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]>

Author: rscharfe

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;