ash: implement "exec -a ARGV0 CMD ARGV1..."

function                                             old     new   delta
execcmd                                               71     112     +41
shellexec                                            221     224      +3
evalcommand                                         1158    1161      +3
localcmd                                             364     366      +2
unaliascmd                                           163     154      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 49/-9)              Total: 40 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 044f166be..e170bec2a 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -3345,11 +3345,9 @@ unaliascmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 {
         int i;
 
-        while ((i = nextopt("a")) != '\0') {
-                if (i == 'a') {
-                        rmaliases();
-                        return 0;
-                }
+        while (nextopt("a") != '\0') {
+                rmaliases();
+                return 0;
         }
         for (i = 0; *argptr; argptr++) {
                 if (unalias(*argptr)) {
@@ -9354,7 +9352,14 @@ truecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 static int FAST_FUNC
 execcmd(int argc UNUSED_PARAM, char **argv)
 {
-        if (argv[1]) {
+        optionarg = NULL;
+        while (nextopt("a:") != '\0')
+                /* nextopt() sets optionarg to "-a ARGV0" */;
+
+        argv = argptr;
+        if (argv[0]) {
+                char *prog;
+
                 iflag = 0;              /* exit on error */
                 mflag = 0;
                 optschanged();
@@ -9370,7 +9375,10 @@ execcmd(int argc UNUSED_PARAM, char **argv)
                 /*setsignal(SIGTSTP); - unnecessary because of mflag=0 */
                 /*setsignal(SIGTTOU); - unnecessary because of mflag=0 */
 
-                shellexec(argv[1], argv + 1, pathval(), 0);
+                prog = argv[0];
+                if (optionarg)
+                        argv[0] = optionarg;
+                shellexec(prog, argv, pathval(), 0);
                 /* NOTREACHED */
         }
         return 0;