diff options
| -rw-r--r-- | glnx-fdio.c | 42 | ||||
| -rw-r--r-- | glnx-fdio.h | 4 |
2 files changed, 44 insertions, 2 deletions
diff --git a/glnx-fdio.c b/glnx-fdio.c index 1dc5ffd..12879cd 100644 --- a/glnx-fdio.c +++ b/glnx-fdio.c @@ -363,8 +363,7 @@ glnx_link_tmpfile_at (GLnxTmpfile *tmpf, { /* This case we have O_TMPFILE, so our reference to it is via /proc/self/fd */ char proc_fd_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(tmpf->fd) + 1]; - - sprintf (proc_fd_path, "/proc/self/fd/%i", tmpf->fd); + snprintf (proc_fd_path, sizeof (proc_fd_path), "/proc/self/fd/%i", tmpf->fd); if (replace) { @@ -424,6 +423,45 @@ glnx_link_tmpfile_at (GLnxTmpfile *tmpf, return TRUE; } +/* glnx_tmpfile_reopen_rdonly: + * @tmpf: tmpfile + * @error: Error + * + * Give up write access to the file descriptior. One use + * case for this is fs-verity, which requires a read-only fd. + * It could also be useful to allocate an anonymous tmpfile + * write some sort of caching/indexing data to it, then reopen it + * read-only thereafter. + **/ +gboolean +glnx_tmpfile_reopen_rdonly (GLnxTmpfile *tmpf, + GError **error) +{ + g_return_val_if_fail (tmpf->fd >= 0, FALSE); + g_return_val_if_fail (tmpf->src_dfd == AT_FDCWD || tmpf->src_dfd >= 0, FALSE); + + glnx_fd_close int rdonly_fd = -1; + + if (tmpf->path) + { + if (!glnx_openat_rdonly (tmpf->src_dfd, tmpf->path, FALSE, &rdonly_fd, error)) + return FALSE; + } + else + { + /* This case we have O_TMPFILE, so our reference to it is via /proc/self/fd */ + char proc_fd_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(tmpf->fd) + 1]; + snprintf (proc_fd_path, sizeof (proc_fd_path), "/proc/self/fd/%i", tmpf->fd); + + if (!glnx_openat_rdonly (AT_FDCWD, proc_fd_path, TRUE, &rdonly_fd, error)) + return FALSE; + } + + glnx_close_fd (&tmpf->fd); + tmpf->fd = glnx_steal_fd (&rdonly_fd); + return TRUE; +} + /** * glnx_openat_rdonly: * @dfd: File descriptor for origin directory diff --git a/glnx-fdio.h b/glnx-fdio.h index d97ea36..9c57dc5 100644 --- a/glnx-fdio.h +++ b/glnx-fdio.h @@ -111,6 +111,10 @@ glnx_link_tmpfile_at (GLnxTmpfile *tmpf, GError **error); gboolean +glnx_tmpfile_reopen_rdonly (GLnxTmpfile *tmpf, + GError **error); + +gboolean glnx_openat_rdonly (int dfd, const char *path, gboolean follow, |