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, 5 insertions, 0 deletions

diff --git a/testsp.c b/testsp.c
index 1d9f396..089b9d5 100644
--- a/testsp.c
+++ b/testsp.c
@@ -36,8 +36,13 @@ int main(int argc, char **argv)
   (void) argc;
 
   if (argv[0] && argv[1] && !argv[2]) {
+    if (!safepath_init()) {
+      printf("%s: unable to initialize safepath library\n", argv[0]);
+      return EXIT_FAILURE;
+    }
     int res = safepath_check(argv[1]);
     printf("safepath_check(\"%s\") == %s\n", argv[1], safepath_strerr(res));
+    safepath_cleanup();
     return res == SAFEPATH_OK ? 0 : EXIT_FAILURE;
   } else if (argv[0]) {
     printf("%s: requires exactly one argument\n", argv[0]);