Allow debugfs to be extended for use by test programs

This change allows debugfs to be reused as the base for e2fsprogs
internal test programs, by linking debugfs object files with
additional object file(s) that define additional commands.  The test
program's object file(s) should define their own comand table, and
define the symbol extra_cmds to be a pointer to the ss_request_table.
In addition, the symbol debug_prog_name can be used to override the
name of the program printed in the version banner and in the ss
prompt.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 8fa2412..bcd9a9b 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -38,6 +38,8 @@
 #include "../version.h"
 
 extern ss_request_table debug_cmds;
+ss_request_table *extra_cmds;
+char *debug_prog_name;
 
 ext2_filsys	current_fs = NULL;
 ext2_ino_t	root, cwd;
@@ -1798,7 +1800,7 @@
 {
 	int		retval;
 	int		sci_idx;
-	const char	*usage = "Usage: debugfs [-b blocksize] [-s superblock] [-f cmd_file] [-R request] [-V] [[-w] [-c] device]";
+	const char	*usage = "Usage: %s [-b blocksize] [-s superblock] [-f cmd_file] [-R request] [-V] [[-w] [-c] device]";
 	int		c;
 	int		open_flags = EXT2_FLAG_SOFTSUPP_FEATURES;
 	char		*request = 0;
@@ -1809,9 +1811,12 @@
 	int		catastrophic = 0;
 	char		*data_filename = 0;
 	
+	if (debug_prog_name == 0)
+		debug_prog_name = "debugfs";
+
 	add_error_table(&et_ext2_error_table);
-	fprintf (stderr, "debugfs %s (%s)\n", E2FSPROGS_VERSION,
-		 E2FSPROGS_DATE);
+	fprintf (stderr, "%s %s (%s)\n", debug_prog_name,
+		 E2FSPROGS_VERSION, E2FSPROGS_DATE);
 
 	while ((c = getopt (argc, argv, "iwcR:f:b:s:Vd:")) != EOF) {
 		switch (c) {
@@ -1847,7 +1852,7 @@
 				error_message(EXT2_ET_BASE));
 			exit(0);
 		default:
-			com_err(argv[0], 0, usage);
+			com_err(argv[0], 0, usage, debug_prog_name);
 			return 1;
 		}
 	}
@@ -1856,7 +1861,7 @@
 				superblock, blocksize, catastrophic,
 				data_filename);
 	
-	sci_idx = ss_create_invocation("debugfs", "0.0", (char *) NULL,
+	sci_idx = ss_create_invocation(debug_prog_name, "0.0", (char *) NULL,
 				       &debug_cmds, &retval);
 	if (retval) {
 		ss_perror(sci_idx, retval, "creating invocation");
@@ -1869,6 +1874,12 @@
 		ss_perror(sci_idx, retval, "adding standard requests");
 		exit (1);
 	}
+	if (extra_cmds)
+		ss_add_request_table (sci_idx, extra_cmds, 1, &retval);
+	if (retval) {
+		ss_perror(sci_idx, retval, "adding extra requests");
+		exit (1);
+	}
 	if (request) {
 		retval = 0;
 		retval = ss_execute_line(sci_idx, request);