git/builtin-merge.c
Junio C Hamano 446247db78 merge: fix numerus bugs around "trivial merge" area
The "trivial merge" codepath wants to optimize itself by making an
internal call to the read-tree machinery, but it does not read the index
before doing so, and the codepath is never exercised.  Incidentally, this
failure to read the index upfront means that the safety to refuse doing
anything when the index is unmerged does not kick in, either.

These two problem are fixed by using read_cache_unmerged() that does read
the index before checking if it is unmerged at the beginning of
cmd_merge().

The primary logic of the merge, however, assumes that the process never
reads the index in-core, and the call to write_cache_as_tree() it makes
from write_tree_trivial() will always read from the on-disk index that is
prepared the strategy back-ends.  This assumption is now broken by the
above fix.  To fix this issue, we now call discard_cache() before calling
write_tree_trivial() when it wants to write the on-disk index as a tree.

When multiple strategies are tried, their results are evaluated by reading
the resulting index and inspecting it.  The codepath needs to make a call
to read_cache() for each successful strategy, and for that to work, they
need to discard_cache() the one read by the previous round.

Also the "trivial merge" forgot that the current commit is one of the
parents of the resulting commit.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-23 18:17:22 -07:00

1146 lines
28 KiB
C

/*
* Builtin "git merge"
*
* Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
*
* Based on git-merge.sh by Junio C Hamano.
*/
#include "cache.h"
#include "parse-options.h"
#include "builtin.h"
#include "run-command.h"
#include "diff.h"
#include "refs.h"
#include "commit.h"
#include "diffcore.h"
#include "revision.h"
#include "unpack-trees.h"
#include "cache-tree.h"
#include "dir.h"
#include "utf8.h"
#include "log-tree.h"
#include "color.h"
#include "rerere.h"
#define DEFAULT_TWOHEAD (1<<0)
#define DEFAULT_OCTOPUS (1<<1)
#define NO_FAST_FORWARD (1<<2)
#define NO_TRIVIAL (1<<3)
struct strategy {
const char *name;
unsigned attr;
};
static const char * const builtin_merge_usage[] = {
"git-merge [options] <remote>...",
"git-merge [options] <msg> HEAD <remote>",
NULL
};
static int show_diffstat = 1, option_log, squash;
static int option_commit = 1, allow_fast_forward = 1;
static int allow_trivial = 1, have_message;
static struct strbuf merge_msg;
static struct commit_list *remoteheads;
static unsigned char head[20], stash[20];
static struct strategy **use_strategies;
static size_t use_strategies_nr, use_strategies_alloc;
static const char *branch;
static struct strategy all_strategy[] = {
{ "recursive", DEFAULT_TWOHEAD | NO_TRIVIAL },
{ "octopus", DEFAULT_OCTOPUS },
{ "resolve", 0 },
{ "ours", NO_FAST_FORWARD | NO_TRIVIAL },
{ "subtree", NO_FAST_FORWARD | NO_TRIVIAL },
};
static const char *pull_twohead, *pull_octopus;
static int option_parse_message(const struct option *opt,
const char *arg, int unset)
{
struct strbuf *buf = opt->value;
if (unset)
strbuf_setlen(buf, 0);
else if (arg) {
strbuf_addf(buf, "%s\n\n", arg);
have_message = 1;
} else
return error("switch `m' requires a value");
return 0;
}
static struct strategy *get_strategy(const char *name)
{
int i;
struct strbuf err;
if (!name)
return NULL;
for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
if (!strcmp(name, all_strategy[i].name))
return &all_strategy[i];
strbuf_init(&err, 0);
for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
strbuf_addf(&err, " %s", all_strategy[i].name);
fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
fprintf(stderr, "Available strategies are:%s.\n", err.buf);
exit(1);
}
static void append_strategy(struct strategy *s)
{
ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
use_strategies[use_strategies_nr++] = s;
}
static int option_parse_strategy(const struct option *opt,
const char *name, int unset)
{
if (unset)
return 0;
append_strategy(get_strategy(name));
return 0;
}
static int option_parse_n(const struct option *opt,
const char *arg, int unset)
{
show_diffstat = unset;
return 0;
}
static struct option builtin_merge_options[] = {
{ OPTION_CALLBACK, 'n', NULL, NULL, NULL,
"do not show a diffstat at the end of the merge",
PARSE_OPT_NOARG, option_parse_n },
OPT_BOOLEAN(0, "stat", &show_diffstat,
"show a diffstat at the end of the merge"),
OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
OPT_BOOLEAN(0, "log", &option_log,
"add list of one-line log to merge commit message"),
OPT_BOOLEAN(0, "squash", &squash,
"create a single commit instead of doing a merge"),
OPT_BOOLEAN(0, "commit", &option_commit,
"perform a commit if the merge succeeds (default)"),
OPT_BOOLEAN(0, "ff", &allow_fast_forward,
"allow fast forward (default)"),
OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
"merge strategy to use", option_parse_strategy),
OPT_CALLBACK('m', "message", &merge_msg, "message",
"message to be used for the merge commit (if any)",
option_parse_message),
OPT_END()
};
/* Cleans up metadata that is uninteresting after a succeeded merge. */
static void drop_save(void)
{
unlink(git_path("MERGE_HEAD"));
unlink(git_path("MERGE_MSG"));
}
static void save_state(void)
{
int len;
struct child_process cp;
struct strbuf buffer = STRBUF_INIT;
const char *argv[] = {"stash", "create", NULL};
memset(&cp, 0, sizeof(cp));
cp.argv = argv;
cp.out = -1;
cp.git_cmd = 1;
if (start_command(&cp))
die("could not run stash.");
len = strbuf_read(&buffer, cp.out, 1024);
close(cp.out);
if (finish_command(&cp) || len < 0)
die("stash failed");
else if (!len)
return;
strbuf_setlen(&buffer, buffer.len-1);
if (get_sha1(buffer.buf, stash))
die("not a valid object: %s", buffer.buf);
}
static void reset_hard(unsigned const char *sha1, int verbose)
{
int i = 0;
const char *args[6];
args[i++] = "read-tree";
if (verbose)
args[i++] = "-v";
args[i++] = "--reset";
args[i++] = "-u";
args[i++] = sha1_to_hex(sha1);
args[i] = NULL;
if (run_command_v_opt(args, RUN_GIT_CMD))
die("read-tree failed");
}
static void restore_state(void)
{
struct strbuf sb;
const char *args[] = { "stash", "apply", NULL, NULL };
if (is_null_sha1(stash))
return;
reset_hard(head, 1);
strbuf_init(&sb, 0);
args[2] = sha1_to_hex(stash);
/*
* It is OK to ignore error here, for example when there was
* nothing to restore.
*/
run_command_v_opt(args, RUN_GIT_CMD);
strbuf_release(&sb);
refresh_cache(REFRESH_QUIET);
}
/* This is called when no merge was necessary. */
static void finish_up_to_date(const char *msg)
{
printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
drop_save();
}
static void squash_message(void)
{
struct rev_info rev;
struct commit *commit;
struct strbuf out;
struct commit_list *j;
int fd;
printf("Squash commit -- not updating HEAD\n");
fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
if (fd < 0)
die("Could not write to %s", git_path("SQUASH_MSG"));
init_revisions(&rev, NULL);
rev.ignore_merges = 1;
rev.commit_format = CMIT_FMT_MEDIUM;
commit = lookup_commit(head);
commit->object.flags |= UNINTERESTING;
add_pending_object(&rev, &commit->object, NULL);
for (j = remoteheads; j; j = j->next)
add_pending_object(&rev, &j->item->object, NULL);
setup_revisions(0, NULL, &rev, NULL);
if (prepare_revision_walk(&rev))
die("revision walk setup failed");
strbuf_init(&out, 0);
strbuf_addstr(&out, "Squashed commit of the following:\n");
while ((commit = get_revision(&rev)) != NULL) {
strbuf_addch(&out, '\n');
strbuf_addf(&out, "commit %s\n",
sha1_to_hex(commit->object.sha1));
pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
NULL, NULL, rev.date_mode, 0);
}
write(fd, out.buf, out.len);
close(fd);
strbuf_release(&out);
}
static int run_hook(const char *name)
{
struct child_process hook;
const char *argv[3], *env[2];
char index[PATH_MAX];
argv[0] = git_path("hooks/%s", name);
if (access(argv[0], X_OK) < 0)
return 0;
snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
env[0] = index;
env[1] = NULL;
if (squash)
argv[1] = "1";
else
argv[1] = "0";
argv[2] = NULL;
memset(&hook, 0, sizeof(hook));
hook.argv = argv;
hook.no_stdin = 1;
hook.stdout_to_stderr = 1;
hook.env = env;
return run_command(&hook);
}
static void finish(const unsigned char *new_head, const char *msg)
{
struct strbuf reflog_message;
strbuf_init(&reflog_message, 0);
if (!msg)
strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
else {
printf("%s\n", msg);
strbuf_addf(&reflog_message, "%s: %s",
getenv("GIT_REFLOG_ACTION"), msg);
}
if (squash) {
squash_message();
} else {
if (!merge_msg.len)
printf("No merge message -- not updating HEAD\n");
else {
const char *argv_gc_auto[] = { "gc", "--auto", NULL };
update_ref(reflog_message.buf, "HEAD",
new_head, head, 0,
DIE_ON_ERR);
/*
* We ignore errors in 'gc --auto', since the
* user should see them.
*/
run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
}
}
if (new_head && show_diffstat) {
struct diff_options opts;
diff_setup(&opts);
opts.output_format |=
DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
opts.detect_rename = DIFF_DETECT_RENAME;
if (diff_use_color_default > 0)
DIFF_OPT_SET(&opts, COLOR_DIFF);
if (diff_setup_done(&opts) < 0)
die("diff_setup_done failed");
diff_tree_sha1(head, new_head, "", &opts);
diffcore_std(&opts);
diff_flush(&opts);
}
/* Run a post-merge hook */
run_hook("post-merge");
strbuf_release(&reflog_message);
}
/* Get the name for the merge commit's message. */
static void merge_name(const char *remote, struct strbuf *msg)
{
struct object *remote_head;
unsigned char branch_head[20], buf_sha[20];
struct strbuf buf;
const char *ptr;
int len, early;
memset(branch_head, 0, sizeof(branch_head));
remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
if (!remote_head)
die("'%s' does not point to a commit", remote);
strbuf_init(&buf, 0);
strbuf_addstr(&buf, "refs/heads/");
strbuf_addstr(&buf, remote);
resolve_ref(buf.buf, branch_head, 0, 0);
if (!hashcmp(remote_head->sha1, branch_head)) {
strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
sha1_to_hex(branch_head), remote);
return;
}
/* See if remote matches <name>^^^.. or <name>~<number> */
for (len = 0, ptr = remote + strlen(remote);
remote < ptr && ptr[-1] == '^';
ptr--)
len++;
if (len)
early = 1;
else {
early = 0;
ptr = strrchr(remote, '~');
if (ptr) {
int seen_nonzero = 0;
len++; /* count ~ */
while (*++ptr && isdigit(*ptr)) {
seen_nonzero |= (*ptr != '0');
len++;
}
if (*ptr)
len = 0; /* not ...~<number> */
else if (seen_nonzero)
early = 1;
else if (len == 1)
early = 1; /* "name~" is "name~1"! */
}
}
if (len) {
struct strbuf truname = STRBUF_INIT;
strbuf_addstr(&truname, "refs/heads/");
strbuf_addstr(&truname, remote);
strbuf_setlen(&truname, truname.len - len);
if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
strbuf_addf(msg,
"%s\t\tbranch '%s'%s of .\n",
sha1_to_hex(remote_head->sha1),
truname.buf + 11,
(early ? " (early part)" : ""));
return;
}
}
if (!strcmp(remote, "FETCH_HEAD") &&
!access(git_path("FETCH_HEAD"), R_OK)) {
FILE *fp;
struct strbuf line;
char *ptr;
strbuf_init(&line, 0);
fp = fopen(git_path("FETCH_HEAD"), "r");
if (!fp)
die("could not open %s for reading: %s",
git_path("FETCH_HEAD"), strerror(errno));
strbuf_getline(&line, fp, '\n');
fclose(fp);
ptr = strstr(line.buf, "\tnot-for-merge\t");
if (ptr)
strbuf_remove(&line, ptr-line.buf+1, 13);
strbuf_addbuf(msg, &line);
strbuf_release(&line);
return;
}
strbuf_addf(msg, "%s\t\tcommit '%s'\n",
sha1_to_hex(remote_head->sha1), remote);
}
static int git_merge_config(const char *k, const char *v, void *cb)
{
if (branch && !prefixcmp(k, "branch.") &&
!prefixcmp(k + 7, branch) &&
!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
const char **argv;
int argc;
char *buf;
buf = xstrdup(v);
argc = split_cmdline(buf, &argv);
argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
argc++;
parse_options(argc, argv, builtin_merge_options,
builtin_merge_usage, 0);
free(buf);
}
if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
show_diffstat = git_config_bool(k, v);
else if (!strcmp(k, "pull.twohead"))
return git_config_string(&pull_twohead, k, v);
else if (!strcmp(k, "pull.octopus"))
return git_config_string(&pull_octopus, k, v);
else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
option_log = git_config_bool(k, v);
return git_diff_ui_config(k, v, cb);
}
static int read_tree_trivial(unsigned char *common, unsigned char *head,
unsigned char *one)
{
int i, nr_trees = 0;
struct tree *trees[MAX_UNPACK_TREES];
struct tree_desc t[MAX_UNPACK_TREES];
struct unpack_trees_options opts;
memset(&opts, 0, sizeof(opts));
opts.head_idx = 2;
opts.src_index = &the_index;
opts.dst_index = &the_index;
opts.update = 1;
opts.verbose_update = 1;
opts.trivial_merges_only = 1;
opts.merge = 1;
trees[nr_trees] = parse_tree_indirect(common);
if (!trees[nr_trees++])
return -1;
trees[nr_trees] = parse_tree_indirect(head);
if (!trees[nr_trees++])
return -1;
trees[nr_trees] = parse_tree_indirect(one);
if (!trees[nr_trees++])
return -1;
opts.fn = threeway_merge;
cache_tree_free(&active_cache_tree);
for (i = 0; i < nr_trees; i++) {
parse_tree(trees[i]);
init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
}
if (unpack_trees(nr_trees, t, &opts))
return -1;
return 0;
}
static void write_tree_trivial(unsigned char *sha1)
{
if (write_cache_as_tree(sha1, 0, NULL))
die("git write-tree failed to write a tree");
}
static int try_merge_strategy(const char *strategy, struct commit_list *common,
const char *head_arg)
{
const char **args;
int i = 0, ret;
struct commit_list *j;
struct strbuf buf;
args = xmalloc((4 + commit_list_count(common) +
commit_list_count(remoteheads)) * sizeof(char *));
strbuf_init(&buf, 0);
strbuf_addf(&buf, "merge-%s", strategy);
args[i++] = buf.buf;
for (j = common; j; j = j->next)
args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
args[i++] = "--";
args[i++] = head_arg;
for (j = remoteheads; j; j = j->next)
args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
args[i] = NULL;
ret = run_command_v_opt(args, RUN_GIT_CMD);
strbuf_release(&buf);
i = 1;
for (j = common; j; j = j->next)
free((void *)args[i++]);
i += 2;
for (j = remoteheads; j; j = j->next)
free((void *)args[i++]);
free(args);
return -ret;
}
static void count_diff_files(struct diff_queue_struct *q,
struct diff_options *opt, void *data)
{
int *count = data;
(*count) += q->nr;
}
static int count_unmerged_entries(void)
{
const struct index_state *state = &the_index;
int i, ret = 0;
for (i = 0; i < state->cache_nr; i++)
if (ce_stage(state->cache[i]))
ret++;
return ret;
}
static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
{
struct tree *trees[MAX_UNPACK_TREES];
struct unpack_trees_options opts;
struct tree_desc t[MAX_UNPACK_TREES];
int i, fd, nr_trees = 0;
struct dir_struct dir;
struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
refresh_cache(REFRESH_QUIET);
fd = hold_locked_index(lock_file, 1);
memset(&trees, 0, sizeof(trees));
memset(&opts, 0, sizeof(opts));
memset(&t, 0, sizeof(t));
memset(&dir, 0, sizeof(dir));
dir.show_ignored = 1;
dir.exclude_per_dir = ".gitignore";
opts.dir = &dir;
opts.head_idx = 1;
opts.src_index = &the_index;
opts.dst_index = &the_index;
opts.update = 1;
opts.verbose_update = 1;
opts.merge = 1;
opts.fn = twoway_merge;
trees[nr_trees] = parse_tree_indirect(head);
if (!trees[nr_trees++])
return -1;
trees[nr_trees] = parse_tree_indirect(remote);
if (!trees[nr_trees++])
return -1;
for (i = 0; i < nr_trees; i++) {
parse_tree(trees[i]);
init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
}
if (unpack_trees(nr_trees, t, &opts))
return -1;
if (write_cache(fd, active_cache, active_nr) ||
commit_locked_index(lock_file))
die("unable to write new index file");
return 0;
}
static void split_merge_strategies(const char *string, struct strategy **list,
int *nr, int *alloc)
{
char *p, *q, *buf;
if (!string)
return;
buf = xstrdup(string);
q = buf;
for (;;) {
p = strchr(q, ' ');
if (!p) {
ALLOC_GROW(*list, *nr + 1, *alloc);
(*list)[(*nr)++].name = xstrdup(q);
free(buf);
return;
} else {
*p = '\0';
ALLOC_GROW(*list, *nr + 1, *alloc);
(*list)[(*nr)++].name = xstrdup(q);
q = ++p;
}
}
}
static void add_strategies(const char *string, unsigned attr)
{
struct strategy *list = NULL;
int list_alloc = 0, list_nr = 0, i;
memset(&list, 0, sizeof(list));
split_merge_strategies(string, &list, &list_nr, &list_alloc);
if (list) {
for (i = 0; i < list_nr; i++)
append_strategy(get_strategy(list[i].name));
return;
}
for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
if (all_strategy[i].attr & attr)
append_strategy(&all_strategy[i]);
}
static int merge_trivial(void)
{
unsigned char result_tree[20], result_commit[20];
struct commit_list *parent = xmalloc(sizeof(struct commit_list *));
write_tree_trivial(result_tree);
printf("Wonderful.\n");
parent->item = lookup_commit(head);
parent->next = xmalloc(sizeof(struct commit_list *));
parent->next->item = remoteheads->item;
parent->next->next = NULL;
commit_tree(merge_msg.buf, result_tree, parent, result_commit);
finish(result_commit, "In-index merge");
drop_save();
return 0;
}
static int finish_automerge(struct commit_list *common,
unsigned char *result_tree,
const char *wt_strategy)
{
struct commit_list *parents = NULL, *j;
struct strbuf buf = STRBUF_INIT;
unsigned char result_commit[20];
free_commit_list(common);
if (allow_fast_forward) {
parents = remoteheads;
commit_list_insert(lookup_commit(head), &parents);
parents = reduce_heads(parents);
} else {
struct commit_list **pptr = &parents;
pptr = &commit_list_insert(lookup_commit(head),
pptr)->next;
for (j = remoteheads; j; j = j->next)
pptr = &commit_list_insert(j->item, pptr)->next;
}
free_commit_list(remoteheads);
strbuf_addch(&merge_msg, '\n');
commit_tree(merge_msg.buf, result_tree, parents, result_commit);
strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
finish(result_commit, buf.buf);
strbuf_release(&buf);
drop_save();
return 0;
}
static int suggest_conflicts(void)
{
FILE *fp;
int pos;
fp = fopen(git_path("MERGE_MSG"), "a");
if (!fp)
die("Could open %s for writing", git_path("MERGE_MSG"));
fprintf(fp, "\nConflicts:\n");
for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
if (ce_stage(ce)) {
fprintf(fp, "\t%s\n", ce->name);
while (pos + 1 < active_nr &&
!strcmp(ce->name,
active_cache[pos + 1]->name))
pos++;
}
}
fclose(fp);
rerere();
printf("Automatic merge failed; "
"fix conflicts and then commit the result.\n");
return 1;
}
static struct commit *is_old_style_invocation(int argc, const char **argv)
{
struct commit *second_token = NULL;
if (argc > 1) {
unsigned char second_sha1[20];
if (get_sha1(argv[1], second_sha1))
return NULL;
second_token = lookup_commit_reference_gently(second_sha1, 0);
if (!second_token)
die("'%s' is not a commit", argv[1]);
if (hashcmp(second_token->object.sha1, head))
return NULL;
}
return second_token;
}
static int evaluate_result(void)
{
int cnt = 0;
struct rev_info rev;
discard_cache();
if (read_cache() < 0)
die("failed to read the cache");
/* Check how many files differ. */
init_revisions(&rev, "");
setup_revisions(0, NULL, &rev, NULL);
rev.diffopt.output_format |=
DIFF_FORMAT_CALLBACK;
rev.diffopt.format_callback = count_diff_files;
rev.diffopt.format_callback_data = &cnt;
run_diff_files(&rev, 0);
/*
* Check how many unmerged entries are
* there.
*/
cnt += count_unmerged_entries();
return cnt;
}
int cmd_merge(int argc, const char **argv, const char *prefix)
{
unsigned char result_tree[20];
struct strbuf buf;
const char *head_arg;
int flag, head_invalid = 0, i;
int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
struct commit_list *common = NULL;
const char *best_strategy = NULL, *wt_strategy = NULL;
struct commit_list **remotes = &remoteheads;
setup_work_tree();
if (read_cache_unmerged())
die("You are in the middle of a conflicted merge.");
/*
* Check if we are _not_ on a detached HEAD, i.e. if there is a
* current branch.
*/
branch = resolve_ref("HEAD", head, 0, &flag);
if (branch && !prefixcmp(branch, "refs/heads/"))
branch += 11;
if (is_null_sha1(head))
head_invalid = 1;
git_config(git_merge_config, NULL);
/* for color.ui */
if (diff_use_color_default == -1)
diff_use_color_default = git_use_color_default;
argc = parse_options(argc, argv, builtin_merge_options,
builtin_merge_usage, 0);
if (squash) {
if (!allow_fast_forward)
die("You cannot combine --squash with --no-ff.");
option_commit = 0;
}
if (!argc)
usage_with_options(builtin_merge_usage,
builtin_merge_options);
/*
* This could be traditional "merge <msg> HEAD <commit>..." and
* the way we can tell it is to see if the second token is HEAD,
* but some people might have misused the interface and used a
* committish that is the same as HEAD there instead.
* Traditional format never would have "-m" so it is an
* additional safety measure to check for it.
*/
strbuf_init(&buf, 0);
if (!have_message && is_old_style_invocation(argc, argv)) {
strbuf_addstr(&merge_msg, argv[0]);
head_arg = argv[1];
argv += 2;
argc -= 2;
} else if (head_invalid) {
struct object *remote_head;
/*
* If the merged head is a valid one there is no reason
* to forbid "git merge" into a branch yet to be born.
* We do the same for "git pull".
*/
if (argc != 1)
die("Can merge only exactly one commit into "
"empty head");
remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
if (!remote_head)
die("%s - not something we can merge", argv[0]);
update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
DIE_ON_ERR);
reset_hard(remote_head->sha1, 0);
return 0;
} else {
struct strbuf msg;
/* We are invoked directly as the first-class UI. */
head_arg = "HEAD";
/*
* All the rest are the commits being merged;
* prepare the standard merge summary message to
* be appended to the given message. If remote
* is invalid we will die later in the common
* codepath so we discard the error in this
* loop.
*/
strbuf_init(&msg, 0);
for (i = 0; i < argc; i++)
merge_name(argv[i], &msg);
fmt_merge_msg(option_log, &msg, &merge_msg);
if (merge_msg.len)
strbuf_setlen(&merge_msg, merge_msg.len-1);
}
if (head_invalid || !argc)
usage_with_options(builtin_merge_usage,
builtin_merge_options);
strbuf_addstr(&buf, "merge");
for (i = 0; i < argc; i++)
strbuf_addf(&buf, " %s", argv[i]);
setenv("GIT_REFLOG_ACTION", buf.buf, 0);
strbuf_reset(&buf);
for (i = 0; i < argc; i++) {
struct object *o;
o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
if (!o)
die("%s - not something we can merge", argv[i]);
remotes = &commit_list_insert(lookup_commit(o->sha1),
remotes)->next;
strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
setenv(buf.buf, argv[i], 1);
strbuf_reset(&buf);
}
if (!use_strategies) {
if (!remoteheads->next)
add_strategies(pull_twohead, DEFAULT_TWOHEAD);
else
add_strategies(pull_octopus, DEFAULT_OCTOPUS);
}
for (i = 0; i < use_strategies_nr; i++) {
if (use_strategies[i]->attr & NO_FAST_FORWARD)
allow_fast_forward = 0;
if (use_strategies[i]->attr & NO_TRIVIAL)
allow_trivial = 0;
}
if (!remoteheads->next)
common = get_merge_bases(lookup_commit(head),
remoteheads->item, 1);
else {
struct commit_list *list = remoteheads;
commit_list_insert(lookup_commit(head), &list);
common = get_octopus_merge_bases(list);
free(list);
}
update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
DIE_ON_ERR);
if (!common)
; /* No common ancestors found. We need a real merge. */
else if (!remoteheads->next && !common->next &&
common->item == remoteheads->item) {
/*
* If head can reach all the merge then we are up to date.
* but first the most common case of merging one remote.
*/
finish_up_to_date("Already up-to-date.");
return 0;
} else if (allow_fast_forward && !remoteheads->next &&
!common->next &&
!hashcmp(common->item->object.sha1, head)) {
/* Again the most common case of merging one remote. */
struct strbuf msg;
struct object *o;
char hex[41];
strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
printf("Updating %s..%s\n",
hex,
find_unique_abbrev(remoteheads->item->object.sha1,
DEFAULT_ABBREV));
strbuf_init(&msg, 0);
strbuf_addstr(&msg, "Fast forward");
if (have_message)
strbuf_addstr(&msg,
" (no commit created; -m option ignored)");
o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
0, NULL, OBJ_COMMIT);
if (!o)
return 1;
if (checkout_fast_forward(head, remoteheads->item->object.sha1))
return 1;
finish(o->sha1, msg.buf);
drop_save();
return 0;
} else if (!remoteheads->next && common->next)
;
/*
* We are not doing octopus and not fast forward. Need
* a real merge.
*/
else if (!remoteheads->next && !common->next && option_commit) {
/*
* We are not doing octopus, not fast forward, and have
* only one common.
*/
refresh_cache(REFRESH_QUIET);
if (allow_trivial) {
/* See if it is really trivial. */
git_committer_info(IDENT_ERROR_ON_NO_NAME);
printf("Trying really trivial in-index merge...\n");
if (!read_tree_trivial(common->item->object.sha1,
head, remoteheads->item->object.sha1))
return merge_trivial();
printf("Nope.\n");
}
} else {
/*
* An octopus. If we can reach all the remote we are up
* to date.
*/
int up_to_date = 1;
struct commit_list *j;
for (j = remoteheads; j; j = j->next) {
struct commit_list *common_one;
/*
* Here we *have* to calculate the individual
* merge_bases again, otherwise "git merge HEAD^
* HEAD^^" would be missed.
*/
common_one = get_merge_bases(lookup_commit(head),
j->item, 1);
if (hashcmp(common_one->item->object.sha1,
j->item->object.sha1)) {
up_to_date = 0;
break;
}
}
if (up_to_date) {
finish_up_to_date("Already up-to-date. Yeeah!");
return 0;
}
}
/* We are going to make a new commit. */
git_committer_info(IDENT_ERROR_ON_NO_NAME);
/*
* At this point, we need a real merge. No matter what strategy
* we use, it would operate on the index, possibly affecting the
* working tree, and when resolved cleanly, have the desired
* tree in the index -- this means that the index must be in
* sync with the head commit. The strategies are responsible
* to ensure this.
*/
if (use_strategies_nr != 1) {
/*
* Stash away the local changes so that we can try more
* than one.
*/
save_state();
} else {
memcpy(stash, null_sha1, 20);
}
for (i = 0; i < use_strategies_nr; i++) {
int ret;
if (i) {
printf("Rewinding the tree to pristine...\n");
restore_state();
}
if (use_strategies_nr != 1)
printf("Trying merge strategy %s...\n",
use_strategies[i]->name);
/*
* Remember which strategy left the state in the working
* tree.
*/
wt_strategy = use_strategies[i]->name;
ret = try_merge_strategy(use_strategies[i]->name,
common, head_arg);
if (!option_commit && !ret) {
merge_was_ok = 1;
/*
* This is necessary here just to avoid writing
* the tree, but later we will *not* exit with
* status code 1 because merge_was_ok is set.
*/
ret = 1;
}
if (ret) {
/*
* The backend exits with 1 when conflicts are
* left to be resolved, with 2 when it does not
* handle the given merge at all.
*/
if (ret == 1) {
int cnt = evaluate_result();
if (best_cnt <= 0 || cnt <= best_cnt) {
best_strategy = use_strategies[i]->name;
best_cnt = cnt;
}
}
if (merge_was_ok)
break;
else
continue;
}
/* Automerge succeeded. */
discard_cache();
write_tree_trivial(result_tree);
automerge_was_ok = 1;
break;
}
/*
* If we have a resulting tree, that means the strategy module
* auto resolved the merge cleanly.
*/
if (automerge_was_ok)
return finish_automerge(common, result_tree, wt_strategy);
/*
* Pick the result from the best strategy and have the user fix
* it up.
*/
if (!best_strategy) {
restore_state();
if (use_strategies_nr > 1)
fprintf(stderr,
"No merge strategy handled the merge.\n");
else
fprintf(stderr, "Merge with strategy %s failed.\n",
use_strategies[0]->name);
return 2;
} else if (best_strategy == wt_strategy)
; /* We already have its result in the working tree. */
else {
printf("Rewinding the tree to pristine...\n");
restore_state();
printf("Using the %s to prepare resolving by hand.\n",
best_strategy);
try_merge_strategy(best_strategy, common, head_arg);
}
if (squash)
finish(NULL, NULL);
else {
int fd;
struct commit_list *j;
for (j = remoteheads; j; j = j->next)
strbuf_addf(&buf, "%s\n",
sha1_to_hex(j->item->object.sha1));
fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
if (fd < 0)
die("Could open %s for writing",
git_path("MERGE_HEAD"));
if (write_in_full(fd, buf.buf, buf.len) != buf.len)
die("Could not write to %s", git_path("MERGE_HEAD"));
close(fd);
strbuf_addch(&merge_msg, '\n');
fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
if (fd < 0)
die("Could open %s for writing", git_path("MERGE_MSG"));
if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
merge_msg.len)
die("Could not write to %s", git_path("MERGE_MSG"));
close(fd);
}
if (merge_was_ok) {
fprintf(stderr, "Automatic merge went well; "
"stopped before committing as requested\n");
return 0;
} else
return suggest_conflicts();
}