hush: fix login shell's signal handling; add -l option so that it's easier to test

function                                             old     new   delta
hush_main                                            958    1001     +43
install_special_sighandlers                           47      52      +5
packed_usage                                       28752   28741     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 48/-11)             Total: 37 bytes

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

1 files changed, 35 insertions, 32 deletions

diff --git a/shell/hush.c b/shell/hush.c
index b2c3a752e..cdd4be4e3 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -260,7 +260,7 @@ typedef void (*hush_sighandler_t)(int);
  * therefore we don't show them either.
  */
 //usage:#define hush_trivial_usage
-//usage:        "[-nx] [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]"
+//usage:        "[-nxl] [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]"
 //usage:#define hush_full_usage "\n\n"
 //usage:        "Unix shell interpreter"
 
@@ -1493,8 +1493,8 @@ static sighandler_t pick_sighandler(unsigned sig)
                         handler = record_pending_signo;
                         /* TTIN/TTOU/TSTS can't be set to record_pending_signo
                          * in order to ignore them: they will be raised
-                         * in an endless loop then when we try to do some
-                         * terminal ioctls! We do nave to _ignore_ these.
+                         * in an endless loop when we try to do some
+                         * terminal ioctls! We do have to _ignore_ these.
                          */
                         if (SPECIAL_JOBSTOP_SIGS & sigmask)
                                 handler = SIG_IGN;
@@ -1508,9 +1508,6 @@ static void hush_exit(int exitcode)
 {
         fflush_all();
         if (G.exiting <= 0 && G.traps && G.traps[0] && G.traps[0][0]) {
-                /* Prevent recursion:
-                 * trap "echo Hi; exit" EXIT; exit
-                 */
                 char *argv[3];
                 /* argv[0] is unused */
                 argv[1] = G.traps[0];
@@ -5474,7 +5471,8 @@ static void reset_traps_to_defaults(void)
         G_fatal_sig_mask = 0;
 #endif
         G.special_sig_mask &= ~SPECIAL_INTERACTIVE_SIGS;
-        /* SIGQUIT and maybe SPECIAL_JOBSTOP_SIGS remain set in G.special_sig_mask */
+        /* SIGQUIT,SIGCHLD and maybe SPECIAL_JOBSTOP_SIGS
+         * remain set in G.special_sig_mask */
 
         if (!G.traps)
                 return;
@@ -5537,7 +5535,6 @@ static void re_execute_shell(char ***to_free, const char *s,
                 for (sig = 1; sig < NSIG; sig++) {
                         if (G.traps[sig] && !G.traps[sig][0])
                                 empty_trap_mask |= 1LL << sig;
-///vda: optimize
                 }
         }
 
@@ -7540,9 +7537,6 @@ static void install_special_sighandlers(void)
 {
         unsigned mask;
 
-        if (G.special_sig_mask != 0)
-                return;
-
         /* Which signals are shell-special? */
         mask = (1 << SIGQUIT) | (1 << SIGCHLD);
         if (G_interactive_fd) {
@@ -7550,9 +7544,12 @@ static void install_special_sighandlers(void)
                 if (G_saved_tty_pgrp) /* we have ctty, job control sigs work */
                         mask |= SPECIAL_JOBSTOP_SIGS;
         }
-        G.special_sig_mask = mask;
-
-        install_sighandlers(mask);
+        /* Careful, do not re-install handlers we already installed */
+        if (G.special_sig_mask != mask) {
+                unsigned diff = mask & ~G.special_sig_mask;
+                G.special_sig_mask = mask;
+                install_sighandlers(diff);
+        }
 }
 
 #if ENABLE_HUSH_JOB
@@ -7573,17 +7570,14 @@ static void install_fatal_sighandlers(void)
         /* bash 3.2 seems to handle these just like 'fatal' ones */
                 + (1 << SIGPIPE)
                 + (1 << SIGALRM)
-        /* if we are interactive, SIGHUP, SIGTERM and SIGINT are masked.
+        /* if we are interactive, SIGHUP, SIGTERM and SIGINT are special sigs.
          * if we aren't interactive... but in this case
-         * we never want to restore pgrp on exit, and this fn is not called */
+         * we never want to restore pgrp on exit, and this fn is not called
+         */
                 /*+ (1 << SIGHUP )*/
                 /*+ (1 << SIGTERM)*/
                 /*+ (1 << SIGINT )*/
         ;
-        /* special_sig_mask'ed signals are set to record_pending_signo
-         * no need to set handler for them.
-         */
-        /*mask &= ~G.special_sig_mask; - they never overlap */
         G_fatal_sig_mask = mask;
 
         install_sighandlers(mask);
@@ -7632,6 +7626,10 @@ static int set_mode(int state, char mode, const char *o_opt)
 int hush_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int hush_main(int argc, char **argv)
 {
+        enum {
+                OPT_login = (1 << 0),
+        };
+        unsigned flags;
         int opt;
         unsigned builtin_argc;
         char **e;
@@ -7735,8 +7733,6 @@ int hush_main(int argc, char **argv)
 # endif
 #endif
 
-        G.global_argc = argc;
-        G.global_argv = argv;
         /* Initialize some more globals to non-zero values */
         cmdedit_update_prompt();
 
@@ -7752,14 +7748,14 @@ int hush_main(int argc, char **argv)
          * "sh -c <cmds>" or login shell's /etc/profile and friends.
          * If we later decide that we are interactive, we run install_special_sighandlers()
          * in order to intercept (more) signals.
-//FIXME: re-running is currently most likely broken, it's a no-op.
          */
 
         /* Parse options */
         /* http://www.opengroup.org/onlinepubs/9699919799/utilities/sh.html */
+        flags = (argv[0] && argv[0][0] == '-') ? OPT_login : 0;
         builtin_argc = 0;
         while (1) {
-                opt = getopt(argc, argv, "+c:xins"
+                opt = getopt(argc, argv, "+c:xinsl"
 #if !BB_MMU
                                 "<:$:R:V:"
 # if ENABLE_HUSH_FUNCTIONS
@@ -7820,6 +7816,9 @@ int hush_main(int argc, char **argv)
                         /* "-s" means "read from stdin", but this is how we always
                          * operate, so simply do nothing here. */
                         break;
+                case 'l':
+                        flags |= OPT_login;
+                        break;
 #if !BB_MMU
                 case '<': /* "big heredoc" support */
                         full_write1_str(optarg);
@@ -7843,7 +7842,6 @@ int hush_main(int argc, char **argv)
                                 install_special_sighandlers();
                                 G.traps = xzalloc(sizeof(G.traps[0]) * NSIG);
                                 for (sig = 1; sig < NSIG; sig++) {
-///vda: fixme: more efficient code
                                         if (empty_trap_mask & (1LL << sig)) {
                                                 G.traps[sig] = xzalloc(1); /* == xstrdup(""); */
                                                 signal(sig, SIG_IGN);
@@ -7886,13 +7884,18 @@ int hush_main(int argc, char **argv)
                 }
         } /* option parsing loop */
 
+        /* Skip options. Try "hush -l": $1 should not be "-l"! */
+        G.global_argc = argc - (optind - 1);
+        G.global_argv = argv + (optind - 1);
+        G.global_argv[0] = argv[0];
+
         if (!G.root_pid) {
                 G.root_pid = getpid();
                 G.root_ppid = getppid();
         }
 
         /* If we are login shell... */
-        if (argv[0] && argv[0][0] == '-') {
+        if (flags & OPT_login) {
                 FILE *input;
                 debug_printf("sourcing /etc/profile\n");
                 input = fopen_for_read("/etc/profile");
@@ -7911,17 +7914,17 @@ int hush_main(int argc, char **argv)
                  */
         }
 
-        if (argv[optind]) {
+        if (G.global_argv[1]) {
                 FILE *input;
                 /*
                  * "bash <script>" (which is never interactive (unless -i?))
                  * sources $BASH_ENV here (without scanning $PATH).
                  * If called as sh, does the same but with $ENV.
                  */
-                debug_printf("running script '%s'\n", argv[optind]);
-                G.global_argv = argv + optind;
-                G.global_argc = argc - optind;
-                input = xfopen_for_read(argv[optind]);
+                G.global_argc--;
+                G.global_argv++;
+                debug_printf("running script '%s'\n", G.global_argv[0]);
+                input = xfopen_for_read(G.global_argv[0]);
                 close_on_exec_on(fileno(input));
                 install_special_sighandlers();
                 parse_and_run_file(input);
@@ -7984,7 +7987,7 @@ int hush_main(int argc, char **argv)
                         }
                 }
 
-                /* Block some signals */
+                /* Install more signal handlers */
                 install_special_sighandlers();
 
                 if (G_saved_tty_pgrp) {