I have seen a few requests from users on other forums for a way to find a diff between two
snapshots and some scripts have been created[1] which parse a btrfs-send stream to get this
information.
This patch adds native JSON format output support to the btrfs-receive dump command which would
make writing such scripts much easier as they can use JSON parsing libraries rather than string
or binary decoding.
Usage: btrfs send --no-data <subvolume> | btrfs receive --dump-json
Sample output:
[
{"operation": "subvol", "path": "./2021-01-16T03:01:36+00:00", "uuid":
"4f6756a2-c8e8-614b-beaa-483de9a7ed13", "transid": 47864957},
{"operation": "chown", "path": "./2021-01-16T03:01:36+00:00/", "gid": 0,
"uid": 0},
{"operation": "chmod", "path": "./2021-01-16T03:01:36+00:00/", "mode": "755"},
{"operation": "utimes", "path": "./2021-01-16T03:01:36+00:00/", "atime":
"2021-01-16T03:00:30+0000", "mtime": "1970-01-01T01:00:00+0100", "ctime":
"2021-01-13T03:00:38+0000"},
{"operation": "mkdir", "path": "./2021-01-16T03:01:36+00:00/o257-2524-0"},
{"operation": "rename", "path": "./2021-01-16T03:01:36+00:00/o257-2524-0", "dest":
"./2021-01-16T03:01:36+00:00/grub"},
{}
]
Patch is against current btrfs-progs master.
[1] https://github.com/sysnux/btrfs-snapshots-diff
Signed-off-by: Steven Davies <bt...@steev.me.uk>
---
cmds/receive-dump.c | 268 +++++++++++++++++++++++++++++++++++++++++-----------
cmds/receive-dump.h | 1 +
cmds/receive.c | 20 +++-
3 files changed, 234 insertions(+), 55 deletions(-)
diff --git a/cmds/receive-dump.c b/cmds/receive-dump.c
index 648d9314..2c1af22e 100644
--- a/cmds/receive-dump.c
+++ b/cmds/receive-dump.c
@@ -51,7 +51,7 @@
* Returns the length of the escaped characters. Unprintable characters are
* escaped as octals.
*/
-static int print_path_escaped(const char *path)
+static int print_path_escaped(const char *path, int json)
{
size_t i;
size_t path_len = strlen(path);
@@ -61,27 +61,44 @@ static int print_path_escaped(const char *path)
char c = path[i];
len++;
- switch (c) {
- case '\a': putchar('\\'); putchar('a'); len++; break;
- case '\b': putchar('\\'); putchar('b'); len++; break;
- case '\e': putchar('\\'); putchar('e'); len++; break;
- case '\f': putchar('\\'); putchar('f'); len++; break;
- case '\n': putchar('\\'); putchar('n'); len++; break;
- case '\r': putchar('\\'); putchar('r'); len++; break;
- case '\t': putchar('\\'); putchar('t'); len++; break;
- case '\v': putchar('\\'); putchar('v'); len++; break;
- case ' ': putchar('\\'); putchar(' '); len++; break;
- case '\\': putchar('\\'); putchar('\\'); len++; break;
- default:
- if (!isprint(c)) {
- printf("\\%c%c%c",
- '0' + ((c & 0300) >> 6),
- '0' + ((c & 070) >> 3),
- '0' + (c & 07));
- len += 3;
- } else {
- putchar(c);
- }
+ if (!json) {
+ switch (c) {
+ case '\a': putchar('\\'); putchar('a'); len++; break;
+ case '\b': putchar('\\'); putchar('b'); len++; break;
+ case '\e': putchar('\\'); putchar('e'); len++; break;
+ case '\f': putchar('\\'); putchar('f'); len++; break;
+ case '\n': putchar('\\'); putchar('n'); len++; break;
+ case '\r': putchar('\\'); putchar('r'); len++; break;
+ case '\t': putchar('\\'); putchar('t'); len++; break;
+ case '\v': putchar('\\'); putchar('v'); len++; break;
+ case ' ': putchar('\\'); putchar(' '); len++; break;
+ case '\\': putchar('\\'); putchar('\\'); len++; break;
+ default:
+ if (!isprint(c)) {
+ printf("\\%c%c%c",
+ '0' + ((c & 0300) >>
6),
+ '0' + ((c & 070) >>
3),
+ '0' + (c & 07));
+ len += 3;
+ } else {
+ putchar(c);
+ }
+ }
+ } else {
+ if (c < 0x20) {
+ printf("\\u%04x", c);
+ len += 5;
+ } else if (c == '\\') {
+ putchar('\\');
+ putchar('\\');
+ len++;
+ } else if (c == '"') {
+ putchar('\\');
+ putchar('"');
+ len++;
+ } else {
+ putchar(c);
+ }
}
}
return len;
@@ -109,22 +126,41 @@ static int __print_dump(int subvol, void *user, const
char *path,
out_path = full_path;
}
- /* Unified header */
- printf("%-16s", title);
- ret = print_path_escaped(out_path);
- if (!fmt) {
+
+ if (!r->json) {
+ /* Unified header */
+ printf("%-16s", title);
+ ret = print_path_escaped(out_path, r->json);
+ if (!fmt) {
+ putchar('\n');
+ return 0;
+ }
+ /* Short paths are aligned to 32 chars; longer paths get a
single space */
+ do {
+ putchar(' ');
+ } while (++ret < 32);
+ va_start(args, fmt);
+ /* Operation specified ones */
+ vprintf(fmt, args);
+ va_end(args);
putchar('\n');
- return 0;
- }
- /* Short paths are aligned to 32 chars; longer paths get a single space
*/
- do {
+ } else {
+ /* Unified header */
+ printf(" {\"operation\": \"%s\", \"path\": \"", title);
+ ret = print_path_escaped(out_path, r->json);
+ putchar('"');
+ if (!fmt) {
+ printf("},\n");
+ return 0;
+ }
+ putchar(',');
putchar(' ');
- } while (++ret < 32);
- va_start(args, fmt);
- /* Operation specified ones */
- vprintf(fmt, args);
- va_end(args);
- putchar('\n');
+ va_start(args, fmt);
+ /* Operation specified ones */
+ vprintf(fmt, args);
+ va_end(args);
+ printf("},\n");
+ }
return 0;
}
@@ -140,11 +176,18 @@ static int print_subvol(const char *path, const u8 *uuid,
u64 ctransid,
void *user)
{
char uuid_str[BTRFS_UUID_UNPARSED_SIZE];
+ struct btrfs_dump_send_args *r = user;
uuid_unparse(uuid, uuid_str);
- return PRINT_DUMP_SUBVOL(user, path, "subvol", "uuid=%s transid=%llu",
- uuid_str, ctransid);
+ if (!r->json) {
+ return PRINT_DUMP_SUBVOL(user, path, "subvol",
+ "uuid=%s transid=%llu", uuid_str, ctransid);
+ } else {
+ return PRINT_DUMP_SUBVOL(user, path, "subvol",
+ "\"uuid\": \"%s\", \"transid\": %llu",
+ uuid_str, ctransid);
+ }
}
static int print_snapshot(const char *path, const u8 *uuid, u64 ctransid,
@@ -154,14 +197,23 @@ static int print_snapshot(const char *path, const u8
*uuid, u64 ctransid,
char uuid_str[BTRFS_UUID_UNPARSED_SIZE];
char parent_uuid_str[BTRFS_UUID_UNPARSED_SIZE];
int ret;
+ struct btrfs_dump_send_args *r = user;
uuid_unparse(uuid, uuid_str);
uuid_unparse(parent_uuid, parent_uuid_str);
- ret = PRINT_DUMP_SUBVOL(user, path, "snapshot",
- "uuid=%s transid=%llu parent_uuid=%s parent_transid=%llu",
+ if (r->json) {
+ ret = PRINT_DUMP_SUBVOL(user, path, "snapshot",
+ "uuid=%s transid=%llu parent_uuid=%s
parent_transid=%llu",
uuid_str, ctransid, parent_uuid_str,
parent_ctransid);
+ } else {
+ ret = PRINT_DUMP_SUBVOL(user, path, "snapshot",
+ "\"uuid\": \"%s\", \"transid\": %llu, \"parent_uuid\":
\"%s\", \
+ \"parent_transid\": %llu",
+ uuid_str, ctransid, parent_uuid_str,
+ parent_ctransid);
+ }
return ret;
}
@@ -177,8 +229,16 @@ static int print_mkdir(const char *path, void *user)
static int print_mknod(const char *path, u64 mode, u64 dev, void *user)
{
- return PRINT_DUMP(user, path, "mknod", "mode=%llo dev=0x%llx", mode,
- dev);
+ struct btrfs_dump_send_args *r = user;
+
+ if (!r->json) {
+ return PRINT_DUMP(user, path, "mknod", "mode=%llo dev=0x%llx",
+ mode, dev);
+ } else {
+ return PRINT_DUMP(user, path,
+ "mknod", "\"mode\": \"%llo\", \"dev\": \"0x%llx\"",
+ mode, dev);
+ }
}
static int print_mkfifo(const char *path, void *user)
@@ -203,12 +263,26 @@ static int print_rename(const char *from, const char *to,
void *user)
int ret;
PATH_CAT_OR_RET("rename", full_to, r->full_subvol_path, to, ret);
- return PRINT_DUMP(user, from, "rename", "dest=%s", full_to);
+ if (!r->json) {
+ ret = PRINT_DUMP(user, from, "rename", "dest=%s", full_to);
+ } else {
+ ret = PRINT_DUMP(user, from, "rename", "\"dest\": \"%s\"",
+ full_to);
+ }
+ return ret;
}
static int print_link(const char *path, const char *lnk, void *user)
{
- return PRINT_DUMP(user, path, "link", "dest=%s", lnk);
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "link", "dest=%s", lnk);
+ } else {
+ ret = PRINT_DUMP(user, path, "link", "\"dest\": \"%s\"", lnk);
+ }
+ return ret;
}
static int print_unlink(const char *path, void *user)
@@ -224,8 +298,18 @@ static int print_rmdir(const char *path, void *user)
static int print_write(const char *path, const void *data, u64 offset,
u64 len, void *user)
{
- return PRINT_DUMP(user, path, "write", "offset=%llu len=%llu",
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "write", "offset=%llu len=%llu",
+ offset, len);
+ } else {
+ ret = PRINT_DUMP(user, path,
+ "write", "\"offset\": %llu, \"len\": %llu",
offset, len);
+ }
+ return ret;
}
static int print_clone(const char *path, u64 offset, u64 len,
@@ -239,37 +323,93 @@ static int print_clone(const char *path, u64 offset, u64
len,
PATH_CAT_OR_RET("clone", full_path, r->full_subvol_path, clone_path,
ret);
- return PRINT_DUMP(user, path, "clone",
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "clone",
"offset=%llu len=%llu from=%s clone_offset=%llu",
offset, len, full_path, clone_offset);
+ } else {
+ ret = PRINT_DUMP(user, path, "clone",
+ "\"offset\": %llu, \"len\": %llu, \"from\": \"%s\""
+ ", \"clone_offset\": %llu",
+ offset, len, full_path, clone_offset);
+ }
+ return ret;
}
static int print_set_xattr(const char *path, const char *name,
const void *data, int len, void *user)
{
- return PRINT_DUMP(user, path, "set_xattr", "name=%s data=%.*s len=%d",
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path,
+ "set_xattr", "name=%s data=%.*s len=%d",
+ name, len, (char *)data, len);
+ } else {
+ ret = PRINT_DUMP(user, path,
+ "set_xattr", "\"name\": \"%s\""
+ ", \"data\": \"%.*s\", \"len\": %d",
name, len, (char *)data, len);
+ }
+ return ret;
}
static int print_remove_xattr(const char *path, const char *name, void *user)
{
+ struct btrfs_dump_send_args *r = user;
+ int ret;
- return PRINT_DUMP(user, path, "remove_xattr", "name=%s", name);
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "remove_xattr", "name=%s", name);
+ } else {
+ ret = PRINT_DUMP(user, path, "remove_xattr",
+ "\"name\": \"%s\"", name);
+ }
+ return ret;
}
static int print_truncate(const char *path, u64 size, void *user)
{
- return PRINT_DUMP(user, path, "truncate", "size=%llu", size);
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "truncate", "size=%llu", size);
+ } else {
+ ret = PRINT_DUMP(user, path, "truncate", "\"size\": %llu",
size);
+ }
+ return ret;
}
static int print_chmod(const char *path, u64 mode, void *user)
{
- return PRINT_DUMP(user, path, "chmod", "mode=%llo", mode);
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "chmod", "mode=%llo", mode);
+ } else {
+ ret = PRINT_DUMP(user, path, "chmod", "\"mode\": \"%llo\"",
mode);
+ }
+ return ret;
}
static int print_chown(const char *path, u64 uid, u64 gid, void *user)
{
- return PRINT_DUMP(user, path, "chown", "gid=%llu uid=%llu", gid, uid);
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "chown", "gid=%llu uid=%llu",
+ gid, uid);
+ } else {
+ ret = PRINT_DUMP(user, path, "chown",
+ "\"gid\": %llu, \"uid\": %llu",
+ gid, uid);
+ }
+ return ret;
}
static int sprintf_timespec(struct timespec *ts, char *dest, int max_size)
@@ -297,6 +437,8 @@ static int print_utimes(const char *path, struct timespec
*at,
struct timespec *mt, struct timespec *ct,
void *user)
{
+ struct btrfs_dump_send_args *r = user;
+ int ret;
char at_str[TIME_STRING_MAX];
char mt_str[TIME_STRING_MAX];
char ct_str[TIME_STRING_MAX];
@@ -305,15 +447,33 @@ static int print_utimes(const char *path, struct timespec
*at,
sprintf_timespec(mt, mt_str, TIME_STRING_MAX - 1) < 0 ||
sprintf_timespec(ct, ct_str, TIME_STRING_MAX - 1) < 0)
return -EINVAL;
- return PRINT_DUMP(user, path, "utimes", "atime=%s mtime=%s ctime=%s",
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path,
+ "utimes", "atime=%s mtime=%s ctime=%s",
+ at_str, mt_str, ct_str);
+ } else {
+ ret = PRINT_DUMP(user, path, "utimes",
+ "\"atime\": \"%s\", \"mtime\": \"%s\", " \
+ "\"ctime\": \"%s\"",
at_str, mt_str, ct_str);
+ }
+ return ret;
}
static int print_update_extent(const char *path, u64 offset, u64 len,
void *user)
{
- return PRINT_DUMP(user, path, "update_extent", "offset=%llu len=%llu",
- offset, len);
+ struct btrfs_dump_send_args *r = user;
+ int ret;
+
+ if (!r->json) {
+ ret = PRINT_DUMP(user, path, "update_extent",
+ "offset=%llu len=%llu", offset, len);
+ } else {
+ ret = PRINT_DUMP(user, path, "update_extent",
+ "\"offset\": %llu, \"len\": %llu", offset, len);
+ }
+ return ret;
}
struct btrfs_send_ops btrfs_print_send_ops = {
diff --git a/cmds/receive-dump.h b/cmds/receive-dump.h
index 06a61085..d62462d0 100644
--- a/cmds/receive-dump.h
+++ b/cmds/receive-dump.h
@@ -22,6 +22,7 @@
struct btrfs_dump_send_args {
char full_subvol_path[PATH_MAX];
char root_path[PATH_MAX];
+ int json;
};
extern struct btrfs_send_ops btrfs_print_send_ops;
diff --git a/cmds/receive.c b/cmds/receive.c
index 2aaba3ff..e977e9db 100644
--- a/cmds/receive.c
+++ b/cmds/receive.c
@@ -1244,6 +1244,8 @@ static const char * const cmd_receive_usage[] = {
" this file system is mounted.",
"--dump dump stream metadata, one line per operation,",
" does not require the MOUNT parameter",
+ "--dump-json dump stream metadata in JSON format,",
+ " does not require the MOUNT parameter",
"-v deprecated, alias for global -v option",
HELPINFO_INSERT_GLOBALS,
HELPINFO_INSERT_VERBOSE,
@@ -1260,6 +1262,7 @@ static int cmd_receive(const struct cmd_struct *cmd, int
argc, char **argv)
int receive_fd = fileno(stdin);
u64 max_errors = 1;
int dump = 0;
+ int dump_json = 0;
int ret = 0;
memset(&rctx, 0, sizeof(rctx));
@@ -1285,11 +1288,13 @@ static int cmd_receive(const struct cmd_struct *cmd,
int argc, char **argv)
optind = 0;
while (1) {
int c;
- enum { GETOPT_VAL_DUMP = 257 };
+ enum { GETOPT_VAL_DUMP = 257,
+ GETOPT_VAL_DUMP_JSON = 258 };
static const struct option long_opts[] = {
{ "max-errors", required_argument, NULL, 'E' },
{ "chroot", no_argument, NULL, 'C' },
{ "dump", no_argument, NULL, GETOPT_VAL_DUMP },
+ { "dump-json", no_argument, NULL, GETOPT_VAL_DUMP_JSON
},
{ "quiet", no_argument, NULL, 'q' },
{ NULL, 0, NULL, 0 }
};
@@ -1333,6 +1338,10 @@ static int cmd_receive(const struct cmd_struct *cmd, int
argc, char **argv)
case GETOPT_VAL_DUMP:
dump = 1;
break;
+ case GETOPT_VAL_DUMP_JSON:
+ dump = 1;
+ dump_json = 1;
+ break;
default:
usage_unknown_option(cmd, argv);
}
@@ -1360,12 +1369,21 @@ static int cmd_receive(const struct cmd_struct *cmd,
int argc, char **argv)
dump_args.root_path[1] = '\0';
dump_args.full_subvol_path[0] = '.';
dump_args.full_subvol_path[1] = '\0';
+ dump_args.json = dump_json;
+ if (dump_json) {
+ putchar('[');
+ putchar('\n');
+ }
ret = btrfs_read_and_process_send_stream(receive_fd,
&btrfs_print_send_ops, &dump_args, 0, max_errors);
if (ret < 0) {
errno = -ret;
error("failed to dump the send stream: %m");
}
+ if (dump_json) {
+ //Add an empty record so there isn't a trailing ,
+ printf(" {}\n]");
+ }
} else {
ret = do_receive(&rctx, tomnt, realmnt, receive_fd, max_errors);
}
