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/* Test for signed comparison bug in memmove (bug 25620).
Copyright (C) 2020-2024 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 shifts a memory region which is a bit larger than 2 GiB
by one byte. In order to make it more likely that the memory
allocation succeeds on 32-bit systems, most of the allocation
consists of shared pages. Only a portion at the start and end of
the allocation are unshared, and contain a specific non-repeating
bit pattern. */
#include <array_length.h>
#include <libc-diag.h>
#include <stdint.h>
#include <string.h>
#include <support/blob_repeat.h>
#include <support/check.h>
#include <support/xunistd.h>
#include <sys/mman.h>
#include <unistd.h>
#define TEST_MAIN
#define TEST_NAME "memmove"
#include "test-string.h"
#include <support/test-driver.h>
IMPL (memmove, 1)
/* Size of the part of the allocation which is not shared, at the
start and the end of the overall allocation. 4 MiB. */
enum { unshared_size = (size_t) 4U << 20 };
/* The allocation is 2 GiB plus 8 MiB. This should work with all page
sizes that occur in practice. */
enum { allocation_size = ((size_t) 2U << 30) + 2 * unshared_size };
/* Compute the expected byte at the given index. This is used to
produce a non-repeating pattern. */
static inline unsigned char
expected_value (size_t index)
{
uint32_t randomized = 0x9e3779b9 * index; /* Based on golden ratio. */
return randomized >> 25; /* Result is in the range [0, 127]. */
}
/* Used to count mismatches up to a limit, to avoid creating a huge
test output file. */
static unsigned int mismatch_count;
/* Check ACTUAL == EXPECTED. Use INDEX for error reporting. Exit the
process after too many errors. */
static inline void
check_one_index (size_t index, unsigned char actual, unsigned char expected)
{
if (actual != expected)
{
printf ("error: mismatch at index %zu: expected 0x%02x, got 0x%02x\n",
index, actual, expected);
++mismatch_count;
if (mismatch_count > 200)
FAIL_EXIT1 ("bailing out due to too many errors");
}
}
static int
test_main (void)
{
test_init ();
FOR_EACH_IMPL (impl, 0)
{
printf ("info: testing %s\n", impl->name);
/* Check that the allocation sizes are multiples of the page
size. */
TEST_COMPARE (allocation_size % xsysconf (_SC_PAGESIZE), 0);
TEST_COMPARE (unshared_size % xsysconf (_SC_PAGESIZE), 0);
/* The repeating pattern has the MSB set in all bytes. */
unsigned char repeating_pattern[128];
for (unsigned int i = 0; i < array_length (repeating_pattern); ++i)
repeating_pattern[i] = 0x80 | i;
struct support_blob_repeat repeat
= support_blob_repeat_allocate_shared (repeating_pattern,
sizeof (repeating_pattern),
(allocation_size
/ sizeof (repeating_pattern)));
if (repeat.start == NULL)
FAIL_UNSUPPORTED ("repeated blob allocation failed: %m");
TEST_COMPARE (repeat.size, allocation_size);
/* Unshared the start and the end of the allocation. */
unsigned char *start = repeat.start;
xmmap (start, unshared_size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1);
xmmap (start + allocation_size - unshared_size, unshared_size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1);
/* Initialize the non-repeating pattern. */
for (size_t i = 0; i < unshared_size; ++i)
start[i] = expected_value (i);
for (size_t i = allocation_size - unshared_size; i < allocation_size;
++i)
start[i] = expected_value (i);
/* Make sure that there was really no sharing. */
asm volatile ("" ::: "memory");
for (size_t i = 0; i < unshared_size; ++i)
TEST_COMPARE (start[i], expected_value (i));
for (size_t i = allocation_size - unshared_size; i < allocation_size;
++i)
TEST_COMPARE (start[i], expected_value (i));
/* Used for a nicer error diagnostic using
TEST_COMPARE_BLOB. */
unsigned char expected_start[128];
memcpy (expected_start, start + 1, sizeof (expected_start));
unsigned char expected_end[128];
memcpy (expected_end,
start + allocation_size - sizeof (expected_end),
sizeof (expected_end));
/* Move the entire allocation forward by one byte. */
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about string function argument overflows. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Warray-bounds");
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-overflow");
#endif
memmove (start, start + 1, allocation_size - 1);
DIAG_POP_NEEDS_COMMENT;
/* Check that the unshared of the memory region have been
shifted as expected. The TEST_COMPARE_BLOB checks are
redundant, but produce nicer diagnostics. */
asm volatile ("" ::: "memory");
TEST_COMPARE_BLOB (expected_start, sizeof (expected_start),
start, sizeof (expected_start));
TEST_COMPARE_BLOB (expected_end, sizeof (expected_end),
start + allocation_size - sizeof (expected_end) - 1,
sizeof (expected_end));
for (size_t i = 0; i < unshared_size - 1; ++i)
check_one_index (i, start[i], expected_value (i + 1));
/* The gap between the checked start and end area of the mapping
has shared mappings at unspecified boundaries, so do not
check the expected values in the middle. */
for (size_t i = allocation_size - unshared_size; i < allocation_size - 1;
++i)
check_one_index (i, start[i], expected_value (i + 1));
support_blob_repeat_free (&repeat);
}
return 0;
}
#include <support/test-driver.c>
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