tdb: add -e option to tdbdump (and docment it).

This allows for an emergency best-effort dump.  It's a little better than
strings(1).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Autobuild-User(master): Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date(master): Thu Oct  4 03:16:06 CEST 2012 on sn-devel-104

2 files changed, 53 insertions, 3 deletions

diff --git a/lib/tdb/manpages/tdbdump.8.xml b/lib/tdb/manpages/tdbdump.8.xml
index 90465e53e8..3420193243 100644
--- a/lib/tdb/manpages/tdbdump.8.xml
+++ b/lib/tdb/manpages/tdbdump.8.xml
@@ -19,6 +19,9 @@
 <refsynopsisdiv>
 	<cmdsynopsis>
 		<command>tdbdump</command>
+		<arg choice="opt">-k <replaceable>keyname</replaceable></arg>
+		<arg choice="opt">-e</arg>
+		<arg choice="opt">-h</arg>
 		<arg choice="req">filename</arg>
 	</cmdsynopsis>
 </refsynopsisdiv>
@@ -39,6 +42,34 @@
 	</para>
 </refsect1>
 
+<refsect1>
+	<title>OPTIONS</title>
+
+	<variablelist>
+
+		<varlistentry>
+		<term>-h</term>
+		<listitem><para>
+		Get help information.
+		</para></listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>-k <replaceable>keyname</replaceable></term>
+		<listitem><para>
+		The <command>-k</command> option restricts dumping to a single key, if found.
+		</para> </listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>-e</term>
+		<listitem><para>
+		The <command>-e</command> tries to dump out from a corrupt database.  Naturally, such a dump is unreliable, at best.
+		</para></listitem>
+		</varlistentry>
+
+	</variablelist>
+</refsect1>
 
 <refsect1>
 	<title>VERSION</title>
diff --git a/lib/tdb/tools/tdbdump.c b/lib/tdb/tools/tdbdump.c
index bb11200ec4..bcd395fd5a 100644
--- a/lib/tdb/tools/tdbdump.c
+++ b/lib/tdb/tools/tdbdump.c
@@ -86,7 +86,18 @@ static void log_stderr(struct tdb_context *tdb, enum tdb_debug_level level,
 	va_end(ap);
 }
 
-static int dump_tdb(const char *fname, const char *keyname)
+static void emergency_walk(TDB_DATA key, TDB_DATA dbuf, void *keyname)
+{
+	if (keyname) {
+		if (key.dsize != strlen(keyname))
+			return;
+		if (memcmp(key.dptr, keyname, key.dsize) != 0)
+			return;
+	}
+	traverse_fn(NULL, key, dbuf, NULL);
+}
+
+static int dump_tdb(const char *fname, const char *keyname, bool emergency)
 {
 	TDB_CONTEXT *tdb;
 	TDB_DATA key, value;
@@ -98,6 +109,9 @@ static int dump_tdb(const char *fname, const char *keyname)
 		return 1;
 	}
 
+	if (emergency) {
+		return tdb_rescue(tdb, emergency_walk, keyname) == 0;
+	}
 	if (!keyname) {
 		return tdb_traverse(tdb, traverse_fn, NULL) == -1 ? 1 : 0;
 	} else {
@@ -120,11 +134,13 @@ static void usage( void)
 	printf( "Usage: tdbdump [options] <filename>\n\n");
 	printf( "   -h          this help message\n");
 	printf( "   -k keyname  dumps value of keyname\n");
+	printf( "   -e          emergency dump, for corrupt databases\n");
 }
 
  int main(int argc, char *argv[])
 {
 	char *fname, *keyname=NULL;
+	bool emergency = false;
 	int c;
 
 	if (argc < 2) {
@@ -132,7 +148,7 @@ static void usage( void)
 		exit(1);
 	}
 
-	while ((c = getopt( argc, argv, "hk:")) != -1) {
+	while ((c = getopt( argc, argv, "hk:e")) != -1) {
 		switch (c) {
 		case 'h':
 			usage();
@@ -140,6 +156,9 @@ static void usage( void)
 		case 'k':
 			keyname = optarg;
 			break;
+		case 'e':
+			emergency = true;
+			break;
 		default:
 			usage();
 			exit( 1);
@@ -148,5 +167,5 @@ static void usage( void)
 
 	fname = argv[optind];
 
-	return dump_tdb(fname, keyname);
+	return dump_tdb(fname, keyname, emergency);
 }