Make sure errno is preserved, if it can contain details about the gdbm error.

* src/gdbmdefs.h (SAVE_ERRNO): New macro.
* src/gdbmopen.c: Use SAVE_ERRNO where it is important to
preserve system errno.
* src/mmap.c: Likewise.

* doc/gdbm.texinfo: Document which gdbm errors can
be detailed by inspecting the system errno.

1 files changed, 1 insertions, 5 deletions

diff --git a/src/mmap.c b/src/mmap.c
index 44101e9..8735624 100644
--- a/src/mmap.c
+++ b/src/mmap.c
@@ -134,10 +134,8 @@ _gdbm_mapped_remap (GDBM_FILE dbf, off_t size, int flag)
 
   if (_gdbm_file_size (dbf, &file_size))
     {
-      int ec = errno;
+      SAVE_ERRNO (_gdbm_mapped_unmap (dbf));
       gdbm_errno = GDBM_FILE_STAT_ERROR;
-      _gdbm_mapped_unmap (dbf);
-      errno = ec;
       return -1; 
     }
 
@@ -332,9 +330,7 @@ _gdbm_mapped_lseek (GDBM_FILE dbf, off_t offset, int whence)
  	    off_t file_size;
 	    if (_gdbm_file_size (dbf, &file_size))
 	      {
-		int ec = errno;
 		gdbm_errno = GDBM_FILE_STAT_ERROR;
-		errno = ec;
 		return -1;
 	      }
 	    needle = file_size - offset;