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.

5 files changed, 51 insertions, 19 deletions

diff --git a/ChangeLog b/ChangeLog
index 460ab4f..d3bd1d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,18 @@
 2011-08-17  Sergey Poznyakoff  <gray@gnu.org.ua>
 
+	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.
+
+2011-08-17  Sergey Poznyakoff  <gray@gnu.org.ua>
+	
 	Introduce new error code.
 	
 	* configure.ac, NEWS: Raise patchlevel to 90.
diff --git a/doc/gdbm.texinfo b/doc/gdbm.texinfo
index 98e3bc3..8487de2 100644
--- a/doc/gdbm.texinfo
+++ b/doc/gdbm.texinfo
@@ -1350,23 +1350,35 @@ The library was not able to open a disk file.  This can be set by
 @code{gdbm_open} (@pxref{Open}), @code{gdbm_export} and
 @code{gdbm_import} functions (@pxref{Flat files}).
 
+Inspect the value of the system @code{errno} variable to get more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_WRITE_ERROR
 @item GDBM_FILE_WRITE_ERROR
 Writing to a disk file failed.  This can be set by
 @code{gdbm_open} (@pxref{Open}), @code{gdbm_export} and
 @code{gdbm_import} functions.
 
+Inspect the value of the system @code{errno} variable to get more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_SEEK_ERROR
 @item GDBM_FILE_SEEK_ERROR
 Positioning in a disk file failed.  This can be set by
 @code{gdbm_open} (@pxref{Open}) function.
 
+Inspect the value of the system @code{errno} variable to get a more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_READ_ERROR
 @item GDBM_FILE_READ_ERROR
 Reading from a disk file failed.  This can be set by
 @code{gdbm_open} (@pxref{Open}), @code{gdbm_export} and
 @code{gdbm_import} functions.
 
+Inspect the value of the system @code{errno} variable to get a more
+detailed diagnostics.
+
 @kwindex GDBM_BAD_MAGIC_NUMBER
 @item GDBM_BAD_MAGIC_NUMBER
 The file given as argument to @code{gdbm_open} function is not a valid
@@ -1464,6 +1476,9 @@ Set by the @code{gdbm_export} function if supplied an invalid
 @item GDBM_FILE_STAT_ERROR
 Getting information about a disk file failed.  The system @code{errno}
 will give more details about the error.
+
+This error can be set by the following functions: @code{gdbm_open},
+@code{gdbm_reorganize}.
 @end table
 
 @node Compatibility
diff --git a/src/gdbmdefs.h b/src/gdbmdefs.h
index 28995de..b5922e3 100644
--- a/src/gdbmdefs.h
+++ b/src/gdbmdefs.h
@@ -204,5 +204,15 @@ struct gdbm_file_info {
 				  begins */
       };
 
+/* Execute CODE without clobbering errno */
+#define SAVE_ERRNO(code)			\
+  do						\
+    {						\
+      int __ec = errno;				\
+      code;					\
+      errno = __ec;				\
+    }						\
+  while (0)					\
+
 /* Now define all the routines in use. */
 #include "proto.h"
diff --git a/src/gdbmopen.c b/src/gdbmopen.c
index 2029499..a8a488f 100644
--- a/src/gdbmopen.c
+++ b/src/gdbmopen.c
@@ -145,8 +145,8 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
     }
   if (dbf->desc < 0)
     {
-      free (dbf->name);
-      free (dbf);
+      SAVE_ERRNO (free (dbf->name);
+                  free (dbf));
       gdbm_errno = GDBM_FILE_OPEN_ERROR;
       return NULL;
     }
@@ -154,12 +154,10 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
   /* Get the status of the file. */
   if (fstat (dbf->desc, &file_stat))
     {
-      int ec = errno;
-      close (dbf->desc);
-      free (dbf->name);
-      free (dbf);
+      SAVE_ERRNO (close (dbf->desc);
+		  free (dbf->name);
+		  free (dbf));
       gdbm_errno = GDBM_FILE_STAT_ERROR;
-      errno = ec;
       return NULL;
     }
   
@@ -286,7 +284,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       num_bytes = __write (dbf, dbf->header, dbf->header->block_size);
       if (num_bytes != dbf->header->block_size)
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_WRITE_ERROR;
 	  return NULL;
 	}
@@ -295,7 +293,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       num_bytes = __write (dbf, dbf->dir, dbf->header->dir_size);
       if (num_bytes != dbf->header->dir_size)
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_WRITE_ERROR;
 	  return NULL;
 	}
@@ -304,7 +302,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       num_bytes = __write (dbf, dbf->bucket, dbf->header->bucket_size);
       if (num_bytes != dbf->header->bucket_size)
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_WRITE_ERROR;
 	  return NULL;
 	}
@@ -325,7 +323,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       num_bytes = __read (dbf, &partial_header, sizeof (gdbm_file_header));
       if (num_bytes != sizeof (gdbm_file_header))
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_READ_ERROR;
 	  return NULL;
 	}
@@ -365,7 +363,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
 			  dbf->header->block_size-sizeof (gdbm_file_header));
       if (num_bytes != dbf->header->block_size-sizeof (gdbm_file_header))
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_READ_ERROR;
 	  return NULL;
 	}
@@ -383,7 +381,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       file_pos = __lseek (dbf, dbf->header->dir, L_SET);
       if (file_pos != dbf->header->dir)
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_SEEK_ERROR;
 	  return NULL;
 	}
@@ -391,7 +389,7 @@ gdbm_open (const char *file, int block_size, int flags, int mode,
       num_bytes = __read (dbf, dbf->dir, dbf->header->dir_size);
       if (num_bytes != dbf->header->dir_size)
 	{
-	  gdbm_close (dbf);
+	  SAVE_ERRNO (gdbm_close (dbf));
 	  gdbm_errno = GDBM_FILE_READ_ERROR;
 	  return NULL;
 	}
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;