ln.c revision 1.37
1 /* $NetBSD: ln.c,v 1.37 2017/04/21 11:28:35 christos 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 * 4. 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 1.37 2017/04/21 11:28:35 christos 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 exit(linkit(argv[0], argv[1], 0)); 100 } 101 102 while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1) 103 switch (ch) { 104 case 'F': 105 Fflag = 1; 106 break; 107 case 'L': 108 Pflag = 0; 109 break; 110 case 'P': 111 Pflag = 1; 112 break; 113 case 'f': 114 fflag = 1; 115 iflag = 0; 116 wflag = 0; 117 break; 118 case 'h': 119 case 'n': 120 hflag = 1; 121 break; 122 case 'i': 123 iflag = 1; 124 fflag = 0; 125 break; 126 case 's': 127 sflag = 1; 128 break; 129 case 'v': 130 vflag = 1; 131 break; 132 case 'w': 133 wflag = 1; 134 break; 135 case '?': 136 default: 137 usage(); 138 } 139 140 argv += optind; 141 argc -= optind; 142 143 linkch = sflag ? '-' : '='; 144 if (sflag == 0) 145 Fflag = 0; 146 if (Fflag == 1 && iflag == 0) { 147 fflag = 1; 148 wflag = 0; /* Implied when fflag != 0 */ 149 } 150 151 switch(argc) { 152 case 0: 153 usage(); 154 /* NOTREACHED */ 155 case 1: /* ln source */ 156 exit(linkit(argv[0], ".", 1)); 157 case 2: /* ln source target */ 158 exit(linkit(argv[0], argv[1], 0)); 159 default: 160 ; 161 } 162 /* ln source1 source2 directory */ 163 targetdir = argv[argc - 1]; 164 if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) { 165 /* 166 * We were asked not to follow symlinks, but found one at 167 * the target--simulate "not a directory" error 168 */ 169 errno = ENOTDIR; 170 err(1, "%s", targetdir); 171 } 172 if (stat(targetdir, &sb)) 173 err(1, "%s", targetdir); 174 if (!S_ISDIR(sb.st_mode)) 175 usage(); 176 for (exitval = 0; *argv != targetdir; ++argv) 177 exitval |= linkit(*argv, targetdir, 1); 178 exit(exitval); 179 } 180 181 /* 182 * Two pathnames refer to the same directory entry if the directories match 183 * and the final components' names match. 184 */ 185 static int 186 samedirent(const char *path1, const char *path2) 187 { 188 const char *file1, *file2; 189 char pathbuf[PATH_MAX]; 190 struct stat sb1, sb2; 191 192 if (strcmp(path1, path2) == 0) 193 return 1; 194 file1 = strrchr(path1, '/'); 195 if (file1 != NULL) 196 file1++; 197 else 198 file1 = path1; 199 file2 = strrchr(path2, '/'); 200 if (file2 != NULL) 201 file2++; 202 else 203 file2 = path2; 204 if (strcmp(file1, file2) != 0) 205 return 0; 206 if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX) 207 return 0; 208 if (file1 == path1) 209 memcpy(pathbuf, ".", 2); 210 else { 211 memcpy(pathbuf, path1, file1 - path1); 212 pathbuf[file1 - path1] = '\0'; 213 } 214 if (stat(pathbuf, &sb1) != 0) 215 return 0; 216 if (file2 == path2) 217 memcpy(pathbuf, ".", 2); 218 else { 219 memcpy(pathbuf, path2, file2 - path2); 220 pathbuf[file2 - path2] = '\0'; 221 } 222 if (stat(pathbuf, &sb2) != 0) 223 return 0; 224 return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino; 225 } 226 227 static int 228 linkit(const char *source, const char *target, int isdir) 229 { 230 struct stat sb; 231 const char *p; 232 int ch, exists, first; 233 char path[PATH_MAX]; 234 char wbuf[PATH_MAX]; 235 char bbuf[PATH_MAX]; 236 237 if (!sflag) { 238 /* If source doesn't exist, quit now. */ 239 if ((Pflag ? lstat : stat)(source, &sb)) { 240 warn("%s", source); 241 return (1); 242 } 243 /* Only symbolic links to directories. */ 244 if (S_ISDIR(sb.st_mode)) { 245 errno = EISDIR; 246 warn("%s", source); 247 return (1); 248 } 249 } 250 251 /* 252 * If the target is a directory (and not a symlink if hflag), 253 * append the source's name. 254 */ 255 if (isdir || 256 (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) || 257 (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) { 258 if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) || 259 (p = basename(bbuf)) == NULL || 260 snprintf(path, sizeof(path), "%s/%s", target, p) >= 261 (ssize_t)sizeof(path)) { 262 errno = ENAMETOOLONG; 263 warn("%s", source); 264 return (1); 265 } 266 target = path; 267 } 268 269 /* 270 * If the link source doesn't exist, and a symbolic link was 271 * requested, and -w was specified, give a warning. 272 */ 273 if (sflag && wflag) { 274 if (*source == '/') { 275 /* Absolute link source. */ 276 if (stat(source, &sb) != 0) 277 warn("warning: %s inaccessible", source); 278 } else { 279 /* 280 * Relative symlink source. Try to construct the 281 * absolute path of the source, by appending `source' 282 * to the parent directory of the target. 283 */ 284 strlcpy(bbuf, target, sizeof(bbuf)); 285 p = dirname(bbuf); 286 if (p != NULL) { 287 (void)snprintf(wbuf, sizeof(wbuf), "%s/%s", 288 p, source); 289 if (stat(wbuf, &sb) != 0) 290 warn("warning: %s", source); 291 } 292 } 293 } 294 295 /* 296 * If the file exists, first check it is not the same directory entry. 297 */ 298 exists = !lstat(target, &sb); 299 if (exists) { 300 if (!sflag && samedirent(source, target)) { 301 warnx("%s and %s are the same directory entry", 302 source, target); 303 return (1); 304 } 305 } 306 /* 307 * Then unlink it forcibly if -f was specified 308 * and interactively if -i was specified. 309 */ 310 if (fflag && exists) { 311 if (Fflag && S_ISDIR(sb.st_mode)) { 312 if (rmdir(target)) { 313 warn("%s", target); 314 return (1); 315 } 316 } else if (unlink(target)) { 317 warn("%s", target); 318 return (1); 319 } 320 } else if (iflag && exists) { 321 fflush(stdout); 322 fprintf(stderr, "replace %s? ", target); 323 324 first = ch = getchar(); 325 while(ch != '\n' && ch != EOF) 326 ch = getchar(); 327 if (first != 'y' && first != 'Y') { 328 fprintf(stderr, "not replaced\n"); 329 return (1); 330 } 331 332 if (Fflag && S_ISDIR(sb.st_mode)) { 333 if (rmdir(target)) { 334 warn("%s", target); 335 return (1); 336 } 337 } else if (unlink(target)) { 338 warn("%s", target); 339 return (1); 340 } 341 } 342 343 /* Attempt the link. */ 344 if (sflag ? symlink(source, target) : 345 linkat(AT_FDCWD, source, AT_FDCWD, target, 346 Pflag ? 0 : AT_SYMLINK_FOLLOW)) { 347 warn("%s", target); 348 return (1); 349 } 350 if (vflag) 351 (void)printf("%s %c> %s\n", target, linkch, source); 352 return (0); 353 } 354 355 static __dead void 356 usage(void) 357 { 358 (void)fprintf(stderr, 359 "usage: %s [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]\n" 360 " %s [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir\n" 361 " link source_file target_file\n", getprogname(), getprogname()); 362 exit(1); 363 } 364
Indexes created Mon Sep 29 21:09:56 GMT 2025