1194 lines
36 KiB
C
1194 lines
36 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
|
||
*
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||
* Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
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*
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* Portions derived from systemd:
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* Copyright 2010 Lennart Poettering
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*
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* This library is free software; you can redistribute it and/or
|
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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||
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <sys/ioctl.h>
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#include <sys/sendfile.h>
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#include <errno.h>
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#include <glnx-fdio.h>
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#include <glnx-dirfd.h>
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#include <glnx-errors.h>
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#include <glnx-xattrs.h>
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#include <glnx-backport-autoptr.h>
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#include <glnx-backports.h>
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#include <glnx-local-alloc.h>
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#include <glnx-missing.h>
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/* The standardized version of BTRFS_IOC_CLONE */
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#ifndef FICLONE
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#define FICLONE _IOW(0x94, 9, int)
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#endif
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/* Returns the number of chars needed to format variables of the
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* specified type as a decimal string. Adds in extra space for a
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* negative '-' prefix (hence works correctly on signed
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* types). Includes space for the trailing NUL. */
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#define DECIMAL_STR_MAX(type) \
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(2+(sizeof(type) <= 1 ? 3 : \
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sizeof(type) <= 2 ? 5 : \
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sizeof(type) <= 4 ? 10 : \
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sizeof(type) <= 8 ? 20 : sizeof(int[-2*(sizeof(type) > 8)])))
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gboolean
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||
glnx_stdio_file_flush (FILE *f, GError **error)
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{
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||
if (fflush (f) != 0)
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return glnx_throw_errno_prefix (error, "fflush");
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if (ferror (f) != 0)
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return glnx_throw_errno_prefix (error, "ferror");
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return TRUE;
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}
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/* An implementation of renameat2(..., RENAME_NOREPLACE)
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* with fallback to a non-atomic version.
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*/
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int
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glnx_renameat2_noreplace (int olddirfd, const char *oldpath,
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int newdirfd, const char *newpath)
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{
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#ifndef ENABLE_WRPSEUDO_COMPAT
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if (renameat2 (olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE) < 0)
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{
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if (G_IN_SET(errno, EINVAL, ENOSYS))
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{
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/* Fall through */
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}
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else
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{
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return -1;
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}
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}
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else
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return TRUE;
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#endif
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if (linkat (olddirfd, oldpath, newdirfd, newpath, 0) < 0)
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return -1;
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if (unlinkat (olddirfd, oldpath, 0) < 0)
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return -1;
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return 0;
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}
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static gboolean
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rename_file_noreplace_at (int olddirfd, const char *oldpath,
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int newdirfd, const char *newpath,
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gboolean ignore_eexist,
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||
GError **error)
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{
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if (glnx_renameat2_noreplace (olddirfd, oldpath,
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newdirfd, newpath) < 0)
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{
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||
if (errno == EEXIST && ignore_eexist)
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{
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(void) unlinkat (olddirfd, oldpath, 0);
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return TRUE;
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}
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else
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return glnx_throw_errno_prefix (error, "renameat");
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}
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return TRUE;
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}
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/* An implementation of renameat2(..., RENAME_EXCHANGE)
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* with fallback to a non-atomic version.
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*/
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int
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glnx_renameat2_exchange (int olddirfd, const char *oldpath,
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int newdirfd, const char *newpath)
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{
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#ifndef ENABLE_WRPSEUDO_COMPAT
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if (renameat2 (olddirfd, oldpath, newdirfd, newpath, RENAME_EXCHANGE) == 0)
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return 0;
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else
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{
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||
if (G_IN_SET(errno, ENOSYS, EINVAL))
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||
{
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||
/* Fall through */
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||
}
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else
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{
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return -1;
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}
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}
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#endif
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/* Fallback */
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{ char *old_tmp_name_buf = glnx_strjoina (oldpath, ".XXXXXX");
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/* This obviously isn't race-free, but doing better gets tricky, since if
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* we're here the kernel isn't likely to support RENAME_NOREPLACE either.
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* Anyways, upgrade the kernel. Failing that, avoid use of this function in
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* shared subdirectories like /tmp.
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*/
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glnx_gen_temp_name (old_tmp_name_buf);
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const char *old_tmp_name = old_tmp_name_buf;
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/* Move old out of the way */
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if (renameat (olddirfd, oldpath, olddirfd, old_tmp_name) < 0)
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return -1;
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/* Now move new into its place */
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if (renameat (newdirfd, newpath, olddirfd, oldpath) < 0)
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return -1;
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||
/* And finally old(tmp) into new */
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if (renameat (olddirfd, old_tmp_name, newdirfd, newpath) < 0)
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return -1;
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}
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return 0;
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}
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/* Deallocate a tmpfile, closing the fd and deleting the path, if any. This is
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* normally called by default by the autocleanup attribute, but you can also
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* invoke this directly.
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*/
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void
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glnx_tmpfile_clear (GLnxTmpfile *tmpf)
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{
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/* Support being passed NULL so we work nicely in a GPtrArray */
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if (!tmpf)
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return;
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if (!tmpf->initialized)
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return;
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glnx_close_fd (&tmpf->fd);
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/* If ->path is set, we're likely aborting due to an error. Clean it up */
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if (tmpf->path)
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{
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(void) unlinkat (tmpf->src_dfd, tmpf->path, 0);
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g_free (tmpf->path);
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||
}
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tmpf->initialized = FALSE;
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}
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static gboolean
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open_tmpfile_core (int dfd, const char *subpath,
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int flags,
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GLnxTmpfile *out_tmpf,
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GError **error)
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||
{
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||
/* Picked this to match mkstemp() */
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const guint mode = 0600;
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dfd = glnx_dirfd_canonicalize (dfd);
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/* Creates a temporary file, that shall be renamed to "target"
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* later. If possible, this uses O_TMPFILE – in which case
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* "ret_path" will be returned as NULL. If not possible a the
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* tempoary path name used is returned in "ret_path". Use
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* link_tmpfile() below to rename the result after writing the file
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* in full. */
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||
#if defined(O_TMPFILE) && !defined(DISABLE_OTMPFILE) && !defined(ENABLE_WRPSEUDO_COMPAT)
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{
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glnx_autofd int fd = openat (dfd, subpath, O_TMPFILE|flags, mode);
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if (fd == -1 && !(G_IN_SET(errno, ENOSYS, EISDIR, EOPNOTSUPP)))
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return glnx_throw_errno_prefix (error, "open(O_TMPFILE)");
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if (fd != -1)
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{
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/* Workaround for https://sourceware.org/bugzilla/show_bug.cgi?id=17523
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* See also https://github.com/ostreedev/ostree/issues/991
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*/
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if (fchmod (fd, mode) < 0)
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return glnx_throw_errno_prefix (error, "fchmod");
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out_tmpf->initialized = TRUE;
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out_tmpf->src_dfd = dfd; /* Copied; caller must keep open */
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out_tmpf->fd = glnx_steal_fd (&fd);
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out_tmpf->path = NULL;
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return TRUE;
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}
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}
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/* Fallthrough */
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#endif
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const guint count_max = 100;
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{ g_autofree char *tmp = g_strconcat (subpath, "/tmp.XXXXXX", NULL);
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for (int count = 0; count < count_max; count++)
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{
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glnx_gen_temp_name (tmp);
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glnx_autofd int fd = openat (dfd, tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|flags, mode);
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if (fd < 0)
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{
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if (errno == EEXIST)
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continue;
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else
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return glnx_throw_errno_prefix (error, "Creating temp file");
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}
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else
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{
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out_tmpf->initialized = TRUE;
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out_tmpf->src_dfd = dfd; /* Copied; caller must keep open */
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out_tmpf->fd = glnx_steal_fd (&fd);
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out_tmpf->path = g_steal_pointer (&tmp);
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return TRUE;
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}
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}
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}
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g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
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"Exhausted %u attempts to create temporary file", count_max);
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return FALSE;
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}
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/* Allocate a temporary file, using Linux O_TMPFILE if available. The file mode
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* will be 0600.
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*
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* The result will be stored in @out_tmpf, which is caller allocated
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* so you can store it on the stack in common scenarios.
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*
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* The directory fd @dfd must live at least as long as the output @out_tmpf.
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||
*/
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gboolean
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glnx_open_tmpfile_linkable_at (int dfd,
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const char *subpath,
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int flags,
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GLnxTmpfile *out_tmpf,
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GError **error)
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{
|
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/* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE;
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* it's used for glnx_open_anonymous_tmpfile().
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||
*/
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g_return_val_if_fail ((flags & O_EXCL) == 0, FALSE);
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||
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return open_tmpfile_core (dfd, subpath, flags, out_tmpf, error);
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||
}
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||
|
||
|
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/* A variant of `glnx_open_tmpfile_linkable_at()` which doesn't support linking.
|
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* Useful for true temporary storage. The fd will be allocated in the specified
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||
* directory.
|
||
*/
|
||
gboolean
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||
glnx_open_anonymous_tmpfile_full (int flags,
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||
const char *dir,
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||
GLnxTmpfile *out_tmpf,
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||
GError **error)
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||
{
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||
/* Add in O_EXCL */
|
||
if (!open_tmpfile_core (AT_FDCWD, dir, flags | O_EXCL, out_tmpf, error))
|
||
return FALSE;
|
||
if (out_tmpf->path)
|
||
{
|
||
(void) unlinkat (out_tmpf->src_dfd, out_tmpf->path, 0);
|
||
g_clear_pointer (&out_tmpf->path, g_free);
|
||
}
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||
out_tmpf->anonymous = TRUE;
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||
out_tmpf->src_dfd = -1;
|
||
return TRUE;
|
||
}
|
||
|
||
/* A variant of `glnx_open_tmpfile_linkable_at()` which doesn't support linking.
|
||
* Useful for true temporary storage. The fd will be allocated in `$TMPDIR` if
|
||
* set or `/var/tmp` otherwise.
|
||
*
|
||
* If you need the file on a specific filesystem use glnx_open_anonymous_tmpfile_full()
|
||
* which lets you pass a directory.
|
||
*/
|
||
gboolean
|
||
glnx_open_anonymous_tmpfile (int flags,
|
||
GLnxTmpfile *out_tmpf,
|
||
GError **error)
|
||
{
|
||
return glnx_open_anonymous_tmpfile_full (flags,
|
||
getenv("TMPDIR") ?: "/var/tmp",
|
||
out_tmpf,
|
||
error);
|
||
}
|
||
|
||
/* Use this after calling glnx_open_tmpfile_linkable_at() to give
|
||
* the file its final name (link into place).
|
||
*/
|
||
gboolean
|
||
glnx_link_tmpfile_at (GLnxTmpfile *tmpf,
|
||
GLnxLinkTmpfileReplaceMode mode,
|
||
int target_dfd,
|
||
const char *target,
|
||
GError **error)
|
||
{
|
||
const gboolean replace = (mode == GLNX_LINK_TMPFILE_REPLACE);
|
||
const gboolean ignore_eexist = (mode == GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST);
|
||
|
||
g_return_val_if_fail (!tmpf->anonymous, FALSE);
|
||
g_return_val_if_fail (tmpf->fd >= 0, FALSE);
|
||
g_return_val_if_fail (tmpf->src_dfd == AT_FDCWD || tmpf->src_dfd >= 0, FALSE);
|
||
|
||
/* Unlike the original systemd code, this function also supports
|
||
* replacing existing files.
|
||
*/
|
||
|
||
/* We have `tmpfile_path` for old systems without O_TMPFILE. */
|
||
if (tmpf->path)
|
||
{
|
||
if (replace)
|
||
{
|
||
/* We have a regular tempfile, we're overwriting - this is a
|
||
* simple renameat().
|
||
*/
|
||
if (renameat (tmpf->src_dfd, tmpf->path, target_dfd, target) < 0)
|
||
return glnx_throw_errno_prefix (error, "renameat");
|
||
}
|
||
else
|
||
{
|
||
/* We need to use renameat2(..., NOREPLACE) or emulate it */
|
||
if (!rename_file_noreplace_at (tmpf->src_dfd, tmpf->path, target_dfd, target,
|
||
ignore_eexist,
|
||
error))
|
||
return FALSE;
|
||
}
|
||
/* Now, clear the pointer so we don't try to unlink it */
|
||
g_clear_pointer (&tmpf->path, g_free);
|
||
}
|
||
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 (replace)
|
||
{
|
||
/* In this case, we had our temp file atomically hidden, but now
|
||
* we need to make it visible in the FS so we can do a rename.
|
||
* Ideally, linkat() would gain AT_REPLACE or so.
|
||
*/
|
||
/* TODO - avoid double alloca, we can just alloca a copy of
|
||
* the pathname plus space for tmp.XXXXX */
|
||
char *dnbuf = strdupa (target);
|
||
const char *dn = dirname (dnbuf);
|
||
char *tmpname_buf = glnx_strjoina (dn, "/tmp.XXXXXX");
|
||
|
||
const guint count_max = 100;
|
||
guint count;
|
||
for (count = 0; count < count_max; count++)
|
||
{
|
||
glnx_gen_temp_name (tmpname_buf);
|
||
|
||
if (linkat (AT_FDCWD, proc_fd_path, target_dfd, tmpname_buf, AT_SYMLINK_FOLLOW) < 0)
|
||
{
|
||
if (errno == EEXIST)
|
||
continue;
|
||
else
|
||
return glnx_throw_errno_prefix (error, "linkat");
|
||
}
|
||
else
|
||
break;
|
||
}
|
||
if (count == count_max)
|
||
{
|
||
g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
|
||
"Exhausted %u attempts to create temporary file", count);
|
||
return FALSE;
|
||
}
|
||
if (!glnx_renameat (target_dfd, tmpname_buf, target_dfd, target, error))
|
||
{
|
||
/* This is currently the only case where we need to have
|
||
* a cleanup unlinkat() still with O_TMPFILE.
|
||
*/
|
||
(void) unlinkat (target_dfd, tmpname_buf, 0);
|
||
return FALSE;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
if (linkat (AT_FDCWD, proc_fd_path, target_dfd, target, AT_SYMLINK_FOLLOW) < 0)
|
||
{
|
||
if (errno == EEXIST && mode == GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST)
|
||
;
|
||
else
|
||
return glnx_throw_errno_prefix (error, "linkat");
|
||
}
|
||
}
|
||
|
||
}
|
||
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
|
||
* @path: Pathname, relative to @dfd
|
||
* @follow: Whether or not to follow symbolic links in the final component
|
||
* @out_fd: (out): File descriptor
|
||
* @error: Error
|
||
*
|
||
* Use openat() to open a file, with flags `O_RDONLY | O_CLOEXEC | O_NOCTTY`.
|
||
* Like the other libglnx wrappers, will use `TEMP_FAILURE_RETRY` and
|
||
* also includes @path in @error in case of failure.
|
||
*/
|
||
gboolean
|
||
glnx_openat_rdonly (int dfd,
|
||
const char *path,
|
||
gboolean follow,
|
||
int *out_fd,
|
||
GError **error)
|
||
{
|
||
int flags = O_RDONLY | O_CLOEXEC | O_NOCTTY;
|
||
if (!follow)
|
||
flags |= O_NOFOLLOW;
|
||
int fd = TEMP_FAILURE_RETRY (openat (dfd, path, flags));
|
||
if (fd == -1)
|
||
return glnx_throw_errno_prefix (error, "openat(%s)", path);
|
||
*out_fd = fd;
|
||
return TRUE;
|
||
}
|
||
|
||
static guint8*
|
||
glnx_fd_readall_malloc (int fd,
|
||
gsize *out_len,
|
||
gboolean nul_terminate,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
const guint maxreadlen = 4096;
|
||
|
||
struct stat stbuf;
|
||
if (!glnx_fstat (fd, &stbuf, error))
|
||
return FALSE;
|
||
|
||
gsize buf_allocated;
|
||
if (S_ISREG (stbuf.st_mode) && stbuf.st_size > 0)
|
||
buf_allocated = stbuf.st_size;
|
||
else
|
||
buf_allocated = 16;
|
||
|
||
g_autofree guint8* buf = g_malloc (buf_allocated);
|
||
|
||
gsize buf_size = 0;
|
||
while (TRUE)
|
||
{
|
||
gsize readlen = MIN (buf_allocated - buf_size, maxreadlen);
|
||
|
||
if (g_cancellable_set_error_if_cancelled (cancellable, error))
|
||
return FALSE;
|
||
|
||
gssize bytes_read;
|
||
do
|
||
bytes_read = read (fd, buf + buf_size, readlen);
|
||
while (G_UNLIKELY (bytes_read == -1 && errno == EINTR));
|
||
if (G_UNLIKELY (bytes_read == -1))
|
||
return glnx_null_throw_errno (error);
|
||
if (bytes_read == 0)
|
||
break;
|
||
|
||
buf_size += bytes_read;
|
||
if (buf_allocated - buf_size < maxreadlen)
|
||
buf = g_realloc (buf, buf_allocated *= 2);
|
||
}
|
||
|
||
if (nul_terminate)
|
||
{
|
||
if (buf_allocated - buf_size == 0)
|
||
buf = g_realloc (buf, buf_allocated + 1);
|
||
buf[buf_size] = '\0';
|
||
}
|
||
|
||
*out_len = buf_size;
|
||
return g_steal_pointer (&buf);
|
||
}
|
||
|
||
/**
|
||
* glnx_fd_readall_bytes:
|
||
* @fd: A file descriptor
|
||
* @cancellable: Cancellable:
|
||
* @error: Error
|
||
*
|
||
* Read all data from file descriptor @fd into a #GBytes. It's
|
||
* recommended to only use this for small files.
|
||
*
|
||
* Returns: (transfer full): A newly allocated #GBytes
|
||
*/
|
||
GBytes *
|
||
glnx_fd_readall_bytes (int fd,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
gsize len;
|
||
guint8 *buf = glnx_fd_readall_malloc (fd, &len, FALSE, cancellable, error);
|
||
if (!buf)
|
||
return NULL;
|
||
return g_bytes_new_take (buf, len);
|
||
}
|
||
|
||
/**
|
||
* glnx_fd_readall_utf8:
|
||
* @fd: A file descriptor
|
||
* @out_len: (out): Returned length
|
||
* @cancellable: Cancellable:
|
||
* @error: Error
|
||
*
|
||
* Read all data from file descriptor @fd, validating
|
||
* the result as UTF-8.
|
||
*
|
||
* Returns: (transfer full): A string validated as UTF-8, or %NULL on error.
|
||
*/
|
||
char *
|
||
glnx_fd_readall_utf8 (int fd,
|
||
gsize *out_len,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
gsize len;
|
||
g_autofree guint8 *buf = glnx_fd_readall_malloc (fd, &len, TRUE, cancellable, error);
|
||
if (!buf)
|
||
return FALSE;
|
||
|
||
if (!g_utf8_validate ((char*)buf, len, NULL))
|
||
{
|
||
g_set_error (error,
|
||
G_IO_ERROR,
|
||
G_IO_ERROR_INVALID_DATA,
|
||
"Invalid UTF-8");
|
||
return FALSE;
|
||
}
|
||
|
||
if (out_len)
|
||
*out_len = len;
|
||
return (char*)g_steal_pointer (&buf);
|
||
}
|
||
|
||
/**
|
||
* glnx_file_get_contents_utf8_at:
|
||
* @dfd: Directory file descriptor
|
||
* @subpath: Path relative to @dfd
|
||
* @out_len: (out) (allow-none): Optional length
|
||
* @cancellable: Cancellable
|
||
* @error: Error
|
||
*
|
||
* Read the entire contents of the file referred
|
||
* to by @dfd and @subpath, validate the result as UTF-8.
|
||
* The length is optionally stored in @out_len.
|
||
*
|
||
* Returns: (transfer full): UTF-8 validated text, or %NULL on error
|
||
*/
|
||
char *
|
||
glnx_file_get_contents_utf8_at (int dfd,
|
||
const char *subpath,
|
||
gsize *out_len,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
dfd = glnx_dirfd_canonicalize (dfd);
|
||
|
||
glnx_autofd int fd = -1;
|
||
if (!glnx_openat_rdonly (dfd, subpath, TRUE, &fd, error))
|
||
return NULL;
|
||
|
||
gsize len;
|
||
g_autofree char *buf = glnx_fd_readall_utf8 (fd, &len, cancellable, error);
|
||
if (G_UNLIKELY(!buf))
|
||
return FALSE;
|
||
|
||
if (out_len)
|
||
*out_len = len;
|
||
return g_steal_pointer (&buf);
|
||
}
|
||
|
||
/**
|
||
* glnx_readlinkat_malloc:
|
||
* @dfd: Directory file descriptor
|
||
* @subpath: Subpath
|
||
* @cancellable: Cancellable
|
||
* @error: Error
|
||
*
|
||
* Read the value of a symlink into a dynamically
|
||
* allocated buffer.
|
||
*/
|
||
char *
|
||
glnx_readlinkat_malloc (int dfd,
|
||
const char *subpath,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
dfd = glnx_dirfd_canonicalize (dfd);
|
||
|
||
size_t l = 100;
|
||
for (;;)
|
||
{
|
||
g_autofree char *c = g_malloc (l);
|
||
ssize_t n = TEMP_FAILURE_RETRY (readlinkat (dfd, subpath, c, l-1));
|
||
if (n < 0)
|
||
return glnx_null_throw_errno_prefix (error, "readlinkat");
|
||
|
||
if ((size_t) n < l-1)
|
||
{
|
||
c[n] = 0;
|
||
return g_steal_pointer (&c);
|
||
}
|
||
|
||
l *= 2;
|
||
}
|
||
|
||
g_assert_not_reached ();
|
||
}
|
||
|
||
static gboolean
|
||
copy_symlink_at (int src_dfd,
|
||
const char *src_subpath,
|
||
const struct stat *src_stbuf,
|
||
int dest_dfd,
|
||
const char *dest_subpath,
|
||
GLnxFileCopyFlags copyflags,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
g_autofree char *buf = glnx_readlinkat_malloc (src_dfd, src_subpath, cancellable, error);
|
||
if (!buf)
|
||
return FALSE;
|
||
|
||
if (TEMP_FAILURE_RETRY (symlinkat (buf, dest_dfd, dest_subpath)) != 0)
|
||
return glnx_throw_errno_prefix (error, "symlinkat");
|
||
|
||
if (!(copyflags & GLNX_FILE_COPY_NOXATTRS))
|
||
{
|
||
g_autoptr(GVariant) xattrs = NULL;
|
||
|
||
if (!glnx_dfd_name_get_all_xattrs (src_dfd, src_subpath, &xattrs,
|
||
cancellable, error))
|
||
return FALSE;
|
||
|
||
if (!glnx_dfd_name_set_all_xattrs (dest_dfd, dest_subpath, xattrs,
|
||
cancellable, error))
|
||
return FALSE;
|
||
}
|
||
|
||
if (TEMP_FAILURE_RETRY (fchownat (dest_dfd, dest_subpath,
|
||
src_stbuf->st_uid, src_stbuf->st_gid,
|
||
AT_SYMLINK_NOFOLLOW)) != 0)
|
||
return glnx_throw_errno_prefix (error, "fchownat");
|
||
|
||
return TRUE;
|
||
}
|
||
|
||
#define COPY_BUFFER_SIZE (16*1024)
|
||
|
||
/* Most of the code below is from systemd, but has been reindented to GNU style,
|
||
* and changed to use POSIX error conventions (return -1, set errno) to more
|
||
* conveniently fit in with the rest of libglnx.
|
||
*/
|
||
|
||
/* Like write(), but loop until @nbytes are written, or an error
|
||
* occurs.
|
||
*
|
||
* On error, -1 is returned an @errno is set. NOTE: This is an
|
||
* API change from previous versions of this function.
|
||
*/
|
||
int
|
||
glnx_loop_write(int fd, const void *buf, size_t nbytes)
|
||
{
|
||
g_return_val_if_fail (fd >= 0, -1);
|
||
g_return_val_if_fail (buf, -1);
|
||
|
||
errno = 0;
|
||
|
||
const uint8_t *p = buf;
|
||
while (nbytes > 0)
|
||
{
|
||
ssize_t k = write(fd, p, nbytes);
|
||
if (k < 0)
|
||
{
|
||
if (errno == EINTR)
|
||
continue;
|
||
|
||
return -1;
|
||
}
|
||
|
||
if (k == 0) /* Can't really happen */
|
||
{
|
||
errno = EIO;
|
||
return -1;
|
||
}
|
||
|
||
p += k;
|
||
nbytes -= k;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Read from @fdf until EOF, writing to @fdt. If max_bytes is -1, a full-file
|
||
* clone will be attempted. Otherwise Linux copy_file_range(), sendfile()
|
||
* syscall will be attempted. If none of those work, this function will do a
|
||
* plain read()/write() loop.
|
||
*
|
||
* The file descriptor @fdf must refer to a regular file.
|
||
*
|
||
* If provided, @max_bytes specifies the maximum number of bytes to read from @fdf.
|
||
* On error, this function returns `-1` and @errno will be set.
|
||
*/
|
||
int
|
||
glnx_regfile_copy_bytes (int fdf, int fdt, off_t max_bytes)
|
||
{
|
||
/* Last updates from systemd as of commit 6bda23dd6aaba50cf8e3e6024248cf736cc443ca */
|
||
static int have_cfr = -1; /* -1 means unknown */
|
||
bool try_cfr = have_cfr != 0;
|
||
static int have_sendfile = -1; /* -1 means unknown */
|
||
bool try_sendfile = have_sendfile != 0;
|
||
|
||
g_return_val_if_fail (fdf >= 0, -1);
|
||
g_return_val_if_fail (fdt >= 0, -1);
|
||
g_return_val_if_fail (max_bytes >= -1, -1);
|
||
|
||
/* If we've requested to copy the whole range, try a full-file clone first.
|
||
*/
|
||
if (max_bytes == (off_t) -1)
|
||
{
|
||
if (ioctl (fdt, FICLONE, fdf) == 0)
|
||
return 0;
|
||
/* Fall through */
|
||
struct stat stbuf;
|
||
|
||
/* Gather the size so we can provide the whole thing at once to
|
||
* copy_file_range() or sendfile().
|
||
*/
|
||
if (fstat (fdf, &stbuf) < 0)
|
||
return -1;
|
||
max_bytes = stbuf.st_size;
|
||
}
|
||
|
||
while (TRUE)
|
||
{
|
||
ssize_t n;
|
||
|
||
/* First, try copy_file_range(). Note this is an inlined version of
|
||
* try_copy_file_range() from systemd upstream, which works better since
|
||
* we use POSIX errno style.
|
||
*/
|
||
if (try_cfr)
|
||
{
|
||
n = copy_file_range (fdf, NULL, fdt, NULL, max_bytes, 0u);
|
||
if (n < 0)
|
||
{
|
||
if (errno == ENOSYS)
|
||
{
|
||
/* No cfr in kernel, mark as permanently unavailable
|
||
* and fall through to sendfile().
|
||
*/
|
||
have_cfr = 0;
|
||
try_cfr = false;
|
||
}
|
||
else if (G_IN_SET (errno, EXDEV, EOPNOTSUPP))
|
||
/* We won't try cfr again for this run, but let's be
|
||
* conservative and not mark it as available/unavailable until
|
||
* we know for sure.
|
||
*/
|
||
try_cfr = false;
|
||
else
|
||
return -1;
|
||
}
|
||
else
|
||
{
|
||
/* cfr worked, mark it as available */
|
||
if (have_cfr == -1)
|
||
have_cfr = 1;
|
||
|
||
if (n == 0) /* EOF */
|
||
break;
|
||
else
|
||
/* Success! */
|
||
goto next;
|
||
}
|
||
}
|
||
|
||
/* Next try sendfile(); this version is also changed from systemd upstream
|
||
* to match the same logic we have for copy_file_range().
|
||
*/
|
||
if (try_sendfile)
|
||
{
|
||
n = sendfile (fdt, fdf, NULL, max_bytes);
|
||
if (n < 0)
|
||
{
|
||
if (G_IN_SET (errno, EINVAL, ENOSYS))
|
||
{
|
||
/* No sendfile(), or it doesn't work on regular files.
|
||
* Mark it as permanently unavailable, and fall through
|
||
* to plain read()/write().
|
||
*/
|
||
have_sendfile = 0;
|
||
try_sendfile = false;
|
||
}
|
||
else
|
||
return -1;
|
||
}
|
||
else
|
||
{
|
||
/* sendfile() worked, mark it as available */
|
||
if (have_sendfile == -1)
|
||
have_sendfile = 1;
|
||
|
||
if (n == 0) /* EOF */
|
||
break;
|
||
else if (n > 0)
|
||
/* Succcess! */
|
||
goto next;
|
||
}
|
||
}
|
||
|
||
/* As a fallback just copy bits by hand */
|
||
{ size_t m = COPY_BUFFER_SIZE;
|
||
if (max_bytes != (off_t) -1)
|
||
{
|
||
if ((off_t) m > max_bytes)
|
||
m = (size_t) max_bytes;
|
||
}
|
||
char buf[m];
|
||
|
||
n = TEMP_FAILURE_RETRY (read (fdf, buf, m));
|
||
if (n < 0)
|
||
return -1;
|
||
if (n == 0) /* EOF */
|
||
break;
|
||
|
||
if (glnx_loop_write (fdt, buf, (size_t) n) < 0)
|
||
return -1;
|
||
}
|
||
|
||
next:
|
||
if (max_bytes != (off_t) -1)
|
||
{
|
||
g_assert_cmpint (max_bytes, >=, n);
|
||
max_bytes -= n;
|
||
if (max_bytes == 0)
|
||
break;
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/**
|
||
* glnx_file_copy_at:
|
||
* @src_dfd: Source directory fd
|
||
* @src_subpath: Subpath relative to @src_dfd
|
||
* @src_stbuf: (allow-none): Optional stat buffer for source; if a stat() has already been done
|
||
* @dest_dfd: Target directory fd
|
||
* @dest_subpath: Destination name
|
||
* @copyflags: Flags
|
||
* @cancellable: cancellable
|
||
* @error: Error
|
||
*
|
||
* Perform a full copy of the regular file or symbolic link from @src_subpath to
|
||
* @dest_subpath; if @src_subpath is anything other than a regular file or
|
||
* symbolic link, an error will be returned.
|
||
*
|
||
* If the source is a regular file and the destination exists as a symbolic
|
||
* link, the symbolic link will not be followed; rather the link itself will be
|
||
* replaced. Related to this: for regular files, when `GLNX_FILE_COPY_OVERWRITE`
|
||
* is specified, this function always uses `O_TMPFILE` (if available) and does a
|
||
* rename-into-place rather than `open(O_TRUNC)`.
|
||
*/
|
||
gboolean
|
||
glnx_file_copy_at (int src_dfd,
|
||
const char *src_subpath,
|
||
const struct stat *src_stbuf,
|
||
int dest_dfd,
|
||
const char *dest_subpath,
|
||
GLnxFileCopyFlags copyflags,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
/* Canonicalize dfds */
|
||
src_dfd = glnx_dirfd_canonicalize (src_dfd);
|
||
dest_dfd = glnx_dirfd_canonicalize (dest_dfd);
|
||
|
||
if (g_cancellable_set_error_if_cancelled (cancellable, error))
|
||
return FALSE;
|
||
|
||
/* Automatically do stat() if no stat buffer was supplied */
|
||
struct stat local_stbuf;
|
||
if (!src_stbuf)
|
||
{
|
||
if (!glnx_fstatat (src_dfd, src_subpath, &local_stbuf, AT_SYMLINK_NOFOLLOW, error))
|
||
return FALSE;
|
||
src_stbuf = &local_stbuf;
|
||
}
|
||
|
||
/* For symlinks, defer entirely to copy_symlink_at() */
|
||
if (S_ISLNK (src_stbuf->st_mode))
|
||
{
|
||
return copy_symlink_at (src_dfd, src_subpath, src_stbuf,
|
||
dest_dfd, dest_subpath,
|
||
copyflags,
|
||
cancellable, error);
|
||
}
|
||
else if (!S_ISREG (src_stbuf->st_mode))
|
||
{
|
||
g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
|
||
"Cannot copy non-regular/non-symlink file: %s", src_subpath);
|
||
return FALSE;
|
||
}
|
||
|
||
/* Regular file path below here */
|
||
|
||
glnx_autofd int src_fd = -1;
|
||
if (!glnx_openat_rdonly (src_dfd, src_subpath, FALSE, &src_fd, error))
|
||
return FALSE;
|
||
|
||
/* Open a tmpfile for dest. Particularly for AT_FDCWD calls, we really want to
|
||
* open in the target directory, otherwise we may not be able to link.
|
||
*/
|
||
g_auto(GLnxTmpfile) tmp_dest = { 0, };
|
||
{ char *dnbuf = strdupa (dest_subpath);
|
||
const char *dn = dirname (dnbuf);
|
||
if (!glnx_open_tmpfile_linkable_at (dest_dfd, dn, O_WRONLY | O_CLOEXEC,
|
||
&tmp_dest, error))
|
||
return FALSE;
|
||
}
|
||
|
||
if (glnx_regfile_copy_bytes (src_fd, tmp_dest.fd, (off_t) -1) < 0)
|
||
return glnx_throw_errno_prefix (error, "regfile copy");
|
||
|
||
if (!(copyflags & GLNX_FILE_COPY_NOCHOWN))
|
||
{
|
||
if (fchown (tmp_dest.fd, src_stbuf->st_uid, src_stbuf->st_gid) != 0)
|
||
return glnx_throw_errno_prefix (error, "fchown");
|
||
}
|
||
|
||
if (!(copyflags & GLNX_FILE_COPY_NOXATTRS))
|
||
{
|
||
g_autoptr(GVariant) xattrs = NULL;
|
||
|
||
if (!glnx_fd_get_all_xattrs (src_fd, &xattrs,
|
||
cancellable, error))
|
||
return FALSE;
|
||
|
||
if (!glnx_fd_set_all_xattrs (tmp_dest.fd, xattrs,
|
||
cancellable, error))
|
||
return FALSE;
|
||
}
|
||
|
||
/* Always chmod after setting xattrs, in case the file has mode 0400 or less,
|
||
* like /etc/shadow. Linux currently allows write() on non-writable open files
|
||
* but not fsetxattr().
|
||
*/
|
||
if (fchmod (tmp_dest.fd, src_stbuf->st_mode & 07777) != 0)
|
||
return glnx_throw_errno_prefix (error, "fchmod");
|
||
|
||
struct timespec ts[2];
|
||
ts[0] = src_stbuf->st_atim;
|
||
ts[1] = src_stbuf->st_mtim;
|
||
(void) futimens (tmp_dest.fd, ts);
|
||
|
||
if (copyflags & GLNX_FILE_COPY_DATASYNC)
|
||
{
|
||
if (fdatasync (tmp_dest.fd) < 0)
|
||
return glnx_throw_errno_prefix (error, "fdatasync");
|
||
}
|
||
|
||
const GLnxLinkTmpfileReplaceMode replacemode =
|
||
(copyflags & GLNX_FILE_COPY_OVERWRITE) ?
|
||
GLNX_LINK_TMPFILE_REPLACE :
|
||
GLNX_LINK_TMPFILE_NOREPLACE;
|
||
|
||
if (!glnx_link_tmpfile_at (&tmp_dest, replacemode, dest_dfd, dest_subpath, error))
|
||
return FALSE;
|
||
|
||
return TRUE;
|
||
}
|
||
|
||
/**
|
||
* glnx_file_replace_contents_at:
|
||
* @dfd: Directory fd
|
||
* @subpath: Subpath
|
||
* @buf: (array len=len) (element-type guint8): File contents
|
||
* @len: Length (if `-1`, assume @buf is `NUL` terminated)
|
||
* @flags: Flags
|
||
* @cancellable: Cancellable
|
||
* @error: Error
|
||
*
|
||
* Create a new file, atomically replacing the contents of @subpath
|
||
* (relative to @dfd) with @buf. By default, if the file already
|
||
* existed, fdatasync() will be used before rename() to ensure stable
|
||
* contents. This and other behavior can be controlled via @flags.
|
||
*
|
||
* Note that no metadata from the existing file is preserved, such as
|
||
* uid/gid or extended attributes. The default mode will be `0644`.
|
||
*/
|
||
gboolean
|
||
glnx_file_replace_contents_at (int dfd,
|
||
const char *subpath,
|
||
const guint8 *buf,
|
||
gsize len,
|
||
GLnxFileReplaceFlags flags,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
return glnx_file_replace_contents_with_perms_at (dfd, subpath, buf, len,
|
||
(mode_t) -1, (uid_t) -1, (gid_t) -1,
|
||
flags, cancellable, error);
|
||
}
|
||
|
||
/**
|
||
* glnx_file_replace_contents_with_perms_at:
|
||
* @dfd: Directory fd
|
||
* @subpath: Subpath
|
||
* @buf: (array len=len) (element-type guint8): File contents
|
||
* @len: Length (if `-1`, assume @buf is `NUL` terminated)
|
||
* @mode: File mode; if `-1`, use `0644`
|
||
* @flags: Flags
|
||
* @cancellable: Cancellable
|
||
* @error: Error
|
||
*
|
||
* Like glnx_file_replace_contents_at(), but also supports
|
||
* setting mode, and uid/gid.
|
||
*/
|
||
gboolean
|
||
glnx_file_replace_contents_with_perms_at (int dfd,
|
||
const char *subpath,
|
||
const guint8 *buf,
|
||
gsize len,
|
||
mode_t mode,
|
||
uid_t uid,
|
||
gid_t gid,
|
||
GLnxFileReplaceFlags flags,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
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);
|
||
|
||
/* With O_TMPFILE we can't use umask, and we can't sanely query the
|
||
* umask...let's assume something relatively standard.
|
||
*/
|
||
if (mode == (mode_t) -1)
|
||
mode = 0644;
|
||
|
||
g_auto(GLnxTmpfile) tmpf = { 0, };
|
||
if (!glnx_open_tmpfile_linkable_at (dfd, dn, O_WRONLY | O_CLOEXEC,
|
||
&tmpf, error))
|
||
return FALSE;
|
||
|
||
if (len == -1)
|
||
len = strlen ((char*)buf);
|
||
|
||
if (!glnx_try_fallocate (tmpf.fd, 0, len, error))
|
||
return FALSE;
|
||
|
||
if (glnx_loop_write (tmpf.fd, buf, len) < 0)
|
||
return glnx_throw_errno_prefix (error, "write");
|
||
|
||
if (!nodatasync || increasing_mtime)
|
||
{
|
||
if (!glnx_fstatat_allow_noent (dfd, subpath, &stbuf, AT_SYMLINK_NOFOLLOW, error))
|
||
return FALSE;
|
||
has_stbuf = errno != ENOENT;
|
||
}
|
||
|
||
if (!nodatasync)
|
||
{
|
||
gboolean do_sync;
|
||
if (!has_stbuf)
|
||
do_sync = datasync_new;
|
||
else
|
||
do_sync = TRUE;
|
||
|
||
if (do_sync)
|
||
{
|
||
if (TEMP_FAILURE_RETRY (fdatasync (tmpf.fd)) != 0)
|
||
return glnx_throw_errno_prefix (error, "fdatasync");
|
||
}
|
||
}
|
||
|
||
if (uid != (uid_t) -1)
|
||
{
|
||
if (TEMP_FAILURE_RETRY (fchown (tmpf.fd, uid, gid)) != 0)
|
||
return glnx_throw_errno_prefix (error, "fchown");
|
||
}
|
||
|
||
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;
|
||
|
||
return TRUE;
|
||
}
|