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Linux: Add test case for bug 33245 

The copy_file_range system call seems to be the only one that can
return an off64_t value.  Use FUSE to exercise this, without actually
creating such large files or copying any data.  Due to FUSE protocol
limitations, only sizes up to UINT_MAX can be tested, but this is
sufficient to check for the presence of bug 33245.

The FUSE protocol limitations are raised here:

  copy_file_range return value on FUSE
  <https://lore.kernel.org/all/lhuh5ynl8z5.fsf@oldenburg.str.redhat.com/>

Reviewed-by: Sam James <sam@gentoo.org>
Reviewed-by: Collin Funk <collin.funk1@gmail.com>
This commit is contained in:
Florian Weimer 2025-08-02 12:44:51 +02:00
parent e5363e6f46
commit 9a2aceb076
2 changed files with 240 additions and 0 deletions
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1
sysdeps/unix/sysv/linux/Makefile
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@ -192,6 +192,7 @@ tests += \
tst-clone \
tst-clone2 \
tst-clone3 \
tst-copy_file_range-large \
tst-epoll \
tst-epoll-ioctls \
tst-fanotify \

239
sysdeps/unix/sysv/linux/tst-copy_file_range-large.c Normal file
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@ -0,0 +1,239 @@
/* Test for copy_file_range with large sizes (bug 33245).
Copyright (C) 2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* This test exercises copy_file_range with various large file sizes
on FUSE filesystems to verify proper handling of system call return
values. No data is actually copied. */
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <support/check.h>
#include <support/fuse.h>
#include <support/support.h>
#include <support/test-driver.h>
#include <support/xthread.h>
#include <support/xunistd.h>
#include <sys/stat.h>
#include <unistd.h>
static void
fuse_thread (struct support_fuse *f, void *closure)
{
/* Node IDs for our test files. */
enum { NODE_SOURCE = 2, NODE_DEST = 3 };
/* A large size, so that the kernel does not fail the
copy_file_range attempt before performing the FUSE callback.
Only the source file size matters to the kernel, but both files
use the same size for simplicity. */
const uint64_t file_size = 1LLU << 61;
struct fuse_in_header *inh;
while ((inh = support_fuse_next (f)) != NULL)
{
if (support_fuse_handle_mountpoint (f)
|| (inh->nodeid == 1 && support_fuse_handle_directory (f)))
continue;
switch (inh->opcode)
{
case FUSE_LOOKUP:
{
char *name = support_fuse_cast (LOOKUP, inh);
int node = 0;
if (inh->nodeid == 1 && strcmp (name, "source") == 0)
node = NODE_SOURCE;
else if (inh->nodeid == 1 && strcmp (name, "dest") == 0)
node = NODE_DEST;
if (node != 0)
{
struct fuse_entry_out *out
= support_fuse_prepare_entry (f, node);
out->attr.mode = S_IFREG | 0600;
out->attr.size = file_size;
support_fuse_reply_prepared (f);
}
else
support_fuse_reply_error (f, ENOENT);
}
break;
case FUSE_OPEN:
/* File open */
{
if (inh->nodeid == NODE_SOURCE || inh->nodeid == NODE_DEST)
{
struct fuse_open_out out = { .fh = inh->nodeid };
support_fuse_reply (f, &out, sizeof (out));
}
else
support_fuse_reply_error (f, ENOENT);
}
break;
case FUSE_GETATTR:
/* Get file attributes */
if (inh->nodeid == NODE_SOURCE || inh->nodeid == NODE_DEST)
{
struct fuse_attr_out *out = support_fuse_prepare_attr (f);
out->attr.mode = S_IFREG | 0600;
out->attr.size = file_size;
support_fuse_reply_prepared (f);
}
else
support_fuse_reply_error (f, ENOENT);
break;
case FUSE_COPY_FILE_RANGE:
{
struct fuse_copy_file_range_in *p
= support_fuse_cast (COPY_FILE_RANGE, inh);
/* Verify this is a copy from source to dest, starting at
offset 0. */
TEST_COMPARE (p->fh_in, NODE_SOURCE);
TEST_COMPARE (p->nodeid_out, NODE_DEST);
TEST_COMPARE (p->off_in, 0);
TEST_COMPARE (p->off_out, 0);
TEST_VERIFY (p->len > 0);
TEST_VERIFY (p->len <= file_size);
/* Pretend the copy succeeded. */
struct fuse_write_out out = { .size = p->len };
support_fuse_reply (f, &out, sizeof (out));
}
break;
case FUSE_FLUSH:
support_fuse_reply_empty (f);
break;
default:
support_fuse_reply_error (f, EIO);
}
}
}
static void
test_size (struct support_fuse *f, off64_t size)
{
/* On 32-bit targets, not all possible return values from
copy_file_range are representable. The current (Linux 6.5.18)
kernel FUSE implementation can produce negative non-error results
from copy_file_range in the range [1UL << 31, UINT_MAX - 4095],
but this seems to be a FUSE bug. */
if (size != (ssize_t) size)
{
printf ("info:%s size 0x%llx is too large for ssize_t\n",
test_verbose ? " " : "", (unsigned long long int) size);
return;
}
verbose_printf ("info: testing copy size 0x%llx\n",
(unsigned long long int) size);
const char *mountpoint = support_fuse_mountpoint (f);
char *source_path = xasprintf ("%s/source", mountpoint);
char *dest_path = xasprintf ("%s/dest", mountpoint);
int source_fd = xopen (source_path, O_RDONLY, 0);
int dest_fd = xopen (dest_path, O_WRONLY, 0);
ssize_t copied = copy_file_range (source_fd, NULL, dest_fd, NULL, size, 0);
/* Avoid FAIL_UNSUPPORTED if it is likely bogus due to previous
copy_file_range successes. */
if (copied == -1 && errno == ENOSYS)
{
/* Unmounting avoids a test hang on exit. */
xclose (dest_fd);
xclose (source_fd);
support_fuse_unmount (f);
FAIL_UNSUPPORTED ("copy_file_range not supported");
}
TEST_COMPARE (copied, size);
xclose (dest_fd);
xclose (source_fd);
free (dest_path);
free (source_path);
}
static void
test_all_sizes (struct support_fuse *f)
{
test_size (f, 0); /* Not actually handled by the callback. */
test_size (f, 20);
test_size (f, 1 << 30);
test_size (f, INT_MAX);
for (int i = 0; i <= 5; ++i)
test_size (f, (1U << 31) + i);
for (int i = -4100; i <= -4090; ++i)
test_size (f, UINT_MAX + i);
for (int i = -100; i <= 0; ++i)
test_size (f, UINT_MAX + i);
/* We would like to test larger values than UINT_MAX here, but they
do not work because the FUSE protocol uses uint32_t for the
copy_file_range result in struct fuse_write_out. */
}
static void *
test_cancel_state_variants (void *f_ptr)
{
struct support_fuse *f = (struct support_fuse *) f_ptr;
verbose_printf ("info: testing default cancellation settings\n");
test_all_sizes (f);
verbose_printf ("info: testing with cancellation disabled\n");
TEST_COMPARE (pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL), 0);
test_all_sizes (f);
verbose_printf ("info: testing with cancellation enabled\n");
TEST_COMPARE (pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, NULL), 0);
test_all_sizes (f);
return NULL;
}
static int
do_test (void)
{
support_fuse_init ();
struct support_fuse *f = support_fuse_mount (fuse_thread, NULL);
verbose_printf ("info: testing on main thread\n");
test_cancel_state_variants (f);
verbose_printf ("info: testing on secondary thread\n");
TEST_VERIFY (xpthread_join (xpthread_create
(NULL, test_cancel_state_variants, f))
== NULL);
verbose_printf ("info: testing on separate thread\n");
support_fuse_unmount (f);
return 0;
}
#include <support/test-driver.c>