linux-user: add support for passing contents of argv0

Added switch -0 (zero) which can be used to pass argv[0] to
target process. The main use is for a binfmt_misc wrapper when
the "P - preserve-argv[0]" setting is used.

From: Mika Westerberg

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7115 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 37 insertions, 1 deletions

diff --git a/linux-user/main.c b/linux-user/main.c
index 21e8128b07..b6b02fd5a1 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2215,6 +2215,7 @@ static void usage(void)
            "-drop-ld-preload  drop LD_PRELOAD for target process\n"
            "-E var=value      sets/modifies targets environment variable(s)\n"
            "-U var            unsets targets environment variable(s)\n"
+           "-0 argv0          forces target process argv[0] to be argv0\n"
            "\n"
            "Debug options:\n"
            "-d options   activate log (logfile=%s)\n"
@@ -2266,7 +2267,11 @@ int main(int argc, char **argv, char **envp)
     const char *r;
     int gdbstub_port = 0;
     char **target_environ, **wrk;
+    char **target_argv;
+    int target_argc;
     envlist_t *envlist = NULL;
+    const char *argv0 = NULL;
+    int i;
 
     if (argc <= 1)
         usage();
@@ -2323,6 +2328,9 @@ int main(int argc, char **argv, char **envp)
             r = argv[optind++];
             if (envlist_unsetenv(envlist, r) != 0)
                 usage();
+        } else if (!strcmp(r, "0")) {
+            r = argv[optind++];
+            argv0 = r;
         } else if (!strcmp(r, "s")) {
             if (optind >= argc)
                 break;
@@ -2435,11 +2443,39 @@ int main(int argc, char **argv, char **envp)
     target_environ = envlist_to_environ(envlist, NULL);
     envlist_free(envlist);
 
-    if (loader_exec(filename, argv+optind, target_environ, regs, info) != 0) {
+    /*
+     * Prepare copy of argv vector for target.
+     */
+    target_argc = argc - optind;
+    target_argv = calloc(target_argc + 1, sizeof (char *));
+    if (target_argv == NULL) {
+	(void) fprintf(stderr, "Unable to allocate memory for target_argv\n");
+	exit(1);
+    }
+
+    /*
+     * If argv0 is specified (using '-0' switch) we replace
+     * argv[0] pointer with the given one.
+     */
+    i = 0;
+    if (argv0 != NULL) {
+        target_argv[i++] = strdup(argv0);
+    }
+    for (; i < target_argc; i++) {
+        target_argv[i] = strdup(argv[optind + i]);
+    }
+    target_argv[target_argc] = NULL;
+
+    if (loader_exec(filename, target_argv, target_environ, regs, info) != 0) {
         printf("Error loading %s\n", filename);
         _exit(1);
     }
 
+    for (i = 0; i < target_argc; i++) {
+        free(target_argv[i]);
+    }
+    free(target_argv);
+
     for (wrk = target_environ; *wrk; wrk++) {
         free(*wrk);
     }