git/builtin-checkout.c
Junio C Hamano 291d823e36 checkout: "best effort" checkout
When unpack_trees() returned an error while switching branches, we used to
stop right there, exiting without writing the index out or switching HEAD.

This is Ok when unpack_trees() returned an error because it detected
untracked files or locally modified paths that could be overwritten by
branch switching, because that error return is done before we start to
modify the work tree.  But it is undesirable if unpack_trees() already
started to update the work tree and a failure is returned because some but
not all paths are updated in the work tree, perhaps because a directory
that some files need to go in was read-only by mistake, or a file that
will be overwritten by branch switching had a mandatory lock on it and we
failed to unlink it.

This changes the behaviour upon such an error to complete the branch
switching; the files updated in the work tree will hopefully be much more
consistent with the index and HEAD derived from the switched-to branch.

We still issue error messages, and exit the command with non-zero status,
so scripted callers need to notice it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-29 17:35:22 -07:00

579 lines
15 KiB
C

#include "cache.h"
#include "builtin.h"
#include "parse-options.h"
#include "refs.h"
#include "commit.h"
#include "tree.h"
#include "tree-walk.h"
#include "unpack-trees.h"
#include "dir.h"
#include "run-command.h"
#include "merge-recursive.h"
#include "branch.h"
#include "diff.h"
#include "revision.h"
#include "remote.h"
static const char * const checkout_usage[] = {
"git checkout [options] <branch>",
"git checkout [options] [<branch>] -- <file>...",
NULL,
};
static int post_checkout_hook(struct commit *old, struct commit *new,
int changed)
{
struct child_process proc;
const char *name = git_path("hooks/post-checkout");
const char *argv[5];
if (access(name, X_OK) < 0)
return 0;
memset(&proc, 0, sizeof(proc));
argv[0] = name;
argv[1] = xstrdup(sha1_to_hex(old->object.sha1));
argv[2] = xstrdup(sha1_to_hex(new->object.sha1));
argv[3] = changed ? "1" : "0";
argv[4] = NULL;
proc.argv = argv;
proc.no_stdin = 1;
proc.stdout_to_stderr = 1;
return run_command(&proc);
}
static int update_some(const unsigned char *sha1, const char *base, int baselen,
const char *pathname, unsigned mode, int stage)
{
int len;
struct cache_entry *ce;
if (S_ISGITLINK(mode))
return 0;
if (S_ISDIR(mode))
return READ_TREE_RECURSIVE;
len = baselen + strlen(pathname);
ce = xcalloc(1, cache_entry_size(len));
hashcpy(ce->sha1, sha1);
memcpy(ce->name, base, baselen);
memcpy(ce->name + baselen, pathname, len - baselen);
ce->ce_flags = create_ce_flags(len, 0);
ce->ce_mode = create_ce_mode(mode);
add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
return 0;
}
static int read_tree_some(struct tree *tree, const char **pathspec)
{
read_tree_recursive(tree, "", 0, 0, pathspec, update_some);
/* update the index with the given tree's info
* for all args, expanding wildcards, and exit
* with any non-zero return code.
*/
return 0;
}
static int checkout_paths(struct tree *source_tree, const char **pathspec)
{
int pos;
struct checkout state;
static char *ps_matched;
unsigned char rev[20];
int flag;
struct commit *head;
int errs = 0;
int newfd;
struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
newfd = hold_locked_index(lock_file, 1);
read_cache();
if (source_tree)
read_tree_some(source_tree, pathspec);
for (pos = 0; pathspec[pos]; pos++)
;
ps_matched = xcalloc(1, pos);
for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
pathspec_match(pathspec, ps_matched, ce->name, 0);
}
if (report_path_error(ps_matched, pathspec, 0))
return 1;
/* Now we are committed to check them out */
memset(&state, 0, sizeof(state));
state.force = 1;
state.refresh_cache = 1;
for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
if (pathspec_match(pathspec, NULL, ce->name, 0)) {
errs |= checkout_entry(ce, &state, NULL);
}
}
if (write_cache(newfd, active_cache, active_nr) ||
commit_locked_index(lock_file))
die("unable to write new index file");
resolve_ref("HEAD", rev, 0, &flag);
head = lookup_commit_reference_gently(rev, 1);
errs |= post_checkout_hook(head, head, 0);
return errs;
}
static void show_local_changes(struct object *head)
{
struct rev_info rev;
/* I think we want full paths, even if we're in a subdirectory. */
init_revisions(&rev, NULL);
rev.abbrev = 0;
rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
add_pending_object(&rev, head, NULL);
run_diff_index(&rev, 0);
}
static void describe_detached_head(char *msg, struct commit *commit)
{
struct strbuf sb;
strbuf_init(&sb, 0);
parse_commit(commit);
pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
fprintf(stderr, "%s %s... %s\n", msg,
find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
strbuf_release(&sb);
}
struct checkout_opts {
int quiet;
int merge;
int force;
int writeout_error;
char *new_branch;
int new_branch_log;
enum branch_track track;
};
static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
{
struct unpack_trees_options opts;
struct tree_desc tree_desc;
memset(&opts, 0, sizeof(opts));
opts.head_idx = -1;
opts.update = worktree;
opts.skip_unmerged = !worktree;
opts.reset = 1;
opts.merge = 1;
opts.fn = oneway_merge;
opts.verbose_update = !o->quiet;
opts.src_index = &the_index;
opts.dst_index = &the_index;
parse_tree(tree);
init_tree_desc(&tree_desc, tree->buffer, tree->size);
switch (unpack_trees(1, &tree_desc, &opts)) {
case -2:
o->writeout_error = 1;
/*
* We return 0 nevertheless, as the index is all right
* and more importantly we have made best efforts to
* update paths in the work tree, and we cannot revert
* them.
*/
case 0:
return 0;
default:
return 128;
}
}
struct branch_info {
const char *name; /* The short name used */
const char *path; /* The full name of a real branch */
struct commit *commit; /* The named commit */
};
static void setup_branch_path(struct branch_info *branch)
{
struct strbuf buf;
strbuf_init(&buf, 0);
strbuf_addstr(&buf, "refs/heads/");
strbuf_addstr(&buf, branch->name);
branch->path = strbuf_detach(&buf, NULL);
}
static int merge_working_tree(struct checkout_opts *opts,
struct branch_info *old, struct branch_info *new)
{
int ret;
struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
int newfd = hold_locked_index(lock_file, 1);
read_cache();
if (opts->force) {
ret = reset_tree(new->commit->tree, opts, 1);
if (ret)
return ret;
} else {
struct tree_desc trees[2];
struct tree *tree;
struct unpack_trees_options topts;
memset(&topts, 0, sizeof(topts));
topts.head_idx = -1;
topts.src_index = &the_index;
topts.dst_index = &the_index;
topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
refresh_cache(REFRESH_QUIET);
if (unmerged_cache()) {
error("you need to resolve your current index first");
return 1;
}
/* 2-way merge to the new branch */
topts.update = 1;
topts.merge = 1;
topts.gently = opts->merge;
topts.verbose_update = !opts->quiet;
topts.fn = twoway_merge;
topts.dir = xcalloc(1, sizeof(*topts.dir));
topts.dir->show_ignored = 1;
topts.dir->exclude_per_dir = ".gitignore";
tree = parse_tree_indirect(old->commit->object.sha1);
init_tree_desc(&trees[0], tree->buffer, tree->size);
tree = parse_tree_indirect(new->commit->object.sha1);
init_tree_desc(&trees[1], tree->buffer, tree->size);
ret = unpack_trees(2, trees, &topts);
if (ret == -1) {
/*
* Unpack couldn't do a trivial merge; either
* give up or do a real merge, depending on
* whether the merge flag was used.
*/
struct tree *result;
struct tree *work;
if (!opts->merge)
return 1;
parse_commit(old->commit);
/* Do more real merge */
/*
* We update the index fully, then write the
* tree from the index, then merge the new
* branch with the current tree, with the old
* branch as the base. Then we reset the index
* (but not the working tree) to the new
* branch, leaving the working tree as the
* merged version, but skipping unmerged
* entries in the index.
*/
add_files_to_cache(NULL, NULL, 0);
work = write_tree_from_memory();
ret = reset_tree(new->commit->tree, opts, 1);
if (ret)
return ret;
merge_trees(new->commit->tree, work, old->commit->tree,
new->name, "local", &result);
ret = reset_tree(new->commit->tree, opts, 0);
if (ret)
return ret;
}
}
if (write_cache(newfd, active_cache, active_nr) ||
commit_locked_index(lock_file))
die("unable to write new index file");
if (!opts->force)
show_local_changes(&new->commit->object);
return 0;
}
static void report_tracking(struct branch_info *new, struct checkout_opts *opts)
{
/*
* We have switched to a new branch; is it building on
* top of another branch, and if so does that other branch
* have changes we do not have yet?
*/
char *base;
unsigned char sha1[20];
struct commit *ours, *theirs;
char symmetric[84];
struct rev_info revs;
const char *rev_argv[10];
int rev_argc;
int num_ours, num_theirs;
const char *remote_msg;
struct branch *branch = branch_get(new->name);
/*
* Nothing to report unless we are marked to build on top of
* somebody else.
*/
if (!branch || !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
return;
/*
* If what we used to build on no longer exists, there is
* nothing to report.
*/
base = branch->merge[0]->dst;
if (!resolve_ref(base, sha1, 1, NULL))
return;
theirs = lookup_commit(sha1);
ours = new->commit;
if (!hashcmp(sha1, ours->object.sha1))
return; /* we are the same */
/* Run "rev-list --left-right ours...theirs" internally... */
rev_argc = 0;
rev_argv[rev_argc++] = NULL;
rev_argv[rev_argc++] = "--left-right";
rev_argv[rev_argc++] = symmetric;
rev_argv[rev_argc++] = "--";
rev_argv[rev_argc] = NULL;
strcpy(symmetric, sha1_to_hex(ours->object.sha1));
strcpy(symmetric + 40, "...");
strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
init_revisions(&revs, NULL);
setup_revisions(rev_argc, rev_argv, &revs, NULL);
prepare_revision_walk(&revs);
/* ... and count the commits on each side. */
num_ours = 0;
num_theirs = 0;
while (1) {
struct commit *c = get_revision(&revs);
if (!c)
break;
if (c->object.flags & SYMMETRIC_LEFT)
num_ours++;
else
num_theirs++;
}
if (!prefixcmp(base, "refs/remotes/")) {
remote_msg = " remote";
base += strlen("refs/remotes/");
} else {
remote_msg = "";
}
if (!num_theirs)
printf("Your branch is ahead of the tracked%s branch '%s' "
"by %d commit%s.\n",
remote_msg, base,
num_ours, (num_ours == 1) ? "" : "s");
else if (!num_ours)
printf("Your branch is behind the tracked%s branch '%s' "
"by %d commit%s,\n"
"and can be fast-forwarded.\n",
remote_msg, base,
num_theirs, (num_theirs == 1) ? "" : "s");
else
printf("Your branch and the tracked%s branch '%s' "
"have diverged,\nand respectively "
"have %d and %d different commit(s) each.\n",
remote_msg, base,
num_ours, num_theirs);
}
static void update_refs_for_switch(struct checkout_opts *opts,
struct branch_info *old,
struct branch_info *new)
{
struct strbuf msg;
const char *old_desc;
if (opts->new_branch) {
create_branch(old->name, opts->new_branch, new->name, 0,
opts->new_branch_log, opts->track);
new->name = opts->new_branch;
setup_branch_path(new);
}
strbuf_init(&msg, 0);
old_desc = old->name;
if (!old_desc)
old_desc = sha1_to_hex(old->commit->object.sha1);
strbuf_addf(&msg, "checkout: moving from %s to %s",
old_desc, new->name);
if (new->path) {
create_symref("HEAD", new->path, msg.buf);
if (!opts->quiet) {
if (old->path && !strcmp(new->path, old->path))
fprintf(stderr, "Already on \"%s\"\n",
new->name);
else
fprintf(stderr, "Switched to%s branch \"%s\"\n",
opts->new_branch ? " a new" : "",
new->name);
}
} else if (strcmp(new->name, "HEAD")) {
update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
REF_NODEREF, DIE_ON_ERR);
if (!opts->quiet) {
if (old->path)
fprintf(stderr, "Note: moving to \"%s\" which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n git checkout -b <new_branch_name>\n", new->name);
describe_detached_head("HEAD is now at", new->commit);
}
}
remove_branch_state();
strbuf_release(&msg);
if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
report_tracking(new, opts);
}
static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
{
int ret = 0;
struct branch_info old;
unsigned char rev[20];
int flag;
memset(&old, 0, sizeof(old));
old.path = resolve_ref("HEAD", rev, 0, &flag);
old.commit = lookup_commit_reference_gently(rev, 1);
if (!(flag & REF_ISSYMREF))
old.path = NULL;
if (old.path && !prefixcmp(old.path, "refs/heads/"))
old.name = old.path + strlen("refs/heads/");
if (!new->name) {
new->name = "HEAD";
new->commit = old.commit;
if (!new->commit)
die("You are on a branch yet to be born");
parse_commit(new->commit);
}
/*
* If the new thing isn't a branch and isn't HEAD and we're
* not starting a new branch, and we want messages, and we
* weren't on a branch, and we're moving to a new commit,
* describe the old commit.
*/
if (!new->path && strcmp(new->name, "HEAD") && !opts->new_branch &&
!opts->quiet && !old.path && new->commit != old.commit)
describe_detached_head("Previous HEAD position was", old.commit);
if (!old.commit) {
if (!opts->quiet) {
fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);
}
opts->force = 1;
}
ret = merge_working_tree(opts, &old, new);
if (ret)
return ret;
update_refs_for_switch(opts, &old, new);
ret = post_checkout_hook(old.commit, new->commit, 1);
return ret || opts->writeout_error;
}
int cmd_checkout(int argc, const char **argv, const char *prefix)
{
struct checkout_opts opts;
unsigned char rev[20];
const char *arg;
struct branch_info new;
struct tree *source_tree = NULL;
struct option options[] = {
OPT__QUIET(&opts.quiet),
OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
OPT_SET_INT('t', "track", &opts.track, "track",
BRANCH_TRACK_EXPLICIT),
OPT_BOOLEAN('f', NULL, &opts.force, "force"),
OPT_BOOLEAN('m', NULL, &opts.merge, "merge"),
OPT_END(),
};
memset(&opts, 0, sizeof(opts));
memset(&new, 0, sizeof(new));
git_config(git_default_config, NULL);
opts.track = git_branch_track;
argc = parse_options(argc, argv, options, checkout_usage, 0);
if (argc) {
arg = argv[0];
if (get_sha1(arg, rev))
;
else if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
new.name = arg;
setup_branch_path(&new);
if (resolve_ref(new.path, rev, 1, NULL))
new.commit = lookup_commit_reference(rev);
else
new.path = NULL;
parse_commit(new.commit);
source_tree = new.commit->tree;
argv++;
argc--;
} else if ((source_tree = parse_tree_indirect(rev))) {
argv++;
argc--;
}
}
if (argc && !strcmp(argv[0], "--")) {
argv++;
argc--;
}
if (!opts.new_branch && (opts.track != git_branch_track))
die("git checkout: --track and --no-track require -b");
if (opts.force && opts.merge)
die("git checkout: -f and -m are incompatible");
if (argc) {
const char **pathspec = get_pathspec(prefix, argv);
if (!pathspec)
die("invalid path specification");
/* Checkout paths */
if (opts.new_branch || opts.force || opts.merge) {
if (argc == 1) {
die("git checkout: updating paths is incompatible with switching branches/forcing\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
} else {
die("git checkout: updating paths is incompatible with switching branches/forcing");
}
}
return checkout_paths(source_tree, pathspec);
}
if (new.name && !new.commit) {
die("Cannot switch branch to a non-commit.");
}
return switch_branches(&opts, &new);
}