Hello Brian, hello Mark,
I am the to-be new maintainer of the symlinks package¹ and am
investigating its bugs.
On 2007-01-22 03:10 +0100, Brian White wrote:
> There's a problem with the patch. While it will indeed convert a
> relative path to an absolute one, it will also convert any absolute
> paths it finds in to relative ones.
>
> Attached is an updated patch that avoids this.
[patch snipped]
I think this option would be quite useful, thanks a lot for your patch.
However, there are still some problems that need to be resolved:
- If both the -c and -a options are specified, the latter wins (because
the symlink is first converted to relative, then back to absolute).
It would make more sense to error out, since the two options are not
really compatible.
- The option -a even "changes" links that are already absolute.
Attached is the version of symlinks.c in my current git repository (it
already has a patch for #153496²) and a patch based on yours.
Cheers,
Sven
¹ http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=486001
² http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=153496
#define _FILE_OFFSET_BITS 64
#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE
#include <unistd.h>
#include <stdlib.h>
#ifndef _POSIX_SOURCE
#define _POSIX_SOURCE
#endif
#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <fcntl.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <time.h>
#include <stddef.h>
#include <errno.h>
#ifndef S_ISLNK
#define S_ISLNK(mode) (((mode) & (_S_IFMT)) == (_S_IFLNK))
#endif
#ifndef PATH_MAX
#define PATH_MAX 1024
#endif
#define progver "%s: scan/change symbolic links - v1.2 - by Mark Lord\n\n"
static char *progname;
static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
testing = 0;
/*
* tidypath removes excess slashes and "." references from a path string
*/
static int substr (char *s, char *old, char *new)
{
char *tmp = NULL;
int oldlen = strlen(old), newlen = 0;
if (NULL == strstr(s, old))
return 0;
if (new)
newlen = strlen(new);
if (newlen > oldlen) {
if ((tmp = malloc(strlen(s))) == NULL) {
fprintf(stderr, "no memory\n");
exit (1);
}
}
while (NULL != (s = strstr(s, old))) {
char *p, *old_s = s;
if (new) {
if (newlen > oldlen)
old_s = strcpy(tmp, s);
p = new;
while (*p)
*s++ = *p++;
}
p = old_s + oldlen;
while ((*s++ = *p++));
}
if (tmp)
free(tmp);
return 1;
}
static int tidy_path (char *path)
{
int tidied = 0;
char *s, *p;
strcat(path,"/"); /* tmp trailing slash simplifies things */
while (substr(path, "/./", "/"))
tidied = 1;
while (substr(path, "//", "/"))
tidied = 1;
while (NULL != (p = strstr(path,"/../"))) {
for (s = p+3; p != path && *--p != '/';);
if (*p != '/')
break;
if (p == path)
++p;
while ((*p++ = *s++));
tidied = 1;
}
if (!*path)
strcpy(path,"/");
p = path + strlen(path) - 1;
if (p != path && *p == '/')
*p-- = '\0'; /* remove tmp trailing slash */
while (p != path && *p == '/') { /* remove any others */
*p-- = '\0';
tidied = 1;
}
while (!strncmp(path,"./",2)) {
for (p = path, s = path+2; (*p++ = *s++););
tidied = 1;
}
return tidied;
}
static int shorten_path (char *path, char *abspath)
{
static char dir[PATH_MAX];
int shortened = 0;
char *p;
/* get rid of unnecessary "../dir" sequences */
while (abspath && strlen(abspath) > 1 && (p = strstr(path,"../"))) {
/* find innermost occurance of "../dir", and save "dir" */
int slashes = 2;
char *a, *s, *d = dir;
while ((s = strstr(p+3, "../"))) {
++slashes;
p = s;
}
s = p+3;
*d++ = '/';
while (*s && *s != '/')
*d++ = *s++;
*d++ = '/';
*d = '\0';
if (!strcmp(dir,"//"))
break;
/* note: p still points at ../dir */
if (*s != '/' || !*++s)
break;
a = abspath + strlen(abspath) - 1;
while (slashes-- > 0) {
if (a <= abspath)
goto ughh;
while (*--a != '/') {
if (a <= abspath)
goto ughh;
}
}
if (strncmp(dir, a, strlen(dir)))
break;
while ((*p++ = *s++)); /* delete the ../dir */
shortened = 1;
}
ughh:
return shortened;
}
static void fix_symlink (char *path, dev_t my_dev)
{
static char lpath[PATH_MAX], new[PATH_MAX], abspath[PATH_MAX];
char *p, *np, *lp, *tail, *msg;
struct stat stbuf;
int c, fix_abs = 0, fix_messy = 0, fix_long = 0;
if ((c = readlink(path, lpath, sizeof(lpath))) == -1) {
perror(path);
return;
}
lpath[c] = '\0'; /* readlink does not null terminate it */
/* construct the absolute address of the link */
abspath[0] = '\0';
if (lpath[0] != '/') {
strcat(abspath,path);
if (((c = strlen(abspath)) > 0) && (abspath[c-1] == '/'))
abspath[c-1] = '\0';
if ((p = strrchr(abspath,'/')) != NULL)
*p = '\0';
strcat(abspath,"/");
}
strcat(abspath,lpath);
(void) tidy_path(abspath);
/* check for various things */
if (stat(abspath, &stbuf) == -1) {
printf("dangling: %s -> %s\n", path, lpath);
if (delete) {
if (unlink (path)) {
perror(path);
} else
printf("deleted: %s -> %s\n", path, lpath);
}
return;
}
if (stbuf.st_dev != my_dev) {
msg = "other_fs:";
} else if (lpath[0] == '/') {
msg = "absolute:";
fix_abs = 1;
} else if (verbose) {
msg = "relative:";
} else
msg = NULL;
fix_messy = tidy_path(strcpy(new,lpath));
if (shorten)
fix_long = shorten_path(new, path);
if (!fix_abs) {
if (fix_messy)
msg = "messy: ";
else if (fix_long)
msg = "lengthy: ";
}
if (msg != NULL)
printf("%s %s -> %s\n", msg, path, lpath);
if (!(fix_links || testing) || !(fix_messy || fix_abs || fix_long))
return;
if (fix_abs) {
/* convert an absolute link to relative: */
/* point tail at first part of lpath that differs from path */
/* point p at first part of path that differs from lpath */
(void) tidy_path(lpath);
tail = lp = lpath;
p = path;
while (*p && (*p == *lp)) {
if (*lp++ == '/') {
tail = lp;
while (*++p == '/');
}
}
/* now create new, with "../"s followed by tail */
np = new;
while (*p) {
if (*p++ == '/') {
*np++ = '.';
*np++ = '.';
*np++ = '/';
while (*p == '/') ++p;
}
}
strcpy (np, tail);
(void) tidy_path(new);
}
shorten_path (new, path);
if (!testing) {
if (unlink (path)) {
perror(path);
return;
}
if (symlink(new, path)) {
perror(path);
return;
}
}
printf("changed: %s -> %s\n", path, new);
}
static void dirwalk (char *path, int pathlen, dev_t dev)
{
char *name;
DIR *dfd;
static struct stat st;
static struct dirent *dp;
if ((dfd = opendir(path)) == NULL) {
perror(path);
return;
}
name = path + pathlen;
if (*(name-1) != '/')
*name++ = '/';
while ((dp = readdir(dfd)) != NULL ) {
strcpy(name, dp->d_name);
if (strcmp(name, ".") && strcmp(name,"..")) {
if (lstat(path, &st) == -1) {
perror(path);
} else if (st.st_dev == dev) {
if (S_ISLNK(st.st_mode)) {
fix_symlink (path, dev);
} else if (recurse && S_ISDIR(st.st_mode)) {
dirwalk(path, strlen(path), dev);
}
}
}
}
closedir(dfd);
path[pathlen] = '\0';
}
static void usage_error (void)
{
fprintf(stderr, progver, progname);
fprintf(stderr, "Usage:\t%s [-crsv] dirlist\n\n", progname);
fprintf(stderr, "Flags:\t-c == change absolute/messy links to
relative\n"
"\t-d == delete dangling links\n"
"\t-r == recurse into subdirs\n"
"\t-s == shorten lengthy links\n"
"\t-v == verbose (show all symlinks)\n\n");
exit(1);
}
int main(int argc, char **argv)
{
static char path[PATH_MAX+2], cwd[PATH_MAX+2];
int dircount = 0;
char c, *p;
if ((progname = (char *) strrchr(*argv, '/')) == NULL)
progname = *argv;
else
progname++;
if (NULL == getcwd(cwd,PATH_MAX)) {
fprintf(stderr,"getcwd() failed\n");
return (1);
}
if (!*cwd || cwd[strlen(cwd)-1] != '/')
strcat(cwd,"/");
while (--argc) {
p = *++argv;
if (*p == '-') {
if (*++p == '\0')
usage_error();
while ((c = *p++)) {
if (c == 'v') verbose = 1;
else if (c == 'c') fix_links = 1;
else if (c == 'r') recurse = 1;
else if (c == 'd') delete = 1;
else if (c == 's') shorten = 1;
else if (c == 't') testing = 1;
else usage_error();
}
} else {
struct stat st;
if (*p == '/')
*path = '\0';
else
strcpy(path,cwd);
tidy_path(strcat(path, p));
if (lstat(path, &st) == -1)
perror(path);
else
dirwalk(path, strlen(path), st.st_dev);
++dircount;
}
}
if (dircount == 0)
usage_error();
return (0);
}
diff --git a/symlinks.c b/symlinks.c
index c1d3e2c..f0dd8e3 100644
--- a/symlinks.c
+++ b/symlinks.c
@@ -29,7 +29,7 @@
#define progver "%s: scan/change symbolic links - v1.2 - by Mark Lord\n\n"
static char *progname;
-static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
testing = 0;
+static int verbose = 0, fix_links = 0, recurse = 0, delete = 0, shorten = 0,
testing = 0, make_absolute_links = 0;
/*
* tidypath removes excess slashes and "." references from a path string
@@ -156,7 +156,7 @@ ughh:
static void fix_symlink (char *path, dev_t my_dev)
{
static char lpath[PATH_MAX], new[PATH_MAX], abspath[PATH_MAX];
- char *p, *np, *lp, *tail, *msg;
+ char *p, *np, *lp, *tail, *msg = NULL;
struct stat stbuf;
int c, fix_abs = 0, fix_messy = 0, fix_long = 0;
@@ -193,12 +193,16 @@ static void fix_symlink (char *path, dev_t my_dev)
if (stbuf.st_dev != my_dev) {
msg = "other_fs:";
} else if (lpath[0] == '/') {
- msg = "absolute:";
- fix_abs = 1;
+ if (!make_absolute_links || verbose) {
+ msg = "absolute:";
+ }
+ if (!make_absolute_links) {
+ fix_abs = 1;
+ }
} else if (verbose) {
msg = "relative:";
- } else
- msg = NULL;
+ }
+
fix_messy = tidy_path(strcpy(new,lpath));
if (shorten)
fix_long = shorten_path(new, path);
@@ -210,7 +214,8 @@ static void fix_symlink (char *path, dev_t my_dev)
}
if (msg != NULL)
printf("%s %s -> %s\n", msg, path, lpath);
- if (!(fix_links || testing) || !(fix_messy || fix_abs || fix_long))
+
+ if (!(fix_links || testing || make_absolute_links) || !(fix_messy ||
fix_abs || fix_long || make_absolute_links))
return;
if (fix_abs) {
@@ -239,6 +244,12 @@ static void fix_symlink (char *path, dev_t my_dev)
}
strcpy (np, tail);
(void) tidy_path(new);
+ } else if (make_absolute_links) {
+ /* turn relative link into an absolute one */
+ if (!realpath(path, new)) {
+ perror(path);
+ return;
+ }
}
shorten_path (new, path);
if (!testing) {
@@ -293,6 +304,7 @@ static void usage_error (void)
fprintf(stderr, progver, progname);
fprintf(stderr, "Usage:\t%s [-crsv] dirlist\n\n", progname);
fprintf(stderr, "Flags:\t-c == change absolute/messy links to
relative\n"
+ "\t-a == make absolute links from relative\n"
"\t-d == delete dangling links\n"
"\t-r == recurse into subdirs\n"
"\t-s == shorten lengthy links\n"
@@ -326,6 +338,7 @@ int main(int argc, char **argv)
while ((c = *p++)) {
if (c == 'v') verbose = 1;
else if (c == 'c') fix_links = 1;
+ else if (c == 'a') make_absolute_links = 1;
else if (c == 'r') recurse = 1;
else if (c == 'd') delete = 1;
else if (c == 's') shorten = 1;
