# [PATCH 1/3] Prepare execv_git_cmd() for removal of builtins from the filesystem

5 messages from 2007-12-02 to 2007-12-02. Participants: Junio C Hamano, Christian Couder, Johannes Schindelin.
Thread: https://gitlist.dev/t/11090

## Junio C Hamano, 2007-12-02 07:03

Subject: [PATCH 1/3] Prepare execv_git_cmd() for removal of builtins from the filesystem
Message-ID: <1196579005-5662-1-git-send-email-gitster@pobox.com>
URL: https://gitlist.dev/e/1196579005-5662-1-git-send-email-gitster%40pobox.com

```
Currently, execv_git_cmd() always try running the dashed form, which
means we cannot easily remove the git-foo hardlinks for built-in
commands.  This updates the function to always exec "git foo" form, and
makes sure "git" potty does not infinitely recurse to itself.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 exec_cmd.c |   31 ++++++++++++-------------------
 git.c      |   32 +++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/exec_cmd.c b/exec_cmd.c
index 2d0a758..10b2908 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -65,32 +65,25 @@ void setup_path(const char *cmd_path)
 
 int execv_git_cmd(const char **argv)
 {
-	struct strbuf cmd;
-	const char *tmp;
-
-	strbuf_init(&cmd, 0);
-	strbuf_addf(&cmd, "git-%s", argv[0]);
+	int argc;
+	const char **nargv;
 
-	/*
-	 * argv[0] must be the git command, but the argv array
-	 * belongs to the caller, and may be reused in
-	 * subsequent loop iterations. Save argv[0] and
-	 * restore it on error.
-	 */
-	tmp = argv[0];
-	argv[0] = cmd.buf;
+	for (argc = 0; argv[argc]; argc++)
+		; /* just counting */
+	nargv = xmalloc(sizeof(*nargv) * (argc + 2));
 
-	trace_argv_printf(argv, -1, "trace: exec:");
+	nargv[0] = "git";
+	for (argc = 0; argv[argc]; argc++)
+		nargv[argc + 1] = argv[argc];
+	nargv[argc + 1] = NULL;
+	trace_argv_printf(nargv, -1, "trace: exec:");
 
 	/* execvp() can only ever return if it fails */
-	execvp(cmd.buf, (char **)argv);
+	execvp("git", (char **)nargv);
 
 	trace_printf("trace: exec failed: %s\n", strerror(errno));
 
-	argv[0] = tmp;
-
-	strbuf_release(&cmd);
-
+	free(nargv);
 	return -1;
 }
 
diff --git a/git.c b/git.c
index 01bbbc7..d690426 100644
--- a/git.c
+++ b/git.c
@@ -382,6 +382,36 @@ static void handle_internal_command(int argc, const char **argv)
 	}
 }
 
+static void execv_dashed_external(const char **argv)
+{
+	struct strbuf cmd;
+	const char *tmp;
+
+	strbuf_init(&cmd, 0);
+	strbuf_addf(&cmd, "git-%s", argv[0]);
+
+	/*
+	 * argv[0] must be the git command, but the argv array
+	 * belongs to the caller, and may be reused in
+	 * subsequent loop iterations. Save argv[0] and
+	 * restore it on error.
+	 */
+	tmp = argv[0];
+	argv[0] = cmd.buf;
+
+	trace_argv_printf(argv, -1, "trace: exec:");
+
+	/* execvp() can only ever return if it fails */
+	execvp(cmd.buf, (char **)argv);
+
+	trace_printf("trace: exec failed: %s\n", strerror(errno));
+
+	argv[0] = tmp;
+
+	strbuf_release(&cmd);
+}
+
+
 int main(int argc, const char **argv)
 {
 	const char *cmd = argv[0] ? argv[0] : "git-help";
@@ -445,7 +475,7 @@ int main(int argc, const char **argv)
 		handle_internal_command(argc, argv);
 
 		/* .. then try the external ones */
-		execv_git_cmd(argv);
+		execv_dashed_external(argv);
 
 		/* It could be an alias -- this works around the insanity
 		 * of overriding "git log" with "git show" by having
-- 
1.5.3.6.2090.g4ece0

```

## Junio C Hamano, 2007-12-02 07:03

Subject: [PATCH 2/3] Avoid double exec() in execv_git_cmd()
Message-ID: <1196579005-5662-2-git-send-email-gitster@pobox.com>
URL: https://gitlist.dev/e/1196579005-5662-2-git-send-email-gitster%40pobox.com
In-Reply-To: <1196579005-5662-1-git-send-email-gitster@pobox.com>

```
This avoids double exec() when execv_git_cmd() is used to spawn an
external git command.

For this, execv_git_cmd() needs to be able to tell what's built-in.
This is done by introducing a new function git_builtin_command() that
checks the list of built-in commands and returns a pointer to the
cmd_struct if found.  The same function is used from the git potty.

This unfortunately pulls all built-in functions to libgit.a, so any
external command that happens to link with exec_cmd.o will need to pull
them in.  I am not sure if that is worth it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Makefile   |    7 +-
 exec_cmd.c |  208 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 exec_cmd.h |    8 ++
 git.c      |  155 +-------------------------------------------
 4 files changed, 210 insertions(+), 168 deletions(-)

diff --git a/Makefile b/Makefile
index a7e44a3..6907954 100644
--- a/Makefile
+++ b/Makefile
@@ -893,7 +893,8 @@ git.o git.spec \
 	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) $<
 
 exec_cmd.o: exec_cmd.c GIT-CFLAGS
-	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' $<
+	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) \
+		-DGIT_VERSION='"$(GIT_VERSION)"' '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' $<
 builtin-init-db.o: builtin-init-db.c GIT-CFLAGS
 	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) -DDEFAULT_GIT_TEMPLATE_DIR='"$(template_dir_SQ)"' $<
 
@@ -923,8 +924,8 @@ $(LIB_OBJS) $(BUILTIN_OBJS): $(LIB_H)
 $(patsubst git-%$X,%.o,$(PROGRAMS)): $(LIB_H) $(wildcard */*.h)
 builtin-revert.o builtin-runstatus.o wt-status.o: wt-status.h
 
-$(LIB_FILE): $(LIB_OBJS)
-	$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(LIB_OBJS)
+$(LIB_FILE): $(LIB_OBJS) $(BUILTIN_OBJS)
+	$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(LIB_OBJS) $(BUILTIN_OBJS)
 
 XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o \
 	xdiff/xmerge.o
diff --git a/exec_cmd.c b/exec_cmd.c
index 10b2908..db61540 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -1,3 +1,4 @@
+#include "builtin.h"
 #include "cache.h"
 #include "exec_cmd.h"
 #include "quote.h"
@@ -63,27 +64,206 @@ void setup_path(const char *cmd_path)
 	strbuf_release(&new_path);
 }
 
+#define RUN_SETUP	(1<<0)
+#define USE_PAGER	(1<<1)
+/*
+ * require working tree to be present -- anything uses this needs
+ * RUN_SETUP for reading from the configuration file.
+ */
+#define NEED_WORK_TREE	(1<<2)
+
+const char git_version_string[] = GIT_VERSION;
+const char git_usage_string[] =
+	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
+
+int run_builtin_command(struct cmd_struct *p, int argc, const char **argv)
+{
+	int status;
+	struct stat st;
+	const char *prefix;
+
+	prefix = NULL;
+	if (p->option & RUN_SETUP)
+		prefix = setup_git_directory();
+	if (p->option & USE_PAGER)
+		setup_pager();
+	if (p->option & NEED_WORK_TREE)
+		setup_work_tree();
+
+	trace_argv_printf(argv, argc, "trace: built-in: git");
+
+	status = p->fn(argc, argv, prefix);
+	if (status)
+		return status & 0xff;
+
+	/* Somebody closed stdout? */
+	if (fstat(fileno(stdout), &st))
+		return 0;
+	/* Ignore write errors for pipes and sockets.. */
+	if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
+		return 0;
+
+	/* Check for ENOSPC and EIO errors.. */
+	if (fflush(stdout))
+		die("write failure on standard output: %s", strerror(errno));
+	if (ferror(stdout))
+		die("unknown write failure on standard output");
+	if (fclose(stdout))
+		die("close failed on standard output: %s", strerror(errno));
+	return 0;
+}
+
+static struct cmd_struct builtin_command[] = {
+	{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
+	{ "annotate", cmd_annotate, RUN_SETUP },
+	{ "apply", cmd_apply },
+	{ "archive", cmd_archive },
+	{ "blame", cmd_blame, RUN_SETUP },
+	{ "branch", cmd_branch, RUN_SETUP },
+	{ "bundle", cmd_bundle },
+	{ "cat-file", cmd_cat_file, RUN_SETUP },
+	{ "check-attr", cmd_check_attr, RUN_SETUP | NEED_WORK_TREE },
+	{ "check-ref-format", cmd_check_ref_format },
+	{ "checkout-index", cmd_checkout_index, RUN_SETUP | NEED_WORK_TREE},
+	{ "cherry", cmd_cherry, RUN_SETUP },
+	{ "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
+	{ "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
+	{ "commit-tree", cmd_commit_tree, RUN_SETUP },
+	{ "config", cmd_config },
+	{ "count-objects", cmd_count_objects, RUN_SETUP },
+	{ "describe", cmd_describe, RUN_SETUP },
+	{ "diff", cmd_diff },
+	{ "diff-files", cmd_diff_files },
+	{ "diff-index", cmd_diff_index, RUN_SETUP },
+	{ "diff-tree", cmd_diff_tree, RUN_SETUP },
+	{ "fetch", cmd_fetch, RUN_SETUP },
+	{ "fetch--tool", cmd_fetch__tool, RUN_SETUP },
+	{ "fetch-pack", cmd_fetch_pack, RUN_SETUP },
+	{ "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
+	{ "for-each-ref", cmd_for_each_ref, RUN_SETUP },
+	{ "format-patch", cmd_format_patch, RUN_SETUP },
+	{ "fsck", cmd_fsck, RUN_SETUP },
+	{ "fsck-objects", cmd_fsck, RUN_SETUP },
+	{ "gc", cmd_gc, RUN_SETUP },
+	{ "get-tar-commit-id", cmd_get_tar_commit_id },
+	{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
+	{ "help", cmd_help },
+#ifndef NO_CURL
+	{ "http-fetch", cmd_http_fetch, RUN_SETUP },
+#endif
+	{ "init", cmd_init_db },
+	{ "init-db", cmd_init_db },
+	{ "log", cmd_log, RUN_SETUP | USE_PAGER },
+	{ "ls-files", cmd_ls_files, RUN_SETUP },
+	{ "ls-remote", cmd_ls_remote },
+	{ "ls-tree", cmd_ls_tree, RUN_SETUP },
+	{ "mailinfo", cmd_mailinfo },
+	{ "mailsplit", cmd_mailsplit },
+	{ "merge-base", cmd_merge_base, RUN_SETUP },
+	{ "merge-file", cmd_merge_file },
+	{ "merge-ours", cmd_merge_ours, RUN_SETUP },
+	{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
+	{ "name-rev", cmd_name_rev, RUN_SETUP },
+	{ "pack-objects", cmd_pack_objects, RUN_SETUP },
+	{ "pack-refs", cmd_pack_refs, RUN_SETUP },
+	{ "peek-remote", cmd_ls_remote },
+	{ "pickaxe", cmd_blame, RUN_SETUP },
+	{ "prune", cmd_prune, RUN_SETUP },
+	{ "prune-packed", cmd_prune_packed, RUN_SETUP },
+	{ "push", cmd_push, RUN_SETUP },
+	{ "read-tree", cmd_read_tree, RUN_SETUP },
+	{ "reflog", cmd_reflog, RUN_SETUP },
+	{ "repo-config", cmd_config },
+	{ "rerere", cmd_rerere, RUN_SETUP },
+	{ "reset", cmd_reset, RUN_SETUP },
+	{ "rev-list", cmd_rev_list, RUN_SETUP },
+	{ "rev-parse", cmd_rev_parse },
+	{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
+	{ "rm", cmd_rm, RUN_SETUP },
+	{ "runstatus", cmd_runstatus, RUN_SETUP | NEED_WORK_TREE },
+	{ "send-pack", cmd_send_pack, RUN_SETUP },
+	{ "shortlog", cmd_shortlog, RUN_SETUP | USE_PAGER },
+	{ "show", cmd_show, RUN_SETUP | USE_PAGER },
+	{ "show-branch", cmd_show_branch, RUN_SETUP },
+	{ "show-ref", cmd_show_ref, RUN_SETUP },
+	{ "stripspace", cmd_stripspace },
+	{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
+	{ "tag", cmd_tag, RUN_SETUP },
+	{ "tar-tree", cmd_tar_tree },
+	{ "unpack-objects", cmd_unpack_objects, RUN_SETUP },
+	{ "update-index", cmd_update_index, RUN_SETUP },
+	{ "update-ref", cmd_update_ref, RUN_SETUP },
+	{ "upload-archive", cmd_upload_archive },
+	{ "verify-pack", cmd_verify_pack },
+	{ "verify-tag", cmd_verify_tag, RUN_SETUP },
+	{ "version", cmd_version },
+	{ "whatchanged", cmd_whatchanged, RUN_SETUP | USE_PAGER },
+	{ "write-tree", cmd_write_tree, RUN_SETUP },
+};
+
+struct cmd_struct *git_builtin_command(const char *name)
+{
+	unsigned int hi, lo;
+	lo = 0;
+	hi = ARRAY_SIZE(builtin_command);
+	do {
+		unsigned mi = (lo + hi) / 2;
+		int cmp = strcmp(builtin_command[mi].cmd, name);
+		if (!cmp)
+			return &builtin_command[mi];
+		if (cmp > 0)
+			hi = mi;
+		else
+			lo = mi + 1;
+	} while (lo < hi);
+	return NULL;
+}
+
 int execv_git_cmd(const char **argv)
 {
-	int argc;
-	const char **nargv;
+	/*
+	 * We exec "git foo" for builtin commands, but exec "git-foo"
+	 * if "foo" is not a built-in, to avoid double exec overhead.
+	 */
+	if (!git_builtin_command(argv[0])) {
+		struct strbuf cmd;
+		const char *save;
+
+		strbuf_init(&cmd, 0);
+		strbuf_addf(&cmd, "git-%s", argv[0]);
 
-	for (argc = 0; argv[argc]; argc++)
-		; /* just counting */
-	nargv = xmalloc(sizeof(*nargv) * (argc + 2));
+		save = argv[0];
+		argv[0] = cmd.buf;
+		trace_argv_printf(argv, -1, "trace: exec:");
 
-	nargv[0] = "git";
-	for (argc = 0; argv[argc]; argc++)
-		nargv[argc + 1] = argv[argc];
-	nargv[argc + 1] = NULL;
-	trace_argv_printf(nargv, -1, "trace: exec:");
+		execvp(argv[0], (char **)argv);
 
-	/* execvp() can only ever return if it fails */
-	execvp("git", (char **)nargv);
+		trace_printf("trace: exec failed: %s\n", strerror(errno));
+		strbuf_release(&cmd);
+		argv[0] = save;
+	}
+	else {
+		int argc;
+		const char **nargv;
 
-	trace_printf("trace: exec failed: %s\n", strerror(errno));
+		for (argc = 0; argv[argc]; argc++)
+			; /* just counting */
+		nargv = xmalloc(sizeof(*nargv) * (argc + 2));
 
-	free(nargv);
+		nargv[0] = "git";
+		for (argc = 0; argv[argc]; argc++)
+			nargv[argc + 1] = argv[argc];
+		nargv[argc + 1] = NULL;
+
+		trace_argv_printf(nargv, -1, "trace: exec:");
+
+		/* execvp() can only ever return if it fails */
+		execvp("git", (char **)nargv);
+
+		trace_printf("trace: exec failed: %s\n", strerror(errno));
+
+		free(nargv);
+	}
 	return -1;
 }
 
diff --git a/exec_cmd.h b/exec_cmd.h
index a892355..184bc1d 100644
--- a/exec_cmd.h
+++ b/exec_cmd.h
@@ -7,5 +7,13 @@ extern void setup_path(const char *);
 extern int execv_git_cmd(const char **argv); /* NULL terminated */
 extern int execl_git_cmd(const char *cmd, ...);
 
+struct cmd_struct {
+	const char *cmd;
+	int (*fn)(int, const char **, const char *);
+	int option;
+};
+
+extern struct cmd_struct *git_builtin_command(const char *);
+extern int run_builtin_command(struct cmd_struct *p, int argc, const char **argv);
 
 #endif /* GIT_EXEC_CMD_H */
diff --git a/git.c b/git.c
index d690426..9d86f5c 100644
--- a/git.c
+++ b/git.c
@@ -3,9 +3,6 @@
 #include "cache.h"
 #include "quote.h"
 
-const char git_usage_string[] =
-	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
-
 static int handle_options(const char*** argv, int* argc, int* envchanged)
 {
 	int handled = 0;
@@ -222,151 +219,10 @@ static int handle_alias(int *argcp, const char ***argv)
 	return ret;
 }
 
-const char git_version_string[] = GIT_VERSION;
-
-#define RUN_SETUP	(1<<0)
-#define USE_PAGER	(1<<1)
-/*
- * require working tree to be present -- anything uses this needs
- * RUN_SETUP for reading from the configuration file.
- */
-#define NEED_WORK_TREE	(1<<2)
-
-struct cmd_struct {
-	const char *cmd;
-	int (*fn)(int, const char **, const char *);
-	int option;
-};
-
-static int run_command(struct cmd_struct *p, int argc, const char **argv)
-{
-	int status;
-	struct stat st;
-	const char *prefix;
-
-	prefix = NULL;
-	if (p->option & RUN_SETUP)
-		prefix = setup_git_directory();
-	if (p->option & USE_PAGER)
-		setup_pager();
-	if (p->option & NEED_WORK_TREE)
-		setup_work_tree();
-
-	trace_argv_printf(argv, argc, "trace: built-in: git");
-
-	status = p->fn(argc, argv, prefix);
-	if (status)
-		return status & 0xff;
-
-	/* Somebody closed stdout? */
-	if (fstat(fileno(stdout), &st))
-		return 0;
-	/* Ignore write errors for pipes and sockets.. */
-	if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
-		return 0;
-
-	/* Check for ENOSPC and EIO errors.. */
-	if (fflush(stdout))
-		die("write failure on standard output: %s", strerror(errno));
-	if (ferror(stdout))
-		die("unknown write failure on standard output");
-	if (fclose(stdout))
-		die("close failed on standard output: %s", strerror(errno));
-	return 0;
-}
-
 static void handle_internal_command(int argc, const char **argv)
 {
 	const char *cmd = argv[0];
-	static struct cmd_struct commands[] = {
-		{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
-		{ "annotate", cmd_annotate, RUN_SETUP },
-		{ "apply", cmd_apply },
-		{ "archive", cmd_archive },
-		{ "blame", cmd_blame, RUN_SETUP },
-		{ "branch", cmd_branch, RUN_SETUP },
-		{ "bundle", cmd_bundle },
-		{ "cat-file", cmd_cat_file, RUN_SETUP },
-		{ "checkout-index", cmd_checkout_index,
-			RUN_SETUP | NEED_WORK_TREE},
-		{ "check-ref-format", cmd_check_ref_format },
-		{ "check-attr", cmd_check_attr, RUN_SETUP | NEED_WORK_TREE },
-		{ "cherry", cmd_cherry, RUN_SETUP },
-		{ "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
-		{ "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
-		{ "commit-tree", cmd_commit_tree, RUN_SETUP },
-		{ "config", cmd_config },
-		{ "count-objects", cmd_count_objects, RUN_SETUP },
-		{ "describe", cmd_describe, RUN_SETUP },
-		{ "diff", cmd_diff },
-		{ "diff-files", cmd_diff_files },
-		{ "diff-index", cmd_diff_index, RUN_SETUP },
-		{ "diff-tree", cmd_diff_tree, RUN_SETUP },
-		{ "fetch", cmd_fetch, RUN_SETUP },
-		{ "fetch-pack", cmd_fetch_pack, RUN_SETUP },
-		{ "fetch--tool", cmd_fetch__tool, RUN_SETUP },
-		{ "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
-		{ "for-each-ref", cmd_for_each_ref, RUN_SETUP },
-		{ "format-patch", cmd_format_patch, RUN_SETUP },
-		{ "fsck", cmd_fsck, RUN_SETUP },
-		{ "fsck-objects", cmd_fsck, RUN_SETUP },
-		{ "gc", cmd_gc, RUN_SETUP },
-		{ "get-tar-commit-id", cmd_get_tar_commit_id },
-		{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
-		{ "help", cmd_help },
-#ifndef NO_CURL
-		{ "http-fetch", cmd_http_fetch, RUN_SETUP },
-#endif
-		{ "init", cmd_init_db },
-		{ "init-db", cmd_init_db },
-		{ "log", cmd_log, RUN_SETUP | USE_PAGER },
-		{ "ls-files", cmd_ls_files, RUN_SETUP },
-		{ "ls-tree", cmd_ls_tree, RUN_SETUP },
-		{ "ls-remote", cmd_ls_remote },
-		{ "mailinfo", cmd_mailinfo },
-		{ "mailsplit", cmd_mailsplit },
-		{ "merge-base", cmd_merge_base, RUN_SETUP },
-		{ "merge-file", cmd_merge_file },
-		{ "merge-ours", cmd_merge_ours, RUN_SETUP },
-		{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
-		{ "name-rev", cmd_name_rev, RUN_SETUP },
-		{ "pack-objects", cmd_pack_objects, RUN_SETUP },
-		{ "peek-remote", cmd_ls_remote },
-		{ "pickaxe", cmd_blame, RUN_SETUP },
-		{ "prune", cmd_prune, RUN_SETUP },
-		{ "prune-packed", cmd_prune_packed, RUN_SETUP },
-		{ "push", cmd_push, RUN_SETUP },
-		{ "read-tree", cmd_read_tree, RUN_SETUP },
-		{ "reflog", cmd_reflog, RUN_SETUP },
-		{ "repo-config", cmd_config },
-		{ "rerere", cmd_rerere, RUN_SETUP },
-		{ "reset", cmd_reset, RUN_SETUP },
-		{ "rev-list", cmd_rev_list, RUN_SETUP },
-		{ "rev-parse", cmd_rev_parse },
-		{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
-		{ "rm", cmd_rm, RUN_SETUP },
-		{ "runstatus", cmd_runstatus, RUN_SETUP | NEED_WORK_TREE },
-		{ "send-pack", cmd_send_pack, RUN_SETUP },
-		{ "shortlog", cmd_shortlog, RUN_SETUP | USE_PAGER },
-		{ "show-branch", cmd_show_branch, RUN_SETUP },
-		{ "show", cmd_show, RUN_SETUP | USE_PAGER },
-		{ "stripspace", cmd_stripspace },
-		{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
-		{ "tag", cmd_tag, RUN_SETUP },
-		{ "tar-tree", cmd_tar_tree },
-		{ "unpack-objects", cmd_unpack_objects, RUN_SETUP },
-		{ "update-index", cmd_update_index, RUN_SETUP },
-		{ "update-ref", cmd_update_ref, RUN_SETUP },
-		{ "upload-archive", cmd_upload_archive },
-		{ "verify-tag", cmd_verify_tag, RUN_SETUP },
-		{ "version", cmd_version },
-		{ "whatchanged", cmd_whatchanged, RUN_SETUP | USE_PAGER },
-		{ "write-tree", cmd_write_tree, RUN_SETUP },
-		{ "verify-pack", cmd_verify_pack },
-		{ "show-ref", cmd_show_ref, RUN_SETUP },
-		{ "pack-refs", cmd_pack_refs, RUN_SETUP },
-	};
-	int i;
+	struct cmd_struct *builtin;
 
 	/* Turn "git cmd --help" into "git help cmd" */
 	if (argc > 1 && !strcmp(argv[1], "--help")) {
@@ -374,12 +230,9 @@ static void handle_internal_command(int argc, const char **argv)
 		argv[0] = cmd = "help";
 	}
 
-	for (i = 0; i < ARRAY_SIZE(commands); i++) {
-		struct cmd_struct *p = commands+i;
-		if (strcmp(p->cmd, cmd))
-			continue;
-		exit(run_command(p, argc, argv));
-	}
+	builtin = git_builtin_command(cmd);
+	if (builtin)
+		exit(run_builtin_command(builtin, argc, argv));
 }
 
 static void execv_dashed_external(const char **argv)
-- 
1.5.3.6.2090.g4ece0

```

## Junio C Hamano, 2007-12-02 07:03

Subject: [PATCH 3/3] git-shell: accept "git foo" form
Message-ID: <1196579005-5662-3-git-send-email-gitster@pobox.com>
URL: https://gitlist.dev/e/1196579005-5662-3-git-send-email-gitster%40pobox.com
In-Reply-To: <1196579005-5662-2-git-send-email-gitster@pobox.com>

```
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 shell.c |   26 +++++++++++++++-----------
 1 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/shell.c b/shell.c
index 9826109..729797c 100644
--- a/shell.c
+++ b/shell.c
@@ -19,17 +19,13 @@ static int do_generic_cmd(const char *me, char *arg)
 	return execv_git_cmd(my_argv);
 }
 
-static int do_cvs_cmd(const char *me, char *arg)
+static int do_cvs_cmd(void)
 {
 	const char *cvsserver_argv[3] = {
 		"cvsserver", "server", NULL
 	};
 
-	if (!arg || strcmp(arg, "server"))
-		die("git-cvsserver only handles server: %s", arg);
-
 	setup_path(NULL);
-
 	return execv_git_cmd(cvsserver_argv);
 }
 
@@ -40,7 +36,6 @@ static struct commands {
 } cmd_list[] = {
 	{ "git-receive-pack", do_generic_cmd },
 	{ "git-upload-pack", do_generic_cmd },
-	{ "cvs", do_cvs_cmd },
 	{ NULL },
 };
 
@@ -49,15 +44,24 @@ int main(int argc, char **argv)
 	char *prog;
 	struct commands *cmd;
 
+	/*
+	 * Special hack to pretend to be a CVS server
+	 */
 	if (argc == 2 && !strcmp(argv[1], "cvs server"))
-		argv--;
-	/* We want to see "-c cmd args", and nothing else */
-	else if (argc != 3 || strcmp(argv[1], "-c"))
+		exit(do_cvs_cmd());
+
+	/*
+	 * We do not accept anything but "-c" followed by "cmd arg",
+	 * where "cmd" is a very limited subset of git commands.
+	 */
+	if (argc != 3 || strcmp(argv[1], "-c"))
 		die("What do you think I am? A shell?");
 
 	prog = argv[2];
-	argv += 2;
-	argc -= 2;
+	if (!strncmp(prog, "git", 3) && isspace(prog[3]))
+		/* Accept "git foo" as if the caller said "git-foo". */
+		prog[3] = '-';
+
 	for (cmd = cmd_list ; cmd->name ; cmd++) {
 		int len = strlen(cmd->name);
 		char *arg;
-- 
1.5.3.6.2090.g4ece0

```

## Christian Couder, 2007-12-02 08:48

Subject: Re: [PATCH 1/3] Prepare execv_git_cmd() for removal of builtins from the filesystem
Message-ID: <200712020948.47084.chriscool@tuxfamily.org>
URL: https://gitlist.dev/e/200712020948.47084.chriscool%40tuxfamily.org
In-Reply-To: <1196579005-5662-1-git-send-email-gitster@pobox.com>

```
Le dimanche 2 décembre 2007, Junio C Hamano a écrit :
> +	for (argc = 0; argv[argc]; argc++)
> +		; /* just counting */
> +	nargv = xmalloc(sizeof(*nargv) * (argc + 2));
>
> -	trace_argv_printf(argv, -1, "trace: exec:");
> +	nargv[0] = "git";
> +	for (argc = 0; argv[argc]; argc++)
> +		nargv[argc + 1] = argv[argc];
> +	nargv[argc + 1] = NULL;
> +	trace_argv_printf(nargv, -1, "trace: exec:");

Minor nit: now that the number of arguments is known, we could perhaps use 
the argument count instead of -1 in trace_argv_printf, so that it is not 
computed again in quote.c:sq_quote_argv, like this:

trace_argv_printf(nargv, argc + 1, "trace: exec:");

Christian.

```

## Johannes Schindelin, 2007-12-02 12:24

Subject: Re: [PATCH 2/3] Avoid double exec() in execv_git_cmd()
Message-ID: <Pine.LNX.4.64.0712021221410.27959@racer.site>
URL: https://gitlist.dev/e/Pine.LNX.4.64.0712021221410.27959%40racer.site
In-Reply-To: <1196579005-5662-2-git-send-email-gitster@pobox.com>

```
Hi,

On Sat, 1 Dec 2007, Junio C Hamano wrote:

> This avoids double exec() when execv_git_cmd() is used to spawn an
> external git command.
> 
> For this, execv_git_cmd() needs to be able to tell what's built-in.
> This is done by introducing a new function git_builtin_command() that
> checks the list of built-in commands and returns a pointer to the
> cmd_struct if found.  The same function is used from the git potty.

IMNSHO this does not buy us anything, compared to my patch series.  Your 
patch is larger, distributes the responsibility for the builtins to two 
files instead of one, and since we control what is builtin and what not, 
is not really less fragile with respect to what needs to be initialised.

Besides, we lose a great opportunity to go in the direction of 
libification.

Ciao,
Dscho

```