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, 15 insertions, 0 deletions

diff --git a/doc/gdbm.texinfo b/doc/gdbm.texinfo
index 98e3bc3..8487de2 100644
--- a/doc/gdbm.texinfo
+++ b/doc/gdbm.texinfo
@@ -1352,2 +1352,5 @@ The library was not able to open a disk file.  This can be set by
 
+Inspect the value of the system @code{errno} variable to get more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_WRITE_ERROR
@@ -1358,2 +1361,5 @@ Writing to a disk file failed.  This can be set by
 
+Inspect the value of the system @code{errno} variable to get more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_SEEK_ERROR
@@ -1363,2 +1369,5 @@ Positioning in a disk file failed.  This can be set by
 
+Inspect the value of the system @code{errno} variable to get a more
+detailed diagnostics.
+
 @kwindex GDBM_FILE_READ_ERROR
@@ -1369,2 +1378,5 @@ Reading from a disk file failed.  This can be set by
 
+Inspect the value of the system @code{errno} variable to get a more
+detailed diagnostics.
+
 @kwindex GDBM_BAD_MAGIC_NUMBER
@@ -1466,2 +1478,5 @@ 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