[PATCH] xfs_io: changes to statx interface

[David Howells <dhowells@redhat.com>]

Eric Sandeen <sandeen@sandeen.net> wrote:

> Wire up the statx syscall to xfs_io.
> 
> xfs_io> help statx
> statx [-O | -m mask][-FDLA] -- extended information about the currently open file
> ...

I would like to make the attached changes, to make it more capable, except
that xfs_io seems to precheck the "-m mask" argument somewhere:

	[root@andromeda ~]# xfs_io -c statx -m all /dev/null
	non-numeric mode -- all

and interprets "-c" for itself on the command line:

	[root@andromeda ~]# xfs_io -c statx -c /dev/null
	command "/dev/null" not found

though both these seem to work when used from xfs_io's command prompt.  I
guess I should switch -c to -C and also -m to -M since it's not a file mode as
I think the core is expecting.

Also, how do you get xfs_io to tell you what fd it has opened from its own
command prompt?  I would need to pass that to the -d flag as a dir fd.

David
---
commit 03e4ca1cdc59aaa362fdd51f079493a1f0da254c
Author: David Howells <dhowells@redhat.com>
Date:   Tue Mar 28 10:42:23 2017 +0100

    changes

diff --git a/io/stat.c b/io/stat.c
index a7aebcd..0b05ec9 100644
--- a/io/stat.c
+++ b/io/stat.c
@@ -189,12 +189,14 @@ statx_help(void)
 " Display extended file status.\n"
 "\n"
 " Options:\n"
-" -m mask -- Specify the field mask for the statx call (default STATX_ALL)\n"
+" -c -- Compare against fstat/fstatat on the same file/fd\n"
+" -d dirfd -- Use a specific directory fd\n"
+" -f -- Do fstat equivalent and operate on fd\n"
+" -m mask -- Specify the field mask for the statx call (can also be 'basic' or 'all'; default STATX_ALL)\n"
 " -A -- Suppress terminal automount traversal\n"
 " -D -- Don't sync attributes with the server\n"
 " -F -- Force the attributes to be sync'd with the server\n"
 " -L -- Follow symlinks (statx link target)\n"
-" -O -- Add only basic stats (STATX_BASIC_STATS) to default mask\n"
 "\n"));
 }
 
@@ -227,6 +229,65 @@ dump_statx(struct statx *stx)
 }
 
 /*
+ * Compare the contents of a statx struct with that of a stat struct and check
+ * that they're the same.
+ */
+static int
+cmp_statx(const struct statx *stx, const struct stat *st)
+{
+	const char *what = NULL;
+
+#define cmp(x) \
+	do {					\
+		what = #x;		\
+		if (stx->stx_##x != st->st_##x)	\
+			goto mismatch;		\
+	} while (0)
+
+	cmp(blksize);
+	cmp(nlink);
+	cmp(uid);
+	cmp(gid);
+	cmp(mode);
+	cmp(ino);
+	cmp(size);
+	cmp(blocks);
+
+#define devcmp(x) \
+	do {						\
+		what = #x".major";			\
+		if (stx->stx_##x##_major != major(st->st_##x))	\
+			goto mismatch;			\
+		what = #x".minor";			\
+		if (stx->stx_##x##_minor != minor(st->st_##x))	\
+			goto mismatch;			\
+	} while (0)
+
+	devcmp(dev);
+	devcmp(rdev);
+
+#define timecmp(x) \
+	do {						\
+		what = #x".tv_sec";			\
+		if (stx->stx_##x##time.tv_sec != st->st_##x##tim.tv_sec)	\
+			goto mismatch;			\
+		what = #x".tv_nsec";			\
+		if (stx->stx_##x##time.tv_nsec != st->st_##x##tim.tv_nsec)	\
+			goto mismatch;			\
+	} while (0)
+
+	timecmp(a);
+	timecmp(c);
+	timecmp(m);
+
+	return 0;
+
+mismatch:
+	fprintf(stderr, "Mismatch between stat and statx output (%s)\n", what);
+	return -1;
+}
+
+/*
  * options:
  * 	- input flags - query type
  * 	- output style for flags (and all else?) (chars vs. hex?)
@@ -239,16 +300,31 @@ statx_f(
 {
 	int		c;
 	struct statx	stx;
+	struct stat	st;
 	int		atflag = AT_SYMLINK_NOFOLLOW;
-	unsigned int	m_mask = 0;	/* mask requested with -m */
-	int		Oflag = 0, mflag = 0;	/* -O or -m was used */
 	unsigned int	mask = STATX_ALL;
+	int		use_fd = 0;
+	int		dirfd = AT_FDCWD;
+	int		compare = 0;
 
-	while ((c = getopt(argc, argv, "m:FDLOA")) != EOF) {
+	while ((c = getopt(argc, argv, "d:cfm:FDLA")) != EOF) {
 		switch (c) {
+		case 'c':
+			compare = 1;
+			break;
+		case 'd':
+			dirfd = strtoul(optarg, NULL, 0);
+			break;
+		case 'f':
+			use_fd = 1;
+			break;
 		case 'm':
-			m_mask = atoi(optarg);
-			mflag = 1;
+			if (strcmp(optarg, "basic") == 0)
+				mask = STATX_BASIC_STATS;
+			else if (strcmp(optarg, "all") == 0)
+				mask = STATX_ALL;
+			else
+				mask = strtoul(optarg, NULL, 0);
 			break;
 		case 'F':
 			atflag &= ~AT_STATX_SYNC_TYPE;
@@ -261,10 +337,6 @@ statx_f(
 		case 'L':
 			atflag &= ~AT_SYMLINK_NOFOLLOW;
 			break;
-		case 'O':
-			mask = STATX_BASIC_STATS;
-			Oflag = 1;
-			break;
 		case 'A':
 			atflag |= AT_NO_AUTOMOUNT;
 			break;
@@ -273,23 +345,38 @@ statx_f(
 		}
 	}
 
-	if (Oflag && mflag) {
-		printf("Cannot specify both -m mask and -O\n");
-		return 0;
+	memset(&stx, 0xbf, sizeof(stx));
+
+	if (use_fd) {
+		if (statx(file->fd, NULL, atflag, mask, &stx) < 0) {
+			perror("statx");
+			return 0;
+		}
+	} else {
+		if (statx(dirfd, file->name, atflag, mask, &stx) < 0) {
+			perror("statx");
+			return 0;
+		}
 	}
 
-	/* -m overrides any other mask options */
-	if (mflag)
-		mask = m_mask;
+	if (compare) {
+		if (use_fd) {
+			if (fstat(file->fd, &st) < 0) {
+				perror("fstat");
+				return 0;
+			}
+		} else {
+			if (fstatat(dirfd, file->name, &st,
+				    atflag & ~AT_STATX_SYNC_TYPE) < 0) {
+				perror("fstatat");
+				return 0;
+			}
+		}
 
-	memset(&stx, 0xbf, sizeof(stx));
-	if (statx(AT_FDCWD, file->name, atflag, mask, &stx) < 0) {
-		perror("statx");
-		return 0;
+		cmp_statx(&stx, &st);
 	}
-
+	
 	dump_statx(&stx);
-
 	return 0;
 }