Improve error diagnostics of mmap_full_file().

[paraslash.git] / fd.c

diff --git a/fd.c b/fd.c
index 6f9266f47a56cd8dee3e99b8651d12a89bb4069b..9b6c6917232eb5063bb3acaad51a24ea53226389 100644 (file)
--- a/fd.c
+++ b/fd.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2011 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2012 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -541,6 +541,22 @@ int mmap_full_file(const char *path, int open_mode, void **map,
                goto out;
        }
        *size = file_status.st_size;
+       /*
+        * If the file is empty, *size is zero and mmap() would return EINVAL
+        * (Invalid argument). This error is common enough to spend an extra
+        * error code which explicitly states the problem.
+        */
+       ret = -E_EMPTY;
+       if (*size == 0)
+               goto out;
+       /*
+        * If fd refers to a directory, mmap() returns ENODEV (No such device),
+        * at least on Linux. "Is a directory" seems to be more to the point.
+        */
+       ret = -ERRNO_TO_PARA_ERROR(EISDIR);
+       if (S_ISDIR(file_status.st_mode))
+               goto out;
+
        ret = para_mmap(*size, mmap_prot, mmap_flags, fd, 0, map);
 out:
        if (ret < 0 || !fd_ptr)
@@ -563,6 +579,9 @@ out:
 int para_munmap(void *start, size_t length)
 {
        int err;
+
+       if (!start)
+               return 0;
        if (munmap(start, length) >= 0)
                return 1;
        err = errno;