source: MondoRescue/branches/3.3/mindi-busybox/coreutils/truncate.c@ 3621

/*
 * Mini truncate implementation for busybox
 *
 * Copyright (C) 2015 by Ari Sundholm <ari@tuxera.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//config:config TRUNCATE
//config:   bool "truncate"
//config:   default y
//config:   help
//config:     truncate truncates files to a given size. If a file does
//config:     not exist, it is created unless told otherwise.

//kbuild:lib-$(CONFIG_TRUNCATE) += truncate.o
//applet:IF_TRUNCATE(APPLET_NOFORK(truncate, truncate, BB_DIR_USR_BIN, BB_SUID_DROP, truncate))

//usage:#define truncate_trivial_usage
//usage:       "[-c] -s SIZE FILE..."
//usage:#define truncate_full_usage "\n\n"
//usage:    "Truncate FILEs to the given size\n"
//usage:    "\n -c  Do not create files"
//usage:    "\n -s SIZE Truncate to SIZE"
//usage:
//usage:#define truncate_example_usage
//usage:    "$ truncate -s 1G foo"

#include "libbb.h"

#if ENABLE_LFS
# define XATOU_SFX xatoull_sfx
#else
# define XATOU_SFX xatoul_sfx
#endif

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

int truncate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int truncate_main(int argc UNUSED_PARAM, char **argv)
{
    unsigned opts;
    int flags = O_WRONLY | O_NONBLOCK;
    int ret = EXIT_SUCCESS;
    char *size_str;
    off_t size;

    enum {
        OPT_NOCREATE  = (1 << 0),
        OPT_SIZE = (1 << 1),
    };

    opt_complementary = "s:-1";
    opts = getopt32(argv, "cs:", &size_str);

    if (!(opts & OPT_NOCREATE))
        flags |= O_CREAT;

    // TODO: coreutils 8.17 also support "m" (lowercase) suffix
    // with truncate, but not with dd!
    // We share kMG_suffixes[], so we can't make both tools
    // compatible at once...
    size = XATOU_SFX(size_str, kMG_suffixes);

    argv += optind;
    while (*argv) {
        int fd = open(*argv, flags, 0666);
        if (fd < 0) {
            if (errno != ENOENT || !(opts & OPT_NOCREATE)) {
                bb_perror_msg("%s: open", *argv);
                ret = EXIT_FAILURE;
            }
            /* else: ENOENT && OPT_NOCREATE:
             * do not report error, exitcode is also 0.
             */
        } else {
            if (ftruncate(fd, size) == -1) {
                bb_perror_msg("%s: truncate", *argv);
                ret = EXIT_FAILURE;
            }
            xclose(fd);
        }
        ++argv;
    }

    return ret;
}