1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1987, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/stat.h> 34 35 #include <err.h> 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <libgen.h> 39 #include <limits.h> 40 #include <stdbool.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 static bool fflag; /* Unlink existing files. */ 47 static bool Fflag; /* Remove empty directories also. */ 48 static bool hflag; /* Check new name for symlink first. */ 49 static bool iflag; /* Interactive mode. */ 50 static bool Pflag; /* Create hard links to symlinks. */ 51 static bool sflag; /* Symbolic, not hard, link. */ 52 static bool vflag; /* Verbose output. */ 53 static bool wflag; /* Warn if symlink target does not 54 * exist, and -f is not enabled. */ 55 static char linkch; 56 57 static int linkit(const char *, const char *, bool); 58 static void link_usage(void) __dead2; 59 static void usage(void) __dead2; 60 61 int 62 main(int argc, char *argv[]) 63 { 64 struct stat sb; 65 char *targetdir; 66 int ch, exitval; 67 68 /* 69 * Test for the special case where the utility is called as 70 * "link", for which the functionality provided is greatly 71 * simplified. 72 */ 73 if (strcmp(getprogname(), "link") == 0) { 74 while (getopt(argc, argv, "") != -1) 75 link_usage(); 76 argc -= optind; 77 argv += optind; 78 if (argc != 2) 79 link_usage(); 80 if (lstat(argv[1], &sb) == 0) 81 errc(1, EEXIST, "%s", argv[1]); 82 /* 83 * We could simply call link(2) here, but linkit() 84 * performs additional checks and gives better 85 * diagnostics. 86 */ 87 exit(linkit(argv[0], argv[1], false)); 88 } 89 90 while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1) 91 switch (ch) { 92 case 'F': 93 Fflag = true; 94 break; 95 case 'L': 96 Pflag = false; 97 break; 98 case 'P': 99 Pflag = true; 100 break; 101 case 'f': 102 fflag = true; 103 iflag = false; 104 wflag = false; 105 break; 106 case 'h': 107 case 'n': 108 hflag = true; 109 break; 110 case 'i': 111 iflag = true; 112 fflag = false; 113 break; 114 case 's': 115 sflag = true; 116 break; 117 case 'v': 118 vflag = true; 119 break; 120 case 'w': 121 wflag = true; 122 break; 123 case '?': 124 default: 125 usage(); 126 } 127 128 argv += optind; 129 argc -= optind; 130 131 linkch = sflag ? '-' : '='; 132 if (!sflag) 133 Fflag = false; 134 if (Fflag && !iflag) { 135 fflag = true; 136 wflag = false; /* Implied when fflag is true */ 137 } 138 139 switch (argc) { 140 case 0: 141 usage(); 142 /* NOTREACHED */ 143 case 1: /* ln source */ 144 exit(linkit(argv[0], ".", true)); 145 case 2: /* ln source target */ 146 exit(linkit(argv[0], argv[1], false)); 147 default: 148 ; 149 } 150 /* ln source1 source2 directory */ 151 targetdir = argv[argc - 1]; 152 if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) { 153 /* 154 * We were asked not to follow symlinks, but found one at 155 * the target--simulate "not a directory" error 156 */ 157 errno = ENOTDIR; 158 err(1, "%s", targetdir); 159 } 160 if (stat(targetdir, &sb)) 161 err(1, "%s", targetdir); 162 if (!S_ISDIR(sb.st_mode)) 163 usage(); 164 for (exitval = 0; *argv != targetdir; ++argv) 165 exitval |= linkit(*argv, targetdir, true); 166 exit(exitval); 167 } 168 169 /* 170 * Two pathnames refer to the same directory entry if the directories match 171 * and the final components' names match. 172 */ 173 static int 174 samedirent(const char *path1, const char *path2) 175 { 176 const char *file1, *file2; 177 char pathbuf[PATH_MAX]; 178 struct stat sb1, sb2; 179 180 if (strcmp(path1, path2) == 0) 181 return 1; 182 file1 = strrchr(path1, '/'); 183 if (file1 != NULL) 184 file1++; 185 else 186 file1 = path1; 187 file2 = strrchr(path2, '/'); 188 if (file2 != NULL) 189 file2++; 190 else 191 file2 = path2; 192 if (strcmp(file1, file2) != 0) 193 return 0; 194 if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX) 195 return 0; 196 if (file1 == path1) 197 memcpy(pathbuf, ".", 2); 198 else { 199 memcpy(pathbuf, path1, file1 - path1); 200 pathbuf[file1 - path1] = '\0'; 201 } 202 if (stat(pathbuf, &sb1) != 0) 203 return 0; 204 if (file2 == path2) 205 memcpy(pathbuf, ".", 2); 206 else { 207 memcpy(pathbuf, path2, file2 - path2); 208 pathbuf[file2 - path2] = '\0'; 209 } 210 if (stat(pathbuf, &sb2) != 0) 211 return 0; 212 return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino; 213 } 214 215 static int 216 linkit(const char *source, const char *target, bool isdir) 217 { 218 char path[PATH_MAX]; 219 char wbuf[PATH_MAX]; 220 char bbuf[PATH_MAX]; 221 struct stat sb; 222 const char *p; 223 int ch, first; 224 bool exists; 225 226 if (!sflag) { 227 /* If source doesn't exist, quit now. */ 228 if ((Pflag ? lstat : stat)(source, &sb)) { 229 warn("%s", source); 230 return (1); 231 } 232 /* Only symbolic links to directories. */ 233 if (S_ISDIR(sb.st_mode)) { 234 errno = EISDIR; 235 warn("%s", source); 236 return (1); 237 } 238 } 239 240 /* 241 * If the target is a directory (and not a symlink if hflag), 242 * append the source's name, unless Fflag is set. 243 */ 244 if (!Fflag && (isdir || 245 (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) || 246 (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode)))) { 247 if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) || 248 (p = basename(bbuf)) == NULL || 249 snprintf(path, sizeof(path), "%s/%s", target, p) >= 250 (ssize_t)sizeof(path)) { 251 errno = ENAMETOOLONG; 252 warn("%s", source); 253 return (1); 254 } 255 target = path; 256 } 257 258 /* 259 * If the link source doesn't exist, and a symbolic link was 260 * requested, and -w was specified, give a warning. 261 */ 262 if (sflag && wflag) { 263 if (*source == '/') { 264 /* Absolute link source. */ 265 if (stat(source, &sb) != 0) 266 warn("warning: %s inaccessible", source); 267 } else { 268 /* 269 * Relative symlink source. Try to construct the 270 * absolute path of the source, by appending `source' 271 * to the parent directory of the target. 272 */ 273 strlcpy(bbuf, target, sizeof(bbuf)); 274 p = dirname(bbuf); 275 if (p != NULL) { 276 (void)snprintf(wbuf, sizeof(wbuf), "%s/%s", 277 p, source); 278 if (stat(wbuf, &sb) != 0) 279 warn("warning: %s", source); 280 } 281 } 282 } 283 284 /* 285 * If the file exists, first check it is not the same directory entry. 286 */ 287 exists = lstat(target, &sb) == 0; 288 if (exists) { 289 if (!sflag && samedirent(source, target)) { 290 warnx("%s and %s are the same directory entry", 291 source, target); 292 return (1); 293 } 294 } 295 /* 296 * Then unlink it forcibly if -f was specified 297 * and interactively if -i was specified. 298 */ 299 if (fflag && exists) { 300 if (Fflag && S_ISDIR(sb.st_mode)) { 301 if (rmdir(target)) { 302 warn("%s", target); 303 return (1); 304 } 305 } else if (unlink(target)) { 306 warn("%s", target); 307 return (1); 308 } 309 } else if (iflag && exists) { 310 fflush(stdout); 311 fprintf(stderr, "replace %s? ", target); 312 313 first = ch = getchar(); 314 while(ch != '\n' && ch != EOF) 315 ch = getchar(); 316 if (first != 'y' && first != 'Y') { 317 fprintf(stderr, "not replaced\n"); 318 return (1); 319 } 320 321 if (Fflag && S_ISDIR(sb.st_mode)) { 322 if (rmdir(target)) { 323 warn("%s", target); 324 return (1); 325 } 326 } else if (unlink(target)) { 327 warn("%s", target); 328 return (1); 329 } 330 } 331 332 /* Attempt the link. */ 333 if (sflag ? symlink(source, target) : 334 linkat(AT_FDCWD, source, AT_FDCWD, target, 335 Pflag ? 0 : AT_SYMLINK_FOLLOW)) { 336 warn("%s", target); 337 return (1); 338 } 339 if (vflag) 340 (void)printf("%s %c> %s\n", target, linkch, source); 341 return (0); 342 } 343 344 static void 345 link_usage(void) 346 { 347 (void)fprintf(stderr, "usage: link source_file target_file\n"); 348 exit(1); 349 } 350 351 static void 352 usage(void) 353 { 354 (void)fprintf(stderr, "%s\n%s\n", 355 "usage: ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]", 356 " ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir"); 357 exit(1); 358 } 359