diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/create.c | 54 |
1 files changed, 38 insertions, 16 deletions
diff --git a/src/create.c b/src/create.c index 30db2b5c..ebca3a93 100644 --- a/src/create.c +++ b/src/create.c @@ -1639,8 +1639,6 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) { union block *header; char type; - off_t original_size; - struct timespec original_ctime; off_t block_ordinal = -1; int fd = 0; bool is_dir; @@ -1683,10 +1681,11 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) return; } - st->archive_file_size = original_size = st->stat.st_size; + struct stat st1 = st->stat; + st->archive_file_size = st->stat.st_size; st->atime = get_stat_atime (&st->stat); st->mtime = get_stat_mtime (&st->stat); - st->ctime = original_ctime = get_stat_ctime (&st->stat); + st->ctime = get_stat_ctime (&st->stat); #ifdef S_ISHIDDEN if (S_ISHIDDEN (st->stat.st_mode)) @@ -1736,7 +1735,7 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) if (is_dir || S_ISREG (st->stat.st_mode) || S_ISCTG (st->stat.st_mode)) { bool ok; - struct stat final_stat; + struct stat st2; xattrs_acls_get (parentfd, name, st, 0, !is_dir); xattrs_selinux_get (parentfd, name, st, fd); @@ -1804,31 +1803,54 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) errno = - parentfd; ok = false; } - else - ok = fstatat (parentfd, name, &final_stat, fstatat_flags) == 0; } else - ok = fstat (fd, &final_stat) == 0; + ok = fstat (fd, &st2) == 0; if (! ok) file_removed_diag (p, top_level, stat_diag); } - if (ok) + if (ok && fd) { - if ((timespec_cmp (get_stat_ctime (&final_stat), original_ctime) != 0 - /* Original ctime will change if the file is a directory and - --remove-files is given */ - && !(remove_files_option && is_dir)) - || original_size < final_stat.st_size) + /* Heuristically check whether the file is the same in all + attributes that tar cares about and can easily check. + Although the check is not perfect since it does not + consult file contents, it is typically good enough. + Do not check atime which is saved only to replace it later. + Do not check ctime where changes might be benign (e.g., + another process creates a hard link to the file). */ + + /* If the file's user ID, group ID or mode changed, tar may + have output the wrong info for the file. */ + ok &= st1.st_uid == st2.st_uid; + ok &= st1.st_gid == st2.st_gid; + ok &= st1.st_mode == st2.st_mode; + + /* Likewise for the file's mtime, but skip this check if it + is a directory possibly updated by --remove-files. */ + if (! (is_dir && remove_files_option)) + ok &= ! timespec_cmp (get_stat_mtime (&st1), + get_stat_mtime (&st2)); + + /* Likewise for the file's size, but skip this check if it + is a directory as tar does not output directory sizes. + Although dump_regular_file caught regular file shrinkage, + it shouldn't hurt to check for shrinkage again now; + plus, the file may have grown. */ + if (!is_dir) + ok &= st1.st_size == st2.st_size; + + if (!ok) { WARNOPT (WARN_FILE_CHANGED, (0, 0, _("%s: file changed as we read it"), quotearg_colon (p))); - set_exit_status (TAREXIT_DIFFERS); + if (! ignore_failed_read_option) + set_exit_status (TAREXIT_DIFFERS); } else if (atime_preserve_option == replace_atime_preserve - && fd && (is_dir || original_size != 0) + && timespec_cmp (st->atime, get_stat_atime (&st2)) != 0 && set_file_atime (fd, parentfd, name, st->atime) != 0) utime_error (p); } |