From ac1065014bf3cbeb5f9ef4a121efc2e133510748 Mon Sep 17 00:00:00 2001
From: Zach Brown <zab@versity.com>
Date: Wed, 14 Feb 2018 11:58:21 -0800
Subject: [PATCH] scoutfs-utils: add stat -s option

Lots of tests run scout stat and parse a single value.  Give them an
option to have the only output be that value so they don't have to pull
it out of the output.

Signed-off-by: Zach Brown <zab@versity.com>
---
 utils/src/stat.c | 83 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 69 insertions(+), 14 deletions(-)

diff --git a/utils/src/stat.c b/utils/src/stat.c
index 2def6cea..2ae1a91e 100644
--- a/utils/src/stat.c
+++ b/utils/src/stat.c
@@ -7,6 +7,8 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <string.h>
+#include <getopt.h>
+#include <assert.h>
 
 #include "sparse.h"
 #include "util.h"
@@ -14,20 +16,75 @@
 #include "ioctl.h"
 #include "cmd.h"
 
+#define FIELD(f) {						\
+	.name = #f,						\
+	.offset = offsetof(struct scoutfs_ioctl_stat_more, f),	\
+}
+
+static struct stat_more_field {
+	char *name;
+	size_t offset;
+} fields[] = {
+	FIELD(meta_seq),
+	FIELD(data_seq),
+	FIELD(data_version),
+	FIELD(online_blocks),
+	FIELD(offline_blocks),
+	{ NULL, }
+};
+
+#define for_each_field(f) \
+	for (f = fields; f->name; f++)
+
+static struct option long_ops[] = {
+	{ "single_field", 1, NULL, 's' },
+	{ NULL, 0, NULL, 0}
+};
+
 static int stat_more_cmd(int argc, char **argv)
 {
 	struct scoutfs_ioctl_stat_more stm;
+	struct stat_more_field *single = NULL;
+	struct stat_more_field *fi;
+	char *single_name = NULL;
 	char *path;
 	int ret;
 	int fd;
 	int i;
+	int c;
 
-	if (argc == 1) {
+	while ((c = getopt_long(argc, argv, "s:", long_ops, NULL)) != -1) {
+		switch (c) {
+		case 's':
+			single_name = strdup(optarg);
+			assert(single_name);
+			break;
+		case '?':
+		default:
+			return -EINVAL;
+		}
+	}
+
+	if (single_name) {
+		for_each_field(fi) {
+			if (strcmp(fi->name, single_name) == 0) {
+				single = fi;
+				break;
+			}
+		}
+		if (!single) {
+			fprintf(stderr, "unknown stat_more field: '%s'\n",
+				single_name);
+			return -EINVAL;
+		}
+	}
+
+	if (optind >= argc) {
 		fprintf(stderr, "must specify at least one path argument\n");
 		return -EINVAL;
 	}
 
-	for (i = 1; i < argc; i++) {
+	for (i = optind; i < argc; i++) {
 		path = argv[i];
 
 		fd = open(path, O_RDONLY);
@@ -46,19 +103,17 @@ static int stat_more_cmd(int argc, char **argv)
 			ret = -errno;
 			fprintf(stderr, "stat_more ioctl failed on '%s': "
 				"%s (%d)\n", path, strerror(errno), errno);
+
+		} else if (single) {
+			printf("%llu\n",
+			       *(u64 *)((void *)&stm + single->offset));
+
 		} else {
-			printf("path            %s\n"
-			       "meta_seq        %llu\n"
-			       "data_seq        %llu\n"
-			       "data_version    %llu\n"
-			       "online_blocks   %llu\n"
-			       "offline_blocks  %llu\n",
-				path,
-				stm.meta_seq,
-				stm.data_seq,
-				stm.data_version,
-				stm.online_blocks,
-				stm.offline_blocks);
+			printf("%-17s %s\n", "path", path);
+			for_each_field(fi) {
+				printf("%-17s %llu\n", fi->name,
+				       *(u64 *)((void *)&stm + fi->offset));
+			}
 		}
 
 		close(fd);