sq_quote_argv and add_to_string rework with strbuf's.

* sq_quote_buf is made public, and works on a strbuf.
* sq_quote_argv also works on a strbuf.
* make sq_quote_argv take a "maxlen" argument to check the buffer won't grow
  too big.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 86 insertions, 137 deletions

diff --git a/connect.c b/connect.c
index 1653a0ef7f..06d279e37c 100644
--- a/connect.c
+++ b/connect.c
@@ -577,16 +577,13 @@ pid_t git_connect(int fd[2], char *url, const char *prog, int flags)
 	if (pid < 0)
 		die("unable to fork");
 	if (!pid) {
-		char command[MAX_CMD_LEN];
-		char *posn = command;
-		int size = MAX_CMD_LEN;
-		int of = 0;
+		struct strbuf cmd;
 
-		of |= add_to_string(&posn, &size, prog, 0);
-		of |= add_to_string(&posn, &size, " ", 0);
-		of |= add_to_string(&posn, &size, path, 1);
-
-		if (of)
+		strbuf_init(&cmd, MAX_CMD_LEN);
+		strbuf_addstr(&cmd, prog);
+		strbuf_addch(&cmd, ' ');
+		sq_quote_buf(&cmd, path);
+		if (cmd.len >= MAX_CMD_LEN)
 			die("command line too long");
 
 		dup2(pipefd[1][0], 0);
@@ -606,10 +603,10 @@ pid_t git_connect(int fd[2], char *url, const char *prog, int flags)
 				ssh_basename++;
 
 			if (!port)
-				execlp(ssh, ssh_basename, host, command, NULL);
+				execlp(ssh, ssh_basename, host, cmd.buf, NULL);
 			else
 				execlp(ssh, ssh_basename, "-p", port, host,
-				       command, NULL);
+				       cmd.buf, NULL);
 		}
 		else {
 			unsetenv(ALTERNATE_DB_ENVIRONMENT);
@@ -618,7 +615,7 @@ pid_t git_connect(int fd[2], char *url, const char *prog, int flags)
 			unsetenv(GIT_WORK_TREE_ENVIRONMENT);
 			unsetenv(GRAFT_ENVIRONMENT);
 			unsetenv(INDEX_ENVIRONMENT);
-			execlp("sh", "sh", "-c", command, NULL);
+			execlp("sh", "sh", "-c", cmd.buf, NULL);
 		}
 		die("exec failed");
 	}
diff --git a/git.c b/git.c
index 56ae8ccccf..9eaca1d671 100644
--- a/git.c
+++ b/git.c
@@ -187,19 +187,13 @@ static int handle_alias(int *argcp, const char ***argv)
 	if (alias_string) {
 		if (alias_string[0] == '!') {
 			if (*argcp > 1) {
-				int i, sz = PATH_MAX;
-				char *s = xmalloc(sz), *new_alias = s;
+				struct strbuf buf;
 
-				add_to_string(&s, &sz, alias_string, 0);
+				strbuf_init(&buf, PATH_MAX);
+				strbuf_addstr(&buf, alias_string);
+				sq_quote_argv(&buf, (*argv) + 1, *argcp - 1, PATH_MAX);
 				free(alias_string);
-				alias_string = new_alias;
-				for (i = 1; i < *argcp &&
-					!add_to_string(&s, &sz, " ", 0) &&
-					!add_to_string(&s, &sz, (*argv)[i], 1)
-					; i++)
-					; /* do nothing */
-				if (!sz)
-					die("Too many or long arguments");
+				alias_string = buf.buf;
 			}
 			trace_printf("trace: alias to shell cmd: %s => %s\n",
 				     alias_command, alias_string + 1);
diff --git a/quote.c b/quote.c
index b1efe188d4..800fd88c9a 100644
--- a/quote.c
+++ b/quote.c
@@ -12,37 +12,31 @@
  *  a'b      ==> a'\''b    ==> 'a'\''b'
  *  a!b      ==> a'\!'b    ==> 'a'\!'b'
  */
-#undef EMIT
-#define EMIT(x) do { if (++len < n) *bp++ = (x); } while(0)
-
 static inline int need_bs_quote(char c)
 {
 	return (c == '\'' || c == '!');
 }
 
-static size_t sq_quote_buf(char *dst, size_t n, const char *src)
+void sq_quote_buf(struct strbuf *dst, const char *src)
 {
-	char c;
-	char *bp = dst;
-	size_t len = 0;
-
-	EMIT('\'');
-	while ((c = *src++)) {
-		if (need_bs_quote(c)) {
-			EMIT('\'');
-			EMIT('\\');
-			EMIT(c);
-			EMIT('\'');
-		} else {
-			EMIT(c);
+	char *to_free = NULL;
+
+	if (dst->buf == src)
+		to_free = strbuf_detach(dst);
+
+	strbuf_addch(dst, '\'');
+	while (*src) {
+		size_t len = strcspn(src, "'\\");
+		strbuf_add(dst, src, len);
+		src += len;
+		while (need_bs_quote(*src)) {
+			strbuf_addstr(dst, "'\\");
+			strbuf_addch(dst, *src++);
+			strbuf_addch(dst, '\'');
 		}
 	}
-	EMIT('\'');
-
-	if ( n )
-		*bp = 0;
-
-	return len;
+	strbuf_addch(dst, '\'');
+	free(to_free);
 }
 
 void sq_quote_print(FILE *stream, const char *src)
@@ -62,11 +56,10 @@ void sq_quote_print(FILE *stream, const char *src)
 	fputc('\'', stream);
 }
 
-char *sq_quote_argv(const char** argv, int count)
+void sq_quote_argv(struct strbuf *dst, const char** argv, int count,
+                   size_t maxlen)
 {
-	char *buf, *to;
 	int i;
-	size_t len = 0;
 
 	/* Count argv if needed. */
 	if (count < 0) {
@@ -74,53 +67,14 @@ char *sq_quote_argv(const char** argv, int count)
 			; /* just counting */
 	}
 
-	/* Special case: no argv. */
-	if (!count)
-		return xcalloc(1,1);
-
-	/* Get destination buffer length. */
-	for (i = 0; i < count; i++)
-		len += sq_quote_buf(NULL, 0, argv[i]) + 1;
-
-	/* Alloc destination buffer. */
-	to = buf = xmalloc(len + 1);
-
 	/* Copy into destination buffer. */
+	strbuf_grow(dst, 32 * count);
 	for (i = 0; i < count; ++i) {
-		*to++ = ' ';
-		to += sq_quote_buf(to, len, argv[i]);
+		strbuf_addch(dst, ' ');
+		sq_quote_buf(dst, argv[i]);
+		if (maxlen && dst->len > maxlen)
+			die("Too many or long arguments");
 	}
-
-	return buf;
-}
-
-/*
- * Append a string to a string buffer, with or without shell quoting.
- * Return true if the buffer overflowed.
- */
-int add_to_string(char **ptrp, int *sizep, const char *str, int quote)
-{
-	char *p = *ptrp;
-	int size = *sizep;
-	int oc;
-	int err = 0;
-
-	if (quote)
-		oc = sq_quote_buf(p, size, str);
-	else {
-		oc = strlen(str);
-		memcpy(p, str, (size <= oc) ? size - 1 : oc);
-	}
-
-	if (size <= oc) {
-		err = 1;
-		oc = size - 1;
-	}
-
-	*ptrp += oc;
-	**ptrp = '\0';
-	*sizep -= oc;
-	return err;
 }
 
 char *sq_dequote(char *arg)
diff --git a/quote.h b/quote.h
index 2769f71c93..4287990998 100644
--- a/quote.h
+++ b/quote.h
@@ -29,13 +29,10 @@
  */
 
 extern void sq_quote_print(FILE *stream, const char *src);
-extern char *sq_quote_argv(const char** argv, int count);
 
-/*
- * Append a string to a string buffer, with or without shell quoting.
- * Return true if the buffer overflowed.
- */
-extern int add_to_string(char **ptrp, int *sizep, const char *str, int quote);
+extern void sq_quote_buf(struct strbuf *, const char *src);
+extern void sq_quote_argv(struct strbuf *, const char **argv, int count,
+                          size_t maxlen);
 
 /* This unwraps what sq_quote() produces in place, but returns
  * NULL if the input does not look like what sq_quote would have
diff --git a/rsh.c b/rsh.c
index 5754a230e2..016d72ead7 100644
--- a/rsh.c
+++ b/rsh.c
@@ -10,12 +10,9 @@ int setup_connection(int *fd_in, int *fd_out, const char *remote_prog,
 	char *host;
 	char *path;
 	int sv[2];
-	char command[COMMAND_SIZE];
-	char *posn;
-	int sizen;
-	int of;
 	int i;
 	pid_t pid;
+	struct strbuf cmd;
 
 	if (!strcmp(url, "-")) {
 		*fd_in = 0;
@@ -36,24 +33,23 @@ int setup_connection(int *fd_in, int *fd_out, const char *remote_prog,
 	if (!path) {
 		return error("Bad URL: %s", url);
 	}
+
 	/* $GIT_RSH <host> "env GIT_DIR=<path> <remote_prog> <args...>" */
-	sizen = COMMAND_SIZE;
-	posn = command;
-	of = 0;
-	of |= add_to_string(&posn, &sizen, "env ", 0);
-	of |= add_to_string(&posn, &sizen, GIT_DIR_ENVIRONMENT "=", 0);
-	of |= add_to_string(&posn, &sizen, path, 1);
-	of |= add_to_string(&posn, &sizen, " ", 0);
-	of |= add_to_string(&posn, &sizen, remote_prog, 1);
+	strbuf_init(&cmd, COMMAND_SIZE);
+	strbuf_addstr(&cmd, "env ");
+	strbuf_addstr(&cmd, GIT_DIR_ENVIRONMENT "=");
+	sq_quote_buf(&cmd, path);
+	strbuf_addch(&cmd, ' ');
+	sq_quote_buf(&cmd, remote_prog);
 
-	for ( i = 0 ; i < rmt_argc ; i++ ) {
-		of |= add_to_string(&posn, &sizen, " ", 0);
-		of |= add_to_string(&posn, &sizen, rmt_argv[i], 1);
+	for (i = 0 ; i < rmt_argc ; i++) {
+		strbuf_addch(&cmd, ' ');
+		sq_quote_buf(&cmd, rmt_argv[i]);
 	}
 
-	of |= add_to_string(&posn, &sizen, " -", 0);
+	strbuf_addstr(&cmd, " -");
 
-	if ( of )
+	if (cmd.len >= COMMAND_SIZE)
 		return error("Command line too long");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv))
@@ -74,7 +70,7 @@ int setup_connection(int *fd_in, int *fd_out, const char *remote_prog,
 		close(sv[1]);
 		dup2(sv[0], 0);
 		dup2(sv[0], 1);
-		execlp(ssh, ssh_basename, host, command, NULL);
+		execlp(ssh, ssh_basename, host, cmd.buf, NULL);
 	}
 	close(sv[0]);
 	*fd_in = sv[1];
diff --git a/trace.c b/trace.c
index 91548a56ec..69fa05e644 100644
--- a/trace.c
+++ b/trace.c
@@ -64,7 +64,7 @@ static const char err_msg[] = "Could not trace into fd given by "
 
 void trace_printf(const char *fmt, ...)
 {
-	char buf[8192];
+	struct strbuf buf;
 	va_list ap;
 	int fd, len, need_close = 0;
 
@@ -72,12 +72,22 @@ void trace_printf(const char *fmt, ...)
 	if (!fd)
 		return;
 
+	strbuf_init(&buf, 0);
 	va_start(ap, fmt);
-	len = vsnprintf(buf, sizeof(buf), fmt, ap);
+	len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
 	va_end(ap);
-	if (len >= sizeof(buf))
-		die("unreasonnable trace length");
-	write_or_whine_pipe(fd, buf, len, err_msg);
+	if (len >= strbuf_avail(&buf)) {
+		strbuf_grow(&buf, len - strbuf_avail(&buf) + 128);
+		va_start(ap, fmt);
+		len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
+		va_end(ap);
+		if (len >= strbuf_avail(&buf))
+			die("broken vsnprintf");
+	}
+	strbuf_setlen(&buf, len);
+
+	write_or_whine_pipe(fd, buf.buf, buf.len, err_msg);
+	strbuf_release(&buf);
 
 	if (need_close)
 		close(fd);
@@ -85,31 +95,32 @@ void trace_printf(const char *fmt, ...)
 
 void trace_argv_printf(const char **argv, int count, const char *fmt, ...)
 {
-	char buf[8192];
+	struct strbuf buf;
 	va_list ap;
-	char *argv_str;
-	size_t argv_len;
 	int fd, len, need_close = 0;
 
 	fd = get_trace_fd(&need_close);
 	if (!fd)
 		return;
 
+	strbuf_init(&buf, 0);
 	va_start(ap, fmt);
-	len = vsnprintf(buf, sizeof(buf), fmt, ap);
+	len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
 	va_end(ap);
-	if (len >= sizeof(buf))
-		die("unreasonnable trace length");
-
-	/* Get the argv string. */
-	argv_str = sq_quote_argv(argv, count);
-	argv_len = strlen(argv_str);
-
-	write_or_whine_pipe(fd, buf, len, err_msg);
-	write_or_whine_pipe(fd, argv_str, argv_len, err_msg);
-	write_or_whine_pipe(fd, "\n", 1, err_msg);
+	if (len >= strbuf_avail(&buf)) {
+		strbuf_grow(&buf, len - strbuf_avail(&buf) + 128);
+		va_start(ap, fmt);
+		len = vsnprintf(buf.buf, strbuf_avail(&buf), fmt, ap);
+		va_end(ap);
+		if (len >= strbuf_avail(&buf))
+			die("broken vsnprintf");
+	}
+	strbuf_setlen(&buf, len);
 
-	free(argv_str);
+	sq_quote_argv(&buf, argv, count, 0);
+	strbuf_addch(&buf, '\n');
+	write_or_whine_pipe(fd, buf.buf, buf.len, err_msg);
+	strbuf_release(&buf);
 
 	if (need_close)
 		close(fd);