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Commit 0cf0955a authored by Colin Walters's avatar Colin Walters
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fdio: Add glnx_tmpfile_reopen_rdonly()

For fs-verity.
parent 41ecc544
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......@@ -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
......
......@@ -110,6 +110,10 @@ glnx_link_tmpfile_at (GLnxTmpfile *tmpf,
const char *target,
GError **error);
gboolean
glnx_tmpfile_reopen_rdonly (GLnxTmpfile *tmpf,
GError **error);
gboolean
glnx_openat_rdonly (int dfd,
const char *path,
......
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