hush: set $n properly for "source" builtin

function                                             old     new   delta
restore_G_args                                         -      78     +78
save_and_replace_G_args                                -      64     +64
builtin_source                                        72     107     +35
run_list                                            2549    2367    -182
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 1/1 up/down: 177/-182)           Total: -5 bytes

1 files changed, 57 insertions, 40 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 4a0fc2353..84364e0e7 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -939,6 +939,52 @@ static void free_strings(char **strings)
 }
 
 
+/* Helpers for setting new $n and restoring them back
+ */
+typedef struct save_arg_t {
+        char *sv_argv0;
+        char **sv_g_argv;
+        int sv_g_argc;
+        smallint sv_g_malloced;
+} save_arg_t;
+
+static void save_and_replace_G_args(save_arg_t *sv, char **argv)
+{
+        int n;
+
+        sv->sv_argv0 = argv[0];
+        sv->sv_g_argv = G.global_argv;
+        sv->sv_g_argc = G.global_argc;
+        sv->sv_g_malloced = G.global_args_malloced;
+
+        argv[0] = G.global_argv[0]; /* retain $0 */
+        G.global_argv = argv;
+        G.global_args_malloced = 0;
+
+        n = 1;
+        while (*++argv)
+                n++;
+        G.global_argc = n;
+}
+
+static void restore_G_args(save_arg_t *sv, char **argv)
+{
+        char **pp;
+
+        if (G.global_args_malloced) {
+                /* someone ran "set -- arg1 arg2 ...", undo */
+                pp = G.global_argv;
+                while (*++pp) /* note: does not free $0 */
+                        free(*pp);
+                free(G.global_argv);
+        }
+        argv[0] = sv->sv_argv0;
+        G.global_argv = sv->sv_g_argv;
+        G.global_argc = sv->sv_g_argc;
+        G.global_args_malloced = sv->sv_g_malloced;
+}
+
+
 /* Basic theory of signal handling in shell
  * ========================================
  * This does not describe what hush does, rather, it is current understanding
@@ -2802,54 +2848,24 @@ static void exec_function(nommu_save_t *nommu_save,
 
 static int run_function(const struct function *funcp, char **argv)
 {
-        int n;
-        char **pp;
-        char *sv_argv0;
-        smallint sv_g_malloced;
-        int sv_g_argc;
-        char **sv_g_argv;
-
-        sv_argv0 = argv[0];
-        sv_g_malloced = G.global_args_malloced;
-        sv_g_argc = G.global_argc;
-        sv_g_argv = G.global_argv;
-
-        pp = argv;
-        n = 1;
-        while (*++pp)
-                n++;
-
-        argv[0] = G.global_argv[0]; /* retain $0 */
-        G.global_args_malloced = 0;
-        G.global_argc = n;
-        G.global_argv = argv;
+        int rc;
+        save_arg_t sv;
 
+        save_and_replace_G_args(&sv, argv);
         /* On MMU, funcp->body is always non-NULL */
 #if !BB_MMU
         if (!funcp->body) {
                 /* Function defined by -F */
                 parse_and_run_string(funcp->body_as_string);
-                n = G.last_exitcode;
+                rc = G.last_exitcode;
         } else
 #endif
         {
-                n = run_list(funcp->body);
-        }
-
-        if (G.global_args_malloced) {
-                /* function ran "set -- arg1 arg2 ..." */
-                pp = G.global_argv;
-                while (*++pp)
-                        free(*pp);
-                free(G.global_argv);
+                rc = run_list(funcp->body);
         }
+        restore_G_args(&sv, argv);
 
-        argv[0] = sv_argv0;
-        G.global_args_malloced = sv_g_malloced;
-        G.global_argc = sv_g_argc;
-        G.global_argv = sv_g_argv;
-
-        return n;
+        return rc;
 }
 #endif
 
@@ -6659,6 +6675,7 @@ static int builtin_shift(char **argv)
 static int builtin_source(char **argv)
 {
         FILE *input;
+        save_arg_t sv;
 
         if (*++argv == NULL)
                 return EXIT_FAILURE;
@@ -6672,11 +6689,11 @@ static int builtin_source(char **argv)
         close_on_exec_on(fileno(input));
 
         /* Now run the file */
-        /* TODO: argv and argc are broken; need to save old G.global_argv
-         * (pointer only is OK!) on this stack frame,
-         * set G.global_argv=argv+1, recurse, and restore. */
+        save_and_replace_G_args(&sv, argv);
         parse_and_run_file(input);
+        restore_G_args(&sv, argv);
         fclose(input);
+
         return G.last_exitcode;
 }