c8653f62f
Denis Vlasenko
2009-04-27
Subject
hush: make it possible to have interactive shell on non-ctty. init=/bin/hush: shows prompt, history works, etc.
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shell/hush.c+80 -58
| @@ -417,15 +417,26 @@ struct function { | |
| /* "Globals" within this file */ | |
| /* Sorted roughly by size (smaller offsets == smaller code) */ | |
| struct globals { | |
| + | /* interactive_fd != 0 means we are an interactive shell. |
| + | * If we are, then saved_tty_pgrp can also be != 0, meaning |
| + | * that controlling tty is available. With saved_tty_pgrp == 0, |
| + | * job control still works, but terminal signals |
| + | * (^C, ^Z, ^Y, ^\) won't work at all, and background |
| + | * process groups can only be created with "cmd &". |
| + | * With saved_tty_pgrp != 0, hush will use tcsetpgrp() |
| + | * to give tty to the foreground process group, |
| + | * and will take it back when the group is stopped (^Z) |
| + | * or killed (^C). |
| + | */ |
| #if ENABLE_HUSH_INTERACTIVE | |
| /* 'interactive_fd' is a fd# open to ctty, if we have one | |
| * _AND_ if we decided to act interactively */ | |
| int interactive_fd; | |
| const char *PS1; | |
| const char *PS2; | |
| - | #define G_interactive_fd (G.interactive_fd) |
| + | # define G_interactive_fd (G.interactive_fd) |
| #else | |
| - | #define G_interactive_fd 0 |
| + | # define G_interactive_fd 0 |
| #endif | |
| #if ENABLE_FEATURE_EDITING | |
| line_input_t *line_input_state; | |
| @@ -434,10 +445,9 @@ struct globals { | |
| pid_t last_bg_pid; | |
| #if ENABLE_HUSH_JOB | |
| int run_list_level; | |
| - | pid_t saved_tty_pgrp; |
| int last_jobid; | |
| + | pid_t saved_tty_pgrp; |
| struct pipe *job_list; | |
| - | struct pipe *toplevel_list; |
| #endif | |
| smallint flag_SIGINT; | |
| #if ENABLE_HUSH_LOOPS | |
| @@ -446,7 +456,7 @@ struct globals { | |
| #if ENABLE_HUSH_FUNCTIONS | |
| /* 0: outside of a function (or sourced file) | |
| * -1: inside of a function, ok to use return builtin | |
| - | * 1: return is invoked, skip all till end of func. |
| + | * 1: return is invoked, skip all till end of func |
| */ | |
| smallint flag_return_in_progress; | |
| #endif | |
| @@ -1089,12 +1099,16 @@ static void restore_G_args(save_arg_t *sv, char **argv) | |
| */ | |
| enum { | |
| SPECIAL_INTERACTIVE_SIGS = 0 | |
| - | #if ENABLE_HUSH_JOB |
| - | | (1 << SIGTTIN) | (1 << SIGTTOU) | (1 << SIGTSTP) |
| - | | (1 << SIGHUP) |
| - | #endif |
| | (1 << SIGTERM) | |
| | (1 << SIGINT) | |
| + | | (1 << SIGHUP) |
| + | , |
| + | #if ENABLE_HUSH_JOB |
| + | SPECIAL_JOB_SIGS = 0 |
| + | | (1 << SIGTTIN) |
| + | | (1 << SIGTTOU) |
| + | | (1 << SIGTSTP) |
| + | #endif |
| }; | |
| //static void SIGCHLD_handler(int sig UNUSED_PARAM) | |
| @@ -1122,7 +1136,7 @@ static void sigexit(int sig) | |
| /* Careful: we can end up here after [v]fork. Do not restore | |
| * tty pgrp then, only top-level shell process does that */ | |
| - | if (G_interactive_fd && getpid() == G.root_pid) |
| + | if (G.saved_tty_pgrp && getpid() == G.root_pid) |
| tcsetpgrp(G_interactive_fd, G.saved_tty_pgrp); | |
| /* Not a signal, just exit */ | |
| @@ -3131,7 +3145,7 @@ static const char *get_cmdtext(struct pipe *pi) | |
| len += strlen(*argv) + 1; | |
| } while (*++argv); | |
| p = xmalloc(len); | |
| - | pi->cmdtext = p;// = xmalloc(len); |
| + | pi->cmdtext = p; |
| argv = pi->cmds[0].argv; | |
| do { | |
| len = strlen(*argv); | |
| @@ -3351,10 +3365,12 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe) | |
| { | |
| pid_t p; | |
| int rcode = checkjobs(fg_pipe); | |
| - | /* Job finished, move the shell to the foreground */ |
| - | p = getpgid(0); /* pgid of our process */ |
| - | debug_printf_jobs("fg'ing ourself: getpgid(0)=%d\n", (int)p); |
| - | tcsetpgrp(G_interactive_fd, p); |
| + | if (G.saved_tty_pgrp) { |
| + | /* Job finished, move the shell to the foreground */ |
| + | p = getpgrp(); /* our process group id */ |
| + | debug_printf_jobs("fg'ing ourself: getpgrp()=%d\n", (int)p); |
| + | tcsetpgrp(G_interactive_fd, p); |
| + | } |
| return rcode; | |
| } | |
| #endif | |
| @@ -3606,7 +3622,10 @@ static int run_pipe(struct pipe *pi) | |
| pgrp = pi->pgrp; | |
| if (pgrp < 0) /* true for 1st process only */ | |
| pgrp = getpid(); | |
| - | if (setpgid(0, pgrp) == 0 && pi->followup != PIPE_BG) { |
| + | if (setpgid(0, pgrp) == 0 |
| + | && pi->followup != PIPE_BG |
| + | && G.saved_tty_pgrp /* we have ctty */ |
| + | ) { |
| /* We do it in *every* child, not just first, | |
| * to avoid races */ | |
| tcsetpgrp(G_interactive_fd, pgrp); | |
| @@ -4023,11 +4042,7 @@ static int run_list(struct pipe *pi) | |
| check_and_run_traps(0); | |
| #if ENABLE_HUSH_JOB | |
| if (G.run_list_level == 1) | |
| - | { |
| - | debug_printf_exec("insert_bg_job1\n"); |
| insert_bg_job(pi); | |
| - | debug_printf_exec("insert_bg_job2\n"); |
| - | } |
| #endif | |
| G.last_exitcode = rcode = EXIT_SUCCESS; | |
| debug_printf_exec(": cmd&: exitcode EXIT_SUCCESS\n"); | |
| @@ -5896,8 +5911,11 @@ static void block_signals(int second_time) | |
| unsigned mask; | |
| mask = (1 << SIGQUIT); | |
| - | if (G_interactive_fd) |
| + | if (G_interactive_fd) { |
| mask = (1 << SIGQUIT) | SPECIAL_INTERACTIVE_SIGS; | |
| + | if (G.saved_tty_pgrp) /* we have ctty, job control sigs work */ |
| + | mask |= SPECIAL_JOB_SIGS; |
| + | } |
| G.non_DFL_mask = mask; | |
| if (!second_time) | |
| @@ -6179,52 +6197,55 @@ int hush_main(int argc, char **argv) | |
| if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) { | |
| G.saved_tty_pgrp = tcgetpgrp(STDIN_FILENO); | |
| debug_printf("saved_tty_pgrp:%d\n", G.saved_tty_pgrp); | |
| - | //TODO: "interactive" and "have job control" are two different things. |
| - | //If tcgetpgrp fails here, "have job control" is false, but "interactive" |
| - | //should stay on! Currently, we mix these into one. |
| - | if (G.saved_tty_pgrp >= 0) { |
| - | /* try to dup stdin to high fd#, >= 255 */ |
| - | G_interactive_fd = fcntl(STDIN_FILENO, F_DUPFD, 255); |
| + | if (G.saved_tty_pgrp < 0) |
| + | G.saved_tty_pgrp = 0; |
| + | |
| + | /* try to dup stdin to high fd#, >= 255 */ |
| + | G_interactive_fd = fcntl(STDIN_FILENO, F_DUPFD, 255); |
| + | if (G_interactive_fd < 0) { |
| + | /* try to dup to any fd */ |
| + | G_interactive_fd = dup(STDIN_FILENO); |
| if (G_interactive_fd < 0) { | |
| - | /* try to dup to any fd */ |
| - | G_interactive_fd = dup(STDIN_FILENO); |
| - | if (G_interactive_fd < 0) |
| - | /* give up */ |
| - | G_interactive_fd = 0; |
| + | /* give up */ |
| + | G_interactive_fd = 0; |
| + | G.saved_tty_pgrp = 0; |
| } | |
| - | // TODO: track & disallow any attempts of user |
| - | // to (inadvertently) close/redirect it |
| } | |
| + | // TODO: track & disallow any attempts of user |
| + | // to (inadvertently) close/redirect G_interactive_fd |
| } | |
| debug_printf("interactive_fd:%d\n", G_interactive_fd); | |
| if (G_interactive_fd) { | |
| - | pid_t shell_pgrp; |
| - | |
| - | /* We are indeed interactive shell, and we will perform |
| - | * job control. Setting up for that. */ |
| - | |
| close_on_exec_on(G_interactive_fd); | |
| - | /* If we were run as 'hush &', sleep until we are |
| - | * in the foreground (tty pgrp == our pgrp). |
| - | * If we get started under a job aware app (like bash), |
| - | * make sure we are now in charge so we don't fight over |
| - | * who gets the foreground */ |
| - | while (1) { |
| - | shell_pgrp = getpgrp(); |
| - | G.saved_tty_pgrp = tcgetpgrp(G_interactive_fd); |
| - | if (G.saved_tty_pgrp == shell_pgrp) |
| - | break; |
| - | /* send TTIN to ourself (should stop us) */ |
| - | kill(- shell_pgrp, SIGTTIN); |
| + | |
| + | if (G.saved_tty_pgrp) { |
| + | /* If we were run as 'hush &', sleep until we are |
| + | * in the foreground (tty pgrp == our pgrp). |
| + | * If we get started under a job aware app (like bash), |
| + | * make sure we are now in charge so we don't fight over |
| + | * who gets the foreground */ |
| + | while (1) { |
| + | pid_t shell_pgrp = getpgrp(); |
| + | G.saved_tty_pgrp = tcgetpgrp(G_interactive_fd); |
| + | if (G.saved_tty_pgrp == shell_pgrp) |
| + | break; |
| + | /* send TTIN to ourself (should stop us) */ |
| + | kill(- shell_pgrp, SIGTTIN); |
| + | } |
| } | |
| + | |
| /* Block some signals */ | |
| block_signals(signal_mask_is_inited); | |
| - | /* Set other signals to restore saved_tty_pgrp */ |
| - | set_fatal_handlers(); |
| - | /* Put ourselves in our own process group */ |
| - | bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */ |
| - | /* Grab control of the terminal */ |
| - | tcsetpgrp(G_interactive_fd, getpid()); |
| + | |
| + | if (G.saved_tty_pgrp) { |
| + | /* Set other signals to restore saved_tty_pgrp */ |
| + | set_fatal_handlers(); |
| + | /* Put ourselves in our own process group |
| + | * (bash, too, does this only if ctty is available) */ |
| + | bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */ |
| + | /* Grab control of the terminal */ |
| + | tcsetpgrp(G_interactive_fd, getpid()); |
| + | } |
| /* -1 is special - makes xfuncs longjmp, not exit | |
| * (we reset die_sleep = 0 whereever we [v]fork) */ | |
| enable_restore_tty_pgrp_on_exit(); /* sets die_sleep = -1 */ | |
| @@ -6604,6 +6625,7 @@ static int builtin_fg_bg(char **argv) | |
| if (!G_interactive_fd) | |
| return EXIT_FAILURE; | |
| + | |
| /* If they gave us no args, assume they want the last backgrounded task */ | |
| if (!argv[1]) { | |
| for (pi = G.job_list; pi; pi = pi->next) { | |
| @@ -6628,7 +6650,7 @@ static int builtin_fg_bg(char **argv) | |
| found: | |
| /* TODO: bash prints a string representation | |
| * of job being foregrounded (like "sleep 1 | cat") */ | |
| - | if (argv[0][0] == 'f') { |
| + | if (argv[0][0] == 'f' && G.saved_tty_pgrp) { |
| /* Put the job into the foreground. */ | |
| tcsetpgrp(G_interactive_fd, pi->pgrp); | |
| } | |