci->stages[side].mode;
ci->merged.is_null = !ci->merged.result.mode;
oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
assert(othermask == 2 || othermask == 4);
assert(ci->merged.is_null ==
(ci->filemask == ci->match_mask));
}
} else if (ci->filemask >= 6 &&
(S_IFMT & ci->stages[1].mode) !=
(S_IFMT & ci->stages[2].mode)) {
/*
* Two different items from (file/submodule/symlink)
*/
die("Not yet implemented.");
} else if (ci->filemask >= 6) {
/*
* TODO: Needs a two-way or three-way content merge, but we're
* just being lazy and copying the version from HEAD and
* leaving it as conflicted.
*/
ci->merged.clean = 0;
ci->merged.result.mode = ci->stages[1].mode;
oidcpy(&ci->merged.result.oid, &ci->stages[1].oid);
/* When we fix above, we'll call handle_content_merge() */
(void)handle_content_merge;
} else if (ci->filemask == 3 || ci->filemask == 5) {
/* Modify/delete */
const char *modify_branch, *delete_branch;
int side = (ci->filemask == 5) ? 2 : 1;
int index = opt->priv->call_depth ? 0 : side;
ci->merged.result.mode = ci->stages[index].mode;
oidcpy(&ci->merged.result.oid, &ci->stages[index].oid);
ci->merged.clean = 0;
modify_branch = (side == 1) ? opt->branch1 : opt->branch2;
delete_branch = (side == 1) ? opt->branch2 : opt->branch1;
path_msg(opt, path, 0,
_("CONFLICT (modify/delete): %s deleted in %s "
"and modified in %s. Version %s of %s left "
"in tree."),
path, delete_branch, modify_branch,
modify_branch, path);
} else if (ci->filemask == 2 || ci->filemask == 4) {
/* Added on one side */
int side = (ci->filemask == 4) ? 2 : 1;
ci->merged.result.mode = ci->stages[side].mode;
oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
ci->merged.clean = !ci->df_conflict;
} else if (ci->filemask == 1) {
/* Deleted on both sides */
ci->merged.is_null = 1;
ci->merged.result.mode = 0;
oidcpy(&ci->merged.result.oid, &null_oid);
ci->merged.clean = 1;
}
/*
* If still conflicted, record it separately. This allows us to later
* iterate over just conflicted entries when updating the index instead
* of iterating over all entries.
*/
if (!ci->merged.clean)
strmap_put(&opt->priv->conflicted, path, ci);
record_entry_for_tree(dir_metadata, path, &ci->merged);
}
static void process_entries(struct merge_options *opt,
struct object_id *result_oid)
{
struct hashmap_iter iter;
struct strmap_entry *e;
struct string_list plist = STRING_LIST_INIT_NODUP;
struct string_list_item *entry;
struct directory_versions dir_metadata = { STRING_LIST_INIT_NODUP,
STRING_LIST_INIT_NODUP,
NULL, 0 };
if (strmap_empty(&opt->priv->paths)) {
oidcpy(result_oid, opt->repo->hash_algo->empty_tree);
return;
}
/* Hack to pre-allocate plist to the desired size */
ALLOC_GROW(plist.items, strmap_get_size(&opt->priv->paths), plist.alloc);
/* Put every entry from paths into plist, then sort */
strmap_for_each_entry(&opt->priv->paths, &iter, e) {
string_list_append(&plist, e->key)->util = e->value;
}
plist.cmp = string_list_df_name_compare;
string_list_sort(&plist);
/*
* Iterate over the items in reverse order, so we can handle paths
* below a directory before needing to handle the directory itself.
*
* This allows us to write subtrees before we need to write trees,
* and it also enables sane handling of directory/file conflicts
* (because it allows us to know whether the directory is still in
* the way when it is time to process the file at the same path).
*/
for (entry = &plist.items[plist.nr-1]; entry >= plist.items; --entry) {
char *path = entry->string;
/*
* NOTE: mi may actually be a pointer to a conflict_info, but
* we have to check mi->clean first to see if it's safe to
* reassign to such a pointer type.
*/
struct merged_info *mi = entry->util;
write_completed_directory(opt, mi->directory_name,
&dir_metadata);
if (mi->clean)
record_entry_for_tree(&dir_metadata, path, mi);
else {
struct conflict_info *ci = (struct conflict_info *)mi;
process_entry(opt, path, ci, &dir_metadata);
}
}
if (dir_metadata.offsets.nr != 1 ||
(uintptr_t)dir_metadata.offsets.items[0].util != 0) {
printf("dir_metadata.offsets.nr = %d (should be 1)\n",
dir_metadata.offsets.nr);
printf("dir_metadata.offsets.items[0].util = %u (should be 0)\n",
(unsigned)(uintptr_t)dir_metadata.offsets.items[0].util);
fflush(stdout);
BUG("dir_metadata accounting completely off; shouldn't happen");
}
write_tree(result_oid, &dir_metadata.versions, 0,
opt->repo->hash_algo->rawsz);
string_list_clear(&plist, 0);
string_list_clear(&dir_metadata.versions, 0);
string_list_clear(&dir_metadata.offsets, 0);
}
/*** Function Grouping: functions related to merge_switch_to_result() ***/
static int checkout(struct merge_options *opt,
struct tree *prev,
struct tree *next)
{
/* Switch the index/working copy from old to new */
int ret;
struct tree_desc trees[2];
struct unpack_trees_options unpack_opts;
memset(&unpack_opts, 0, sizeof(unpack_opts));
unpack_opts.head_idx = -1;
unpack_opts.src_index = opt->repo->index;
unpack_opts.dst_index = opt->repo->index;
setup_unpack_trees_porcelain(&unpack_opts, "merge");
/*
* NOTE: if this were just "git checkout" code, we would probably
* read or refresh the cache and check for a conflicted index, but
* builtin/merge.c or sequencer.c really needs to read the index
* and check for conflicted entries before starting merging for a
* good user experience (no sense waiting for merges/rebases before
* erroring out), so there's no reason to duplicate that work here.
*/
/* 2-way merge to the new branch */
unpack_opts.update = 1;
unpack_opts.merge = 1;
unpack_opts.quiet = 0; /* FIXME: sequencer might want quiet? */
unpack_opts.verbose_update = (opt->verbosity > 2);
unpack_opts.fn = twoway_merge;
if (1/* FIXME: opts->overwrite_ignore*/) {
unpack_opts.dir = xcalloc(1, sizeof(*unpack_opts.dir));
unpack_opts.dir->flags |= DIR_SHOW_IGNORED;
setup_standard_excludes(unpack_opts.dir);
}
parse_tree(prev);
init_tree_desc(&trees[0], prev->buffer, prev->size);
parse_tree(next);
init_tree_desc(&trees[1], next->buffer, next->size);
ret = unpack_trees(2, trees, &unpack_opts);
clear_unpack_trees_porcelain(&unpack_opts);
dir_clear(unpack_opts.dir);
FREE_AND_NULL(unpack_opts.dir);
return ret;
}
static int record_conflicted_index_entries(struct merge_options *opt,
struct index_state *index,
struct strmap *paths,
struct strmap *conflicted)
{
struct hashmap_iter iter;
struct strmap_entry *e;
int errs = 0;
int original_cache_nr;
if (strmap_empty(conflicted))
return 0;
original_cache_nr = index->cache_nr;
/* Put every entry from paths into plist, then sort */
strmap_for_each_entry(conflicted, &iter, e) {
const char *path = e->key;
struct conflict_info *ci = e->value;
int pos;
struct cache_entry *ce;
int i;
VERIFY_CI(ci);
/*
* The index will already have a stage=0 entry for this path,
* because we created an as-merged-as-possible version of the
* file and checkout() moved the working copy and index over
* to that version.
*
* However, previous iterations through this loop will have
* added unstaged entries to the end of the cache which
* ignore the standard alphabetical ordering of cache
* entries and break invariants needed for index_name_pos()
* to work. However, we know the entry we want is before
* those appended cache entries, so do a temporary swap on
* cache_nr to only look through entries of interest.
*/
SWAP(index->cache_nr, original_cache_nr);
pos = index_name_pos(index, path, strlen(path));
SWAP(index->cache_nr, original_cache_nr);
if (pos < 0) {
if (ci->filemask != 1)
BUG("Conflicted %s but nothing in basic working tree or index; this shouldn't happen", path);
cache_tree_invalidate_path(index, path);
} else {
ce = index->cache[pos];
/*
* Clean paths with CE_SKIP_WORKTREE set will not be
* written to the working tree by the unpack_trees()
* call in checkout(). Our conflicted entries would
* have appeared clean to that code since we ignored
* the higher order stages. Thus, we need override
* the CE_SKIP_WORKTREE bit and manually write those
* files to the working disk here.
*
* TODO: Implement this CE_SKIP_WORKTREE fixup.
*/
/*
* Mark this cache entry for removal and instead add
* new stage>0 entries corresponding to the
* conflicts. If there are many conflicted entries, we
* want to avoid memmove'ing O(NM) entries by
* inserting the new entries one at a time. So,
* instead, we just add the new cache entries to the
* end (ignoring normal index requirements on sort
* order) and sort the index once we're all done.
*/
ce->ce_flags |= CE_REMOVE;
}
for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
struct version_info *vi;
if (!(ci->filemask & (1ul << i)))
continue;
vi = &ci->stages[i];
ce = make_cache_entry(index, vi->mode, &vi->oid,
path, i+1, 0);
add_index_entry(index, ce, ADD_CACHE_JUST_APPEND);
}
}
/*
* Remove the unused cache entries (and invalidate the relevant
* cache-trees), then sort the index entries to get the conflicted
* entries we added to the end into their right locations.
*/
remove_marked_cache_entries(index, 1);
QSORT(index->cache, index->cache_nr, cmp_cache_name_compare);
return errs;
}
void merge_switch_to_result(struct merge_options *opt,
struct tree *head,
struct merge_result *result,
int update_worktree_and_index,
int display_update_msgs)
{
assert(opt->priv == NULL);
if (result->clean >= 0 && update_worktree_and_index) {
struct merge_options_internal *opti = result->priv;
if (checkout(opt, head, result->tree)) {
/* failure to function */
result->clean = -1;
return;
}
if (record_conflicted_index_entries(opt, opt->repo->index,
&opti->paths,
&opti->conflicted)) {
/* failure to function */
result->clean = -1;
return;
}
}
if (display_update_msgs) {
struct merge_options_internal *opti = result->priv;
struct hashmap_iter iter;
struct strmap_entry *e;
struct string_list olist = STRING_LIST_INIT_NODUP;
int i;
/* Hack to pre-allocate olist to the desired size */
ALLOC_GROW(olist.items, strmap_get_size(&opti->output),
olist.alloc);
/* Put every entry from output into olist, then sort */
strmap_for_each_entry(&opti->output, &iter, e) {
string_list_append(&olist, e->key)->util = e->value;
}
string_list_sort(&olist);
/* Iterate over the items, printing them */
for (i = 0; i < olist.nr; ++i) {
struct strbuf *sb = olist.items[i].util;
printf("%s", sb->buf);
}
string_list_clear(&olist, 0);
}
merge_finalize(opt, result);
}
void merge_finalize(struct merge_options *opt,
struct merge_result *result)
{
struct merge_options_internal *opti = result->priv;
assert(opt->priv == NULL);
clear_or_reinit_internal_opts(opti, 0);
FREE_AND_NULL(opti);
}
/*** Function Grouping: helper functions for merge_incore_*() ***/
static inline void set_commit_tree(struct commit *c, struct tree *t)
{
c->maybe_tree = t;
}
static struct commit *make_virtual_commit(struct repository *repo,
struct tree *tree,
const char *comment)
{
struct commit *commit = alloc_commit_node(repo);
set_merge_remote_desc(commit, comment, (struct object *)commit);
set_commit_tree(commit, tree);
commit->object.parsed = 1;
return commit;
}
static void merge_start(struct merge_options *opt, struct merge_result *result)
{
/* Sanity checks on opt */
assert(opt->repo);
assert(opt->branch1 && opt->branch2);
assert(opt->detect_directory_renames >= MERGE_DIRECTORY_RENAMES_NONE &&
opt->detect_directory_renames <= MERGE_DIRECTORY_RENAMES_TRUE);
assert(opt->rename_limit >= -1);
assert(opt->rename_score >= 0 && opt->rename_score <= MAX_SCORE);
assert(opt->show_rename_progress >= 0 && opt->show_rename_progress <= 1);
assert(opt->xdl_opts >= 0);
assert(opt->recursive_variant >= MERGE_VARIANT_NORMAL &&
opt->recursive_variant <= MERGE_VARIANT_THEIRS);
/*
* detect_renames, verbosity, buffer_output, and obuf are ignored
* fields that were used by "recursive" rather than "ort" -- but
* sanity check them anyway.
*/
assert(opt->detect_renames >= -1 &&
opt->detect_renames <= DIFF_DETECT_COPY);
assert(opt->verbosity >= 0 && opt->verbosity <= 5);
assert(opt->buffer_output <= 2);
assert(opt->obuf.len == 0);
assert(opt->priv == NULL);
/* Default to histogram diff. Actually, just hardcode it...for now. */
opt->xdl_opts = DIFF_WITH_ALG(opt, HISTOGRAM_DIFF);
/* Initialization of opt->priv, our internal merge data */
opt->priv = xcalloc(1, sizeof(*opt->priv));
/*
* Although we initialize opt->priv->paths with strdup_strings=0,
* that's just to avoid making yet another copy of an allocated
* string. Putting the entry into paths means we are taking
* ownership, so we will later free it. paths_to_free is similar.
*
* In contrast, conflicted just has a subset of keys from paths, so
* we don't want to free those (it'd be a duplicate free).
*/
strmap_init_with_options(&opt->priv->paths, NULL, 0);
strmap_init_with_options(&opt->priv->conflicted, NULL, 0);
string_list_init(&opt->priv->paths_to_free, 0);
/*
* keys & strbufs in output will sometimes need to outlive "paths",
* so it will have a copy of relevant keys. It's probably a small
* subset of the overall paths that have special output.
*/
strmap_init(&opt->priv->output);
}
/*** Function Grouping: merge_incore_*() and their internal variants ***/
/*
* Originally from merge_trees_internal(); heavily adapted, though.
*/
static void merge_ort_nonrecursive_internal(struct merge_options *opt,
struct tree *merge_base,
struct tree *side1,
struct tree *side2,
struct merge_result *result)
{
struct object_id working_tree_oid;
if (collect_merge_info(opt, merge_base, side1, side2) != 0) {
/*
* TRANSLATORS: The %s arguments are: 1) tree hash of a merge
* base, and 2-3) the trees for the two trees we're merging.
*/
err(opt, _("collecting merge info failed for trees %s, %s, %s"),
oid_to_hex(&merge_base->object.oid),
oid_to_hex(&side1->object.oid),
oid_to_hex(&side2->object.oid));
result->clean = -1;
return;
}
result->clean = detect_and_process_renames(opt, merge_base,
side1, side2);
process_entries(opt, &working_tree_oid);
/* Set return values */
result->tree = parse_tree_indirect(&working_tree_oid);
/* existence of conflicted entries implies unclean */
result->clean &= strmap_empty(&opt->priv->conflicted);
if (!opt->priv->call_depth) {
result->priv = opt->priv;
opt->priv = NULL;
}
}
/*
* Originally from merge_recursive_internal(); somewhat adapted, though.
*/
static void merge_ort_internal(struct merge_options *opt,
struct commit_list *merge_bases,
struct commit *h1,
struct commit *h2,
struct merge_result *result)
{
struct commit_list *iter;
struct commit *merged_merge_bases;
const char *ancestor_name;
struct strbuf merge_base_abbrev = STRBUF_INIT;
if (!merge_bases) {
merge_bases = get_merge_bases(h1, h2);
/* See merge-ort.h:merge_incore_recursive() declaration NOTE */
merge_bases = reverse_commit_list(merge_bases);
}
merged_merge_bases = pop_commit(&merge_bases);
if (merged_merge_bases == NULL) {
/* if there is no common ancestor, use an empty tree */
struct tree *tree;
tree = lookup_tree(opt->repo, opt->repo->hash_algo->empty_tree);
merged_merge_bases = make_virtual_commit(opt->repo, tree,
"ancestor");
ancestor_name = "empty tree";
} else if (merge_bases) {
ancestor_name = "merged common ancestors";
} else {
strbuf_add_unique_abbrev(&merge_base_abbrev,
&merged_merge_bases->object.oid,
DEFAULT_ABBREV);
ancestor_name = merge_base_abbrev.buf;
}
for (iter = merge_bases; iter; iter = iter->next) {
const char *saved_b1, *saved_b2;
struct commit *prev = merged_merge_bases;
opt->priv->call_depth++;
/*
* When the merge fails, the result contains files
* with conflict markers. The cleanness flag is
* ignored (unless indicating an error), it was never
* actually used, as result of merge_trees has always
* overwritten it: the committed "conflicts" were
* already resolved.
*/
saved_b1 = opt->branch1;
saved_b2 = opt->branch2;
opt->branch1 = "Temporary merge branch 1";
opt->branch2 = "Temporary merge branch 2";
merge_ort_internal(opt, NULL, prev, iter->item, result);
if (result->clean < 0)
return;
opt->branch1 = saved_b1;
opt->branch2 = saved_b2;
opt->priv->call_depth--;
merged_merge_bases = make_virtual_commit(opt->repo,
result->tree,
"merged tree");
commit_list_insert(prev, &merged_merge_bases->parents);
commit_list_insert(iter->item,
&merged_merge_bases->parents->next);
clear_or_reinit_internal_opts(opt->priv, 1);
}
opt->ancestor = ancestor_name;
merge_ort_nonrecursive_internal(opt,
repo_get_commit_tree(opt->repo,
merged_merge_bases),
repo_get_commit_tree(opt->repo, h1),
repo_get_commit_tree(opt->repo, h2),
result);
strbuf_release(&merge_base_abbrev);
opt->ancestor = NULL; /* avoid accidental re-use of opt->ancestor */
}
void merge_incore_nonrecursive(struct merge_options *opt,
struct tree *merge_base,
struct tree *side1,
struct tree *side2,
struct merge_result *result)
{
assert(opt->ancestor != NULL);
merge_start(opt, result);
merge_ort_nonrecursive_internal(opt, merge_base, side1, side2, result);
}
void merge_incore_recursive(struct merge_options *opt,
struct commit_list *merge_bases,
struct commit *side1,
struct commit *side2,
struct merge_result *result)
{
/* We set the ancestor label based on the merge_bases */
assert(opt->ancestor == NULL);
merge_start(opt, result);
merge_ort_internal(opt, merge_bases, side1, side2, result);
}