[PATCH v3 7/7] fssum: add support for checking xattrs

[fdmanana@kernel.org]

From: Filipe Manana <fdmanana@suse.com>

Currently fssum, mostly used for btrfs test cases that test the btrfs send
feature, ignores completely the existence of xattrs. This change teaches
fssum to find xattrs and make them contribute to the checksum of a
filesystem, so that we can catch filesystem bugs regarding missing, corrupt
or not supposed to exist xattrs (i.e. that an incremental btrfs send does
not forget to create, update or remove xattrs).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---

V2: No changes from v1.
V3: No changes from v2 and v1.

 src/fssum.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 129 insertions(+), 14 deletions(-)

diff --git a/src/fssum.c b/src/fssum.c
index f1da72fb..6ba0a95c 100644
--- a/src/fssum.c
+++ b/src/fssum.c
@@ -20,6 +20,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/sysmacros.h>
+#include <sys/xattr.h>
 #ifdef __SOLARIS__
 #include <sys/mkdev.h>
 #endif
@@ -40,7 +41,6 @@
 #endif
 
 /* TODO: add hardlink recognition */
-/* TODO: add xattr/acl */
 
 struct excludes {
 	char *path;
@@ -71,15 +71,16 @@ enum _flags {
 	FLAG_MTIME,
 	FLAG_CTIME,
 	FLAG_DATA,
+	FLAG_XATTRS,
 	FLAG_OPEN_ERROR,
 	FLAG_STRUCTURE,
 	NUM_FLAGS
 };
 
-const char flchar[] = "ugoamcdes";
+const char flchar[] = "ugoamcdxes";
 char line[65536];
 
-int flags[NUM_FLAGS] = {1, 1, 1, 1, 1, 0, 1, 0, 0};
+int flags[NUM_FLAGS] = {1, 1, 1, 1, 1, 0, 1, 1, 0, 0};
 
 char *
 getln(char *buf, int size, FILE *fp)
@@ -135,7 +136,7 @@ usage(void)
 	fprintf(stderr, "    -v          : verbose mode (debugging only)\n");
 	fprintf(stderr,
 		"    -r <file>   : read checksum or manifest from file\n");
-	fprintf(stderr, "    -[ugoamcde] : specify which fields to include in checksum calculation.\n");
+	fprintf(stderr, "    -[ugoamcdxe]: specify which fields to include in checksum calculation.\n");
 	fprintf(stderr, "         u      : include uid\n");
 	fprintf(stderr, "         g      : include gid\n");
 	fprintf(stderr, "         o      : include mode\n");
@@ -143,9 +144,10 @@ usage(void)
 	fprintf(stderr, "         a      : include atime\n");
 	fprintf(stderr, "         c      : include ctime\n");
 	fprintf(stderr, "         d      : include file data\n");
+	fprintf(stderr, "         x      : include xattrs\n");
 	fprintf(stderr, "         e      : include open errors (aborts otherwise)\n");
 	fprintf(stderr, "         s      : include block structure (holes)\n");
-	fprintf(stderr, "    -[UGOAMCDES]: exclude respective field from calculation\n");
+	fprintf(stderr, "    -[UGOAMCDXES]: exclude respective field from calculation\n");
 	fprintf(stderr, "    -n          : reset all flags\n");
 	fprintf(stderr, "    -N          : set all flags\n");
 	fprintf(stderr, "    -x path     : exclude path when building checksum (multiple ok)\n");
@@ -221,6 +223,106 @@ sum_to_string(sum_t *dst)
 }
 
 int
+namecmp(const void *aa, const void *bb)
+{
+	char * const *a = aa;
+	char * const *b = bb;
+
+	return strcmp(*a, *b);
+}
+
+int
+sum_xattrs(int fd, sum_t *dst)
+{
+	ssize_t buflen;
+	ssize_t len;
+	char *buf;
+	char *p;
+	char **names = NULL;
+	int num_xattrs = 0;
+	int ret = 0;
+	int i;
+
+	buflen = flistxattr(fd, NULL, 0);
+	if (buflen < 0)
+		return -errno;
+	/* no xattrs exist */
+	if (buflen == 0)
+		return 0;
+
+	buf = malloc(buflen);
+	if (!buf)
+		return -ENOMEM;
+
+	buflen = flistxattr(fd, buf, buflen);
+	if (buflen < 0) {
+		ret = -errno;
+		goto out;
+	}
+
+	/*
+	 * Keep the list of xattrs sorted, because the order in which they are
+	 * listed is filesystem dependent, so we want to get the same checksum
+	 * on different filesystems.
+	 */
+
+	p = buf;
+	len = buflen;
+	while (len > 0) {
+		int keylen;
+
+		keylen = strlen(p) + 1; /* +1 for NULL terminator */
+		len -= keylen;
+		p += keylen;
+		num_xattrs++;
+	}
+
+	names = malloc(sizeof(char *) * num_xattrs);
+	if (!names) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	p = buf;
+	for (i = 0; i < num_xattrs; i++) {
+		names[i] = p;
+		p += strlen(p) + 1; /* +1 for NULL terminator */
+	}
+
+	qsort(names, num_xattrs, sizeof(char *), namecmp);
+
+	for (i = 0; i < num_xattrs; i++) {
+		len = fgetxattr(fd, names[i], NULL, 0);
+		if (len < 0) {
+			ret = -errno;
+			goto out;
+		}
+		sum_add(dst, names[i], strlen(names[i]));
+		/* no value */
+		if (len == 0)
+			continue;
+		p = malloc(len);
+		if (!p) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		len = fgetxattr(fd, names[i], p, len);
+		if (len < 0) {
+			ret = -errno;
+			free(p);
+			goto out;
+		}
+		sum_add(dst, p, len);
+		free(p);
+	}
+out:
+	free(buf);
+	free(names);
+
+	return ret;
+}
+
+int
 sum_file_data_permissive(int fd, sum_t *dst)
 {
 	int ret;
@@ -401,15 +503,6 @@ malformed:
 		excess_file(fn);
 }
 
-int
-namecmp(const void *aa, const void *bb)
-{
-	char * const *a = aa;
-	char * const *b = bb;
-
-	return strcmp(*a, *b);
-}
-
 void
 sum(int dirfd, int level, sum_t *dircs, char *path_prefix, char *path_in)
 {
@@ -493,6 +586,28 @@ sum(int dirfd, int level, sum_t *dircs, char *path_prefix, char *path_in)
 			sum_add_time(&meta, st.st_mtime);
 		if (flags[FLAG_CTIME])
 			sum_add_time(&meta, st.st_ctime);
+		if (flags[FLAG_XATTRS] &&
+		    (S_ISDIR(st.st_mode) || S_ISREG(st.st_mode))) {
+			fd = openat(dirfd, namelist[i], 0);
+			if (fd == -1 && flags[FLAG_OPEN_ERROR]) {
+				sum_add_u64(&meta, errno);
+			} else if (fd == -1) {
+				fprintf(stderr, "open failed for %s/%s: %s\n",
+					path_prefix, path, strerror(errno));
+				exit(-1);
+			} else {
+				ret = sum_xattrs(fd, &meta);
+				close(fd);
+				if (ret < 0) {
+					fprintf(stderr,
+						"failed to read xattrs from "
+						"%s/%s: %s\n",
+						path_prefix, path,
+						strerror(-ret));
+					exit(-1);
+				}
+			}
+		}
 		if (S_ISDIR(st.st_mode)) {
 			fd = openat(dirfd, namelist[i], 0);
 			if (fd == -1 && flags[FLAG_OPEN_ERROR]) {
-- 
2.11.0