freebsd-dev/bin/ln/ln.c
Ed Schouten f9d4afb439 Put some static keywords in the source code.
For these simple utilities, it doesn't harm to make all global variables
static. In fact, this allows the compiler to perform better forms of
optimisation and analysis.
2011-10-31 08:59:17 +00:00

359 lines
8.6 KiB
C

/*-
* Copyright (c) 1987, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if 0
#ifndef lint
static char const copyright[] =
"@(#) Copyright (c) 1987, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)ln.c 8.2 (Berkeley) 3/31/94";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int fflag; /* Unlink existing files. */
static int Fflag; /* Remove empty directories also. */
static int hflag; /* Check new name for symlink first. */
static int iflag; /* Interactive mode. */
static int Pflag; /* Create hard links to symlinks. */
static int sflag; /* Symbolic, not hard, link. */
static int vflag; /* Verbose output. */
static int wflag; /* Warn if symlink target does not
* exist, and -f is not enabled. */
static char linkch;
int linkit(const char *, const char *, int);
void usage(void);
int
main(int argc, char *argv[])
{
struct stat sb;
char *p, *targetdir;
int ch, exitval;
/*
* Test for the special case where the utility is called as
* "link", for which the functionality provided is greatly
* simplified.
*/
if ((p = strrchr(argv[0], '/')) == NULL)
p = argv[0];
else
++p;
if (strcmp(p, "link") == 0) {
while (getopt(argc, argv, "") != -1)
usage();
argc -= optind;
argv += optind;
if (argc != 2)
usage();
exit(linkit(argv[0], argv[1], 0));
}
while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1)
switch (ch) {
case 'F':
Fflag = 1;
break;
case 'L':
Pflag = 0;
break;
case 'P':
Pflag = 1;
break;
case 'f':
fflag = 1;
iflag = 0;
wflag = 0;
break;
case 'h':
case 'n':
hflag = 1;
break;
case 'i':
iflag = 1;
fflag = 0;
break;
case 's':
sflag = 1;
break;
case 'v':
vflag = 1;
break;
case 'w':
wflag = 1;
break;
case '?':
default:
usage();
}
argv += optind;
argc -= optind;
linkch = sflag ? '-' : '=';
if (sflag == 0)
Fflag = 0;
if (Fflag == 1 && iflag == 0) {
fflag = 1;
wflag = 0; /* Implied when fflag != 0 */
}
switch(argc) {
case 0:
usage();
/* NOTREACHED */
case 1: /* ln source */
exit(linkit(argv[0], ".", 1));
case 2: /* ln source target */
exit(linkit(argv[0], argv[1], 0));
default:
;
}
/* ln source1 source2 directory */
targetdir = argv[argc - 1];
if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
/*
* We were asked not to follow symlinks, but found one at
* the target--simulate "not a directory" error
*/
errno = ENOTDIR;
err(1, "%s", targetdir);
}
if (stat(targetdir, &sb))
err(1, "%s", targetdir);
if (!S_ISDIR(sb.st_mode))
usage();
for (exitval = 0; *argv != targetdir; ++argv)
exitval |= linkit(*argv, targetdir, 1);
exit(exitval);
}
/*
* Two pathnames refer to the same directory entry if the directories match
* and the final components' names match.
*/
static int
samedirent(const char *path1, const char *path2)
{
const char *file1, *file2;
char pathbuf[PATH_MAX];
struct stat sb1, sb2;
if (strcmp(path1, path2) == 0)
return 1;
file1 = strrchr(path1, '/');
if (file1 != NULL)
file1++;
else
file1 = path1;
file2 = strrchr(path2, '/');
if (file2 != NULL)
file2++;
else
file2 = path2;
if (strcmp(file1, file2) != 0)
return 0;
if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
return 0;
if (file1 == path1)
memcpy(pathbuf, ".", 2);
else {
memcpy(pathbuf, path1, file1 - path1);
pathbuf[file1 - path1] = '\0';
}
if (stat(pathbuf, &sb1) != 0)
return 0;
if (file2 == path2)
memcpy(pathbuf, ".", 2);
else {
memcpy(pathbuf, path2, file2 - path2);
pathbuf[file2 - path2] = '\0';
}
if (stat(pathbuf, &sb2) != 0)
return 0;
return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
}
int
linkit(const char *source, const char *target, int isdir)
{
struct stat sb;
const char *p;
int ch, exists, first;
char path[PATH_MAX];
char wbuf[PATH_MAX];
char bbuf[PATH_MAX];
if (!sflag) {
/* If source doesn't exist, quit now. */
if ((Pflag ? lstat : stat)(source, &sb)) {
warn("%s", source);
return (1);
}
/* Only symbolic links to directories. */
if (S_ISDIR(sb.st_mode)) {
errno = EISDIR;
warn("%s", source);
return (1);
}
}
/*
* If the target is a directory (and not a symlink if hflag),
* append the source's name.
*/
if (isdir ||
(lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
(!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) {
if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) ||
(p = basename(bbuf)) == NULL ||
snprintf(path, sizeof(path), "%s/%s", target, p) >=
(ssize_t)sizeof(path)) {
errno = ENAMETOOLONG;
warn("%s", source);
return (1);
}
target = path;
}
/*
* If the link source doesn't exist, and a symbolic link was
* requested, and -w was specified, give a warning.
*/
if (sflag && wflag) {
if (*source == '/') {
/* Absolute link source. */
if (stat(source, &sb) != 0)
warn("warning: %s inaccessible", source);
} else {
/*
* Relative symlink source. Try to construct the
* absolute path of the source, by appending `source'
* to the parent directory of the target.
*/
strlcpy(bbuf, target, sizeof(bbuf));
p = dirname(bbuf);
if (p != NULL) {
(void)snprintf(wbuf, sizeof(wbuf), "%s/%s",
p, source);
if (stat(wbuf, &sb) != 0)
warn("warning: %s", source);
}
}
}
/*
* If the file exists, first check it is not the same directory entry.
*/
exists = !lstat(target, &sb);
if (exists) {
if (!sflag && samedirent(source, target)) {
warnx("%s and %s are the same directory entry",
source, target);
return (1);
}
}
/*
* Then unlink it forcibly if -f was specified
* and interactively if -i was specified.
*/
if (fflag && exists) {
if (Fflag && S_ISDIR(sb.st_mode)) {
if (rmdir(target)) {
warn("%s", target);
return (1);
}
} else if (unlink(target)) {
warn("%s", target);
return (1);
}
} else if (iflag && exists) {
fflush(stdout);
fprintf(stderr, "replace %s? ", target);
first = ch = getchar();
while(ch != '\n' && ch != EOF)
ch = getchar();
if (first != 'y' && first != 'Y') {
fprintf(stderr, "not replaced\n");
return (1);
}
if (Fflag && S_ISDIR(sb.st_mode)) {
if (rmdir(target)) {
warn("%s", target);
return (1);
}
} else if (unlink(target)) {
warn("%s", target);
return (1);
}
}
/* Attempt the link. */
if (sflag ? symlink(source, target) :
linkat(AT_FDCWD, source, AT_FDCWD, target,
Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
warn("%s", target);
return (1);
}
if (vflag)
(void)printf("%s %c> %s\n", target, linkch, source);
return (0);
}
void
usage(void)
{
(void)fprintf(stderr, "%s\n%s\n%s\n",
"usage: ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]",
" ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir",
" link source_file target_file");
exit(1);
}