Use regular expression against /proc symlinks.

* safepath.c (bad_proc): New static variable; regular
expression that matches paths under /proc that traverse
dangerous symlinks.
(bad_proc_rx): Compiled version of above regex.
(abs_path_check): Replace ad-hoc path match with regexec call.
(safepath_init, safepath_deinit): New functions needed because
have to compile a regular expression one time, and then
keep using it. We could do this lazily but then we need
pthread_once to make things thread safe.

* safepath.h (safepath_init, safepath_cleanup): Declared.

* testsp.c (main): Call safepath_init and safepath_cleanup.

1 files changed, 2 insertions, 0 deletions

diff --git a/safepath.h b/safepath.h
index 99786b1..822686f 100644
--- a/safepath.h
+++ b/safepath.h
@@ -48,6 +48,8 @@ enum {
   SAFEPATH_TOOLONG,             /* component or symlink target too long */
 };
 
+int safepath_init(void);
+void safepath_cleanup(void);
 int safepath_check(const char *name);
 const char *safepath_strerr(int err);