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-rw-r--r--symlinks.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/symlinks.c b/symlinks.c
new file mode 100644
index 0000000..5a5e781
--- /dev/null
+++ b/symlinks.c
@@ -0,0 +1,64 @@
+#include "cache.h"
+
+struct pathname {
+ int len;
+ char path[PATH_MAX];
+};
+
+/* Return matching pathname prefix length, or zero if not matching */
+static inline int match_pathname(int len, const char *name, struct pathname *match)
+{
+ int match_len = match->len;
+ return (len > match_len &&
+ name[match_len] == '/' &&
+ !memcmp(name, match->path, match_len)) ? match_len : 0;
+}
+
+static inline void set_pathname(int len, const char *name, struct pathname *match)
+{
+ if (len < PATH_MAX) {
+ match->len = len;
+ memcpy(match->path, name, len);
+ match->path[len] = 0;
+ }
+}
+
+int has_symlink_leading_path(int len, const char *name)
+{
+ static struct pathname link, nonlink;
+ char path[PATH_MAX];
+ struct stat st;
+ char *sp;
+ int known_dir;
+
+ /*
+ * See if the last known symlink cache matches.
+ */
+ if (match_pathname(len, name, &link))
+ return 1;
+
+ /*
+ * Get rid of the last known directory part
+ */
+ known_dir = match_pathname(len, name, &nonlink);
+
+ while ((sp = strchr(name + known_dir + 1, '/')) != NULL) {
+ int thislen = sp - name ;
+ memcpy(path, name, thislen);
+ path[thislen] = 0;
+
+ if (lstat(path, &st))
+ return 0;
+ if (S_ISDIR(st.st_mode)) {
+ set_pathname(thislen, path, &nonlink);
+ known_dir = thislen;
+ continue;
+ }
+ if (S_ISLNK(st.st_mode)) {
+ set_pathname(thislen, path, &link);
+ return 1;
+ }
+ break;
+ }
+ return 0;
+}