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author | Alexander Larsson <alexl@redhat.com> | 2020-11-02 14:37:26 +0100 |
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committer | Alexander Larsson <alexl@redhat.com> | 2020-11-03 11:44:52 +0100 |
commit | 013417ea72aa767aec15259271ef04846070be64 (patch) | |
tree | ad382749a15a56d34bc1c5e8152faaa695f4b2a3 /glnx-fdio.c | |
parent | 1dd01d5ef172fbe7cb385c91ee2a3740962e8074 (diff) | |
download | libglnx-013417ea72aa767aec15259271ef04846070be64.tar.gz |
Add GLNX_FILE_REPLACE_INCREASING_MTIMEreplace-increasing-mtime
This make replaced files have a strictly increasing st_mtime. The main
usecase I have for this is to ensure the summary file mtime increases
because the flatpak tests are failing due to the python httpd used
in the tests rely on st_mtime for the http If-Modified-Since header.
For the tests this breaks all the time since we're just doing a lot of
summary updates. However, I can see this accidentally happening in the
wild too, so i think its proper to always ensure the new summary is
"newer", even though it means it will be timestamped slightly in the
future. In practice this will not happen regularly, and the times it
*does* happen we really do need it.
Diffstat (limited to 'glnx-fdio.c')
-rw-r--r-- | glnx-fdio.c | 44 |
1 files changed, 35 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; |