/* vi: set sw=4 ts=4: */
/*
 * ipcrm.c - utility to allow removal of IPC objects and data structures.
 *
 * 01 Sept 2004 - Rodney Radford <rradford@mindspring.com>
 * Adapted for busybox from util-linux-2.12a.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config IPCRM
//config:       bool "ipcrm (3.2 kb)"
//config:       default y
//config:       help
//config:       The ipcrm utility allows the removal of System V interprocess
//config:       communication (IPC) objects and the associated data structures
//config:       from the system.

//applet:IF_IPCRM(APPLET_NOEXEC(ipcrm, ipcrm, BB_DIR_USR_BIN, BB_SUID_DROP, ipcrm))

//kbuild:lib-$(CONFIG_IPCRM) += ipcrm.o

#include "libbb.h"

/* X/OPEN tells us to use <sys/{types,ipc,sem}.h> for semctl() */
/* X/OPEN tells us to use <sys/{types,ipc,msg}.h> for msgctl() */
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/msg.h>
#include <sys/sem.h>

#if defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED)
/* union semun is defined by including <sys/sem.h> */
#else
/* according to X/OPEN we have to define it ourselves */
union semun {
        int val;
        struct semid_ds *buf;
        unsigned short *array;
        struct seminfo *__buf;
};
#endif

#define IPCRM_LEGACY 1


#if IPCRM_LEGACY

typedef enum type_id {
        SHM,
        SEM,
        MSG
} type_id;

static int remove_ids(type_id type, char **argv)
{
        unsigned long id;
        int nb_errors = 0;
        union semun arg;

        arg.val = 0;

        while (argv[0]) {
                id = bb_strtoul(argv[0], NULL, 10);
                if (errno || id > INT_MAX) {
                        bb_error_msg("invalid id: %s", argv[0]);
                        nb_errors++;
                } else {
                        int ret = 0;
                        if (type == SEM)
                                ret = semctl(id, 0, IPC_RMID, arg);
                        else if (type == MSG)
                                ret = msgctl(id, IPC_RMID, NULL);
                        else if (type ==  SHM)
                                ret = shmctl(id, IPC_RMID, NULL);

                        if (ret) {
                                bb_perror_msg("can't remove id %s", argv[0]);
                                nb_errors++;
                        }
                }
                argv++;
        }

        return nb_errors;
}
#endif /* IPCRM_LEGACY */

//usage:#define ipcrm_trivial_usage
//usage:       "[-MQS key] [-mqs id]"
//usage:#define ipcrm_full_usage "\n\n"
//usage:       "Upper-case options MQS remove an object by shmkey value.\n"
//usage:       "Lower-case options remove an object by shmid value.\n"
//usage:     "\n        -mM     Remove memory segment after last detach"
//usage:     "\n        -qQ     Remove message queue"
//usage:     "\n        -sS     Remove semaphore"

int ipcrm_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ipcrm_main(int argc, char **argv)
{
        int c;
        int error = 0;

        /* if the command is executed without parameters, do nothing */
        if (argc == 1)
                return 0;
#if IPCRM_LEGACY
        /* check to see if the command is being invoked in the old way if so
           then run the old code. Valid commands are msg, shm, sem. */
        {
                type_id what = 0; /* silence gcc */
                char w;

                w = argv[1][0];
                if ( ((w == 'm' && argv[1][1] == 's' && argv[1][2] == 'g')
                       || (argv[1][0] == 's'
                           && ((w = argv[1][1]) == 'h' || w == 'e')
                           && argv[1][2] == 'm')
                     ) && argv[1][3] == '\0'
                ) {
                        if (argc < 3)
                                bb_show_usage();

                        if (w == 'h')
                                what = SHM;
                        else if (w == 'm')
                                what = MSG;
                        else if (w == 'e')
                                what = SEM;

                        if (remove_ids(what, &argv[2]))
                                fflush_stdout_and_exit(EXIT_FAILURE);
                        puts("resource(s) deleted");
                        return 0;
                }
        }
#endif /* IPCRM_LEGACY */

        /* process new syntax to conform with SYSV ipcrm */
        while ((c = getopt(argc, argv, "q:m:s:Q:M:S:")) != -1) {
                int result;
                int id;
                int iskey;
                /* needed to delete semaphores */
                union semun arg;

                if (c == '?') /* option not in the string */
                        bb_show_usage();

                id = 0;
                arg.val = 0;

                iskey = !(c & 0x20); /* uppercase? */
                if (iskey) {
                        /* keys are in hex or decimal */
                        key_t key = xstrtoul(optarg, 0);

                        if (key == IPC_PRIVATE) {
                                error++;
                                bb_error_msg("illegal key (%s)", optarg);
                                continue;
                        }

                        c |= 0x20; /* lowercase. c is 'q', 'm' or 's' now */
                        /* convert key to id */
                        id = ((c == 'q') ? msgget(key, 0) :
                                (c == 'm') ? shmget(key, 0, 0) : semget(key, 0, 0));

                        if (id < 0) {
                                const char *errmsg;

                                error++;
                                switch (errno) {
                                case EACCES:
                                        errmsg = "permission denied for";
                                        break;
                                case EIDRM:
                                        errmsg = "already removed";
                                        break;
                                case ENOENT:
                                        errmsg = "invalid";
                                        break;
                                default:
                                        errmsg = "unknown error in";
                                        break;
                                }
                                bb_error_msg("%s %s (%s)", errmsg, "key", optarg);
                                continue;
                        }
                } else {
                        /* ids are in decimal */
                        id = xatoul(optarg);
                }

                result = ((c == 'q') ? msgctl(id, IPC_RMID, NULL) :
                                (c == 'm') ? shmctl(id, IPC_RMID, NULL) :
                                semctl(id, 0, IPC_RMID, arg));

                if (result) {
                        const char *errmsg;
                        const char *const what = iskey ? "key" : "id";

                        error++;
                        switch (errno) {
                        case EACCES:
                        case EPERM:
                                errmsg = "permission denied for";
                                break;
                        case EINVAL:
                                errmsg = "invalid";
                                break;
                        case EIDRM:
                                errmsg = "already removed";
                                break;
                        default:
                                errmsg = "unknown error in";
                                break;
                        }
                        bb_error_msg("%s %s (%s)", errmsg, what, optarg);
                        continue;
                }
        }

        /* print usage if we still have some arguments left over */
        if (optind != argc) {
                bb_show_usage();
        }

        /* exit value reflects the number of errors encountered */
        return error;
}