Stefan Beller <stefanbeller@xxxxxxxxxxxxxx> writes:
> The motivation of this patch is to get closer to a goal of being
> able to have a core subset of git functionality built in to git.
> That would mean
>
> * people on Windows could get a copy of at least the core parts
> of Git without having to install a Unix-style shell
>
> * people deploying to servers don't have to rewrite the #! line
> or worry about the PATH and quality of installed POSIX
> utilities, if they are only using the built-in part written
> in C
I am not sure what is meant by the latter. Rewriting #! is part of
any scripted Porcelain done by the top-level Makefile, and I do not
think we have seen any problem reports on it.
As to "quality of ... utilities", I think the real issue some people
in the thread had was not about "deploying to servers" but about
installing in a minimalistic chrooted environment where standard
tools may be lacking.
> diff --git a/builtin/repack.c b/builtin/repack.c
> new file mode 100644
> index 0000000..fb050c0
> --- /dev/null
> +++ b/builtin/repack.c
> @@ -0,0 +1,376 @@
> +/*
> + * The shell version was written by Linus Torvalds (2005) and many others.
> + * This is a translation into C by Stefan Beller (2013)
> + */
I am not sure if we want to record "ownership" in the code like
this; it will go stale over time.
> +#include "builtin.h"
> +#include "cache.h"
> +#include "dir.h"
> +#include "parse-options.h"
> +#include "run-command.h"
> +#include "sigchain.h"
> +#include "strbuf.h"
> +#include "string-list.h"
> +#include "argv-array.h"
> +
> +/* enabled by default since 22c79eab (2008-06-25) */
It may be of some value that by default --delta-base-offset is used,
but that can be read from the initialization. Do we need this
comment?
> +static int delta_base_offset = 1;
> +char *packdir;
Does this have to be global?
> +static const char *const git_repack_usage[] = {
> + N_("git repack [options]"),
> + NULL
> +};
> +
> +static int repack_config(const char *var, const char *value, void *cb)
> +{
> + if (!strcmp(var, "repack.usedeltabaseoffset")) {
> + delta_base_offset = git_config_bool(var, value);
> + return 0;
> + }
> + return git_default_config(var, value, cb);
> +}
> +
> +/*
> + * Remove temporary $GIT_OBJECT_DIRECTORY/pack/.tmp-$$-pack-* files.
> + */
> +static void remove_temporary_files(void)
> +{
> + struct strbuf buf = STRBUF_INIT;
> + size_t dirlen, prefixlen;
> + DIR *dir;
> + struct dirent *e;
> +
> + /* .git/objects/pack */
We can read what is in there from two strbuf calls without comment.
> + strbuf_addstr(&buf, get_object_directory());
> + strbuf_addstr(&buf, "/pack");
More importantly, you already know what this directory and what
packtmp prefix are.
Also, you can keep &buf empty until opendir() succeeds.
> + dir = opendir(buf.buf);
> + if (!dir) {
> + strbuf_release(&buf);
> + return;
> + }
> +
> + /* .git/objects/pack/.tmp-$$-pack-* */
> + dirlen = buf.len + 1;
Likewise; it is a good idea to document what "dirlen" points at,
though.
> + strbuf_addf(&buf, "/.tmp-%d-pack-", (int)getpid());
> + prefixlen = buf.len - dirlen;
So in summary:
dir = opendir(packdir);
if (!dir)
return;
strbuf_addf(&buf, "%s-", packtmp);
/* Point at the slash at the end of ".../objects/pack/" */
dirlen = strlen(packdir) + 1;
/* Point at the dash at the end of ".../.tmp-%d-pack-" */
prefixlen = buf.len - dirlen;
You would need to move the initialization of packdir and packtmp
before sigchain_push() in cmd_repack() if you were to do this.
> + while ((e = readdir(dir))) {
> + if (strncmp(e->d_name, buf.buf + dirlen, prefixlen))
> + continue;
> + strbuf_setlen(&buf, dirlen);
> + strbuf_addstr(&buf, e->d_name);
> + unlink(buf.buf);
This unlink(2) could fail, but there is not much we could do here.
> + }
> + closedir(dir);
> + strbuf_release(&buf);
> +}
> +
> +static void remove_pack_on_signal(int signo)
> +{
> + remove_temporary_files();
> + sigchain_pop(signo);
> + raise(signo);
> +}
> +
> +static void get_pack_filenames(struct string_list *fname_list)
> +{
> + DIR *dir;
> + struct dirent *e;
> + char *fname;
> +
> + if (!(dir = opendir(packdir)))
> + return;
> +
> + while ((e = readdir(dir)) != NULL) {
> + if (suffixcmp(e->d_name, ".pack"))
> + continue;
We may want to tighten this to ignore cruft that does not match
/^pack-[0-9a-f]{40}\.pack$/
in a later patch, but this is a faithful rewrite from the original.
> + size_t len = strlen(e->d_name) - strlen(".pack");
decl-after-stmt.
> + fname = xmemdupz(e->d_name, len);
> +
> + if (!file_exists(mkpath("%s/%s.keep", packdir, fname)))
> + string_list_append_nodup(fname_list, fname);
mental note: this is getting names of non-kept packs, not all packs.
> + }
> + closedir(dir);
> +}
> +
> +static void remove_redundant_pack(const char *path, const char *sha1)
These parameter names may want to be changed to clarify what they
are; see below.
> +{
> + const char *exts[] = {".pack", ".idx", ".keep"};
> + int i;
> + struct strbuf buf = STRBUF_INIT;
> + size_t plen;
> +
> + strbuf_addf(&buf, "%s/%s", path, sha1);
This suggests that path[] has ".../objects/pack/pack-" and sha1[] is
a 40-hex representation of the pack name. Calling the former
path_prefix[] and the latter hex[] may be clearer.
> + plen = buf.len;
> +
> + for (i = 0; i < ARRAY_SIZE(exts); i++) {
> + strbuf_setlen(&buf, plen);
> + strbuf_addstr(&buf, exts[i]);
> + unlink(buf.buf);
> + }
> +}
> +
> +int cmd_repack(int argc, const char **argv, const char *prefix)
> +{
> + const char *exts[2] = {".idx", ".pack"};
> + char *packtmp;
> + struct child_process cmd;
> + struct string_list_item *item;
> + struct argv_array cmd_args = ARGV_ARRAY_INIT;
> + struct string_list names = STRING_LIST_INIT_DUP;
> + struct string_list rollback = STRING_LIST_INIT_DUP;
> + struct string_list existing_packs = STRING_LIST_INIT_DUP;
> + struct strbuf line = STRBUF_INIT;
> + int count_packs, ext, ret;
> + FILE *out;
> +
> + /* variables to be filled by option parsing */
> + int pack_everything = 0;
> + int pack_everything_but_loose = 0;
> + int delete_redundant = 0;
> + char *unpack_unreachable = NULL;
> + int window = 0, window_memory = 0;
> + int depth = 0;
> + int max_pack_size = 0;
> + int no_reuse_delta = 0, no_reuse_object = 0;
> + int no_update_server_info = 0;
> + int quiet = 0;
> + int local = 0;
> +
> + struct option builtin_repack_options[] = {
> + OPT_BOOL('a', NULL, &pack_everything,
> + N_("pack everything in a single pack")),
> + OPT_BOOL('A', NULL, &pack_everything_but_loose,
> + N_("same as -a, and turn unreachable objects loose")),
> + OPT_BOOL('d', NULL, &delete_redundant,
> + N_("remove redundant packs, and run git-prune-packed")),
> + OPT_BOOL('f', NULL, &no_reuse_delta,
> + N_("pass --no-reuse-delta to git-pack-objects")),
> + OPT_BOOL('F', NULL, &no_reuse_object,
> + N_("pass --no-reuse-object to git-pack-objects")),
> + OPT_BOOL('n', NULL, &no_update_server_info,
> + N_("do not run git-update-server-info")),
> + OPT__QUIET(&quiet, N_("be quiet")),
> + OPT_BOOL('l', "local", &local,
> + N_("pass --local to git-pack-objects")),
> + OPT_STRING(0, "unpack-unreachable", &unpack_unreachable, N_("approxidate"),
> + N_("with -A, do not loosen objects older than this")),
> + OPT_INTEGER(0, "window", &window,
> + N_("size of the window used for delta compression")),
> + OPT_INTEGER(0, "window-memory", &window_memory,
> + N_("same as the above, but limit memory size instead of entries count")),
> + OPT_INTEGER(0, "depth", &depth,
> + N_("limits the maximum delta depth")),
> + OPT_INTEGER(0, "max-pack-size", &max_pack_size,
> + N_("maximum size of each packfile")),
> + OPT_END()
> + };
> +
> + git_config(repack_config, NULL);
> +
> + argc = parse_options(argc, argv, prefix, builtin_repack_options,
> + git_repack_usage, 0);
Nice. In a later patch we might want to allow --delta-base-offset to
be overridden from the command line and doing config first and then
options second like the above would allow us to do so easily.
> + sigchain_push_common(remove_pack_on_signal);
> + packdir = mkpathdup("%s/pack", get_object_directory());
> + packtmp = mkpathdup("%s/.tmp-%d-pack", packdir, (int)getpid());
> +
> + argv_array_push(&cmd_args, "pack-objects");
> + argv_array_push(&cmd_args, "--keep-true-parents");
> + argv_array_push(&cmd_args, "--honor-pack-keep");
> + argv_array_push(&cmd_args, "--non-empty");
> + argv_array_push(&cmd_args, "--all");
> + argv_array_push(&cmd_args, "--reflog");
> + if (window)
> + argv_array_pushf(&cmd_args, "--window=%u", window);
> + if (window_memory)
> + argv_array_pushf(&cmd_args, "--window-memory=%u", window_memory);
> + if (depth)
> + argv_array_pushf(&cmd_args, "--depth=%u", depth);
> + if (max_pack_size)
> + argv_array_pushf(&cmd_args, "--max_pack_size=%u", max_pack_size);
> + if (no_reuse_delta)
> + argv_array_pushf(&cmd_args, "--no-reuse-delta");
> + if (no_reuse_object)
> + argv_array_pushf(&cmd_args, "--no-reuse-object");
> +
> + if (!pack_everything && !pack_everything_but_loose) {
> + argv_array_push(&cmd_args, "--unpacked");
> + argv_array_push(&cmd_args, "--incremental");
> + } else {
> + get_pack_filenames(&existing_packs);
> +
> + if (existing_packs.nr && delete_redundant) {
> + if (unpack_unreachable)
> + argv_array_pushf(&cmd_args,
> + "--unpack-unreachable=%s",
> + unpack_unreachable);
> + else if (pack_everything_but_loose)
> + argv_array_push(&cmd_args,
> + "--unpack-unreachable");
> + }
> + }
> +
> + if (local)
> + argv_array_push(&cmd_args, "--local");
> + if (quiet)
> + argv_array_push(&cmd_args, "--quiet");
The original seems to push "-q", but it is probably OK to make it
more readable by spelling it out like this.
> + if (delta_base_offset)
> + argv_array_push(&cmd_args, "--delta-base-offset");
> +
> + argv_array_push(&cmd_args, packtmp);
> +
> + memset(&cmd, 0, sizeof(cmd));
> + cmd.argv = cmd_args.argv;
> + cmd.git_cmd = 1;
> + cmd.out = -1;
> + cmd.no_stdin = 1;
> +
> + ret = start_command(&cmd);
> + if (ret)
> + return 1;
> +
> + count_packs = 0;
> + out = xfdopen(cmd.out, "r");
> + while (strbuf_getline(&line, out, '\n') != EOF) {
> + if (line.len != 40)
> + die("repack: Expecting 40 character sha1 lines only from pack-objects.");
> + strbuf_addstr(&line, "");
What is this addstr() about?
> + string_list_append(&names, line.buf);
> + count_packs++;
It probably is more in line with our naming convention to call this
nr_packs, num_packs, etc. "count_packs" sounds more like a boolean
that instructs the code to either count or not bother counting,
which this thing is not.
> + }
> + fclose(out);
> + ret = finish_command(&cmd);
> + if (ret)
> + return 1;
> + argv_array_clear(&cmd_args);
> +
> + if (!count_packs && !quiet)
> + printf("Nothing new to pack.\n");
> +
> + int failed = 0;
decl-after-stmt.
> + for_each_string_list_item(item, &names) {
> + for (ext = 0; ext < 2; ext++) {
> + char *fname, *fname_old;
> + fname = mkpathdup("%s/%s%s", packdir,
> + item->string, exts[ext]);
> + if (!file_exists(fname)) {
> + free(fname);
> + continue;
> + }
> +
> + fname_old = mkpathdup("%s/old-%s%s", packdir,
> + item->string, exts[ext]);
> + if (file_exists(fname_old))
> + unlink(fname_old);
> +
> + if (rename(fname, fname_old)) {
> + failed = 1;
> + break;
"break"-ing from here leaks fname_old. As the only out-of-line call
file_exists() is just a thin wrapper around lstat(), I think it is
fine not to pathdup the fname_old here.
> + }
> + string_list_append_nodup(&rollback, fname);
> + free(fname);
This looks bad, doesn't it? append_nodup() lets &rollback string
list to take the ownership of the piece of memory pointed at by
fname, but then you free it here, no?
If you initialize &rollback with INIT_NODUP, you would not have to
call append_nodup().
> + free(fname_old);
> + }
> + if (failed)
> + break;
> + }
> + if (failed) {
> + struct string_list rollback_failure;
Initialization?
> + for_each_string_list_item(item, &rollback) {
> + char *fname, *fname_old;
> + fname = mkpathdup("%s/%s", packdir, item->string);
> + fname_old = mkpath("%s/old-%s", packdir, item->string);
> + if (rename(fname_old, fname))
> + string_list_append(&rollback_failure, fname);
> + free(fname);
> + }
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