[PATCH 3/3] ash: exec: -a option for setting zeroth arg

[Kaarle Ritvanen]

Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen at datakunkku.fi>
---
 shell/ash.c | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index 58ae950..b799b85 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7744,9 +7744,9 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **
  * have to change the find_command routine as well.
  * argv[-1] must exist and be writable! See tryexec() for why.
  */
-static void shellexec(char **, const char *, int) NORETURN;
+static void shellexec(const char *, char **, const char *, int) NORETURN;
 static void
-shellexec(char **argv, const char *path, int idx)
+shellexec(const char *cmdname, char **argv, const char *path, int idx)
 {
 	char *cmdpath;
 	int e;
@@ -7755,12 +7755,15 @@ shellexec(char **argv, const char *path, int idx)
 	int applet_no = -1; /* used only by FEATURE_SH_STANDALONE */
 
 	envp = listvars(VEXPORT, VUNSET, /*end:*/ NULL);
-	if (strchr(argv[0], '/') != NULL
+	if (!cmdname)
+		cmdname = argv[0];
+
+	if (strchr(cmdname, '/') != NULL
 #if ENABLE_FEATURE_SH_STANDALONE
-	 || (applet_no = find_applet_by_name(argv[0])) >= 0
+	 || (applet_no = find_applet_by_name(cmdname)) >= 0
 #endif
 	) {
-		tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) argv[0], argv, envp);
+		tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) cmdname, argv, envp);
 		if (applet_no >= 0) {
 			/* We tried execing ourself, but it didn't work.
 			 * Maybe /proc/self/exe doesn't exist?
@@ -7772,7 +7775,7 @@ shellexec(char **argv, const char *path, int idx)
 	} else {
  try_PATH:
 		e = ENOENT;
-		while ((cmdpath = path_advance(&path, argv[0])) != NULL) {
+		while ((cmdpath = path_advance(&path, cmdname)) != NULL) {
 			if (--idx < 0 && pathopt == NULL) {
 				tryexec(IF_FEATURE_SH_STANDALONE(-1,) cmdpath, argv, envp);
 				if (errno != ENOENT && errno != ENOTDIR)
@@ -9353,9 +9356,28 @@ truecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 }
 
 static int FAST_FUNC
-execcmd(int argc UNUSED_PARAM, char **argv)
+execcmd(int argc, char **argv)
 {
-	if (argv[1]) {
+	int opt;
+	char *argv0 = NULL;
+	char *cmdname = NULL;
+
+	GETOPT_RESET
+	while ((opt = getopt(argc, argv, "a:")) != -1)
+		switch (opt) {
+		case 'a':
+			argv0 = optarg;
+			break;
+		default:
+			return 1;
+		}
+
+	if (argv[optind]) {
+		if (argv0) {
+			cmdname = argv[optind];
+			argv[optind] = argv0;
+		}
+
 		iflag = 0;              /* exit on error */
 		mflag = 0;
 		optschanged();
@@ -9371,7 +9393,7 @@ execcmd(int argc UNUSED_PARAM, char **argv)
 		/*setsignal(SIGTSTP); - unnecessary because of mflag=0 */
 		/*setsignal(SIGTTOU); - unnecessary because of mflag=0 */
 
-		shellexec(argv + 1, pathval(), 0);
+		shellexec(cmdname, argv + optind, pathval(), 0);
 		/* NOTREACHED */
 	}
 	return 0;
@@ -9773,7 +9795,7 @@ evalcommand(union node *cmd, int flags)
 			/* fall through to exec'ing external program */
 		}
 		listsetvar(varlist.list, VEXPORT|VSTACK);
-		shellexec(argv, path, cmdentry.u.index);
+		shellexec(NULL, argv, path, cmdentry.u.index);
 		/* NOTREACHED */
 	} /* default */
 	case CMDBUILTIN:
-- 
2.9.3