busybox/coreutils/readlink.c

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/* vi: set sw=4 ts=4: */
/*
* Mini readlink implementation for busybox
*
* Copyright (C) 2000,2001 Matt Kraai <kraai@alumni.carnegiemellon.edu>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config READLINK
//config: bool "readlink (3.6 kb)"
//config: default y
//config: help
//config: This program reads a symbolic link and returns the name
//config: of the file it points to
//config:
//config:config FEATURE_READLINK_FOLLOW
//config: bool "Enable canonicalization by following all symlinks (-f)"
//config: default y
//config: depends on READLINK
//config: help
//config: Enable the readlink option (-f).
//applet:IF_READLINK(APPLET_NOFORK(readlink, readlink, BB_DIR_USR_BIN, BB_SUID_DROP, readlink))
//kbuild:lib-$(CONFIG_READLINK) += readlink.o
//usage:#define readlink_trivial_usage
//usage: IF_FEATURE_READLINK_FOLLOW("[-fnv] ") "FILE"
//usage:#define readlink_full_usage "\n\n"
//usage: "Display the value of a symlink"
//usage: IF_FEATURE_READLINK_FOLLOW( "\n"
//usage: "\n -f Canonicalize by following all symlinks"
//usage: "\n -n Don't add newline"
//usage: "\n -v Verbose"
//usage: )
#include "libbb.h"
/*
* # readlink --version
* readlink (GNU coreutils) 6.10
* # readlink --help
* -f, --canonicalize
* canonicalize by following every symlink in
* every component of the given name recursively;
* all but the last component must exist
* -e, --canonicalize-existing
* canonicalize by following every symlink in
* every component of the given name recursively,
* all components must exist
* -m, --canonicalize-missing
* canonicalize by following every symlink in
* every component of the given name recursively,
* without requirements on components existence
* -n, --no-newline do not output the trailing newline
* -q, --quiet, -s, --silent suppress most error messages
* -v, --verbose report error messages
*
* bbox supports: -f (partially) -n -v (fully), -q -s (accepts but ignores)
* Note: we export the -f flag, but our -f behaves like coreutils' -e.
* Unfortunately, there isn't a C lib function we can leverage to get this
* behavior which means we'd have to implement the full stack ourselves :(.
*/
int readlink_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int readlink_main(int argc UNUSED_PARAM, char **argv)
{
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char *buf;
char *fname;
IF_FEATURE_READLINK_FOLLOW(
unsigned opt;
/* We need exactly one non-option argument. */
getopt32: remove opt_complementary function old new delta vgetopt32 1318 1392 +74 runsvdir_main 703 713 +10 bb_make_directory 423 425 +2 collect_cpu 546 545 -1 opt_chars 3 - -3 opt_complementary 4 - -4 tftpd_main 567 562 -5 ntp_init 476 471 -5 zcip_main 1266 1256 -10 xxd_main 428 418 -10 whois_main 140 130 -10 who_main 463 453 -10 which_main 212 202 -10 wget_main 2535 2525 -10 watchdog_main 291 281 -10 watch_main 222 212 -10 vlock_main 399 389 -10 uuencode_main 332 322 -10 uudecode_main 316 306 -10 unlink_main 45 35 -10 udhcpd_main 1482 1472 -10 udhcpc_main 2762 2752 -10 tune2fs_main 290 280 -10 tunctl_main 366 356 -10 truncate_main 218 208 -10 tr_main 518 508 -10 time_main 1134 1124 -10 tftp_main 286 276 -10 telnetd_main 1873 1863 -10 tcpudpsvd_main 1785 1775 -10 taskset_main 521 511 -10 tar_main 1009 999 -10 tail_main 1644 1634 -10 syslogd_main 1967 1957 -10 switch_root_main 368 358 -10 svlogd_main 1454 1444 -10 sv 1296 1286 -10 stat_main 104 94 -10 start_stop_daemon_main 1028 1018 -10 split_main 542 532 -10 sort_main 796 786 -10 slattach_main 624 614 -10 shuf_main 504 494 -10 setsid_main 96 86 -10 setserial_main 1132 1122 -10 setfont_main 388 378 -10 setconsole_main 78 68 -10 sendmail_main 1209 1199 -10 sed_main 677 667 -10 script_main 1077 1067 -10 run_parts_main 325 315 -10 rtcwake_main 454 444 -10 rm_main 175 165 -10 reformime_main 119 109 -10 readlink_main 123 113 -10 rdate_main 246 236 -10 pwdx_main 189 179 -10 pstree_main 317 307 -10 pscan_main 663 653 -10 popmaildir_main 818 808 -10 pmap_main 80 70 -10 nc_main 1042 1032 -10 mv_main 558 548 -10 mountpoint_main 477 467 -10 mount_main 1264 1254 -10 modprobe_main 768 758 -10 modinfo_main 333 323 -10 mktemp_main 200 190 -10 mkswap_main 324 314 -10 mkfs_vfat_main 1489 1479 -10 microcom_main 715 705 -10 md5_sha1_sum_main 521 511 -10 man_main 867 857 -10 makedevs_main 1052 1042 -10 ls_main 563 553 -10 losetup_main 432 422 -10 loadfont_main 89 79 -10 ln_main 524 514 -10 link_main 75 65 -10 ipcalc_main 544 534 -10 iostat_main 2397 2387 -10 install_main 768 758 -10 id_main 480 470 -10 i2cset_main 1239 1229 -10 i2cget_main 380 370 -10 i2cdump_main 1482 1472 -10 i2cdetect_main 682 672 -10 hwclock_main 406 396 -10 httpd_main 741 731 -10 grep_main 837 827 -10 getty_main 1559 1549 -10 fuser_main 297 287 -10 ftpgetput_main 345 335 -10 ftpd_main 2232 2222 -10 fstrim_main 251 241 -10 fsfreeze_main 77 67 -10 fsck_minix_main 2921 2911 -10 flock_main 314 304 -10 flashcp_main 740 730 -10 flash_eraseall_main 833 823 -10 fdformat_main 532 522 -10 expand_main 680 670 -10 eject_main 335 325 -10 dumpleases_main 630 620 -10 du_main 314 304 -10 dos2unix_main 441 431 -10 diff_main 1350 1340 -10 df_main 1064 1054 -10 date_main 1095 1085 -10 cut_main 961 951 -10 cryptpw_main 228 218 -10 crontab_main 575 565 -10 crond_main 1149 1139 -10 cp_main 370 360 -10 common_traceroute_main 3834 3824 -10 common_ping_main 1767 1757 -10 comm_main 239 229 -10 cmp_main 655 645 -10 chrt_main 379 369 -10 chpst_main 704 694 -10 chpasswd_main 308 298 -10 chown_main 171 161 -10 chmod_main 158 148 -10 cat_main 428 418 -10 bzip2_main 120 110 -10 blkdiscard_main 264 254 -10 base64_main 221 211 -10 arping_main 1665 1655 -10 ar_main 556 546 -10 adjtimex_main 406 396 -10 adduser_main 882 872 -10 addgroup_main 411 401 -10 acpid_main 1198 1188 -10 optstring 11 - -11 opt_string 18 - -18 OPT_STR 25 - -25 ubi_tools_main 1288 1258 -30 ls_options 31 - -31 ------------------------------------------------------------------------------ (add/remove: 0/6 grow/shrink: 3/129 up/down: 86/-1383) Total: -1297 bytes text data bss dec hex filename 915428 485 6876 922789 e14a5 busybox_old 914629 485 6872 921986 e1182 busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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opt = getopt32(argv, "^" "fnvsq" "\0" "=1");
fname = argv[optind];
)
IF_NOT_FEATURE_READLINK_FOLLOW(
const unsigned opt = 0;
if (argc != 2) bb_show_usage();
fname = argv[1];
)
/* compat: coreutils readlink reports errors silently via exit code */
if (!(opt & 4)) /* not -v */
logmode = LOGMODE_NONE;
/* NOFORK: only one alloc is allowed; must free */
if (opt & 1) { /* -f */
buf = xmalloc_realpath(fname);
} else {
buf = xmalloc_readlink_or_warn(fname);
}
if (!buf)
return EXIT_FAILURE;
printf((opt & 2) ? "%s" : "%s\n", buf);
free(buf);
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fflush_stdout_and_exit(EXIT_SUCCESS);
}