From 9891d6597770ed884c989885d04da46db5952f0a Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@beefcake.parabola.nu>
Date: Wed, 16 May 2018 10:30:03 -0400
Subject: first pass at cow-extent-map

---
 src/cow-extent-map.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 src/cow-extent-map.c

(limited to 'src')

diff --git a/src/cow-extent-map.c b/src/cow-extent-map.c
new file mode 100644
index 0000000..7cee70c
--- /dev/null
+++ b/src/cow-extent-map.c
@@ -0,0 +1,93 @@
+#define _GNU_SOURCE   /* for program_invocation_name */
+#include <assert.h>   /* for assert(3p) */
+#include <errno.h>    /* for errno, program_invocation_name */
+#include <error.h>    /* for error(3gnu) */
+#include <fcntl.h>    /* for open(2) and O_RDONLY */
+#include <getopt.h>   /* for getopt_long(3gnu), struct option, optind, optarg */
+#include <inttypes.h> /* PRI* */
+#include <stdio.h>    /* for printf(3p), fprintf(3p), stderr */
+#include <stdlib.h>   /* exit(3p), EXIT_SUCCESS, EXIT_FAILURE */
+#include <string.h>   /* for strcmp(3p) */
+
+#include "extent-map.h" /* for uint32_t, fiemap stuff */ 
+
+#define EXIT_INVALIDARGUMENT 2
+#define errusage(format, ...) do { \
+	error(0, 0, format, ## __VA_ARGS__); \
+	fprintf(stderr, "Try '%s --help' for more information.\n", program_invocation_name); \
+	exit(EXIT_INVALIDARGUMENT); \
+} while(0)
+
+int print_extent(struct fiemap_extent extent) {
+	printf("logical=%"PRIu64" "
+	       "physical=%"PRIu64" "
+	       "length=%"PRIu64" "
+	       "flags=0x%"PRIx32"\n",
+	       extent.fe_logical,
+	       extent.fe_physical,
+	       extent.fe_length,
+	       extent.fe_flags);
+	return 0;
+}
+
+void usage() {
+	printf("Usage: %s [OPTIONS] FILENAME\n"
+	       "Print a file extent map.\n"
+	       "\n"
+	       "OPTIONS:\n"
+	       "  --stream=data   Map extents in the data stream (default).\n"
+	       "  --stream=xattr  Map extents in the extended attribute stream.\n"
+	       "  --sync          Sync the file before mapping extents (default).\n"
+	       "  --no-sync       Don't sync the file before mapping extents.\n"
+	       "  -h, --help      Display this help and exit.\n",
+	       program_invocation_name);
+}
+
+int main(int argc, char *argv[]) {
+	char *stream = "data";
+	int sync = 1;
+	struct option long_options[] = {
+		{"stream",  optional_argument, NULL, 1},
+		{"sync",    no_argument,       &sync, 1},
+		{"no-sync", no_argument,       &sync, 0},
+		{"help",    no_argument,       NULL, 'h'},
+		{0},
+	};
+	int flag;
+	while ((flag = getopt_long(argc, argv, "h", long_options, NULL)) >= 0) {
+		switch (flag) {
+		case 0:
+			break;
+		case 1:
+			stream = optarg;
+			break;
+		case 'h':
+			usage();
+			return EXIT_SUCCESS;
+		case '?':
+			fprintf(stderr, "Try '%s --help' for more information.\n", program_invocation_name);
+			return EXIT_INVALIDARGUMENT;
+		default:
+			assert(0);
+		}
+	}
+	if (argc - optind != 1)
+		errusage("wrong number of arguments");
+
+	uint32_t flags = sync ? FIEMAP_FLAG_SYNC : 0;
+	if (strcmp(stream, "data") == 0) {
+		/* do nothing */
+	} else if (strcmp(stream, "xattr") == 0) {
+		flags |= FIEMAP_FLAG_XATTR;
+	} else {
+		errusage("invalid stream name");
+	}
+
+	char *filename = argv[optind];
+	int fd = open(filename, O_RDONLY);
+	if (fd < 0)
+		error(EXIT_FAILURE, errno, "%s", filename);
+
+	fiemap(fd, flags, print_extent);
+	return EXIT_SUCCESS;;
+}
-- 
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