[PATCH] xfs_mdrestore: Don't rewind source file stream
From: Marco A Benatto <hidden>
Date: 2018-02-03 13:16:46
Subsystem:
the rest · Maintainer:
Linus Torvalds
Today, xfs_mdrestore from stdin will fail if the -i flag is specified, because it attempts to rewind the stream after the initial read of the metablock. This fails, and results in an abort with "specified file is not a metadata dump." Read the metablock exactly once in main(), validate the magic, print informational flags if requested, and then pass it to perform_restore() which will then continue the restore process. Reported-by: Darrick J. Wong <redacted> Signed-off-by: Marco A Benatto <redacted> --- mdrestore/xfs_mdrestore.c | 55 +++++++++++++++++++++++------------------------ 1 file changed, 27 insertions(+), 28 deletions(-)
diff --git a/mdrestore/xfs_mdrestore.c b/mdrestore/xfs_mdrestore.c
index 0bb4ac8..3db740d 100644
--- a/mdrestore/xfs_mdrestore.c
+++ b/mdrestore/xfs_mdrestore.c@@ -51,35 +51,34 @@ print_progress(const char *fmt, ...) progress_since_warning = 1; } +/* + * perform_restore() -- do the actual work to restore the metadump + * + * @src_f: A FILE pointer to the source metadump + * @dst_fd: the file descriptor for the target file + * @is_target_file: designates whether the target is a regular file + * @mbp: pointer to metadump's first xfs_metablock, read and verified by the caller + * + * src_f should be positioned just past a read the previously validated metablock + */ static void perform_restore( FILE *src_f, int dst_fd, - int is_target_file) + int is_target_file, + const struct xfs_metablock *mbp) { - xfs_metablock_t *metablock; /* header + index + blocks */ + struct xfs_metablock *metablock, tmb; /* header + index + blocks */ __be64 *block_index; char *block_buffer; int block_size; int max_indices; int cur_index; int mb_count; - xfs_metablock_t tmb; xfs_sb_t sb; int64_t bytes_read; - /* - * read in first blocks (superblock 0), set "inprogress" flag for it, - * read in the rest of the file, and if complete, clear SB 0's - * "inprogress flag" - */ - - if (fread(&tmb, sizeof(tmb), 1, src_f) != 1) - fatal("error reading from file: %s\n", strerror(errno)); - - if (be32_to_cpu(tmb.mb_magic) != XFS_MD_MAGIC) - fatal("specified file is not a metadata dump\n"); - + tmb = *mbp; block_size = 1 << tmb.mb_blocklog; max_indices = (block_size - sizeof(xfs_metablock_t)) / sizeof(__be64);
@@ -211,6 +210,7 @@ main( int open_flags; struct stat statbuf; int is_target_file; + xfs_metablock_t mb; progname = basename(argv[0]);
@@ -237,7 +237,12 @@ main( if (!show_info && argc - optind != 2) usage(); - /* open source */ + /* + * open source and test if this really is a dump. The first metadump block + * will be passed to perform_restore() which will continue to read the + * file from this point. This avoids rewind the stream, which causes + * restore to fail when source was being read from stdin. + */ if (strcmp(argv[optind], "-") == 0) { src_f = stdin; if (isatty(fileno(stdin)))
@@ -248,15 +253,12 @@ main( fatal("cannot open source dump file\n"); } - if (show_info) { - xfs_metablock_t mb; - - if (fread(&mb, sizeof(mb), 1, src_f) != 1) - fatal("error reading from file: %s\n", strerror(errno)); - - if (be32_to_cpu(mb.mb_magic) != XFS_MD_MAGIC) - fatal("specified file is not a metadata dump\n"); + if (fread(&mb, sizeof(mb), 1, src_f) != 1) + fatal("error reading from file: %s\n", strerror(errno)); + if (mb.mb_magic != cpu_to_be32(XFS_MD_MAGIC)) + fatal("specified file is not a metadata dump\n"); + if (show_info) { if (mb.mb_info & XFS_METADUMP_INFO_FLAGS) { printf("%s: %sobfuscated, %s log, %s metadata blocks\n", argv[optind],
@@ -270,9 +272,6 @@ main( if (argc - optind == 1) exit(0); - - /* Go back to the beginning for the restore function */ - fseek(src_f, 0L, SEEK_SET); } optind++;
@@ -301,7 +300,7 @@ main( if (dst_fd < 0) fatal("couldn't open target \"%s\"\n", argv[optind]); - perform_restore(src_f, dst_fd, is_target_file); + perform_restore(src_f, dst_fd, is_target_file, &mb); close(dst_fd); if (src_f != stdin)
--
1.8.3.1