Fix symlink handling and update to version 0.0.6.

[apply-default-acl.git] / src / apply-default-acl.c

diff --git a/src/apply-default-acl.c b/src/apply-default-acl.c
index 6900a636e3ddc94b5045df620c8bf3ab772e73a6..19505282c2acda17960281e966a9d347a5bc1611 100644 (file)
--- a/src/apply-default-acl.c
+++ b/src/apply-default-acl.c
@@ -10,6 +10,7 @@
 #define _GNU_SOURCE
 
 #include <errno.h>
+#include <fcntl.h>  /* AT_FOO constants */
 #include <ftw.h>    /* nftw() et al. */
 #include <getopt.h>
 #include <libgen.h> /* dirname()     */
@@ -50,13 +51,13 @@ mode_t get_mode(const char* path) {
   }
 
   struct stat s;
-  int result = stat(path, &s);
+  int result = lstat(path, &s);
 
   if (result == 0) {
     return s.st_mode;
   }
   else {
-    /* errno will be set already by stat() */
+    /* errno will be set already by lstat() */
     return result;
   }
 }
@@ -77,7 +78,7 @@ bool is_regular_file(const char* path) {
   }
 
   struct stat s;
-  int result = stat(path, &s);
+  int result = lstat(path, &s);
   if (result == 0) {
     return S_ISREG(s.st_mode);
   }
@@ -88,6 +89,42 @@ bool is_regular_file(const char* path) {
 
 
 
+/**
+ * @brief Determine whether or not the given path is accessible.
+ *
+ * @param path
+ *   The path to test.
+ *
+ * @return true if @c path is accessible to the current effective
+ *   user/group, false otherwise.
+ */
+bool path_accessible(const char* path) {
+  if (path == NULL) {
+    return false;
+  }
+
+  /*  Test for access using the effective user and group rather than
+      the real one. */
+  int flags = AT_EACCESS;
+
+  /* Don't follow symlinks when checking for a path's existence,
+     since we won't follow them to set its ACLs either. */
+  flags |= AT_SYMLINK_NOFOLLOW;
+
+  /* If the path is relative, interpret it relative to the current
+     working directory (just like the access() system call). */
+  int result = faccessat(AT_FDCWD, path, F_OK, flags);
+
+  if (result == 0) {
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+
+
 /**
  * @brief Determine whether or not the given path is a directory.
  *
@@ -102,7 +139,7 @@ bool is_directory(const char* path) {
   }
 
   struct stat s;
-  int result = stat(path, &s);
+  int result = lstat(path, &s);
   if (result == 0) {
     return S_ISDIR(s.st_mode);
   }
@@ -971,6 +1008,17 @@ int main(int argc, char* argv[]) {
     const char* target = argv[arg_index];
     bool reapp_result = false;
 
+    /* Make sure we can access the given path before we go out of our
+     * way to please it. Doing this check outside of
+     * apply_default_acl() lets us spit out a better error message for
+     * typos, too.
+     */
+    if (!path_accessible(target)) {
+      fprintf(stderr, "%s: %s: No such file or directory\n", argv[0], target);
+      result = EXIT_FAILURE;
+      continue;
+    }
+
     if (recursive) {
       reapp_result = apply_default_acl_recursive(target, no_exec_mask);
     }