New "introspection" option codes.dircache

* doc/gdbm.texi: Document new option codes.
* src/gdbm.h.in (GDBM_GETDBFORMAT, GDBM_GETDIRDEPTH)
(GDBM_GETBUCKETSIZE): New option codes.
* src/gdbmsetopt.c: Handle new option codes.
(setopt_gdbm_getflags): Return the state of GDBM_CLOEXEC and GDBM_NUMSYNC
bits.

3 files changed, 95 insertions, 9 deletions

diff --git a/doc/gdbm.texi b/doc/gdbm.texi
index 6bc3d01..50d06ba 100644
--- a/doc/gdbm.texi
+++ b/doc/gdbm.texi
@@ -2090,9 +2090,9 @@ point to a @code{size_t} holding the desired cache size, or the
 constant @code{GDBM_CACHE_AUTO}, to adjust the cache size
 automatically.
 
-By default, a newly open database is configured to adapt the cache
-size to the number of index buckets in the database file.  This
-provides for the best performance.
+By default, a newly open database is configured to dynamically
+accommodate the cache size to the number of index buckets in the
+database file.  This provides for the best performance.
 
 If another @var{value} is set, it is adjusted to the nearest larger
 power of two.
@@ -2109,7 +2109,8 @@ gdbm_bucket_count (dbf, &bn);
 ret = gdbm_setopt (dbf, GDBM_SETCACHESIZE, &bn, sizeof (bn));
 @end example
 
-To set the best cache size, use the constant @code{GDBM_CACHE_AUTO}:
+To request the automatically adjustable cache size, use the constant
+@code{GDBM_CACHE_AUTO}:
 
 @example
 size_t bn = GDBM_CACHE_AUTO;
@@ -2118,8 +2119,9 @@ ret = gdbm_setopt (dbf, GDBM_SETCACHESIZE, &bn, sizeof (bn));
 @end defvr
 
 @defvr {Option} GDBM_GETCACHESIZE
-Return the size of the internal bucket cache.  The @var{value} should
-point to a @code{size_t} variable, where the size will be stored.
+Return the actual size of the internal bucket cache.  The @var{value}
+should point to a @code{size_t} variable, where the size will be
+stored.
 @end defvr
 
 @defvr {Option} GDBM_SETCACHEAUTO
@@ -2153,6 +2155,26 @@ its value will be similar to the flags used when opening the database
 (which may have been altered by another calls to @code{gdbm_setopt}).
 @end defvr
 
+@defvr {Option} GDBM_GETDBFORMAT
+Return the database format.  The @var{value} should point to an
+@code{int} variable.  Upon successful return, it will be set to
+@samp{0} if the database is in standard format and @code{GDBM_NUMSYNC}
+if it is in extended format.  @xref{Database format}.
+@end defvr
+
+@defvr {Option} GDBM_GETDIRDEPTH
+Returns the @dfn{directory depth}: the number of initial (most significant)
+bits in hash value that are interpreted as index to the directory.  The
+actual directory size can be computed as @code{1 << @var{value}}.
+
+The @var{value} argument should point to an @code{int}.  
+@end defvr
+
+@defvr {Option} GDBM_GETBUCKETSIZE
+Returns the @dfn{bucket capacity}: maximum number of keys per bucket
+(@code{int}).
+@end defvr
+
 @defvr {Option} GDBM_FASTMODE
 Enable or disable the @dfn{fast writes mode}, i.e.@: writes without
 subsequent synchronization.  The @var{value} should point
diff --git a/src/gdbm.h.in b/src/gdbm.h.in
index 97763fe..e371e9b 100644
--- a/src/gdbm.h.in
+++ b/src/gdbm.h.in
@@ -88,9 +88,13 @@ extern "C" {
 # define GDBM_GETMAXMAPSIZE   14 /* Get maximum mapped memory size */
 # define GDBM_GETDBNAME       15 /* Return database file name */
 # define GDBM_GETBLOCKSIZE    16 /* Return block size */
-
-# define GDBM_GETCACHEAUTO    17 /* Get the value of cache auto-adjustment */
-# define GDBM_SETCACHEAUTO    18 /* Set the value of cache auto-adjustment */
+# define GDBM_GETDBFORMAT     17 /* Return the database format */
+# define GDBM_GETDIRDEPTH     18 /* Directory depth: number of initial (most
+				    significant) bits in hash interpreted as
+				    index to the directory. */
+# define GDBM_GETBUCKETSIZE   19 /* Get number of elements per bucket */
+# define GDBM_GETCACHEAUTO    20 /* Get the value of cache auto-adjustment */
+# define GDBM_SETCACHEAUTO    21 /* Set the value of cache auto-adjustment */
     
 # define GDBM_CACHE_AUTO      0
 
diff --git a/src/gdbmsetopt.c b/src/gdbmsetopt.c
index 52f3211..15c7ada 100644
--- a/src/gdbmsetopt.c
+++ b/src/gdbmsetopt.c
@@ -280,14 +280,24 @@ setopt_gdbm_getflags (GDBM_FILE dbf, void *optval, int optlen)
   else
     {
       int flags = dbf->read_write;
+
       if (!dbf->fast_write)
 	flags |= GDBM_SYNC;
+      
       if (!dbf->file_locking)
 	flags |= GDBM_NOLOCK;
+
       if (!dbf->memory_mapping)
 	flags |= GDBM_NOMMAP;
       else if (dbf->mmap_preread)
 	flags |= GDBM_PREREAD;
+
+      if (dbf->cloexec)
+	flags |= GDBM_CLOEXEC;
+      
+      if (dbf->header->header_magic == GDBM_NUMSYNC_MAGIC)
+	flags |= GDBM_NUMSYNC;
+      
       *(int*) optval = flags;
     }
   return 0;
@@ -326,6 +336,53 @@ setopt_gdbm_getblocksize (GDBM_FILE dbf, void *optval, int optlen)
   GDBM_SET_ERRNO (dbf, GDBM_OPT_BADVAL, FALSE);
   return -1;
 }
+
+static int
+setopt_gdbm_getdbformat (GDBM_FILE dbf, void *optval, int optlen)
+{
+  if (optval && optlen == sizeof (int))
+    {
+      switch (dbf->header->header_magic)
+	{
+	case GDBM_OMAGIC:
+	case GDBM_MAGIC:
+	  *(int*)optval = 0;
+	  break;
+      
+	case GDBM_NUMSYNC_MAGIC:
+	  *(int*)optval = GDBM_NUMSYNC;
+	}
+    }
+  
+  GDBM_SET_ERRNO (dbf, GDBM_OPT_BADVAL, FALSE);
+  return -1;
+}
+
+static int
+setopt_gdbm_getdirdepth (GDBM_FILE dbf, void *optval, int optlen)
+{
+  if (optval && optlen == sizeof (int))
+    {
+      *(int*) optval = dbf->header->dir_bits;
+      return 0;
+    }
+  
+  GDBM_SET_ERRNO (dbf, GDBM_OPT_BADVAL, FALSE);
+  return -1;
+}
+
+static int
+setopt_gdbm_getbucketsize (GDBM_FILE dbf, void *optval, int optlen)
+{
+  if (optval && optlen == sizeof (int))
+    {
+      *(int*) optval = dbf->header->bucket_elems;
+      return 0;
+    }
+  
+  GDBM_SET_ERRNO (dbf, GDBM_OPT_BADVAL, FALSE);
+  return -1;
+}
 
 typedef int (*setopt_handler) (GDBM_FILE, void *, int);
 
@@ -348,6 +405,9 @@ static setopt_handler setopt_handler_tab[] = {
   [GDBM_GETFLAGS]        = setopt_gdbm_getflags,
   [GDBM_GETDBNAME]       = setopt_gdbm_getdbname,
   [GDBM_GETBLOCKSIZE]    = setopt_gdbm_getblocksize,
+  [GDBM_GETDBFORMAT]     = setopt_gdbm_getdbformat,
+  [GDBM_GETDIRDEPTH]     = setopt_gdbm_getdirdepth,
+  [GDBM_GETBUCKETSIZE]   = setopt_gdbm_getbucketsize,
   [GDBM_GETCACHEAUTO]    = setopt_gdbm_getcacheauto,
   [GDBM_SETCACHEAUTO]    = setopt_gdbm_setcacheauto,
 };