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[RFC PATCHv6 1/2] repack: rewrite the shell script in C

From
Stefan Beller <stefanbeller@googlemail.com>
Date
Aug 21, 2013, 17:28 UTC
Message-ID
<1377106096-28195-1-git-send-email-stefanbeller@googlemail.com>
In-Reply-To
<5214F816.3010303@googlemail.com>

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

This patch is meant to be mostly a literal translation of the git-repack script; the intent is that later patches would start using more library facilities, but this patch is meant to be as close to a no-op as possible so it doesn't do that kind of thing.

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
---
 Makefile                                        |   2 +-
 builtin.h                                       |   1 +
 builtin/repack.c                                | 376 ++++++++++++++++++++++++
 git-repack.sh => contrib/examples/git-repack.sh |   0
 git.c                                           |   1 +
 5 files changed, 379 insertions(+), 1 deletion(-)
 create mode 100644 builtin/repack.c
 rename git-repack.sh => contrib/examples/git-repack.sh (100%)
diff --git a/Makefile b/Makefile
index ef442eb..4ec5bbe 100644
--- a/Makefile
+++ b/Makefile
@@ -464,7 +464,6 @@ SCRIPT_SH += git-pull.sh
 SCRIPT_SH += git-quiltimport.sh
 SCRIPT_SH += git-rebase.sh
 SCRIPT_SH += git-remote-testgit.sh
-SCRIPT_SH += git-repack.sh
 SCRIPT_SH += git-request-pull.sh
 SCRIPT_SH += git-stash.sh
 SCRIPT_SH += git-submodule.sh
@@ -972,6 +971,7 @@ BUILTIN_OBJS += builtin/reflog.o
 BUILTIN_OBJS += builtin/remote.o
 BUILTIN_OBJS += builtin/remote-ext.o
 BUILTIN_OBJS += builtin/remote-fd.o
+BUILTIN_OBJS += builtin/repack.o
 BUILTIN_OBJS += builtin/replace.o
 BUILTIN_OBJS += builtin/rerere.o
 BUILTIN_OBJS += builtin/reset.o
diff --git a/builtin.h b/builtin.h
index 8afa2de..b56cf07 100644
--- a/builtin.h
+++ b/builtin.h
@@ -102,6 +102,7 @@ extern int cmd_reflog(int argc, const char **argv, const char *prefix);
 extern int cmd_remote(int argc, const char **argv, const char *prefix);
 extern int cmd_remote_ext(int argc, const char **argv, const char *prefix);
 extern int cmd_remote_fd(int argc, const char **argv, const char *prefix);
+extern int cmd_repack(int argc, const char **argv, const char *prefix);
 extern int cmd_repo_config(int argc, const char **argv, const char *prefix);
 extern int cmd_rerere(int argc, const char **argv, const char *prefix);
 extern int cmd_reset(int argc, const char **argv, const char *prefix);
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)
+ */
+
+#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) */
+static int delta_base_offset = 1;
+char *packdir;
+
+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-$$-pack-* files.
+ */
+static void remove_temporary_files(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	size_t dirlen, prefixlen;
+	DIR *dir;
+	struct dirent *e;
+
+	/* .git/objects/pack */
+	strbuf_addstr(&buf, get_object_directory());
+	strbuf_addstr(&buf, "/pack");
+	dir = opendir(buf.buf);
+	if (!dir) {
+		strbuf_release(&buf);
+		return;
+	}
+
+	/* .git/objects/pack/.tmp-$$-pack-* */
+	dirlen = buf.len + 1;
+	strbuf_addf(&buf, "/.tmp-%d-pack-", (int)getpid());
+	prefixlen = buf.len - dirlen;
+
+	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);
+	}
+	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;
+
+		size_t len = strlen(e->d_name) - strlen(".pack");
+		fname = xmemdupz(e->d_name, len);
+
+		if (!file_exists(mkpath("%s/%s.keep", packdir, fname)))
+			string_list_append_nodup(fname_list, fname);
+	}
+	closedir(dir);
+}
+
+static void remove_redundant_pack(const char *path, const char *sha1)
+{
+	const char *exts[] = {".pack", ".idx", ".keep"};
+	int i;
+	struct strbuf buf = STRBUF_INIT;
+	size_t plen;
+
+	strbuf_addf(&buf, "%s/%s", path, sha1);
+	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);
+
+	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");
+	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, "");
+		string_list_append(&names, line.buf);
+		count_packs++;
+	}
+	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;
+	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;
+			}
+			string_list_append_nodup(&rollback, fname);
+			free(fname);
+			free(fname_old);
+		}
+		if (failed)
+			break;
+	}
+	if (failed) {
+		struct string_list rollback_failure;
+		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);
+		}
+
+		if (rollback.nr) {
+			int i;
+			fprintf(stderr,
+				"WARNING: Some packs in use have been renamed by\n"
+				"WARNING: prefixing old- to their name, in order to\n"
+				"WARNING: replace them with the new version of the\n"
+				"WARNING: file.  But the operation failed, and the\n"
+				"WARNING: attempt to rename them back to their\n"
+				"WARNING: original names also failed.\n"
+				"WARNING: Please rename them in %s manually:\n", packdir);
+			for (i = 0; i < rollback.nr; i++)
+				fprintf(stderr, "WARNING:   old-%s -> %s\n",
+					rollback.items[i].string,
+					rollback.items[i].string);
+		}
+		exit(1);
+	}
+
+	/* Now the ones with the same name are out of the way... */
+	for_each_string_list_item(item, &names) {
+		for (ext = 0; ext < 2; ext++) {
+			char *fname, *fname_old;
+			struct stat statbuffer;
+			fname = mkpathdup("%s/pack-%s%s",
+					packdir, item->string, exts[ext]);
+			fname_old = mkpathdup("%s-%s%s",
+					packtmp, item->string, exts[ext]);
+			if (!stat(fname_old, &statbuffer)) {
+				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
+				chmod(fname_old, statbuffer.st_mode);
+			}
+			if (rename(fname_old, fname))
+				die_errno(_("renaming '%s' failed"), fname_old);
+			free(fname);
+			free(fname_old);
+		}
+	}
+
+	/* Remove the "old-" files */
+	for_each_string_list_item(item, &names) {
+		for (ext = 0; ext < 2; ext++) {
+			char *fname;
+			fname = mkpath("%s/old-pack-%s%s",
+					packdir,
+					item->string,
+					exts[ext]);
+			if (remove_path(fname))
+				warning(_("removing '%s' failed"), fname);
+		}
+	}
+
+	/* End of pack replacement. */
+
+	if (delete_redundant) {
+		sort_string_list(&names);
+		for_each_string_list_item(item, &existing_packs) {
+			char *sha1;
+			size_t len = strlen(item->string);
+			if (len < 40)
+				continue;
+			sha1 = item->string + len - 40;
+			if (!string_list_has_string(&names, sha1))
+				remove_redundant_pack(packdir, item->string);
+		}
+		argv_array_push(&cmd_args, "prune-packed");
+		if (quiet)
+			argv_array_push(&cmd_args, "--quiet");
+
+		memset(&cmd, 0, sizeof(cmd));
+		cmd.argv = cmd_args.argv;
+		cmd.git_cmd = 1;
+		run_command(&cmd);
+		argv_array_clear(&cmd_args);
+	}
+
+	if (!no_update_server_info) {
+		argv_array_push(&cmd_args, "update-server-info");
+		memset(&cmd, 0, sizeof(cmd));
+		cmd.argv = cmd_args.argv;
+		cmd.git_cmd = 1;
+		run_command(&cmd);
+		argv_array_clear(&cmd_args);
+	}
+	return 0;
+}
diff --git a/git-repack.sh b/contrib/examples/git-repack.sh
similarity index 100%
rename from git-repack.sh
rename to contrib/examples/git-repack.sh
diff --git a/git.c b/git.c
index 2025f77..03510be 100644
--- a/git.c
+++ b/git.c
@@ -396,6 +396,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "remote", cmd_remote, RUN_SETUP },
 		{ "remote-ext", cmd_remote_ext },
 		{ "remote-fd", cmd_remote_fd },
+		{ "repack", cmd_repack, RUN_SETUP },
 		{ "replace", cmd_replace, RUN_SETUP },
 		{ "repo-config", cmd_repo_config, RUN_SETUP_GENTLY },
 		{ "rerere", cmd_rerere, RUN_SETUP },

-- 
1.8.4.rc3.1.gc1ebd90
Previous: Stefan BellerNext: Stefan Beller
Message 33 of 72 in “Rewriting git-repack in C”
  1. Rewriting git-repack in CStefan Beller, Aug 13, 2013
  2. repack: rewrite the shell script in C.Stefan Beller, Aug 13, 2013
  3. Matthieu MoyAug 14, 2013
  4. Stefan BellerAug 14, 2013
  5. repack: rewrite the shell script in C.Stefan Beller, Aug 14, 2013
  6. Antoine PelisseAug 14, 2013
  7. Stefan BellerAug 14, 2013
  8. Jeff KingAug 14, 2013
  9. Martin FickAug 14, 2013
  10. Stefan BellerAug 14, 2013
  11. Martin FickAug 14, 2013
  12. Junio C HamanoAug 14, 2013
  13. Martin FickAug 14, 2013
  14. Junio C HamanoAug 15, 2013
  15. [RFC PATCHv2] repack: rewrite the shell script in C.Stefan Beller, Aug 16, 2013
  16. René ScharfeAug 17, 2013
  17. Kyle J. McKayAug 17, 2013
  18. Stefan BellerAug 18, 2013
  19. [RFC PATCHv3] repack: rewrite the shell script in C.Stefan Beller, Aug 18, 2013
  20. Kyle J. McKayAug 18, 2013
  21. René ScharfeAug 18, 2013
  22. [RFC PATCHv4] repack: rewrite the shell script in C.Stefan Beller, Aug 18, 2013
  23. [RFC PATCHv4] repack: rewrite the shell script in C.Stefan Beller, Aug 19, 2013
  24. Johannes SixtAug 20, 2013
  25. Stefan BellerAug 20, 2013
  26. Johannes SixtAug 20, 2013
  27. René ScharfeAug 20, 2013
  28. Stefan BellerAug 20, 2013
  29. repack: rewrite the shell script in C.Stefan Beller, Aug 20, 2013
  30. Jonathan NiederAug 21, 2013
  31. Stefan BellerAug 21, 2013
  32. Stefan BellerAug 21, 2013
  33. 1/2 repack: rewrite the shell script in CStefan Beller, Aug 21, 2013
  34. 2/2 repack: retain the return value of pack-objectsStefan Beller, Aug 21, 2013
  35. Junio C HamanoAug 21, 2013
  36. Matthieu MoyAug 21, 2013
  37. Stefan BellerAug 21, 2013
  38. Junio C HamanoAug 21, 2013
  39. Stefan BellerAug 21, 2013
  40. Johannes SixtAug 22, 2013
  41. Jonathan NiederAug 22, 2013
  42. Matthieu MoyAug 21, 2013
  43. Stefan BellerAug 21, 2013
  44. Matthieu MoyAug 21, 2013
  45. Stefan BellerAug 21, 2013
  46. Matthieu MoyAug 21, 2013
  47. Johannes SixtAug 22, 2013
  48. Johannes SixtAug 22, 2013
  49. repack: rewrite the shell script in C (squashing proposal)Stefan Beller, Aug 22, 2013
  50. Junio C HamanoAug 22, 2013
  51. Jonathan NiederAug 20, 2013
  52. Johannes SixtAug 21, 2013
  53. Stefan BellerAug 20, 2013
  54. Jonathan NiederAug 20, 2013
  55. Dokumenting api-paths.txtStefan Beller, Aug 20, 2013
  56. Jonathan NiederAug 20, 2013
  57. Stefan BellerAug 21, 2013
  58. Junio C HamanoAug 22, 2013
  59. Junio C HamanoAug 14, 2013
  60. Matthieu MoyAug 14, 2013
  61. Stefan BellerAug 15, 2013
  62. Duy NguyenAug 15, 2013
  63. Junio C HamanoAug 14, 2013
  64. Matthieu MoyAug 14, 2013
  65. Martin FickAug 14, 2013
  66. Martin FickAug 15, 2013
  67. Stefan BellerAug 15, 2013
  68. Martin FickAug 15, 2013
  69. Duy NguyenAug 15, 2013
  70. Junio C HamanoAug 14, 2013
  71. Stefan BellerAug 15, 2013
  72. Matthieu MoyAug 14, 2013

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