mirror/flatpak
1
0
Fork 0
mirror of https://github.com/flatpak/flatpak.git synced 2026-03-28 03:45:10 -04:00
Code Issues Packages Projects Releases Wiki Activity

fdio: Use O_EXCL for anonymous tmpfiles

Browse Source 
I noticed while reading the manpage for `linkat()` that `O_TMPFILE`
supports `O_EXCL` to mean exactly what we're doing with the anonymous
tmpfile API.

Change the code to start using it; this required refactoring the internals since
we had a check to be sure the caller wasn't passing `O_EXCL` for the
non-anonymous path which we want to keep.

Presumably the storage system could do smarter things if it knows a file will
always be anonymous, e.g. it doesn't need to journal its data.
This commit is contained in:
Colin Walters
2017-09-11 16:58:53 -04:00
parent 627d4e2f15
commit 806bb46e05
1 changed files with 30 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
glnx-fdio.c
View File

@@ -180,20 +180,11 @@ glnx_tmpfile_clear (GLnxTmpfile *tmpf)
tmpf->initialized = FALSE;
}
/* Allocate a temporary file, using Linux O_TMPFILE if available. The file mode
* will be 0600.
*
* The result will be stored in @out_tmpf, which is caller allocated
* so you can store it on the stack in common scenarios.
*
* The directory fd @dfd must live at least as long as the output @out_tmpf.
*/
gboolean
glnx_open_tmpfile_linkable_at (int dfd,
const char *subpath,
int flags,
GLnxTmpfile *out_tmpf,
GError **error)
static gboolean
open_tmpfile_core (int dfd, const char *subpath,
int flags,
GLnxTmpfile *out_tmpf,
GError **error)
{
const guint mode = 0600;
glnx_fd_close int fd = -1;
@@ -201,9 +192,6 @@ glnx_open_tmpfile_linkable_at (int dfd,
dfd = glnx_dirfd_canonicalize (dfd);
/* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE */
g_return_val_if_fail ((flags & O_EXCL) == 0, FALSE);
/* Creates a temporary file, that shall be renamed to "target"
* later. If possible, this uses O_TMPFILE – in which case
* "ret_path" will be returned as NULL. If not possible a the
@@ -260,6 +248,29 @@ glnx_open_tmpfile_linkable_at (int dfd,
return FALSE;
}
/* Allocate a temporary file, using Linux O_TMPFILE if available. The file mode
* will be 0600.
*
* The result will be stored in @out_tmpf, which is caller allocated
* so you can store it on the stack in common scenarios.
*
* The directory fd @dfd must live at least as long as the output @out_tmpf.
*/
gboolean
glnx_open_tmpfile_linkable_at (int dfd,
const char *subpath,
int flags,
GLnxTmpfile *out_tmpf,
GError **error)
{
/* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE;
* it's used for glnx_open_anonymous_tmpfile().
*/
g_return_val_if_fail ((flags & O_EXCL) == 0, FALSE);
return open_tmpfile_core (dfd, subpath, flags, out_tmpf, error);
}
/* A variant of `glnx_open_tmpfile_linkable_at()` which doesn't support linking.
* Useful for true temporary storage. The fd will be allocated in /var/tmp to
* ensure maximum storage space.
@@ -269,7 +280,8 @@ glnx_open_anonymous_tmpfile (int flags,
GLnxTmpfile *out_tmpf,
GError **error)
{
if (!glnx_open_tmpfile_linkable_at (AT_FDCWD, "/var/tmp", flags, out_tmpf, error))
/* Add in O_EXCL */
if (!open_tmpfile_core (AT_FDCWD, "/var/tmp", flags | O_EXCL, out_tmpf, error))
return FALSE;
if (out_tmpf->path)
{