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authorGravatar Paul Fox <pgf@brightstareng.com>2007-11-08 01:11:41 +0000
committerGravatar Paul Fox <pgf@brightstareng.com>2007-11-08 01:11:41 +0000
commit459a2ba1efa9b84bf12c2f5b8a23fd89912b47ea (patch)
tree5c69b3f763a62d9dd394c1a36bfcfc0f96c07060 /libbb
parent49cce2b8384d2b425a91785ebf155a692df6986c (diff)
downloadbusybox-459a2ba1efa9b84bf12c2f5b8a23fd89912b47ea.tar.gz
busybox-459a2ba1efa9b84bf12c2f5b8a23fd89912b47ea.tar.bz2
new xmalloc_readlink_follow() routine to fully expand trailing symlinks
to get to a "real" file (or directory).
Diffstat (limited to 'libbb')
-rw-r--r--libbb/xreadlink.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index 98b795f56..2f6b1e237 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -32,6 +32,51 @@ char *xmalloc_readlink(const char *path)
return buf;
}
+/*
+ * this routine is not the same as realpath(), which canonicalizes
+ * the given path completely. this routine only follows trailing
+ * symlinks until a real file is reached, and returns its name.
+ * intermediate symlinks are not expanded. as above, a malloced
+ * char* is returned, which must be freed.
+ */
+char *xmalloc_readlink_follow(const char *path)
+{
+ char *buf = NULL, *lpc, *linkpath;
+ int bufsize;
+ smallint looping = 0;
+
+ buf = strdup(path);
+ bufsize = strlen(path) + 1;
+
+ while(1) {
+ linkpath = xmalloc_readlink(buf);
+ if (!linkpath) {
+ if (errno == EINVAL) /* not a symlink */
+ return buf;
+ free(buf);
+ return NULL;
+ }
+
+ if (*linkpath == '/') {
+ free(buf);
+ buf = linkpath;
+ bufsize = strlen(linkpath) + 1;
+ } else {
+ bufsize += strlen(linkpath);
+ if (looping++ > MAXSYMLINKS) {
+ free(linkpath);
+ free(buf);
+ return NULL;
+ }
+ buf = xrealloc(buf, bufsize);
+ lpc = bb_get_last_path_component_strip(buf);
+ strcpy(lpc, linkpath);
+ free(linkpath);
+ }
+ }
+
+}
+
char *xmalloc_readlink_or_warn(const char *path)
{
char *buf = xmalloc_readlink(path);