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util: Add an API to atomic-replace a file, dirfd relative, optional fsync 

This can be used in other places too, but I plan to use it to write
the summary file.
This commit is contained in:
Colin Walters 2015-02-04 14:45:09 -05:00
parent 3b8ed12ab2
commit 65afe1110d
2 changed files with 52 additions and 19 deletions
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64
src/libotutil/ot-gio-utils.c
View File

@ -275,32 +275,26 @@ ot_gfile_load_contents_utf8_allow_noent (GFile *path,
} }
/** /**
* ot_gfile_replace_contents_fsync: * ot_file_replace_contents_at:
* *
* Like g_file_replace_contents(), except always uses fdatasync(). * Like g_file_replace_contents(), except using a fd-relative
* directory, and optionally enforces use of fdatasync().
*/ */
gboolean gboolean
ot_gfile_replace_contents_fsync (GFile *path, ot_file_replace_contents_at (int dfd,
GBytes *contents, const char *path,
GCancellable *cancellable, GBytes *contents,
GError **error) gboolean datasync,
GCancellable *cancellable,
GError **error)
{ {
gboolean ret = FALSE; gboolean ret = FALSE;
int parent_dfd;
int fd; int fd;
const char *target_basename = gs_file_get_basename_cached (path);
gs_unref_object GFile *parent = NULL;
gs_free char *tmpname = NULL; gs_free char *tmpname = NULL;
gs_unref_object GOutputStream *stream = NULL; gs_unref_object GOutputStream *stream = NULL;
gs_unref_object GInputStream *instream = NULL; gs_unref_object GInputStream *instream = NULL;
parent = g_file_get_parent (path); if (!gs_file_open_in_tmpdir_at (dfd, 0644,
if (!gs_file_open_dir_fd (parent, &parent_dfd,
cancellable, error))
goto out;
if (!gs_file_open_in_tmpdir_at (parent_dfd, 0644,
&tmpname, &stream, &tmpname, &stream,
cancellable, error)) cancellable, error))
goto out; goto out;
@ -324,7 +318,7 @@ ot_gfile_replace_contents_fsync (GFile *path,
cancellable, error) < 0) cancellable, error) < 0)
goto out; goto out;
if (fdatasync (fd) != 0) if (datasync && fdatasync (fd) != 0)
{ {
gs_set_error_from_errno (error, errno); gs_set_error_from_errno (error, errno);
goto out; goto out;
@ -333,7 +327,7 @@ ot_gfile_replace_contents_fsync (GFile *path,
if (!g_output_stream_close (stream, cancellable, error)) if (!g_output_stream_close (stream, cancellable, error))
goto out; goto out;
if (renameat (parent_dfd, tmpname, parent_dfd, target_basename) == -1) if (renameat (dfd, tmpname, dfd, path) == -1)
{ {
gs_set_error_from_errno (error, errno); gs_set_error_from_errno (error, errno);
goto out; goto out;
@ -344,7 +338,39 @@ ot_gfile_replace_contents_fsync (GFile *path,
ret = TRUE; ret = TRUE;
out: out:
if (tmpname) if (tmpname)
(void) unlinkat (parent_dfd, tmpname, 0); (void) unlinkat (dfd, tmpname, 0);
return ret;
}
/**
* ot_gfile_replace_contents_fsync:
*
* Like g_file_replace_contents(), except always uses fdatasync().
*/
gboolean
ot_gfile_replace_contents_fsync (GFile *path,
GBytes *contents,
GCancellable *cancellable,
GError **error)
{
gboolean ret = FALSE;
int parent_dfd;
const char *target_basename = gs_file_get_basename_cached (path);
gs_unref_object GFile *parent = NULL;
parent = g_file_get_parent (path);
if (!gs_file_open_dir_fd (parent, &parent_dfd,
cancellable, error))
goto out;
if (!ot_file_replace_contents_at (parent_dfd, target_basename,
contents, TRUE,
cancellable, error))
goto out;
ret = TRUE;
out:
if (parent_dfd != -1) if (parent_dfd != -1)
(void) close (parent_dfd); (void) close (parent_dfd);
return ret; return ret;

7
src/libotutil/ot-gio-utils.h
View File

@ -69,6 +69,13 @@ gboolean ot_gfile_load_contents_utf8_allow_noent (GFile *path,
GCancellable *cancellable, GCancellable *cancellable,
GError **error); GError **error);
gboolean ot_file_replace_contents_at (int dfd,
const char *path,
GBytes *contents,
gboolean datasync,
GCancellable *cancellable,
GError **error);
gboolean ot_gfile_replace_contents_fsync (GFile *path, gboolean ot_gfile_replace_contents_fsync (GFile *path,
GBytes *contents, GBytes *contents,
GCancellable *cancellable, GCancellable *cancellable,