hush: pass $! thru re-execution; try harder on re-exec; give error

 msg if re-exec didn't work; other tweaks in main()

function                                             old     new   delta
hush_main                                           1144    1199     +55
re_execute_shell                                     237     286     +49
file_get                                             240     260     +20
clean_up_after_re_execute                             58      66      +8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 132/0)             Total: 132 bytes

diff --git a/shell/hush.c b/shell/hush.c
index 39d3c01de7635889770fc12274a93bb68b099729..eba7a86df7ac36fa2ef660e31b035cfe52f5cf1b 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -487,7 +487,8 @@ struct globals {
        int global_argc;
        char **global_argv;
 #if !BB_MMU
-       char **argv_for_re_execing;
+       char *argv0_for_re_execing;
+       char **argv_from_re_execing;
 #endif
 #if ENABLE_HUSH_LOOPS
        unsigned depth_break_continue;
@@ -2356,18 +2357,19 @@ static void re_execute_shell(const char *s)
        char **argv, **pp, **pp2;
        unsigned cnt;
 
-       /* 1:hush 2:-$<pid> 3:-?<exitcode> 4:-D<depth> <vars...>
-        * 5:-c 6:<cmd> <argN...> 7:NULL
+       /* 1:hush 2:-$<pid> 3:-!<pid> 4:-?<exitcode> 5:-D<depth> <vars...>
+        * 6:-c 7:<cmd> <argN...> 8:NULL
         */
-       cnt = 7 + G.global_argc;
+       cnt = 8 + G.global_argc;
        for (cur = G.top_var; cur; cur = cur->next) {
                if (!cur->flg_export || cur->flg_read_only)
                        cnt += 2;
        }
-       G.argv_for_re_execing = pp = xzalloc(sizeof(argv[0]) * cnt);
-       *pp++ = (char *) applet_name;
-       *pp++ = xasprintf("-$%u", G.root_pid);
-       *pp++ = xasprintf("-?%u", G.last_return_code);
+       G.argv_from_re_execing = pp = xzalloc(sizeof(argv[0]) * cnt);
+       *pp++ = (char *) G.argv0_for_re_execing;
+       *pp++ = xasprintf("-$%u", (unsigned) G.root_pid);
+       *pp++ = xasprintf("-!%u", (unsigned) G.last_bg_pid);
+       *pp++ = xasprintf("-?%u", (unsigned) G.last_return_code);
 #if ENABLE_HUSH_LOOPS
        *pp++ = xasprintf("-D%u", G.depth_of_loop);
 #endif
@@ -2392,23 +2394,27 @@ static void re_execute_shell(const char *s)
 
        debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
        sigprocmask(SIG_SETMASK, &G.inherited_set, NULL);
-       execv(bb_busybox_exec_path, G.argv_for_re_execing);
-//TODO: fallback for init=/bin/hush?
-       _exit(127);
+       execv(bb_busybox_exec_path, G.argv_from_re_execing);
+       /* Fallback. Useful for init=/bin/hush usage etc */
+       if (G.argv0_for_re_execing[0] == '/')
+               execv(G.argv0_for_re_execing, G.argv_from_re_execing);
+       xfunc_error_retval = 127;
+       bb_error_msg_and_die("can't re-execute the shell");
 }
 
 static void clean_up_after_re_execute(void)
 {
-       char **pp = G.argv_for_re_execing;
+       char **pp = G.argv_from_re_execing;
        if (pp) {
                /* Must match re_execute_shell's allocations */
                free(pp[1]);
                free(pp[2]);
-#if ENABLE_HUSH_LOOPS
                free(pp[3]);
+#if ENABLE_HUSH_LOOPS
+               free(pp[4]);
 #endif
                free(pp);
-               G.argv_for_re_execing = NULL;
+               G.argv_from_re_execing = NULL;
        }
 }
 #else
@@ -3001,8 +3007,8 @@ static void debug_print_tree(struct pipe *pi, int lvl)
                [RES_SNTX ] = "SNTX" ,
        };
        static const char *const GRPTYPE[] = {
-               "()",
                "{}",
+               "()",
 #if ENABLE_HUSH_FUNCTIONS
                "func()",
 #endif
@@ -4990,14 +4996,15 @@ int hush_main(int argc, char **argv)
        };
 
        int opt;
-       FILE *input;
        char **e;
        struct variable *cur_var;
 
        INIT_G();
-
-       G.root_pid = getpid();
-
+       if (EXIT_SUCCESS) /* if EXIT_SUCCESS == 0, is already done */
+               G.last_return_code = EXIT_SUCCESS;
+#if !BB_MMU
+       G.argv0_for_re_execing = argv[0];
+#endif
        /* Deal with HUSH_VERSION */
        G.shell_ver = const_shell_ver; /* copying struct here */
        G.top_var = &G.shell_ver;
@@ -5020,11 +5027,9 @@ int hush_main(int argc, char **argv)
        }
        debug_printf_env("putenv '%s'\n", hush_version_str);
        putenv((char *)hush_version_str); /* reinstate HUSH_VERSION */
-
 #if ENABLE_FEATURE_EDITING
        G.line_input_state = new_line_input_t(FOR_SHELL);
 #endif
-       /* XXX what should these be while sourcing /etc/profile? */
        G.global_argc = argc;
        G.global_argv = argv;
        /* Initialize some more globals to non-zero values */
@@ -5035,31 +5040,19 @@ int hush_main(int argc, char **argv)
        G.PS2 = "> ";
 #endif
 
-       if (EXIT_SUCCESS) /* otherwise is already done */
-               G.last_return_code = EXIT_SUCCESS;
-
-       if (argv[0] && argv[0][0] == '-') {
-               debug_printf("sourcing /etc/profile\n");
-               input = fopen_for_read("/etc/profile");
-               if (input != NULL) {
-                       close_on_exec_on(fileno(input));
-                       parse_and_run_file(input);
-                       fclose(input);
-               }
-       }
-       input = stdin;
-
        /* http://www.opengroup.org/onlinepubs/9699919799/utilities/sh.html */
        while (1) {
                opt = getopt(argc, argv, "c:xins"
 #if !BB_MMU
-                               "$:?:D:R:V:"
+                               "$:!:?:D:R:V:"
 #endif
                );
                if (opt <= 0)
                        break;
                switch (opt) {
                case 'c':
+                       if (!G.root_pid)
+                               G.root_pid = getpid();
                        G.global_argv = argv + optind;
                        if (!argv[optind]) {
                                /* -c 'script' (no params): prevent empty $0 */
@@ -5082,6 +5075,9 @@ int hush_main(int argc, char **argv)
                case '$':
                        G.root_pid = xatoi_u(optarg);
                        break;
+               case '!':
+                       G.last_bg_pid = xatoi_u(optarg);
+                       break;
                case '?':
                        G.last_return_code = xatoi_u(optarg);
                        break;
@@ -5109,6 +5105,21 @@ int hush_main(int argc, char **argv)
 #endif
                }
        }
+
+       if (!G.root_pid)
+               G.root_pid = getpid();
+       if (argv[0] && argv[0][0] == '-') {
+               FILE *input;
+               /* XXX what should argv be while sourcing /etc/profile? */
+               debug_printf("sourcing /etc/profile\n");
+               input = fopen_for_read("/etc/profile");
+               if (input != NULL) {
+                       close_on_exec_on(fileno(input));
+                       parse_and_run_file(input);
+                       fclose(input);
+               }
+       }
+
 #if ENABLE_HUSH_JOB
        /* A shell is interactive if the '-i' flag was given, or if all of
         * the following conditions are met:
@@ -5117,7 +5128,7 @@ int hush_main(int argc, char **argv)
         *    standard input is a terminal
         *    standard output is a terminal
         *    Refer to Posix.2, the description of the 'sh' utility. */
-       if (argv[optind] == NULL && input == stdin
+       if (argv[optind] == NULL
         && isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
        ) {
                G.saved_tty_pgrp = tcgetpgrp(STDIN_FILENO);
@@ -5132,8 +5143,8 @@ int hush_main(int argc, char **argv)
                                        /* give up */
                                        G_interactive_fd = 0;
                        }
-                       // TODO: track & disallow any attempts of user
-                       // to (inadvertently) close/redirect it
+// TODO: track & disallow any attempts of user
+// to (inadvertently) close/redirect it
                }
        }
        init_signal_mask(); /* note: ensures SIGCHLD is not masked */
@@ -5152,7 +5163,7 @@ int hush_main(int argc, char **argv)
        }
 #elif ENABLE_HUSH_INTERACTIVE
 /* no job control compiled, only prompt/line editing */
-       if (argv[optind] == NULL && input == stdin
+       if (argv[optind] == NULL
         && isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
        ) {
                G_interactive_fd = fcntl(STDIN_FILENO, F_DUPFD, 255);
@@ -5169,10 +5180,12 @@ int hush_main(int argc, char **argv)
        }
        init_signal_mask(); /* note: ensures SIGCHLD is not masked */
 #else
+//TODO: we didn't do it for -c or /etc/profile! Shouldn't we?
        init_signal_mask();
 #endif
        /* POSIX allows shell to re-enable SIGCHLD
         * even if it was SIG_IGN on entry */
+//TODO: we didn't do it for -c or /etc/profile! Shouldn't we?
 //     G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
        signal(SIGCHLD, SIG_DFL); // SIGCHLD_handler);
 
@@ -5186,18 +5199,21 @@ int hush_main(int argc, char **argv)
        if (argv[optind] == NULL) {
                parse_and_run_file(stdin);
        } else {
+               FILE *input;
                debug_printf("\nrunning script '%s'\n", argv[optind]);
                G.global_argv = argv + optind;
                G.global_argc = argc - optind;
                input = xfopen_for_read(argv[optind]);
                fcntl(fileno(input), F_SETFD, FD_CLOEXEC);
                parse_and_run_file(input);
+#if ENABLE_FEATURE_CLEAN_UP
+               fclose(input);
+#endif
        }
 
  final_return:
 
 #if ENABLE_FEATURE_CLEAN_UP
-       fclose(input);
        if (G.cwd != bb_msg_unknown)
                free((char*)G.cwd);
        cur_var = G.top_var->next;