symlinks.c revision 993c455552a218f34cc9a16e0b099868d2834ea5 
1#define _FILE_OFFSET_BITS 64
2#define _LARGEFILE_SOURCE
3#define _LARGEFILE64_SOURCE
4
5#include <unistd.h>
6#ifndef _POSIX_SOURCE
7#define _POSIX_SOURCE
8#endif
9#include <stdio.h>
10#include <stdlib.h>
11#ifdef HAVE_MALLOC_H
12#include <malloc.h>
13#endif
14#include <string.h>
15#include <fcntl.h>
16#include <sys/param.h>
17#include <sys/types.h>
18#include <sys/stat.h>
19#include <dirent.h>
20#include <time.h>
21#include <stddef.h>
22#include <errno.h>
23
24#ifndef S_ISLNK
25#define S_ISLNK(mode) (((mode) & (_S_IFMT)) == (_S_IFLNK))
26#endif
27
28#ifndef PATH_MAX
29#define PATH_MAX 1024
30#endif
31
32#define progver "%s: scan/change symbolic links - v1.3 - by Mark Lord\n\n"
33static char *progname;
34static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
35		testing = 0, single_fs = 1;
36
37/*
38 * tidypath removes excess slashes and "." references from a path string
39 */
40
41static int substr (char *s, char *old, char *new)
42{
43	char *tmp = NULL;
44	int oldlen = strlen(old), newlen = 0;
45
46	if (NULL == strstr(s, old))
47		return 0;
48
49	if (new)
50		newlen = strlen(new);
51
52	if (newlen > oldlen) {
53		if ((tmp = malloc(strlen(s))) == NULL) {
54			fprintf(stderr, "no memory\n");
55			exit (1);
56		}
57	}
58
59	while (NULL != (s = strstr(s, old))) {
60		char *p, *old_s = s;
61
62		if (new) {
63			if (newlen > oldlen)
64				old_s = strcpy(tmp, s);
65			p = new;
66			while (*p)
67				*s++ = *p++;
68		}
69		p = old_s + oldlen;
70		while ((*s++ = *p++));
71	}
72	if (tmp)
73		free(tmp);
74	return 1;
75}
76
77
78static int tidy_path (char *path)
79{
80	int tidied = 0;
81	char *s, *p;
82
83	s = path + strlen(path) - 1;
84	if (s[0] != '/') {	/* tmp trailing slash simplifies things */
85		s[1] = '/';
86		s[2] = '\0';
87	}
88	while (substr(path, "/./", "/"))
89		tidied = 1;
90	while (substr(path, "//", "/"))
91		tidied = 1;
92
93	while ((p = strstr(path,"/../")) != NULL) {
94		s = p+3;
95		for (p--; p != path; p--) if (*p == '/') break;
96		if (*p != '/')
97			break;
98		while ((*p++ = *s++));
99		tidied = 1;
100	}
101	if (*path == '\0')
102		strcpy(path,"/");
103	p = path + strlen(path) - 1;
104	if (p != path && *p == '/')
105		*p-- = '\0';	/* remove tmp trailing slash */
106	while (p != path && *p == '/') {	/* remove any others */
107		*p-- = '\0';
108		tidied = 1;
109	}
110	while (!strncmp(path,"./",2)) {
111		for (p = path, s = path+2; (*p++ = *s++););
112		tidied = 1;
113	}
114	return tidied;
115}
116
117static int shorten_path (char *path, char *abspath)
118{
119	static char dir[PATH_MAX];
120	int shortened = 0;
121	char *p;
122
123	/* get rid of unnecessary "../dir" sequences */
124	while (abspath && strlen(abspath) > 1 && (p = strstr(path,"../"))) {
125		/* find innermost occurance of "../dir", and save "dir" */
126		int slashes = 2;
127		char *a, *s, *d = dir;
128		while ((s = strstr(p+3, "../"))) {
129			++slashes;
130			p = s;
131		}
132		s = p+3;
133		*d++ = '/';
134		while (*s && *s != '/')
135			*d++ = *s++;
136		*d++ = '/';
137		*d = '\0';
138		if (!strcmp(dir,"//"))
139			break;
140		/* note: p still points at ../dir */
141		if (*s != '/' || !*++s)
142			break;
143		a = abspath + strlen(abspath) - 1;
144		while (slashes-- > 0) {
145			if (a <= abspath)
146				goto ughh;
147			while (*--a != '/') {
148				if (a <= abspath)
149					goto ughh;
150			}
151		}
152		if (strncmp(dir, a, strlen(dir)))
153			break;
154		while ((*p++ = *s++)); /* delete the ../dir */
155		shortened = 1;
156	}
157ughh:
158	return shortened;
159}
160
161
162static void fix_symlink (char *path, dev_t my_dev)
163{
164	static char lpath[PATH_MAX], new[PATH_MAX], abspath[PATH_MAX];
165	char *p, *np, *lp, *tail, *msg;
166	struct stat stbuf, lstbuf;
167	int c, fix_abs = 0, fix_messy = 0, fix_long = 0;
168
169	if ((c = readlink(path, lpath, sizeof(lpath))) == -1) {
170		perror(path);
171		return;
172	}
173	lpath[c] = '\0';	/* readlink does not null terminate it */
174
175	/* construct the absolute address of the link */
176	abspath[0] = '\0';
177	if (lpath[0] != '/') {
178		strcat(abspath,path);
179		c = strlen(abspath);
180		if ((c > 0) && (abspath[c-1] == '/'))
181			abspath[c-1] = '\0'; /* cut trailing / */
182		if ((p = strrchr(abspath,'/')) != NULL)
183			*p = '\0'; /* cut last component */
184		strcat(abspath,"/");
185	}
186	strcat(abspath,lpath);
187	(void) tidy_path(abspath);
188
189	/* check for various things */
190	if (stat(abspath, &stbuf) == -1) {
191		printf("dangling: %s -> %s\n", path, lpath);
192		if (delete) {
193			if (unlink (path)) {
194				perror(path);
195			} else
196				printf("deleted:  %s -> %s\n", path, lpath);
197		}
198		return;
199	}
200
201	if (single_fs)
202		lstat(abspath, &lstbuf); /* if the above didn't fail, then this shouldn't */
203
204	if (single_fs && lstbuf.st_dev != my_dev) {
205		msg = "other_fs:";
206	} else if (lpath[0] == '/') {
207		msg = "absolute:";
208		fix_abs = 1;
209	} else if (verbose) {
210		msg = "relative:";
211	} else
212		msg = NULL;
213	fix_messy = tidy_path(strcpy(new,lpath));
214	if (shorten)
215		fix_long = shorten_path(new, path);
216	if (!fix_abs) {
217		if (fix_messy)
218			msg = "messy:   ";
219		else if (fix_long)
220			msg = "lengthy: ";
221	}
222	if (msg != NULL)
223		printf("%s %s -> %s\n", msg, path, lpath);
224	if (!(fix_links || testing) || !(fix_messy || fix_abs || fix_long))
225		return;
226
227	if (fix_abs) {
228		/* convert an absolute link to relative: */
229		/* point tail at first part of lpath that differs from path */
230		/* point p    at first part of path  that differs from lpath */
231		(void) tidy_path(lpath);
232		tail = lp = lpath;
233		p = path;
234		while (*p && (*p == *lp)) {
235			if (*lp++ == '/') {
236				tail = lp;
237				while (*++p == '/');
238			}
239		}
240
241		/* now create new, with "../"s followed by tail */
242		np = new;
243		while (*p) {
244			if (*p++ == '/') {
245				*np++ = '.';
246				*np++ = '.';
247				*np++ = '/';
248				while (*p == '/') ++p;
249			}
250		}
251		strcpy (np, tail);
252		(void) tidy_path(new);
253		if (shorten) (void) shorten_path(new, path);
254	}
255	shorten_path(new,path);
256	if (!testing) {
257		if (unlink (path)) {
258			perror(path);
259			return;
260		}
261		if (symlink(new, path)) {
262			perror(path);
263			return;
264		}
265	}
266	printf("changed:  %s -> %s\n", path, new);
267}
268
269static void dirwalk (char *path, int pathlen, dev_t dev)
270{
271 	char *name;
272	DIR *dfd;
273	static struct stat st;
274	static struct dirent *dp;
275
276	if ((dfd = opendir(path)) == NULL) {
277		perror(path);
278		return;
279	}
280
281	name = path + pathlen;
282	if (*(name-1) != '/')
283		*name++ = '/';
284
285	while ((dp = readdir(dfd)) != NULL ) {
286		strcpy(name, dp->d_name);
287                if (strcmp(name, ".") && strcmp(name,"..")) {
288			if (lstat(path, &st) == -1) {
289				perror(path);
290			} else if (st.st_dev == dev) {
291				if (S_ISLNK(st.st_mode)) {
292					fix_symlink (path, dev);
293				} else if (recurse && S_ISDIR(st.st_mode)) {
294					dirwalk(path, strlen(path), dev);
295				}
296			}
297		}
298	}
299	closedir(dfd);
300	path[pathlen] = '\0';
301}
302
303static void usage_error (void)
304{
305	fprintf(stderr, progver, progname);
306	fprintf(stderr, "Usage:\t%s [-cdorstv] LINK|DIR ...\n\n", progname);
307	fprintf(stderr, "Flags:"
308		"\t-c == change absolute/messy links to relative\n"
309		"\t-d == delete dangling links\n"
310		"\t-o == warn about links across file systems\n"
311		"\t-r == recurse into subdirs\n"
312		"\t-s == shorten lengthy links (displayed in output only when -c not specified)\n"
313		"\t-t == show what would be done by -c\n"
314		"\t-v == verbose (show all symlinks)\n\n");
315	exit(1);
316}
317
318int main(int argc, char **argv)
319{
320#if defined (_GNU_SOURCE) && defined (__GLIBC__)
321	static char path[PATH_MAX+2];
322	char* cwd = get_current_dir_name();
323#else
324	static char path[PATH_MAX+2], cwd[PATH_MAX+2];
325#endif
326	int dircount = 0;
327	char c, *p;
328
329	if  ((progname = (char *) strrchr(*argv, '/')) == NULL)
330                progname = *argv;
331        else
332                progname++;
333
334#if defined (_GNU_SOURCE) && defined (__GLIBC__)
335	if (NULL == cwd) {
336		fprintf(stderr,"get_current_dir_name() failed\n");
337#else
338	if (NULL == getcwd(cwd,PATH_MAX)) {
339		fprintf(stderr,"getcwd() failed\n");
340#endif
341		exit (1);
342	}
343#if defined (_GNU_SOURCE) && defined (__GLIBC__)
344	cwd = realloc(cwd, strlen(cwd)+2);
345	if (cwd == NULL) {
346		fprintf(stderr, "realloc() failed\n");
347		exit (1);
348	}
349#endif
350	if (!*cwd || cwd[strlen(cwd)-1] != '/')
351		strcat(cwd,"/");
352
353	while (--argc) {
354		p = *++argv;
355		if (*p == '-') {
356			if (*++p == '\0')
357				usage_error();
358			while ((c = *p++)) {
359				     if (c == 'c')	fix_links = 1;
360				else if (c == 'd')	delete    = 1;
361				else if (c == 'o')	single_fs = 0;
362				else if (c == 'r')	recurse   = 1;
363				else if (c == 's')	shorten   = 1;
364				else if (c == 't')	testing   = 1;
365				else if (c == 'v')	verbose   = 1;
366				else			usage_error();
367			}
368		} else {
369			struct stat st;
370			if (*p == '/')
371				*path = '\0';
372			else
373				strcpy(path,cwd);
374			tidy_path(strcat(path, p));
375			if (lstat(path, &st) == -1)
376				perror(path);
377			else if (S_ISLNK(st.st_mode))
378				fix_symlink(path, st.st_dev);
379			else
380				dirwalk(path, strlen(path), st.st_dev);
381			++dircount;
382		}
383	}
384	if (dircount == 0)
385		usage_error();
386	exit (0);
387}
388