Per-database error state.

Last error code is stored in the database file structure as
well as in the global gdbm_errno.  Special functions are provided
for retrieving and clearing the last error state.

* src/gdbmdefs.h (gdbm_file_info): New member: last_error
* src/gdbm.h.in (gdbm_last_errno, gdbm_set_errno)
(gdbm_clear_error): New protos.
* src/gdbmerrno.c (gdbm_last_errno, gdbm_set_errno)
(gdbm_clear_error): New functions

* NEWS: Update.

* compat/dbminit.c: Use gdbm_set_errno to set error state.
* compat/dbmopen.c: Likewise.
* src/bucket.c: Likewise.
* src/findkey.c: Likewise.
* src/gdbm_load.c: Likewise.
* src/gdbmcount.c: Likewise.
* src/gdbmdelete.c: Likewise.
* src/gdbmdump.c: Likewise.
* src/gdbmexists.c: Likewise.
* src/gdbmexp.c: Likewise.
* src/gdbmfetch.c: Likewise.
* src/gdbmimp.c: Likewise.
* src/gdbmload.c: Likewise.
* src/gdbmopen.c: Likewise.
* src/gdbmreorg.c: Likewise.
* src/gdbmseq.c: Likewise.
* src/gdbmsetopt.c: Likewise.
* src/gdbmstore.c: Likewise.
* src/gdbmsync.c: Likewise.
* src/mmap.c: Likewise.

24 files changed, 221 insertions, 150 deletions

diff --git a/NEWS b/NEWS
index a4f1129..4efabdb 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU dbm NEWS -- history of user-visible changes. 2016-07-08
+GNU dbm NEWS -- history of user-visible changes. 2016-07-09
 Copyright (C) 1990-2016 Free Software Foundation, Inc.
 See the end of file for copying conditions.
 
@@ -21,6 +21,14 @@ return.
 The gdbm_fetch function no longer aborts on memory allocation errors.
 Instead it sets gdbm_errno to GDBM_MALLOC_ERROR and returns NULL datum.
 
+* Per-database error codes
+
+* New functions
+
+** gdbm_last_errno
+
+** gdbm_clear_error
+
 
 Version 1.12, 2016-05-16
 
diff --git a/compat/dbminit.c b/compat/dbminit.c
index 94ddc22..f5c5a65 100644
--- a/compat/dbminit.c
+++ b/compat/dbminit.c
@@ -48,7 +48,7 @@ dbminit (char *file)
       /* Did we successfully open the file? */
       if (_gdbm_file == NULL)
         {
-          gdbm_errno = GDBM_FILE_OPEN_ERROR;
+          gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1);
           return -1;
         }
     }
diff --git a/compat/dbmopen.c b/compat/dbmopen.c
index 7a5127e..f8df3e3 100644
--- a/compat/dbmopen.c
+++ b/compat/dbmopen.c
@@ -71,7 +71,7 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
       
   if (fstat (pagfd, &pagst))
     {
-      gdbm_errno = GDBM_FILE_OPEN_ERROR; /* FIXME: special code? */
+      gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1); /* FIXME: special code? */
       return -1;
     } 
       
@@ -89,14 +89,14 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
                     return pagfd;
                   else
                     {
-                      gdbm_errno = GDBM_FILE_OPEN_ERROR; 
+                      gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1); 
                       return -1;
                     } 
                 }
             }
           else
             {
-              gdbm_errno = GDBM_FILE_OPEN_ERROR;
+              gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1);
               return -1;
             }
         }
@@ -104,7 +104,7 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
         /* ok */;
       else if (st.st_size != DEF_DIR_SIZE)
         {
-          gdbm_errno = GDBM_BAD_MAGIC_NUMBER;
+          gdbm_set_errno (NULL, GDBM_BAD_MAGIC_NUMBER, 1);
           return -1;
         }
       else
@@ -112,13 +112,13 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
           fd = open (file_name, flags);
           if (fd == -1)
             {
-              gdbm_errno = GDBM_FILE_OPEN_ERROR;
+              gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1);
               return fd;
             }
           
           if (read (fd, dirbuf, sizeof (dirbuf)) != sizeof (dirbuf))
             {
-              gdbm_errno = GDBM_FILE_OPEN_ERROR;
+              gdbm_set_errno (NULL, GDBM_FILE_OPEN_ERROR, 1);
               close (fd);
               return -1;
             } 
@@ -135,7 +135,7 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
                 return fd;
             }
           close (fd);
-          gdbm_errno = GDBM_BAD_MAGIC_NUMBER;
+          gdbm_set_errno (NULL, GDBM_BAD_MAGIC_NUMBER, 1);
           return -1;
         }
     }
@@ -151,7 +151,7 @@ ndbm_open_dir_file0 (const char *file_name, int pagfd, int mode)
 
       if (write (fd, dirbuf, sizeof (dirbuf)) != sizeof (dirbuf))
         {
-          gdbm_errno = GDBM_FILE_WRITE_ERROR;
+          gdbm_set_errno (NULL, GDBM_FILE_WRITE_ERROR, 1);
           close (fd);
           fd = -1;
         } 
@@ -168,7 +168,7 @@ ndbm_open_dir_file (const char *base, int pagfd, int mode)
   
   if (!file_name)
     {
-      gdbm_errno = GDBM_MALLOC_ERROR;
+      gdbm_set_errno (NULL, GDBM_MALLOC_ERROR, 1);
       return -1;
     }
   fd = ndbm_open_dir_file0 (strcat (strcpy (file_name, base), DIRSUF),
@@ -212,7 +212,7 @@ dbm_open (char *file, int flags, int mode)
   pag_file = (char *) malloc (strlen (file) + 5);
   if (!pag_file)
     {
-      gdbm_errno = GDBM_MALLOC_ERROR;   /* For the hell of it. */
+      gdbm_set_errno (NULL, GDBM_MALLOC_ERROR, 1); /* For the hell of it. */
       return NULL;
     }
 
@@ -250,7 +250,7 @@ dbm_open (char *file, int flags, int mode)
   if (!dbm)
     {
       free (pag_file);
-      gdbm_errno = GDBM_MALLOC_ERROR;   /* For the hell of it. */
+      gdbm_set_errno (NULL, GDBM_MALLOC_ERROR, 1); /* For the hell of it. */
       return NULL;
     }
       
@@ -259,7 +259,7 @@ dbm_open (char *file, int flags, int mode)
   /* Did we successfully open the file? */
   if (dbm->file == NULL)
     {
-      gdbm_errno = GDBM_FILE_OPEN_ERROR;
+      gdbm_set_errno (dbm, GDBM_FILE_OPEN_ERROR, 1);
       free (dbm);
       dbm = NULL;
     }
diff --git a/src/bucket.c b/src/bucket.c
index c9a951c..ee0e157 100644
--- a/src/bucket.c
+++ b/src/bucket.c
@@ -1,8 +1,8 @@
 /* bucket.c - The routines for playing with hash buckets. */
 
 /* This file is part of GDBM, the GNU data base manager.
-   Copyright (C) 1990, 1991, 1993, 2007, 2011, 2013 Free Software Foundation,
-   Inc.
+   Copyright (C) 1990, 1991, 1993, 2007, 2011, 2013,
+   2016 Free Software Foundation, Inc.
 
    GDBM is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -131,13 +131,13 @@ _gdbm_read_bucket_at (GDBM_FILE dbf, off_t off, hash_bucket *bucket,
   file_pos = __lseek (dbf, off, SEEK_SET);
   if (file_pos != off)
     {
-      gdbm_errno = GDBM_FILE_SEEK_ERROR;
+      gdbm_set_errno (dbf, GDBM_FILE_SEEK_ERROR, 1);
       return -1;
     }
   rc = _gdbm_full_read (dbf, bucket, size);
   if (rc)