[PATCH 6/6] libxcmd: add non-iterating user commands

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

Right now command iteration is not directly controllable by the
user; it is controlled entirely by the application command flag
setup. Sometimes we don't want commands to iterate but only operate
on the currently selected object.

For example, the stat command iterates:

$ xfs_io -c "open -r foo" -c "open bar" -c "file" -c "stat" foo
 000  foo            (foreign,non-sync,non-direct,read-write)
 001  foo            (foreign,non-sync,non-direct,read-only)
[002] bar            (foreign,non-sync,non-direct,read-write)
fd.path = "foo"
fd.flags = non-sync,non-direct,read-write
stat.ino = 462399
stat.type = regular file
stat.size = 776508
stat.blocks = 1528
fd.path = "foo"
fd.flags = non-sync,non-direct,read-only
stat.ino = 462399
stat.type = regular file
stat.size = 776508
stat.blocks = 1528
fd.path = "bar"
fd.flags = non-sync,non-direct,read-write
stat.ino = 475227
stat.type = regular file
stat.size = 0
stat.blocks = 0
$

To do this, add a function to supply a "non-iterating" user command
that will execute an iterating-capable command as though it
CMD_FLAG_ONESHOT was set. Add a new command line option to xfs_io to
drive it (-C <command>) and connect it all up. Document it in the
xfs_io man page, too.

The result of "-C stat":

$ xfs_io -c "open -r foo" -c "open bar" -c "file" -C "stat" foo
 000  foo            (foreign,non-sync,non-direct,read-write)
 001  foo            (foreign,non-sync,non-direct,read-only)
[002] bar            (foreign,non-sync,non-direct,read-write)
fd.path = "bar"
fd.flags = non-sync,non-direct,read-write
stat.ino = 475227
stat.type = regular file
stat.size = 0
stat.blocks = 0
$

Is that we only see the stat output for the active open file
which is "bar".

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
---
 include/command.h |  1 +
 io/init.c         |  7 +++++--
 libxcmd/command.c | 33 +++++++++++++++++++++++++++------
 man/man8/xfs_io.8 | 40 ++++++++++++++++++++++++++++++++++------
 4 files changed, 67 insertions(+), 14 deletions(-)

diff --git a/include/command.h b/include/command.h
index 348002cbe3ed..fb3f5c79b991 100644
--- a/include/command.h
+++ b/include/command.h
@@ -56,6 +56,7 @@ typedef int (*checkfunc_t)(const cmdinfo_t *ci);
 
 extern void		add_command(const cmdinfo_t *ci);
 extern void		add_user_command(char *optarg);
+extern void		add_oneshot_user_command(char *optarg);
 extern void		add_command_iterator(iterfunc_t func);
 extern void		add_check_command(checkfunc_t cf);
 
diff --git a/io/init.c b/io/init.c
index 5ce627ef22c9..cf8573f0ecd5 100644
--- a/io/init.c
+++ b/io/init.c
@@ -34,7 +34,7 @@ void
 usage(void)
 {
 	fprintf(stderr,
-		_("Usage: %s [-adfinrRstVx] [-m mode] [-p prog] [-c cmd]... file\n"),
+_("Usage: %s [-adfinrRstVx] [-m mode] [-p prog] [[-c|-C] cmd]... file\n"),
 		progname);
 	exit(1);
 }
@@ -145,7 +145,7 @@ init(
 	pagesize = getpagesize();
 	gettimeofday(&stopwatch, NULL);
 
-	while ((c = getopt(argc, argv, "ac:dFfim:p:nrRstTVx")) != EOF) {
+	while ((c = getopt(argc, argv, "ac:C:dFfim:p:nrRstTVx")) != EOF) {
 		switch (c) {
 		case 'a':
 			flags |= IO_APPEND;
@@ -153,6 +153,9 @@ init(
 		case 'c':
 			add_user_command(optarg);
 			break;
+		case 'C':
+			add_oneshot_user_command(optarg);
+			break;
 		case 'd':
 			flags |= IO_DIRECT;
 			break;
diff --git a/libxcmd/command.c b/libxcmd/command.c
index decc442a9d03..5917aea42611 100644
--- a/libxcmd/command.c
+++ b/libxcmd/command.c
@@ -25,8 +25,14 @@ int		ncmds;
 
 static iterfunc_t	iter_func;
 static checkfunc_t	check_func;
-static int		ncmdline;
-static char		**cmdline;
+
+struct cmdline {
+	char	*cmdline;
+	bool	iterate;
+};
+
+static int	ncmdline;
+struct cmdline	*cmdline;
 
 static int
 compare(const void *a, const void *b)
@@ -120,12 +126,27 @@ void
 add_user_command(char *optarg)
 {
 	ncmdline++;
-	cmdline = realloc(cmdline, sizeof(char*) * (ncmdline));
+	cmdline = realloc(cmdline, sizeof(struct cmdline) * (ncmdline));
+	if (!cmdline) {
+		perror("realloc");
+		exit(1);
+	}
+	cmdline[ncmdline-1].cmdline = optarg;
+	cmdline[ncmdline-1].iterate = true;
+
+}
+
+void
+add_oneshot_user_command(char *optarg)
+{
+	ncmdline++;
+	cmdline = realloc(cmdline, sizeof(struct cmdline) * (ncmdline));
 	if (!cmdline) {
 		perror("realloc");
 		exit(1);
 	}
-	cmdline[ncmdline-1] = optarg;
+	cmdline[ncmdline-1].cmdline = optarg;
+	cmdline[ncmdline-1].iterate = false;
 }
 
 /*
@@ -212,14 +233,14 @@ command_loop(void)
 
 	/* command line mode */
 	for (i = 0; !done && i < ncmdline; i++) {
-		input = strdup(cmdline[i]);
+		input = strdup(cmdline[i].cmdline);
 		if (!input) {
 			fprintf(stderr,
 				_("cannot strdup command '%s': %s\n"),
 				cmdline[i], strerror(errno));
 			exit(1);
 		}
-		done = process_input(input, true);
+		done = process_input(input, cmdline[i].iterate);
 	}
 	free(cmdline);
 	return;
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 885df7f141e2..9db2d97d8310 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -9,10 +9,13 @@ xfs_io \- debug the I/O path of an XFS filesystem
 .B \-c
 .I cmd
 ] ... [
+.B \-C
+.I cmd
+] ... [
 .B \-p
 .I prog
 ]
-.I file
+.I [ file ]
 .br
 .B xfs_io \-V
 .SH DESCRIPTION
@@ -25,14 +28,39 @@ These code paths include not only the obvious read/write/mmap interfaces
 for manipulating files, but also cover all of the XFS extensions (such
 as space preallocation, additional inode flags, etc).
 .SH OPTIONS
+.B xfs_io
+commands may be run interactively (the default) or as arguments on the
+command line.
+Interactive mode always runs commands on the current open file, whilst commands
+run from the command line may be repeated on all open files rather than just the current
+open file.
+In general, open file iteration will occur for commands that operate on file
+content or state. In contrast, commands that operate on filesystem or
+system-wide state will only be run on the current file regardless of how many
+files are currently open.
+Multiple arguments may be given on the command line and they are run in the
+sequence given. The program exits one all commands have
+been run.
 .TP 1.0i
 .BI \-c " cmd"
-.B xfs_io
-commands may be run interactively (the default) or as arguments on
-the command line. Multiple
+Run the specified command on all currently open files.
+To maintain compatibility with historical usage, commands that can not be run on
+all open files will still be run but only execute once on the current open file.
+Multiple
+.B \-c
+arguments may be given and may be interleaved on the command line in any order
+with
+.B \-C
+commands.
+.TP
+.BI \-C " cmd"
+Run the specified command only on the current open file. 
+Multiple
+.B \-C
+arguments may be given and may be interleaved on the command line in any order
+with
 .B \-c
-arguments may be given. The commands are run in the sequence given,
-then the program exits.
+commands.
 .TP
 .BI \-p " prog"
 Set the program name for prompts and some error messages,
-- 
2.10.2