1 /* $NetBSD: ln.c,v 1.39 2017/04/22 12:22:31 kre Exp $ */ 2 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 #if 0 33 #ifndef lint 34 static char const copyright[] = 35 "@(#) Copyright (c) 1987, 1993, 1994\n\ 36 The Regents of the University of California. All rights reserved.\n"; 37 #endif /* not lint */ 38 39 #ifndef lint 40 static char sccsid[] = "@(#)ln.c 8.2 (Berkeley) 3/31/94"; 41 #endif /* not lint */ 42 #endif 43 #include <sys/cdefs.h> 44 #ifdef __FBSDID 45 __FBSDID("$FreeBSD: head/bin/ln/ln.c 251261 2013-06-02 17:55:00Z eadler $"); 46 #endif 47 __RCSID("$NetBSD: ln.c,v 1.39 2017/04/22 12:22:31 kre Exp $"); 48 49 #include <sys/param.h> 50 #include <sys/stat.h> 51 52 #include <err.h> 53 #include <errno.h> 54 #include <fcntl.h> 55 #include <libgen.h> 56 #include <limits.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 #include <unistd.h> 61 62 static int fflag; /* Unlink existing files. */ 63 static int Fflag; /* Remove empty directories also. */ 64 static int hflag; /* Check new name for symlink first. */ 65 static int iflag; /* Interactive mode. */ 66 static int Pflag; /* Create hard links to symlinks. */ 67 static int sflag; /* Symbolic, not hard, link. */ 68 static int vflag; /* Verbose output. */ 69 static int wflag; /* Warn if symlink target does not 70 * exist, and -f is not enabled. */ 71 static char linkch; 72 73 static int linkit(const char *, const char *, int); 74 static __dead void usage(void); 75 76 int 77 main(int argc, char *argv[]) 78 { 79 struct stat sb; 80 char *p, *targetdir; 81 int ch, exitval; 82 83 /* 84 * Test for the special case where the utility is called as 85 * "link", for which the functionality provided is greatly 86 * simplified. 87 */ 88 if ((p = strrchr(argv[0], '/')) == NULL) 89 p = argv[0]; 90 else 91 ++p; 92 if (strcmp(p, "link") == 0) { 93 while (getopt(argc, argv, "") != -1) 94 usage(); 95 argc -= optind; 96 argv += optind; 97 if (argc != 2) 98 usage(); 99 if (link(argv[0], argv[1]) == -1) 100 err(EXIT_FAILURE, NULL); 101 exit(EXIT_SUCCESS); 102 } 103 104 while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1) 105 switch (ch) { 106 case 'F': 107 Fflag = 1; 108 break; 109 case 'L': 110 Pflag = 0; 111 break; 112 case 'P': 113 Pflag = 1; 114 break; 115 case 'f': 116 fflag = 1; 117 iflag = 0; 118 wflag = 0; 119 break; 120 case 'h': 121 case 'n': 122 hflag = 1; 123 break; 124 case 'i': 125 iflag = 1; 126 fflag = 0; 127 break; 128 case 's': 129 sflag = 1; 130 break; 131 case 'v': 132 vflag = 1; 133 break; 134 case 'w': 135 wflag = 1; 136 break; 137 case '?': 138 default: 139 usage(); 140 } 141 142 argv += optind; 143 argc -= optind; 144 145 linkch = sflag ? '-' : '='; 146 if (sflag == 0) 147 Fflag = 0; 148 if (Fflag == 1 && iflag == 0) { 149 fflag = 1; 150 wflag = 0; /* Implied when fflag != 0 */ 151 } 152 153 switch(argc) { 154 case 0: 155 usage(); 156 /* NOTREACHED */ 157 case 1: /* ln source */ 158 exit(linkit(argv[0], ".", 1)); 159 case 2: /* ln source target */ 160 exit(linkit(argv[0], argv[1], 0)); 161 default: 162 ; 163 } 164 /* ln source1 source2 directory */ 165 targetdir = argv[argc - 1]; 166 if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) { 167 /* 168 * We were asked not to follow symlinks, but found one at 169 * the target--simulate "not a directory" error 170 */ 171 errno = ENOTDIR; 172 err(1, "%s", targetdir); 173 } 174 if (stat(targetdir, &sb)) 175 err(1, "%s", targetdir); 176 if (!S_ISDIR(sb.st_mode)) 177 usage(); 178 for (exitval = 0; *argv != targetdir; ++argv) 179 exitval |= linkit(*argv, targetdir, 1); 180 exit(exitval); 181 } 182 183 /* 184 * Two pathnames refer to the same directory entry if the directories match 185 * and the final components' names match. 186 */ 187 static int 188 samedirent(const char *path1, const char *path2) 189 { 190 const char *file1, *file2; 191 char pathbuf[PATH_MAX]; 192 struct stat sb1, sb2; 193 194 if (strcmp(path1, path2) == 0) 195 return 1; 196 file1 = strrchr(path1, '/'); 197 if (file1 != NULL) 198 file1++; 199 else 200 file1 = path1; 201 file2 = strrchr(path2, '/'); 202 if (file2 != NULL) 203 file2++; 204 else 205 file2 = path2; 206 if (strcmp(file1, file2) != 0) 207 return 0; 208 if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX) 209 return 0; 210 if (file1 == path1) 211 memcpy(pathbuf, ".", 2); 212 else { 213 memcpy(pathbuf, path1, file1 - path1); 214 pathbuf[file1 - path1] = '\0'; 215 } 216 if (stat(pathbuf, &sb1) != 0) 217 return 0; 218 if (file2 == path2) 219 memcpy(pathbuf, ".", 2); 220 else { 221 memcpy(pathbuf, path2, file2 - path2); 222 pathbuf[file2 - path2] = '\0'; 223 } 224 if (stat(pathbuf, &sb2) != 0) 225 return 0; 226 return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino; 227 } 228 229 static int 230 linkit(const char *source, const char *target, int isdir) 231 { 232 struct stat sb; 233 const char *p; 234 int ch, exists, first; 235 char path[PATH_MAX]; 236 char wbuf[PATH_MAX]; 237 char bbuf[PATH_MAX]; 238 239 if (!sflag) { 240 /* If source doesn't exist, quit now. */ 241 if ((Pflag ? lstat : stat)(source, &sb)) { 242 warn("%s", source); 243 return (1); 244 } 245 /* Only symbolic links to directories. */ 246 if (S_ISDIR(sb.st_mode)) { 247 errno = EISDIR; 248 warn("%s", source); 249 return (1); 250 } 251 } 252 253 /* 254 * If the target is a directory (and not a symlink if hflag), 255 * append the source's name. 256 */ 257 if (isdir || 258 (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) || 259 (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) { 260 if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) || 261 (p = basename(bbuf)) == NULL || 262 snprintf(path, sizeof(path), "%s/%s", target, p) >= 263 (ssize_t)sizeof(path)) { 264 errno = ENAMETOOLONG; 265 warn("%s", source); 266 return (1); 267 } 268 target = path; 269 } 270 271 /* 272 * If the link source doesn't exist, and a symbolic link was 273 * requested, and -w was specified, give a warning. 274 */ 275 if (sflag && wflag) { 276 if (*source == '/') { 277 /* Absolute link source. */ 278 if (stat(source, &sb) != 0) 279 warn("warning: %s inaccessible", source); 280 } else { 281 /* 282 * Relative symlink source. Try to construct the 283 * absolute path of the source, by appending `source' 284 * to the parent directory of the target. 285 */ 286 strlcpy(bbuf, target, sizeof(bbuf)); 287 p = dirname(bbuf); 288 if (p != NULL) { 289 (void)snprintf(wbuf, sizeof(wbuf), "%s/%s", 290 p, source); 291 if (stat(wbuf, &sb) != 0) 292 warn("warning: %s", source); 293 } 294 } 295 } 296 297 /* 298 * If the file exists, first check it is not the same directory entry. 299 */ 300 exists = !lstat(target, &sb); 301 if (exists) { 302 if (!sflag && samedirent(source, target)) { 303 warnx("%s and %s are the same directory entry", 304 source, target); 305 return (1); 306 } 307 } 308 /* 309 * Then unlink it forcibly if -f was specified 310 * and interactively if -i was specified. 311 */ 312 if (fflag && exists) { 313 if (Fflag && S_ISDIR(sb.st_mode)) { 314 if (rmdir(target)) { 315 warn("%s", target); 316 return (1); 317 } 318 } else if (unlink(target)) { 319 warn("%s", target); 320 return (1); 321 } 322 } else if (iflag && exists) { 323 fflush(stdout); 324 fprintf(stderr, "replace %s? ", target); 325 326 first = ch = getchar(); 327 while(ch != '\n' && ch != EOF) 328 ch = getchar(); 329 if (first != 'y' && first != 'Y') { 330 fprintf(stderr, "not replaced\n"); 331 return (1); 332 } 333 334 if (Fflag && S_ISDIR(sb.st_mode)) { 335 if (rmdir(target)) { 336 warn("%s", target); 337 return (1); 338 } 339 } else if (unlink(target)) { 340 warn("%s", target); 341 return (1); 342 } 343 } 344 345 /* Attempt the link. */ 346 if (sflag ? symlink(source, target) : 347 linkat(AT_FDCWD, source, AT_FDCWD, target, 348 Pflag ? 0 : AT_SYMLINK_FOLLOW)) { 349 warn("%s", target); 350 return (1); 351 } 352 if (vflag) 353 (void)printf("%s %c> %s\n", target, linkch, source); 354 return (0); 355 } 356 357 static __dead void 358 usage(void) 359 { 360 (void)fprintf(stderr, 361 "usage: %s [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]\n" 362 " %s [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir\n" 363 " link source_file target_file\n", getprogname(), getprogname()); 364 exit(1); 365 } 366