1 files changed, 293 insertions, 0 deletions
diff --git a/libdb/db_btree.c b/libdb/db_btree.c
new file mode 100644
index 0000000..54242c0
--- /dev/null
+++ b/libdb/db_btree.c
@@ -0,0 +1,293 @@
+/*
+ * db_btree.c: low level btree interface routines for man.
+ *
+ * Copyright (C) 1994, 1995 Graeme W. Wilford. (Wilf.)
+ * Copyright (C) 2002 Colin Watson.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Mon Aug  8 20:35:30 BST 1994  Wilf. (G.Wilford@ee.surrey.ac.uk)
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+/* below this line are routines only useful for the BTREE interface */
+#ifdef BTREE
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <sys/file.h> /* for flock() */
+#include <sys/types.h> /* for open() */
+#include <sys/stat.h>
+
+#include "gl_hash_set.h"
+#include "gl_xset.h"
+#include "stat-time.h"
+#include "timespec.h"
+#include "xalloc.h"
+#include "xstrndup.h"
+
+#include "manconfig.h"
+
+#include "debug.h"
+#include "error.h"
+#include "glcontainers.h"
+
+#include "mydbm.h"
+#include "db_storage.h"
+
+gl_set_t loop_check;
+
+/* the Berkeley database libraries do nothing to arbitrate between concurrent
+   database accesses, so we do a simple flock(). If the db is opened in
+   anything but O_RDONLY mode, an exclusive lock is enabled. Otherwise, the
+   lock is shared. A file cannot have both locks at once, and the non
+   blocking method is used ": Try again". This adopts GNU dbm's approach. */
+
+/* release the lock and close the database */
+void man_btree_free (man_btree_wrapper wrap)
+{
+	if (!wrap)
+		return;
+
+	free (wrap->name);
+	if (wrap->file) {
+		(void) flock ((wrap->file->fd) (wrap->file), LOCK_UN);
+		(wrap->file->close) (wrap->file);
+	}
+	free (wrap->mtime);
+	free (wrap);
+}
+
+man_btree_wrapper man_btree_new (const char *name)
+{
+	man_btree_wrapper wrap;
+
+	wrap = xmalloc (sizeof *wrap);
+	wrap->name = xstrdup (name);
+	wrap->file = NULL;
+	wrap->mtime = NULL;
+
+	return wrap;
+}
+
+/* open a btree type database, with file locking. */
+bool man_btree_open (man_btree_wrapper wrap, int flags, int mode)
+{
+	BTREEINFO b;
+	int lock_op;
+	int lock_failed;
+
+	b.flags = 0;		/* do not allow any duplicate keys */
+
+	b.cachesize = 0;	/* default size */
+	b.maxkeypage = 0;	/* default */
+	b.minkeypage = 0;	/* default */
+	b.psize = 0;		/* default page size (2048?) */
+	b.compare = NULL;	/* builtin compare() function */
+	b.prefix = NULL;	/* builtin function */
+	b.lorder = 0;		/* byte order of host */
+
+	if (flags & ~O_RDONLY) {
+		/* flags includes O_RDWR or O_WRONLY, need an exclusive lock */
+		lock_op = LOCK_EX | LOCK_NB;
+	} else {
+		lock_op = LOCK_SH | LOCK_NB;
+	}
+
+	if (!(flags & O_CREAT)) {
+		/* Berkeley DB thinks that a zero-length file means that
+		 * somebody else is writing it, and sleeps for a few
+		 * seconds to give the writer a chance. All very well, but
+		 * the common case is that the database is just zero-length
+		 * because mandb was interrupted or ran out of disk space or
+		 * something like that - so we check for this case by hand
+		 * and ignore the database if it's zero-length.
+		 */
+		struct stat iszero;
+		if (stat (wrap->name, &iszero) < 0)
+			return false;
+		if (iszero.st_size == 0) {
+			errno = EINVAL;
+			return false;
+		}
+	}
+
+	if (flags & O_TRUNC) {
+		/* opening the db is destructive, need to lock first */
+		int fd;
+
+		wrap->file = NULL;
+		lock_failed = 1;
+		fd = open (wrap->name, flags & ~O_TRUNC, mode);
+		if (fd != -1) {
+			if (!(lock_failed = flock (fd, lock_op)))
+				wrap->file = dbopen (wrap->name, flags, mode,
+						     DB_BTREE, &b);
+			close (fd);
+		}
+	} else {
+		wrap->file = dbopen (wrap->name, flags, mode, DB_BTREE, &b);
+		if (wrap->file)
+			lock_failed = flock ((wrap->file->fd) (wrap->file),
+					     lock_op);
+	}
+
+	if (!wrap->file)
+		return false;
+
+	if (lock_failed) {
+		gripe_lock (wrap->name);
+		(wrap->file->close) (wrap->file);
+		return false;
+	}
+
+	return true;
+}
+
+/* do a replace when we have the duplicate flag set on the database -
+   we must do a del and insert, as a direct insert will not wipe out the
+   old entry */
+int man_btree_replace (man_btree_wrapper wrap, datum key, datum cont)
+{
+	return (wrap->file->put) (wrap->file, (DBT *) &key, (DBT *) &cont, 0);
+}
+
+int man_btree_insert (man_btree_wrapper wrap, datum key, datum cont)
+{
+	return (wrap->file->put) (wrap->file, (DBT *) &key, (DBT *) &cont,
+				  R_NOOVERWRITE);
+}
+
+/* generic fetch routine for the btree database */
+datum man_btree_fetch (man_btree_wrapper wrap, datum key)
+{
+	datum data;
+
+	memset (&data, 0, sizeof data);
+
+	if ((wrap->file->get) (wrap->file, (DBT *) &key, (DBT *) &data, 0)) {
+		memset (&data, 0, sizeof data);
+		return data;
+	}
+
+	return copy_datum (data);
+}
+
+/* return 1 if the key exists, 0 otherwise */
+int man_btree_exists (man_btree_wrapper wrap, datum key)
+{
+	datum data;
+	return ((wrap->file->get) (wrap->file, (DBT *) &key, (DBT *) &data,
+				   0) ? 0 : 1);
+}
+
+/* initiate a sequential access */
+static datum man_btree_findkey (man_btree_wrapper wrap, u_int flags)
+{
+	datum key, data;
+	char *loop_check_key;
+
+	memset (&key, 0, sizeof key);
+	memset (&data, 0, sizeof data);
+
+	if (flags == R_FIRST) {
+		if (loop_check) {
+			gl_set_free (loop_check);
+			loop_check = NULL;
+		}
+	}
+	if (!loop_check)
+		loop_check = new_string_set (GL_HASH_SET);
+
+	if (((wrap->file->seq) (wrap->file, (DBT *) &key, (DBT *) &data,
+				flags))) {
+		memset (&key, 0, sizeof key);
+		return key;
+	}
+
+	loop_check_key = xstrndup (MYDBM_DPTR (key), MYDBM_DSIZE (key));
+	if (gl_set_search (loop_check, loop_check_key)) {
+		/* We've seen this key already, which is broken. Return NULL
+		 * so the caller doesn't go round in circles.
+		 */
+		debug ("Corrupt database! Already seen %*s. "
+		       "Attempting to recover ...\n",
+		       (int) MYDBM_DSIZE (key), MYDBM_DPTR (key));
+		memset (&key, 0, sizeof key);
+		free (loop_check_key);
+		return key;
+	}
+
+	gl_set_add (loop_check, loop_check_key);
+
+	return copy_datum (key);
+}
+
+/* return the first key in the db */
+datum man_btree_firstkey (man_btree_wrapper wrap)
+{
+	return man_btree_findkey (wrap, R_FIRST);
+}
+
+/* return the next key in the db. NB. This routine only works if the cursor
+   has been previously set by man_btree_firstkey() since it was last opened. So
+   if we close/reopen a db mid search, we have to manually set up the
+   cursor again. */
+datum man_btree_nextkey (man_btree_wrapper wrap)
+{
+	return man_btree_findkey (wrap, R_NEXT);
+}
+
+/* compound nextkey routine, initialising key and content */
+int man_btree_nextkeydata (man_btree_wrapper wrap, datum *key, datum *cont)
+{
+	int status;
+
+	if ((status = (wrap->file->seq) (wrap->file, (DBT *) key, (DBT *) cont,
+					 R_NEXT)) != 0)
+		return status;
+
+	*key = copy_datum (*key);
+	*cont = copy_datum (*cont);
+
+	return 0;
+}
+
+struct timespec man_btree_get_time (man_btree_wrapper wrap)
+{
+	struct stat st;
+
+	if (!wrap->mtime) {
+		wrap->mtime = XMALLOC (struct timespec);
+		if (fstat ((wrap->file->fd) (wrap->file), &st) < 0) {
+			wrap->mtime->tv_sec = -1;
+			wrap->mtime->tv_nsec = -1;
+		} else
+			*wrap->mtime = get_stat_mtime (&st);
+	}
+
+	return *wrap->mtime;
+}
+
+#endif /* BTREE */