source: MondoRescue/branches/3.2/mindi-busybox/coreutils/ln.c

/* vi: set sw=4 ts=4: */
/*
 * Mini ln implementation for busybox
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

/* BB_AUDIT SUSv3 compliant */
/* BB_AUDIT GNU options missing: -d, -F, -i, and -v. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/ln.html */

//usage:#define ln_trivial_usage
//usage:       "[OPTIONS] TARGET... LINK|DIR"
//usage:#define ln_full_usage "\n\n"
//usage:       "Create a link LINK or DIR/TARGET to the specified TARGET(s)\n"
//usage:     "\n    -s  Make symlinks instead of hardlinks"
//usage:     "\n    -f  Remove existing destinations"
//usage:     "\n    -n  Don't dereference symlinks - treat like normal file"
//usage:     "\n    -b  Make a backup of the target (if exists) before link operation"
//usage:     "\n    -S suf  Use suffix instead of ~ when making backup files"
//usage:     "\n    -T  2nd arg must be a DIR"
//usage:     "\n    -v  Verbose"
//usage:
//usage:#define ln_example_usage
//usage:       "$ ln -s BusyBox /tmp/ls\n"
//usage:       "$ ls -l /tmp/ls\n"
//usage:       "lrwxrwxrwx    1 root     root            7 Apr 12 18:39 ls -> BusyBox*\n"

#include "libbb.h"

/* This is a NOEXEC applet. Be very careful! */


#define LN_SYMLINK          (1 << 0)
#define LN_FORCE            (1 << 1)
#define LN_NODEREFERENCE    (1 << 2)
#define LN_BACKUP           (1 << 3)
#define LN_SUFFIX           (1 << 4)
#define LN_VERBOSE          (1 << 5)
#define LN_LINKFILE         (1 << 6)

int ln_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ln_main(int argc, char **argv)
{
    int status = EXIT_SUCCESS;
    int opts;
    char *last;
    char *src_name;
    char *src;
    char *suffix = (char*)"~";
    struct stat statbuf;
    int (*link_func)(const char *, const char *);

    opt_complementary = "-1"; /* min one arg */
    opts = getopt32(argv, "sfnbS:vT", &suffix);

    last = argv[argc - 1];
    argv += optind;
    argc -= optind;

    if ((opts & LN_LINKFILE) && argc > 2) {
        bb_error_msg_and_die("-T accepts 2 args max");
    }

    if (!argv[1]) {
        /* "ln PATH/TO/FILE" -> "ln PATH/TO/FILE FILE" */
        *--argv = last;
        /* xstrdup is needed: "ln -s PATH/TO/FILE/" is equivalent to
         * "ln -s PATH/TO/FILE/ FILE", not "ln -s PATH/TO/FILE FILE"
         */
        last = bb_get_last_path_component_strip(xstrdup(last));
    }

    do {
        src_name = NULL;
        src = last;

        if (is_directory(src,
                        (opts & LN_NODEREFERENCE) ^ LN_NODEREFERENCE
                        )
        ) {
            if (opts & LN_LINKFILE) {
                bb_error_msg_and_die("'%s' is a directory", src);
            }
            src_name = xstrdup(*argv);
            src = concat_path_file(src, bb_get_last_path_component_strip(src_name));
            free(src_name);
            src_name = src;
        }
        if (!(opts & LN_SYMLINK) && stat(*argv, &statbuf)) {
            // coreutils: "ln dangling_symlink new_hardlink" works
            if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
                bb_simple_perror_msg(*argv);
                status = EXIT_FAILURE;
                free(src_name);
                continue;
            }
        }

        if (opts & LN_BACKUP) {
            char *backup;
            backup = xasprintf("%s%s", src, suffix);
            if (rename(src, backup) < 0 && errno != ENOENT) {
                bb_simple_perror_msg(src);
                status = EXIT_FAILURE;
                free(backup);
                continue;
            }
            free(backup);
            /*
             * When the source and dest are both hard links to the same
             * inode, a rename may succeed even though nothing happened.
             * Therefore, always unlink().
             */
            unlink(src);
        } else if (opts & LN_FORCE) {
            unlink(src);
        }

        link_func = link;
        if (opts & LN_SYMLINK) {
            link_func = symlink;
        }

        if (opts & LN_VERBOSE) {
            printf("'%s' -> '%s'\n", src, *argv);
        }

        if (link_func(*argv, src) != 0) {
            bb_simple_perror_msg(src);
            status = EXIT_FAILURE;
        }

        free(src_name);

    } while ((++argv)[1]);

    return status;
}