/* vi: set sw=4 ts=4: */
/*
 * Mini kill/killall[5] implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config KILL
//config:       bool "kill"
//config:       default y
//config:       help
//config:         The command kill sends the specified signal to the specified
//config:         process or process group. If no signal is specified, the TERM
//config:         signal is sent.
//config:
//config:config KILLALL
//config:       bool "killall"
//config:       default y
//config:       help
//config:         killall sends a signal to all processes running any of the
//config:         specified commands. If no signal name is specified, SIGTERM is
//config:         sent.
//config:
//config:config KILLALL5
//config:       bool "killall5"
//config:       default y
//config:       help
//config:         The SystemV killall command. killall5 sends a signal
//config:         to all processes except kernel threads and the processes
//config:         in its own session, so it won't kill the shell that is running
//config:         the script it was called from.

//applet:IF_KILL(APPLET(kill, BB_DIR_BIN, BB_SUID_DROP))
//applet:IF_KILLALL(APPLET_ODDNAME(killall, kill, BB_DIR_USR_BIN, BB_SUID_DROP, killall))
//applet:IF_KILLALL5(APPLET_ODDNAME(killall5, kill, BB_DIR_USR_SBIN, BB_SUID_DROP, killall5))

//kbuild:lib-$(CONFIG_KILL) += kill.o
//kbuild:lib-$(CONFIG_KILLALL) += kill.o
//kbuild:lib-$(CONFIG_KILLALL5) += kill.o

//usage:#define kill_trivial_usage
//usage:       "[-l] [-SIG] PID..."
//usage:#define kill_full_usage "\n\n"
//usage:       "Send a signal (default: TERM) to given PIDs\n"
//usage:     "\n        -l      List all signal names and numbers"
/* //usage:  "\n        -s SIG  Yet another way of specifying SIG" */
//usage:
//usage:#define kill_example_usage
//usage:       "$ ps | grep apache\n"
//usage:       "252 root     root     S [apache]\n"
//usage:       "263 www-data www-data S [apache]\n"
//usage:       "264 www-data www-data S [apache]\n"
//usage:       "265 www-data www-data S [apache]\n"
//usage:       "266 www-data www-data S [apache]\n"
//usage:       "267 www-data www-data S [apache]\n"
//usage:       "$ kill 252\n"
//usage:
//usage:#define killall_trivial_usage
//usage:       "[-l] [-q] [-SIG] PROCESS_NAME..."
//usage:#define killall_full_usage "\n\n"
//usage:       "Send a signal (default: TERM) to given processes\n"
//usage:     "\n        -l      List all signal names and numbers"
/* //usage:  "\n        -s SIG  Yet another way of specifying SIG" */
//usage:     "\n        -q      Don't complain if no processes were killed"
//usage:
//usage:#define killall_example_usage
//usage:       "$ killall apache\n"
//usage:
//usage:#define killall5_trivial_usage
//usage:       "[-l] [-SIG] [-o PID]..."
//usage:#define killall5_full_usage "\n\n"
//usage:       "Send a signal (default: TERM) to all processes outside current session\n"
//usage:     "\n        -l      List all signal names and numbers"
//usage:     "\n        -o PID  Don't signal this PID"
/* //usage:  "\n        -s SIG  Yet another way of specifying SIG" */

#include "libbb.h"

/* Note: kill_main is directly called from shell in order to implement
 * kill built-in. Shell substitutes job ids with process groups first.
 *
 * This brings some complications:
 *
 * + we can't use xfunc here
 * + we can't use applet_name
 * + we can't use bb_show_usage
 * (Above doesn't apply for killall[5] cases)
 *
 * kill %n gets translated into kill ' -<process group>' by shell (note space!)
 * This is needed to avoid collision with kill -9 ... syntax
 */

int kill_main(int argc UNUSED_PARAM, char **argv)
{
        char *arg;
        pid_t pid;
        int signo = SIGTERM, errors = 0, quiet = 0;
#if ENABLE_KILL && !ENABLE_KILLALL && !ENABLE_KILLALL5
# define killall  0
# define killall5 0
#elif !ENABLE_KILL && ENABLE_KILLALL && !ENABLE_KILLALL5
# define killall  1
# define killall5 0
#elif !ENABLE_KILL && !ENABLE_KILLALL && ENABLE_KILLALL5
# define killall  0
# define killall5 1
#else
/* How to determine who we are? find 3rd char from the end:
 * kill, killall, killall5
 *  ^i       ^a        ^l  - it's unique
 * (checking from the start is complicated by /bin/kill... case) */
        const char char3 = argv[0][strlen(argv[0]) - 3];
# define killall  (ENABLE_KILLALL && char3 == 'a')
# define killall5 (ENABLE_KILLALL5 && char3 == 'l')
#endif

        /* Parse any options */
        arg = *++argv;

        if (!arg || arg[0] != '-') {
                goto do_it_now;
        }

        /* The -l option, which prints out signal names.
         * Intended usage in shell:
         * echo "Died of SIG`kill -l $?`"
         * We try to mimic what kill from coreutils-6.8 does */
        if (arg[1] == 'l' && arg[2] == '\0') {
                arg = *++argv;
                if (!arg) {
                        /* Print the whole signal list */
                        print_signames();
                        return 0;
                }
                /* -l <sig list> */
                do {
                        if (isdigit(arg[0])) {
                                signo = bb_strtou(arg, NULL, 10);
                                if (errno) {
                                        bb_error_msg("unknown signal '%s'", arg);
                                        return EXIT_FAILURE;
                                }
                                /* Exitcodes >= 0x80 are to be treated
                                 * as "killed by signal (exitcode & 0x7f)" */
                                puts(get_signame(signo & 0x7f));
                                /* TODO: 'bad' signal# - coreutils says:
                                 * kill: 127: invalid signal
                                 * we just print "127" instead */
                        } else {
                                signo = get_signum(arg);
                                if (signo < 0) {
                                        bb_error_msg("unknown signal '%s'", arg);
                                        return EXIT_FAILURE;
                                }
                                printf("%d\n", signo);
                        }
                        arg = *++argv;
                } while (arg);
                return EXIT_SUCCESS;
        }

        /* The -q quiet option */
        if (killall && arg[1] == 'q' && arg[2] == '\0') {
                quiet = 1;
                arg = *++argv;
                if (!arg)
                        bb_show_usage();
                if (arg[0] != '-')
                        goto do_it_now;
        }

        arg++; /* skip '-' */

        /* -o PID? (if present, it always is at the end of command line) */
        if (killall5 && arg[0] == 'o')
                goto do_it_now;

        if (argv[1] && arg[0] == 's' && arg[1] == '\0') { /* -s SIG? */
                arg = *++argv;
        } /* else it must be -SIG */
        signo = get_signum(arg);
        if (signo < 0) { /* || signo > MAX_SIGNUM ? */
                bb_error_msg("bad signal name '%s'", arg);
                return EXIT_FAILURE;
        }
        arg = *++argv;

 do_it_now:
        pid = getpid();

        if (killall5) {
                pid_t sid;
                procps_status_t* p = NULL;
                /* compat: exitcode 2 is "no one was signaled" */
                int ret = 2;

                /* Find out our session id */
                sid = getsid(pid);
                /* Stop all processes */
                if (signo != SIGSTOP && signo != SIGCONT)
                        kill(-1, SIGSTOP);
                /* Signal all processes except those in our session */
                while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_SID)) != NULL) {
                        char **args;

                        if (p->sid == (unsigned)sid
                         || p->sid == 0 /* compat: kernel thread, don't signal it */
                         || p->pid == (unsigned)pid
                         || p->pid == 1
                        ) {
                                continue;
                        }

                        /* All remaining args must be -o PID options.
                         * Check p->pid against them. */
                        args = argv;
                        while (*args) {
                                pid_t omit;

                                arg = *args++;
                                if (arg[0] != '-' || arg[1] != 'o') {
                                        bb_error_msg("bad option '%s'", arg);
                                        ret = 1;
                                        goto resume;
                                }
                                arg += 2;
                                if (!arg[0] && *args)
                                        arg = *args++;
                                omit = bb_strtoi(arg, NULL, 10);
                                if (errno) {
                                        bb_error_msg("invalid number '%s'", arg);
                                        ret = 1;
                                        goto resume;
                                }
                                if (p->pid == omit)
                                        goto dont_kill;
                        }
                        kill(p->pid, signo);
                        ret = 0;
 dont_kill: ;
                }
 resume:
                /* And let them continue */
                if (signo != SIGSTOP && signo != SIGCONT)
                        kill(-1, SIGCONT);
                return ret;
        }

        /* Pid or name is required for kill/killall */
        if (!arg) {
                bb_error_msg("you need to specify whom to kill");
                return EXIT_FAILURE;
        }

        if (killall) {
                /* Looks like they want to do a killall.  Do that */
                do {
                        pid_t* pidList;

                        pidList = find_pid_by_name(arg);
                        if (*pidList == 0) {
                                errors++;
                                if (!quiet)
                                        bb_error_msg("%s: no process killed", arg);
                        } else {
                                pid_t *pl;

                                for (pl = pidList; *pl; pl++) {
                                        if (*pl == pid)
                                                continue;
                                        if (kill(*pl, signo) == 0)
                                                continue;
                                        errors++;
                                        if (!quiet)
                                                bb_perror_msg("can't kill pid %d", (int)*pl);
                                }
                        }
                        free(pidList);
                        arg = *++argv;
                } while (arg);
                return errors;
        }

        /* Looks like they want to do a kill. Do that */
        while (arg) {
#if ENABLE_ASH || ENABLE_HUSH
                /*
                 * We need to support shell's "hack formats" of
                 * " -PRGP_ID" (yes, with a leading space)
                 * and " PID1 PID2 PID3" (with degenerate case "")
                 */
                while (*arg != '\0') {
                        char *end;
                        if (*arg == ' ')
                                arg++;
                        pid = bb_strtoi(arg, &end, 10);
                        if (errno && (errno != EINVAL || *end != ' ')) {
                                bb_error_msg("invalid number '%s'", arg);
                                errors++;
                                break;
                        }
                        if (kill(pid, signo) != 0) {
                                bb_perror_msg("can't kill pid %d", (int)pid);
                                errors++;
                        }
                        arg = end; /* can only point to ' ' or '\0' now */
                }
#else
                pid = bb_strtoi(arg, NULL, 10);
                if (errno) {
                        bb_error_msg("invalid number '%s'", arg);
                        errors++;
                } else if (kill(pid, signo) != 0) {
                        bb_perror_msg("can't kill pid %d", (int)pid);
                        errors++;
                }
#endif
                arg = *++argv;
        }
        return errors;
}