blob: 1b223b3c52254fedd1a49821a4316310c2e6791e
| 1 | /* vi: set sw=4 ts=4: */ |
| 2 | /* |
| 3 | * Mini readlink implementation for busybox |
| 4 | * |
| 5 | * Copyright (C) 2000,2001 Matt Kraai <kraai@alumni.carnegiemellon.edu> |
| 6 | * |
| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
| 8 | */ |
| 9 | //config:config READLINK |
| 10 | //config: bool "readlink" |
| 11 | //config: default y |
| 12 | //config: help |
| 13 | //config: This program reads a symbolic link and returns the name |
| 14 | //config: of the file it points to |
| 15 | //config: |
| 16 | //config:config FEATURE_READLINK_FOLLOW |
| 17 | //config: bool "Enable canonicalization by following all symlinks (-f)" |
| 18 | //config: default y |
| 19 | //config: depends on READLINK |
| 20 | //config: help |
| 21 | //config: Enable the readlink option (-f). |
| 22 | |
| 23 | //applet:IF_READLINK(APPLET(readlink, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| 24 | |
| 25 | //kbuild:lib-$(CONFIG_READLINK) += readlink.o |
| 26 | |
| 27 | //usage:#define readlink_trivial_usage |
| 28 | //usage: IF_FEATURE_READLINK_FOLLOW("[-fnv] ") "FILE" |
| 29 | //usage:#define readlink_full_usage "\n\n" |
| 30 | //usage: "Display the value of a symlink" |
| 31 | //usage: IF_FEATURE_READLINK_FOLLOW( "\n" |
| 32 | //usage: "\n -f Canonicalize by following all symlinks" |
| 33 | //usage: "\n -n Don't add newline" |
| 34 | //usage: "\n -v Verbose" |
| 35 | //usage: ) |
| 36 | |
| 37 | #include "libbb.h" |
| 38 | |
| 39 | /* |
| 40 | * # readlink --version |
| 41 | * readlink (GNU coreutils) 6.10 |
| 42 | * # readlink --help |
| 43 | * -f, --canonicalize |
| 44 | * canonicalize by following every symlink in |
| 45 | * every component of the given name recursively; |
| 46 | * all but the last component must exist |
| 47 | * -e, --canonicalize-existing |
| 48 | * canonicalize by following every symlink in |
| 49 | * every component of the given name recursively, |
| 50 | * all components must exist |
| 51 | * -m, --canonicalize-missing |
| 52 | * canonicalize by following every symlink in |
| 53 | * every component of the given name recursively, |
| 54 | * without requirements on components existence |
| 55 | * -n, --no-newline do not output the trailing newline |
| 56 | * -q, --quiet, -s, --silent suppress most error messages |
| 57 | * -v, --verbose report error messages |
| 58 | * |
| 59 | * bbox supports: -f (partially) -n -v (fully), -q -s (accepts but ignores) |
| 60 | * Note: we export the -f flag, but our -f behaves like coreutils' -e. |
| 61 | * Unfortunately, there isn't a C lib function we can leverage to get this |
| 62 | * behavior which means we'd have to implement the full stack ourselves :(. |
| 63 | */ |
| 64 | |
| 65 | int readlink_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 66 | int readlink_main(int argc UNUSED_PARAM, char **argv) |
| 67 | { |
| 68 | char *buf; |
| 69 | char *fname; |
| 70 | |
| 71 | IF_FEATURE_READLINK_FOLLOW( |
| 72 | unsigned opt; |
| 73 | /* We need exactly one non-option argument. */ |
| 74 | opt_complementary = "=1"; |
| 75 | opt = getopt32(argv, "fnvsq"); |
| 76 | fname = argv[optind]; |
| 77 | ) |
| 78 | IF_NOT_FEATURE_READLINK_FOLLOW( |
| 79 | const unsigned opt = 0; |
| 80 | if (argc != 2) bb_show_usage(); |
| 81 | fname = argv[1]; |
| 82 | ) |
| 83 | |
| 84 | /* compat: coreutils readlink reports errors silently via exit code */ |
| 85 | if (!(opt & 4)) /* not -v */ |
| 86 | logmode = LOGMODE_NONE; |
| 87 | |
| 88 | if (opt & 1) { /* -f */ |
| 89 | buf = xmalloc_realpath(fname); |
| 90 | } else { |
| 91 | buf = xmalloc_readlink_or_warn(fname); |
| 92 | } |
| 93 | |
| 94 | if (!buf) |
| 95 | return EXIT_FAILURE; |
| 96 | printf((opt & 2) ? "%s" : "%s\n", buf); |
| 97 | |
| 98 | if (ENABLE_FEATURE_CLEAN_UP) |
| 99 | free(buf); |
| 100 | |
| 101 | fflush_stdout_and_exit(EXIT_SUCCESS); |
| 102 | } |
| 103 |