Hi Joel,
On Wed, 4 Apr 2018, Joel Teichroeb wrote:
> Add a bulitin helper for performing stash commands. Converting
> all at once proved hard to review, so starting with just apply
> let conversion get started without the other command being
s/let/lets the/ s/command/commands/
> finished.
>
> The helper is being implemented as a drop in replacement for
> stash so that when it is complete it can simply be renamed and
> the shell script deleted.
>
> Delete the contents of the apply_stash shell function and replace
> it with a call to stash--helper apply until pop is also
> converted.
>
> [...]
>
> diff --git a/builtin/stash--helper.c b/builtin/stash--helper.c
> new file mode 100644
> index 0000000000..9d00a9547d
> --- /dev/null
> +++ b/builtin/stash--helper.c
> @@ -0,0 +1,431 @@
> +#include "builtin.h"
> +#include "config.h"
> +#include "parse-options.h"
> +#include "refs.h"
> +#include "lockfile.h"
> +#include "cache-tree.h"
> +#include "unpack-trees.h"
> +#include "merge-recursive.h"
> +#include "argv-array.h"
> +#include "run-command.h"
> +#include "dir.h"
> +#include "rerere.h"
> +
> +static const char * const git_stash_helper_usage[] = {
Note to other reviewers: while it would appear that our convention is
usually to cuddle the `*` with the identifier afterwards (i.e. `char
*const` instead of `char * const`), it would *also* appear that we somehow
prefer spaces on both sides when it comes to the _usage:
$ git grep 'usage\[' builtin/*.c | grep -c ' \* '
88
$ git grep 'usage\[' builtin/*.c | grep -c ' \*[^ ]'
18
So much to clean up and make more consistent... (not your problem, Joel)
> + N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
> + NULL
> +};
> +
> +static const char * const git_stash_helper_apply_usage[] = {
> + N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
> + NULL
> +};
> +
> +static const char *ref_stash = "refs/stash";
> +static int quiet;
> +static struct strbuf stash_index_path = STRBUF_INIT;
> +
> +struct stash_info {
> + struct object_id w_commit;
> + struct object_id b_commit;
> + struct object_id i_commit;
> + struct object_id u_commit;
> + struct object_id w_tree;
> + struct object_id b_tree;
> + struct object_id i_tree;
> + struct object_id u_tree;
> + struct strbuf revision;
> + int is_stash_ref;
> + int has_u;
> +};
> +
> +static int grab_oid(struct object_id *oid, const char *fmt, const char *rev)
> +{
> + struct strbuf buf = STRBUF_INIT;
> + int ret;
> +
> + strbuf_addf(&buf, fmt, rev);
> + ret = get_oid(buf.buf, oid);
> + strbuf_release(&buf);
> + return ret;
> +}
It could be even more reusable, by using
int get_oidf(struct object_id *oid, const char *fmt, ...)
{
va_list ap;
char *p;
int ret;
va_start(ap, fmt);
p = xstrvfmt(fmt, ap);
va_end(ap);
ret = get_oid(p, oid);
free(p);
return ret;
}
Feel free to do this as a preparatory patch (it should probably live next
to get_oid()), otherwise there is always an opportunity for a
micro-project (or not so micro- one).
> +static void free_stash_info(struct stash_info *info)
> +{
> + strbuf_release(&info->revision);
> +}
> +
> +static int get_stash_info(struct stash_info *info, int argc, const char
> **argv)
> +{
> + struct strbuf symbolic = STRBUF_INIT;
> + int ret;
> + const char *revision;
> + const char *commit = NULL;
> + char *end_of_rev;
> + char *expanded_ref;
> + struct object_id discard;
I think elsewhere we prefer the name "dummy" for variables that are
assigned without really needing the values.
> +
> + if (argc > 1) {
> + int i;
> + struct strbuf refs_msg = STRBUF_INIT;
> + for (i = 0; i < argc; ++i)
> + strbuf_addf(&refs_msg, " '%s'", argv[i]);
> +
> + fprintf_ln(stderr, _("Too many revisions specified:%s"),
> refs_msg.buf);
Note to interested parties: while it may have been okay for a mere Unix
shell script to output such a message directly to stderr, in C, we need to
use `error()` and start the error message with lower-case. This should
*not* be done as part of the conversion to C, which is kind of bug-for-bug.
> + strbuf_release(&refs_msg);
> +
> + return -1;
> + }
> +
> + if (argc == 1)
> + commit = argv[0];
It is probably a bit too magical to assign `commit = argv[0]` right
away... but it would work, as `argv` is guaranteed to be NULL-terminated.
> +
> + strbuf_init(&info->revision, 0);
> + if (commit == NULL) {
We usually use `!commit` instead of `commit == NULL`. It's just the style
we use, not a judgement.
> + if (!ref_exists(ref_stash)) {
> + free_stash_info(info);
> + return error(_("No stash entries found."));
Technically, the shell version used `die`. We could use the same here,
too, but `error()` seems to be fine, too.
However, if you use `error()` here, you should use it also instead of the
`fprintf(stderr, ...);` above, for "Too many revisions specified".
Also: our convention is to start error messages lower-case because they
are prefixed with `error: `.
But in the interest of a faithful conversion to C, maybe we should start
by using `fprintf(stderr, ...)` first, and only convert to `error()` later
(because that will require changes to the test suite, too).
> + }
> +
> + strbuf_addf(&info->revision, "%s@{0}", ref_stash);
> + } else if (strspn(commit, "0123456789") == strlen(commit)) {
> + strbuf_addf(&info->revision, "%s@{%s}", ref_stash, commit);
> + } else {
> + strbuf_addstr(&info->revision, commit);
> + }
> +
> + revision = info->revision.buf;
> +
> + if (get_oid(revision, &info->w_commit)) {
> + error(_("%s is not a valid reference"), revision);
> + free_stash_info(info);
> + return -1;
> + }
> +
> + if (grab_oid(&info->b_commit, "%s^1", revision) ||
> + grab_oid(&info->w_tree, "%s:", revision) ||
> + grab_oid(&info->b_tree, "%s^1:", revision) ||
> + grab_oid(&info->i_tree, "%s^2:", revision)) {
> +
> + error(_("'%s' is not a stash-like commit"), revision);
> + free_stash_info(info);
> + return -1;
> + }
Fans of keeping Git commands in the form of Unix shell scripts, please
note that this is a deviation from the shell script, but in a good way:
before, if any of those revisions could not be parsed by `git rev-parse`,
the error would not have resulted in a fatal error. Instead, IS_STASH_LIKE
and IS_STASH_REF would have been unchanged, as would be w_commit,
b_commit, w_tree, b_tree and i_tree.
The error checking in C is much better for end users.
> + info->has_u = !grab_oid(&info->u_tree, "%s^3:", revision);
> +
> + end_of_rev = strchrnul(revision, '@');
> + strbuf_add(&symbolic, revision, end_of_rev - revision);
This is a literal translation of the shell script's `"${REV%@*}"`, but I
wonder whether we can do better in C. After all,
`refs/stash@my-laptop@{1}` is possibly a valid stash, when I called `git
fetch laptop refs/stash:refs/stash@my-laptop` regularly.
Let's see.
Nope, we really don't have anything in our "API" to peel off reflog
suffixes... Another micro-project for the future. Nothing that needs to
hold up this patch series. (I am saying this mainly for the benefit of
other reviewers...)
> +
> + ret = dwim_ref(symbolic.buf, symbolic.len, &discard, &expanded_ref);
> + strbuf_release(&symbolic);
> + switch (ret) {
> + case 0: /* Not found, but valid ref */
> + info->is_stash_ref = 0;
> + break;
> + case 1:
> + info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
> + break;
> + default: /* Invalid or ambiguous */
> + free_stash_info(info);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +static int reset_tree(struct object_id *i_tree, int update, int reset)
> +{
> + struct unpack_trees_options opts;
> + int nr_trees = 1;
> + struct tree_desc t[MAX_UNPACK_TREES];
> + struct tree *tree;
> + struct lock_file lock_file = LOCK_INIT;
> +
> + read_cache_preload(NULL);
> + if (refresh_cache(REFRESH_QUIET))
> + return -1;
> +
> + hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
> +
> + memset(&opts, 0, sizeof(opts));
> +
> + tree = parse_tree_indirect(i_tree);
> + if (parse_tree(tree))
> + return -1;
> +
> + init_tree_desc(t, tree->buffer, tree->size);
> +
> + opts.head_idx = 1;
> + opts.src_index = &the_index;
> + opts.dst_index = &the_index;
> + opts.merge = 1;
> + opts.reset = reset;
> + opts.update = update;
> + opts.fn = oneway_merge;
> +
> + if (unpack_trees(nr_trees, t, &opts))
> + return -1;
> +
> + if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
> + return error(_("unable to write new index file"));
> +
> + return 0;
> +}
Oh how I wish we had that as API:
$ git grep -W unpack_trees \*.c | grep init_tree_desc
archive.c- init_tree_desc(&t, args->tree->buffer,
args->tree->size);
builtin/am.c- init_tree_desc(&t[0], head->buffer, head->size);
builtin/am.c- init_tree_desc(&t[1], remote->buffer, remote->size);
builtin/am.c- init_tree_desc(&t[0], tree->buffer, tree->size);
builtin/checkout.c- init_tree_desc(&tree_desc, tree->buffer, tree->size);
builtin/checkout.c- init_tree_desc(&trees[0], tree->buffer,
tree->size);
builtin/checkout.c- init_tree_desc(&trees[1], tree->buffer,
tree->size);
builtin/clone.c- init_tree_desc(&t, tree->buffer, tree->size);
builtin/commit.c- init_tree_desc(&t, tree->buffer, tree->size);
builtin/merge.c- init_tree_desc(t+i, trees[i]->buffer,
trees[i]->size);
builtin/read-tree.c- init_tree_desc(t+i, tree->buffer, tree->size);
diff-lib.c- init_tree_desc(&t, tree->buffer, tree->size);
merge-recursive.c- init_tree_desc_from_tree(t+0, common);
merge-recursive.c- init_tree_desc_from_tree(t+1, head);
merge-recursive.c- init_tree_desc_from_tree(t+2, merge);
merge.c- init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
Looks like a lot of duplication to me. (Again, this is just a lament, and
a suggestion for a future project, not a micro-project, though).
> +
> +static int diff_tree_binary(struct strbuf *out, struct object_id *w_commit)
> +{
> + struct child_process cp = CHILD_PROCESS_INIT;
> + const char *w_commit_hex = oid_to_hex(w_commit);
> +
> + /* Diff-tree would not be very hard to replace with a native function,
> + * however it should be done together with apply_cached.
> + */
> + cp.git_cmd = 1;
> + argv_array_pushl(&cp.args, "diff-tree", "--binary", NULL);
> + argv_array_pushf(&cp.args, "%s^2^..%s^2", w_commit_hex, w_commit_hex);
> +
> + return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
> +}
As I stated before: I think this is good enough for the moment. We can
always spend time later to reduce these spawned processes and call
in-process functions instead. One teeny tiny step at a time.
> +static int apply_cached(struct strbuf *out)
> +{
> + struct child_process cp = CHILD_PROCESS_INIT;
> +
> + /* Apply currently only reads either from stdin or a file, thus
> + * apply_all_patches would have to be updated to optionally take a
> buffer
> + */
> + cp.git_cmd = 1;
> + argv_array_pushl(&cp.args, "apply", "--cached", NULL);
> + return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
> +}
> +
> +static int reset_head(const char *prefix)
> +{
> + struct argv_array args = ARGV_ARRAY_INIT;
> +
> + /* Reset is overall quite simple, however there is no current public API
> + * for resetting.
> + */
> + argv_array_push(&args, "reset");
> + return cmd_reset(args.argc, args.argv, prefix);
> +}
> +
> +static int diff_cached_index(struct strbuf *out, struct object_id *c_tree)
> +{
> + struct child_process cp = CHILD_PROCESS_INIT;
> + const char *c_tree_hex = oid_to_hex(c_tree);
> +
> + /* diff-index is very similar to diff-tree above, and should be
> converted
> + * together with update_index
> + */
> + cp.git_cmd = 1;
> + argv_array_pushl(&cp.args, "diff-index", "--cached", "--name-only",
> "--diff-filter=A", NULL);
We should probably note in the name of this function that we return a list
only of the added files.
> + argv_array_push(&cp.args, c_tree_hex);
> + return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
> +}
> +
> +static int update_index(struct strbuf *out)
> +{
> + struct child_process cp = CHILD_PROCESS_INIT;
> +
> + /* Update-index is very complicated and may need to have a public
> function
> + * exposed in order to remove this forking
> + */
> + cp.git_cmd = 1;
> + argv_array_pushl(&cp.args, "update-index", "--add", "--stdin", NULL);
> + return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
> +}
> +
> +static int restore_untracked(struct object_id *u_tree)
> +{
> + struct child_process cp = CHILD_PROCESS_INIT;
> + int res;
> +
> + /*
> + * We need to run restore files from a given index, but without
> affecting
> + * the current index, so we use GIT_INDEX_FILE with run_command to fork
> + * processes that will not interfere.
> + */
> + cp.git_cmd = 1;
> + argv_array_push(&cp.args, "read-tree");
> + argv_array_push(&cp.args, oid_to_hex(u_tree));
> + argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
> stash_index_path.buf);
> + if (run_command(&cp)) {
> + remove_path(stash_index_path.buf);
> + return -1;
> + }
> +
> + child_process_init(&cp);
> + cp.git_cmd = 1;
> + argv_array_pushl(&cp.args, "checkout-index", "--all", NULL);
> + argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
> stash_index_path.buf);
> +
> + res = run_command(&cp);
> + remove_path(stash_index_path.buf);
> + return res;
> +}
> +
> +static int do_apply_stash(const char *prefix, struct stash_info *info, int
> index)
> +{
> + struct merge_options o;
> + struct object_id c_tree;
> + struct object_id index_tree;
> + const struct object_id *bases[1];
> + int bases_count = 1;
It is always 1, maybe not waste a variable on it? ;-)
> + struct commit *result;
> + int ret;
> + int has_index = index;
> +
> + read_cache_preload(NULL);
> + if (refresh_cache(REFRESH_QUIET))
> + return -1;
> +
> + if (write_cache_as_tree(&c_tree, 0, NULL) || reset_tree(&c_tree, 0, 0))
> + return error(_("Cannot apply a stash in the middle of a
> merge"));
> +
> + if (index) {
> + if (!oidcmp(&info->b_tree, &info->i_tree) || !oidcmp(&c_tree,
> &info->i_tree)) {
> + has_index = 0;
> + } else {
> + struct strbuf out = STRBUF_INIT;
> +
> + if (diff_tree_binary(&out, &info->w_commit)) {
> + strbuf_release(&out);
> + return -1;
> + }
> +
> + ret = apply_cached(&out);
> + strbuf_release(&out);
> + if (ret)
> + return -1;
A more faithful conversion would pipe the output of `git diff-tree
--binary` into `git apply --cached`, but I do not think it is worth
complicating things here.
> +
> + discard_cache();
> + read_cache();
$ git grep -A1 discard_cache | grep -c read_cache
10
I guess that's another idiom we use a lot. (Again, micro-project here.)
> + if (write_cache_as_tree(&index_tree, 0, NULL))
> + return -1;
> +
> + reset_head(prefix);
> + }
> + }
> +
> + if (info->has_u) {
> + if (restore_untracked(&info->u_tree))
> + return error(_("Could not restore untracked files from
> stash"));
> + }
> +
> + init_merge_options(&o);
> +
> + o.branch1 = "Updated upstream";
> + o.branch2 = "Stashed changes";
> +
> + if (!oidcmp(&info->b_tree, &c_tree))
> + o.branch1 = "Version stash was based on";
> +
> + if (quiet)
> + o.verbosity = 0;
> +
> + if (o.verbosity >= 3)
> + printf_ln(_("Merging %s with %s"), o.branch1, o.branch2);
> +
> + bases[0] = &info->b_tree;
> +
> + ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, bases_count,
> bases, &result);
> + if (ret != 0) {
> + rerere(0);
> +
> + if (index)
> + fprintf_ln(stderr, _("Index was not unstashed."));
> +
> + return ret;
> + }
> +
> + if (has_index) {
> + if (reset_tree(&index_tree, 0, 0))
> + return -1;
> + } else {
> + struct strbuf out = STRBUF_INIT;
> +
> + if (diff_cached_index(&out, &c_tree)) {
> + strbuf_release(&out);
> + return -1;
> + }
> +
> + if (reset_tree(&c_tree, 0, 1)) {
> + strbuf_release(&out);
> + return -1;
> + }
> +
> + ret = update_index(&out);
> + strbuf_release(&out);
> + if (ret)
> + return -1;
> +
> + discard_cache();
> + }
> +
> + if (!quiet) {
> + struct argv_array args = ARGV_ARRAY_INIT;
> + /* Status is quite simple and could be replaced with calls to
> wt_status
> + * in the future, but it adds complexities which may require
> more tests
> + */
> + argv_array_push(&args, "status");
> + cmd_status(args.argc, args.argv, prefix);
> + }
This is a change in behavior. The shell script calls `git status` always,
and only *suppresses* the output if `--quiet` was passed. I guess the
difference in behavior really boils down only to refreshing the index.
Maybe we can do that here, too? Something like
if (quiet) {
if (refresh_cache(REFRESH_QUIET))
warning("could not refresh index");
} else {
...
> +
> + return 0;
> +}
> +
> +static int apply_stash(int argc, const char **argv, const char *prefix)
> +{
> + int index = 0;
> + struct stash_info info;
> + int ret;
> + struct option options[] = {
> + OPT__QUIET(&quiet, N_("be quiet, only report errors")),
> + OPT_BOOL(0, "index", &index,
> + N_("attempt to recreate the index")),
> + OPT_END()
> + };
> +
> + argc = parse_options(argc, argv, prefix, options,
> + git_stash_helper_apply_usage, 0);
> +
> + if (get_stash_info(&info, argc, argv))
> + return -1;
> +
> + ret = do_apply_stash(prefix, &info, index);
This is the only caller of that function. But I guess that `pop` also
needs to call it, so I guess it makes sense to keep `do_apply_stash()`
separate.
> + free_stash_info(&info);
> + return ret;
> +}
> +
> +int cmd_stash__helper(int argc, const char **argv, const char *prefix)
> +{
> + int result = 0;
> + pid_t pid = getpid();
> + const char *index_file;
> +
> + struct option options[] = {
> + OPT_END()
> + };
> +
> + git_config(git_default_config, NULL);
> +
> + argc = parse_options(argc, argv, prefix, options,
> git_stash_helper_usage,
> + PARSE_OPT_KEEP_UNKNOWN|PARSE_OPT_KEEP_DASHDASH);
Please keep spaces around the pipe symbol.
> + index_file = get_index_file();
> + strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
> (uintmax_t)pid);
> +
> + if (argc < 1)
> + usage_with_options(git_stash_helper_usage, options);
> + else if (!strcmp(argv[0], "apply"))
> + result = apply_stash(argc, argv, prefix);
> + else {
> + error(_("unknown subcommand: %s"), argv[0]);
> + usage_with_options(git_stash_helper_usage, options);
> + result = 1;
> + }
> +
> + return result;
> +}
> diff --git a/git-stash.sh b/git-stash.sh
> index 94793c1a91..0b5d1f3743 100755
> --- a/git-stash.sh
> +++ b/git-stash.sh
> @@ -566,76 +566,11 @@ assert_stash_ref() {
> }
>
> apply_stash () {
> -
> - assert_stash_like "$@"
> -
> - git update-index -q --refresh || die "$(gettext "unable to refresh
> index")"
> -
> - # current index state
> - c_tree=$(git write-tree) ||
> - die "$(gettext "Cannot apply a stash in the middle of a merge")"
> -
> - unstashed_index_tree=
> - if test -n "$INDEX_OPTION" && test "$b_tree" != "$i_tree" &&
> - test "$c_tree" != "$i_tree"
> - then
> - git diff-tree --binary $s^2^..$s^2 | git apply --cached
> - test $? -ne 0 &&
> - die "$(gettext "Conflicts in index. Try without
> --index.")"
> - unstashed_index_tree=$(git write-tree) ||
> - die "$(gettext "Could not save index tree")"
> - git reset
> - fi
> -
> - if test -n "$u_tree"
> - then
> - GIT_INDEX_FILE="$TMPindex" git read-tree "$u_tree" &&
> - GIT_INDEX_FILE="$TMPindex" git checkout-index --all &&
> - rm -f "$TMPindex" ||
> - die "$(gettext "Could not restore untracked files from stash
> entry")"
> - fi
> -
> - eval "
> - GITHEAD_$w_tree='Stashed changes' &&
> - GITHEAD_$c_tree='Updated upstream' &&
> - GITHEAD_$b_tree='Version stash was based on' &&
> - export GITHEAD_$w_tree GITHEAD_$c_tree GITHEAD_$b_tree
> - "
> -
> - if test -n "$GIT_QUIET"
> - then
> - GIT_MERGE_VERBOSITY=0 && export GIT_MERGE_VERBOSITY
> - fi
> - if git merge-recursive $b_tree -- $c_tree $w_tree
> - then
> - # No conflict
> - if test -n "$unstashed_index_tree"
> - then
> - git read-tree "$unstashed_index_tree"
> - else
> - a="$TMP-added" &&
> - git diff-index --cached --name-only --diff-filter=A
> $c_tree >"$a" &&
> - git read-tree --reset $c_tree &&
> - git update-index --add --stdin <"$a" ||
> - die "$(gettext "Cannot unstage modified files")"
> - rm -f "$a"
> - fi
> - squelch=
> - if test -n "$GIT_QUIET"
> - then
> - squelch='>/dev/null 2>&1'
> - fi
> - (cd "$START_DIR" && eval "git status $squelch") || :
> - else
> - # Merge conflict; keep the exit status from merge-recursive
> - status=$?
> - git rerere
> - if test -n "$INDEX_OPTION"
> - then
> - gettextln "Index was not unstashed." >&2
> - fi
> - exit $status
> - fi
> + cd "$START_DIR"
> + git stash--helper apply "$@"
> + res=$?
> + cd_to_toplevel
Is it important to cd to top-level when we are exiting anyway? I guess it
is, because we are not exiting right away, necessarily: both pop_stash()
and apply_to_branch() call this function. But then, both callers only call
drop_stash() afterwards (which does not perform worktree operations)...
> + return $res
> }
>
> pop_stash() {
> diff --git a/git.c b/git.c
> index ceaa58ef40..6ffe6364ac 100644
> --- a/git.c
> +++ b/git.c
> @@ -466,6 +466,7 @@ static struct cmd_struct commands[] = {
> { "show-branch", cmd_show_branch, RUN_SETUP },
> { "show-ref", cmd_show_ref, RUN_SETUP },
> { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
> + { "stash--helper", cmd_stash__helper, RUN_SETUP | NEED_WORK_TREE },
> { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
> { "stripspace", cmd_stripspace },
> { "submodule--helper", cmd_submodule__helper, RUN_SETUP |
> SUPPORT_SUPER_PREFIX},
> --
> 2.16.3
This patch (apart from the minor suggestions I had) looks very good to me
already. Thank you so much!
Ciao,
Dscho
