run-command: introduce CHILD_PROCESS_INIT

Most struct child_process variables are cleared using memset first after
declaration.  Provide a macro, CHILD_PROCESS_INIT, that can be used to
initialize them statically instead.  That's shorter, doesn't require a
function call and is slightly more readable (especially given that we
already have STRBUF_INIT, ARGV_ARRAY_INIT etc.).

Helped-by: Johannes Sixt <[email protected]>
Signed-off-by: Rene Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Documentation/technical/api-run-command.txt

@@ -96,8 +96,8 @@ command to run in a sub-process.
 
 The caller:
 
-1. allocates and clears (memset(&chld, 0, sizeof(chld));) a
-   struct child_process variable;
+1. allocates and clears (memset(&chld, 0, sizeof(chld)); or
+   using CHILD_PROCESS_INIT) a struct child_process variable;
 2. initializes the members;
 3. calls start_command();
 4. processes the data;

archive-tar.c

@@ -395,7 +395,7 @@ static int write_tar_filter_archive(const struct archiver *ar,
 				    struct archiver_args *args)
 {
 	struct strbuf cmd = STRBUF_INIT;
-	struct child_process filter;
+	struct child_process filter = CHILD_PROCESS_INIT;
 	const char *argv[2];
 	int r;
 
@@ -406,7 +406,6 @@ static int write_tar_filter_archive(const struct archiver *ar,
 	if (args->compression_level >= 0)
 		strbuf_addf(&cmd, " -%d", args->compression_level);
 
-	memset(&filter, 0, sizeof(filter));
 	argv[0] = cmd.buf;
 	argv[1] = NULL;
 	filter.argv = argv;

builtin/add.c

@@ -180,7 +180,7 @@ static int edit_patch(int argc, const char **argv, const char *prefix)
 	char *file = git_pathdup("ADD_EDIT.patch");
 	const char *apply_argv[] = { "apply", "--recount", "--cached",
 		NULL, NULL };
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 	struct rev_info rev;
 	int out;
 	struct stat st;
@@ -214,7 +214,6 @@ static int edit_patch(int argc, const char **argv, const char *prefix)
 	if (!st.st_size)
 		die(_("Empty patch. Aborted."));
 
-	memset(&child, 0, sizeof(child));
 	child.git_cmd = 1;
 	child.argv = apply_argv;
 	if (run_command(&child))

builtin/commit.c

@@ -1508,7 +1508,7 @@ static int run_rewrite_hook(const unsigned char *oldsha1,
 {
 	/* oldsha1 SP newsha1 LF NUL */
 	static char buf[2*40 + 3];
-	struct child_process proc;
+	struct child_process proc = CHILD_PROCESS_INIT;
 	const char *argv[3];
 	int code;
 	size_t n;
@@ -1520,7 +1520,6 @@ static int run_rewrite_hook(const unsigned char *oldsha1,
 	argv[1] = "amend";
 	argv[2] = NULL;
 
-	memset(&proc, 0, sizeof(proc));
 	proc.argv = argv;
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;

builtin/help.c

@@ -79,12 +79,11 @@ static const char *get_man_viewer_info(const char *name)
 static int check_emacsclient_version(void)
 {
 	struct strbuf buffer = STRBUF_INIT;
-	struct child_process ec_process;
+	struct child_process ec_process = CHILD_PROCESS_INIT;
 	const char *argv_ec[] = { "emacsclient", "--version", NULL };
 	int version;
 
 	/* emacsclient prints its version number on stderr */
-	memset(&ec_process, 0, sizeof(ec_process));
 	ec_process.argv = argv_ec;
 	ec_process.err = -1;
 	ec_process.stdout_to_stderr = 1;

builtin/merge.c

@@ -237,11 +237,10 @@ static void drop_save(void)
 static int save_state(unsigned char *stash)
 {
 	int len;
-	struct child_process cp;
+	struct child_process cp = CHILD_PROCESS_INIT;
 	struct strbuf buffer = STRBUF_INIT;
 	const char *argv[] = {"stash", "create", NULL};
 
-	memset(&cp, 0, sizeof(cp));
 	cp.argv = argv;
 	cp.out = -1;
 	cp.git_cmd = 1;

builtin/notes.c

@@ -122,12 +122,11 @@ static void write_commented_object(int fd, const unsigned char *object)
 {
 	const char *show_args[5] =
 		{"show", "--stat", "--no-notes", sha1_to_hex(object), NULL};
-	struct child_process show;
+	struct child_process show = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf cbuf = STRBUF_INIT;
 
 	/* Invoke "git show --stat --no-notes $object" */
-	memset(&show, 0, sizeof(show));
 	show.argv = show_args;
 	show.no_stdin = 1;
 	show.out = -1;

builtin/receive-pack.c

@@ -255,7 +255,7 @@ static int copy_to_sideband(int in, int out, void *arg)
 typedef int (*feed_fn)(void *, const char **, size_t *);
 static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_state)
 {
-	struct child_process proc;
+	struct child_process proc = CHILD_PROCESS_INIT;
 	struct async muxer;
 	const char *argv[2];
 	int code;
@@ -266,7 +266,6 @@ static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_sta
 
 	argv[1] = NULL;
 
-	memset(&proc, 0, sizeof(proc));
 	proc.argv = argv;
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;
@@ -350,7 +349,7 @@ static int run_receive_hook(struct command *commands, const char *hook_name,
 static int run_update_hook(struct command *cmd)
 {
 	const char *argv[5];
-	struct child_process proc;
+	struct child_process proc = CHILD_PROCESS_INIT;
 	int code;
 
 	argv[0] = find_hook("update");
@@ -362,7 +361,6 @@ static int run_update_hook(struct command *cmd)
 	argv[3] = sha1_to_hex(cmd->new_sha1);
 	argv[4] = NULL;
 
-	memset(&proc, 0, sizeof(proc));
 	proc.no_stdin = 1;
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
@@ -598,7 +596,7 @@ static void run_update_post_hook(struct command *commands)
 	struct command *cmd;
 	int argc;
 	const char **argv;
-	struct child_process proc;
+	struct child_process proc = CHILD_PROCESS_INIT;
 	char *hook;
 
 	hook = find_hook("post-update");
@@ -621,7 +619,6 @@ static void run_update_post_hook(struct command *commands)
 	}
 	argv[argc] = NULL;
 
-	memset(&proc, 0, sizeof(proc));
 	proc.no_stdin = 1;
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
@@ -911,7 +908,7 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 	const char *hdr_err;
 	int status;
 	char hdr_arg[38];
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 	int fsck_objects = (receive_fsck_objects >= 0
 			    ? receive_fsck_objects
 			    : transfer_fsck_objects >= 0
@@ -933,7 +930,6 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		argv_array_pushl(&av, "--shallow-file", alt_shallow_file, NULL);
 	}
 
-	memset(&child, 0, sizeof(child));
 	if (ntohl(hdr.hdr_entries) < unpack_limit) {
 		argv_array_pushl(&av, "unpack-objects", hdr_arg, NULL);
 		if (quiet)

builtin/remote-ext.c

@@ -179,9 +179,8 @@ static void send_git_request(int stdin_fd, const char *serv, const char *repo,
 static int run_child(const char *arg, const char *service)
 {
 	int r;
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 
-	memset(&child, 0, sizeof(child));
 	child.in = -1;
 	child.out = -1;
 	child.err = 0;

builtin/repack.c

@@ -133,7 +133,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		{".idx"},
 		{".bitmap", 1},
 	};
-	struct child_process cmd;
+	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
 	struct argv_array cmd_args = ARGV_ARRAY_INIT;
 	struct string_list names = STRING_LIST_INIT_DUP;
@@ -250,7 +250,6 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 
 	argv_array_push(&cmd_args, packtmp);
 
-	memset(&cmd, 0, sizeof(cmd));
 	cmd.argv = cmd_args.argv;
 	cmd.git_cmd = 1;
 	cmd.out = -1;

builtin/replace.c

@@ -197,7 +197,7 @@ static int replace_object(const char *object_ref, const char *replace_ref, int f
 static void export_object(const unsigned char *sha1, enum object_type type,
 			  int raw, const char *filename)
 {
-	struct child_process cmd = { NULL };
+	struct child_process cmd = CHILD_PROCESS_INIT;
 	int fd;
 
 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
@@ -234,7 +234,7 @@ static void import_object(unsigned char *sha1, enum object_type type,
 
 	if (!raw && type == OBJ_TREE) {
 		const char *argv[] = { "mktree", NULL };
-		struct child_process cmd = { argv };
+		struct child_process cmd = CHILD_PROCESS_INIT;
 		struct strbuf result = STRBUF_INIT;
 
 		cmd.argv = argv;

builtin/verify-pack.c

@@ -8,7 +8,7 @@
 
 static int verify_one_pack(const char *path, unsigned int flags)
 {
-	struct child_process index_pack;
+	struct child_process index_pack = CHILD_PROCESS_INIT;
 	const char *argv[] = {"index-pack", NULL, NULL, NULL };
 	struct strbuf arg = STRBUF_INIT;
 	int verbose = flags & VERIFY_PACK_VERBOSE;
@@ -32,7 +32,6 @@ static int verify_one_pack(const char *path, unsigned int flags)
 		strbuf_addstr(&arg, ".pack");
 	argv[2] = arg.buf;
 
-	memset(&index_pack, 0, sizeof(index_pack));
 	index_pack.argv = argv;
 	index_pack.git_cmd = 1;
 

bundle.c

@@ -240,7 +240,7 @@ int create_bundle(struct bundle_header *header, const char *path,
 	int i, ref_count = 0;
 	struct strbuf buf = STRBUF_INIT;
 	struct rev_info revs;
-	struct child_process rls;
+	struct child_process rls = CHILD_PROCESS_INIT;
 	FILE *rls_fout;
 
 	bundle_to_stdout = !strcmp(path, "-");
@@ -258,7 +258,6 @@ int create_bundle(struct bundle_header *header, const char *path,
 	init_revisions(&revs, NULL);
 
 	/* write prerequisites */
-	memset(&rls, 0, sizeof(rls));
 	argv_array_pushl(&rls.args,
 			 "rev-list", "--boundary", "--pretty=oneline",
 			 NULL);
@@ -417,14 +416,13 @@ int unbundle(struct bundle_header *header, int bundle_fd, int flags)
 {
 	const char *argv_index_pack[] = {"index-pack",
 					 "--fix-thin", "--stdin", NULL, NULL};
-	struct child_process ip;
+	struct child_process ip = CHILD_PROCESS_INIT;
 
 	if (flags & BUNDLE_VERBOSE)
 		argv_index_pack[3] = "-v";
 
 	if (verify_bundle(header, 0))
 		return -1;
-	memset(&ip, 0, sizeof(ip));
 	ip.argv = argv_index_pack;
 	ip.in = bundle_fd;
 	ip.no_stdout = 1;

column.c

@@ -367,7 +367,7 @@ int parseopt_column_callback(const struct option *opt,
 }
 
 static int fd_out = -1;
-static struct child_process column_process;
+static struct child_process column_process = CHILD_PROCESS_INIT;
 
 int run_column_filter(int colopts, const struct column_options *opts)
 {

connect.c

@@ -639,7 +639,7 @@ static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 	return protocol;
 }
 
-static struct child_process no_fork;
+static struct child_process no_fork = CHILD_PROCESS_INIT;
 
 /*
  * This returns a dummy child_process if the transport protocol does not

connected.c

@@ -25,7 +25,7 @@ static int check_everything_connected_real(sha1_iterate_fn fn,
 					   struct transport *transport,
 					   const char *shallow_file)
 {
-	struct child_process rev_list;
+	struct child_process rev_list = CHILD_PROCESS_INIT;
 	const char *argv[9];
 	char commit[41];
 	unsigned char sha1[20];
@@ -60,7 +60,6 @@ static int check_everything_connected_real(sha1_iterate_fn fn,
 		argv[ac++] = "--quiet";
 	argv[ac] = NULL;
 
-	memset(&rev_list, 0, sizeof(rev_list));
 	rev_list.argv = argv;
 	rev_list.git_cmd = 1;
 	rev_list.in = -1;

convert.c

@@ -321,7 +321,7 @@ static int filter_buffer(int in, int out, void *data)
 	/*
 	 * Spawn cmd and feed the buffer contents through its stdin.
 	 */
-	struct child_process child_process;
+	struct child_process child_process = CHILD_PROCESS_INIT;
 	struct filter_params *params = (struct filter_params *)data;
 	int write_err, status;
 	const char *argv[] = { NULL, NULL };
@@ -344,7 +344,6 @@ static int filter_buffer(int in, int out, void *data)
 
 	argv[0] = cmd.buf;
 
-	memset(&child_process, 0, sizeof(child_process));
 	child_process.argv = argv;
 	child_process.use_shell = 1;
 	child_process.in = -1;

credential-cache.c

@@ -37,12 +37,11 @@ static int send_request(const char *socket, const struct strbuf *out)
 
 static void spawn_daemon(const char *socket)
 {
-	struct child_process daemon;
+	struct child_process daemon = CHILD_PROCESS_INIT;
 	const char *argv[] = { NULL, NULL, NULL };
 	char buf[128];
 	int r;
 
-	memset(&daemon, 0, sizeof(daemon));
 	argv[0] = "git-credential-cache--daemon";
 	argv[1] = socket;
 	daemon.argv = argv;

credential.c

@@ -205,11 +205,10 @@ static int run_credential_helper(struct credential *c,
 				 const char *cmd,
 				 int want_output)
 {
-	struct child_process helper;
+	struct child_process helper = CHILD_PROCESS_INIT;
 	const char *argv[] = { NULL, NULL };
 	FILE *fp;
 
-	memset(&helper, 0, sizeof(helper));
 	argv[0] = cmd;
 	helper.argv = argv;
 	helper.use_shell = 1;

daemon.c

@@ -259,7 +259,7 @@ static const char *access_hook;
 
 static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 {
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	const char *argv[8];
 	const char **arg = argv;
@@ -277,7 +277,6 @@ static int run_access_hook(struct daemon_service *service, const char *dir, cons
 	*arg = NULL;
 #undef STRARG
 
-	memset(&child, 0, sizeof(child));
 	child.use_shell = 1;
 	child.argv = argv;
 	child.no_stdin = 1;
@@ -406,9 +405,8 @@ static void copy_to_log(int fd)
 
 static int run_service_command(const char **argv)
 {
-	struct child_process cld;
+	struct child_process cld = CHILD_PROCESS_INIT;
 
-	memset(&cld, 0, sizeof(cld));
 	cld.argv = argv;
 	cld.git_cmd = 1;
 	cld.err = -1;
@@ -733,7 +731,7 @@ static void check_dead_children(void)
 static char **cld_argv;
 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 {
-	struct child_process cld = { NULL };
+	struct child_process cld = CHILD_PROCESS_INIT;
 	char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 	char *env[] = { addrbuf, portbuf, NULL };
 

diff.c

@@ -4931,7 +4931,7 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
 	struct diff_tempfile *temp;
 	const char *argv[3];
 	const char **arg = argv;
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	int err = 0;
 
@@ -4940,7 +4940,6 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
 	*arg++ = temp->name;
 	*arg = NULL;
 
-	memset(&child, 0, sizeof(child));
 	child.use_shell = 1;
 	child.argv = argv;
 	child.out = -1;