diff options
-rw-r--r-- | glnx-fdio.c | 44 | ||||
-rw-r--r-- | glnx-fdio.h | 2 |
2 files changed, 37 insertions, 9 deletions
diff --git a/glnx-fdio.c b/glnx-fdio.c index 422bc2d..d4eeb24 100644 --- a/glnx-fdio.c +++ b/glnx-fdio.c @@ -1105,6 +1105,11 @@ glnx_file_replace_contents_with_perms_at (int dfd, { char *dnbuf = strdupa (subpath); const char *dn = dirname (dnbuf); + gboolean increasing_mtime = (flags & GLNX_FILE_REPLACE_INCREASING_MTIME) != 0; + gboolean nodatasync = (flags & GLNX_FILE_REPLACE_NODATASYNC) != 0; + gboolean datasync_new = (flags & GLNX_FILE_REPLACE_DATASYNC_NEW) != 0; + struct stat stbuf; + gboolean has_stbuf = FALSE; dfd = glnx_dirfd_canonicalize (dfd); @@ -1128,34 +1133,55 @@ glnx_file_replace_contents_with_perms_at (int dfd, if (glnx_loop_write (tmpf.fd, buf, len) < 0) return glnx_throw_errno_prefix (error, "write"); - if (!(flags & GLNX_FILE_REPLACE_NODATASYNC)) + if (!nodatasync || increasing_mtime) { - struct stat stbuf; - gboolean do_sync; - if (!glnx_fstatat_allow_noent (dfd, subpath, &stbuf, AT_SYMLINK_NOFOLLOW, error)) return FALSE; - if (errno == ENOENT) - do_sync = (flags & GLNX_FILE_REPLACE_DATASYNC_NEW) > 0; + has_stbuf = errno != ENOENT; + } + + if (!nodatasync) + { + gboolean do_sync; + if (!has_stbuf) + do_sync = datasync_new; else do_sync = TRUE; if (do_sync) { - if (fdatasync (tmpf.fd) != 0) + if (TEMP_FAILURE_RETRY (fdatasync (tmpf.fd)) != 0) return glnx_throw_errno_prefix (error, "fdatasync"); } } if (uid != (uid_t) -1) { - if (fchown (tmpf.fd, uid, gid) != 0) + if (TEMP_FAILURE_RETRY (fchown (tmpf.fd, uid, gid)) != 0) return glnx_throw_errno_prefix (error, "fchown"); } - if (fchmod (tmpf.fd, mode) != 0) + if (TEMP_FAILURE_RETRY (fchmod (tmpf.fd, mode)) != 0) return glnx_throw_errno_prefix (error, "fchmod"); + if (increasing_mtime && has_stbuf) + { + struct stat fd_stbuf; + + if (fstat (tmpf.fd, &fd_stbuf) != 0) + return glnx_throw_errno_prefix (error, "fstat"); + + /* We want to ensure that the new file has a st_mtime (i.e. the second precision) + * is incrementing to avoid mtime check issues when files change often. + */ + if (fd_stbuf.st_mtime <= stbuf.st_mtime) + { + struct timespec ts[2] = { {0, UTIME_OMIT}, {stbuf.st_mtime + 1, 0} }; + if (TEMP_FAILURE_RETRY (futimens (tmpf.fd, ts)) != 0) + return glnx_throw_errno_prefix (error, "futimens"); + } + } + if (!glnx_link_tmpfile_at (&tmpf, GLNX_LINK_TMPFILE_REPLACE, dfd, subpath, error)) return FALSE; diff --git a/glnx-fdio.h b/glnx-fdio.h index f95e473..cc1ed4b 100644 --- a/glnx-fdio.h +++ b/glnx-fdio.h @@ -143,12 +143,14 @@ glnx_file_get_contents_utf8_at (int dfd, * GLnxFileReplaceFlags: * @GLNX_FILE_REPLACE_DATASYNC_NEW: Call fdatasync() even if the file did not exist * @GLNX_FILE_REPLACE_NODATASYNC: Never call fdatasync() + * @GLNX_FILE_REPLACE_INCREASING_MTIME: Ensure that st_mtime increases (in second precision) * * Flags controlling file replacement. */ typedef enum { GLNX_FILE_REPLACE_DATASYNC_NEW = (1 << 0), GLNX_FILE_REPLACE_NODATASYNC = (1 << 1), + GLNX_FILE_REPLACE_INCREASING_MTIME = (1 << 2), } GLnxFileReplaceFlags; gboolean |