mirror of
https://sourceware.org/git/glibc.git
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c5aa5fd40a
The legacy hwcaps mechanism was removed with glibc 2.37: See this commit series: -d178c67535
x86_64: Remove platform directory library loading test -6099908fb8
elf: Remove legacy hwcaps support from the dynamic loader -b78ff5a25d
elf: Remove legacy hwcaps support from ldconfig -4a7094119c
elf: Remove hwcap parameter from add_to_cache signature -cfbf883db3
elf: Remove hwcap and bits_hwcap fields from struct cache_entry -78d9a1620b
Add NEWS entry for legacy hwcaps removal -ab40f20364
elf: Remove _dl_string_hwcap -e76369ed63
elf: Simplify output of hwcap subdirectories in ld.so help According to Florian Weimer, this was an oversight and should also have been removed. As ldconfig does not generate ld.so.cache entries with hwcap/platform bits in the hwcap-field anymore, this patch now skips those entries. Thus currently only named-hwcap-entries and the default entries are allowed. For named-hwcap entries bit 62 is set and also the isa-level bits can be set. For the default entries the hwcap-field is 0. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
521 lines
16 KiB
C
521 lines
16 KiB
C
/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
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Copyright (C) 1996-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C 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 2.1 of the License, or (at your option) any later version.
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The GNU C 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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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <sys/mman.h>
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#include <dl-cache.h>
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#include <dl-procinfo.h>
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#include <stdint.h>
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#include <_itoa.h>
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#include <dl-hwcaps.h>
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#include <dl-isa-level.h>
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/* This is the starting address and the size of the mmap()ed file. */
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static struct cache_file *cache;
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static struct cache_file_new *cache_new;
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static size_t cachesize;
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#ifdef SHARED
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/* This is used to cache the priorities of glibc-hwcaps
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subdirectories. The elements of _dl_cache_priorities correspond to
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the strings in the cache_extension_tag_glibc_hwcaps section. */
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static uint32_t *glibc_hwcaps_priorities;
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static uint32_t glibc_hwcaps_priorities_length;
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static uint32_t glibc_hwcaps_priorities_allocated;
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/* True if the full malloc was used to allocated the array. */
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static bool glibc_hwcaps_priorities_malloced;
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/* Deallocate the glibc_hwcaps_priorities array. */
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static void
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glibc_hwcaps_priorities_free (void)
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{
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/* When the minimal malloc is in use, free does not do anything,
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so it does not make sense to call it. */
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if (glibc_hwcaps_priorities_malloced)
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free (glibc_hwcaps_priorities);
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glibc_hwcaps_priorities = NULL;
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glibc_hwcaps_priorities_allocated = 0;
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}
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/* Ordered comparison of a hwcaps string from the cache on the left
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(identified by its string table index) and a _dl_hwcaps_priorities
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element on the right. */
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static int
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glibc_hwcaps_compare (uint32_t left_index, struct dl_hwcaps_priority *right)
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{
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const char *left_name = (const char *) cache + left_index;
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uint32_t left_name_length = strlen (left_name);
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uint32_t to_compare;
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if (left_name_length < right->name_length)
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to_compare = left_name_length;
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else
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to_compare = right->name_length;
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int cmp = memcmp (left_name, right->name, to_compare);
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if (cmp != 0)
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return cmp;
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if (left_name_length < right->name_length)
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return -1;
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else if (left_name_length > right->name_length)
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return 1;
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else
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return 0;
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}
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/* Initialize the glibc_hwcaps_priorities array and its length,
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glibc_hwcaps_priorities_length. */
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static void
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glibc_hwcaps_priorities_init (void)
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{
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struct cache_extension_all_loaded ext;
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if (!cache_extension_load (cache_new, cache, cachesize, &ext))
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return;
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uint32_t length = (ext.sections[cache_extension_tag_glibc_hwcaps].size
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/ sizeof (uint32_t));
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if (length > glibc_hwcaps_priorities_allocated)
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{
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glibc_hwcaps_priorities_free ();
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uint32_t *new_allocation = malloc (length * sizeof (uint32_t));
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if (new_allocation == NULL)
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/* This effectively disables hwcaps on memory allocation
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errors. */
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return;
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glibc_hwcaps_priorities = new_allocation;
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glibc_hwcaps_priorities_allocated = length;
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glibc_hwcaps_priorities_malloced = __rtld_malloc_is_complete ();
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}
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/* Compute the priorities for the subdirectories by merging the
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array in the cache with the dl_hwcaps_priorities array. */
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const uint32_t *left = ext.sections[cache_extension_tag_glibc_hwcaps].base;
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const uint32_t *left_end = left + length;
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struct dl_hwcaps_priority *right = _dl_hwcaps_priorities;
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struct dl_hwcaps_priority *right_end = right + _dl_hwcaps_priorities_length;
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uint32_t *result = glibc_hwcaps_priorities;
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while (left < left_end && right < right_end)
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{
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if (*left < cachesize)
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{
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int cmp = glibc_hwcaps_compare (*left, right);
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if (cmp == 0)
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{
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*result = right->priority;
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++result;
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++left;
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++right;
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}
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else if (cmp < 0)
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{
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*result = 0;
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++result;
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++left;
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}
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else
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++right;
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}
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else
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{
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*result = 0;
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++result;
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}
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}
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while (left < left_end)
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{
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*result = 0;
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++result;
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++left;
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}
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glibc_hwcaps_priorities_length = length;
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}
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/* Return the priority of the cache_extension_tag_glibc_hwcaps section
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entry at INDEX. Zero means do not use. Otherwise, lower values
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indicate greater preference. */
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static uint32_t
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glibc_hwcaps_priority (uint32_t index)
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{
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/* This does not need to repeated initialization attempts because
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this function is only called if there is glibc-hwcaps data in the
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cache, so the first call initializes the glibc_hwcaps_priorities
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array. */
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if (glibc_hwcaps_priorities_length == 0)
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glibc_hwcaps_priorities_init ();
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if (index < glibc_hwcaps_priorities_length)
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return glibc_hwcaps_priorities[index];
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else
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return 0;
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}
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#endif /* SHARED */
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/* True if PTR is a valid string table index. */
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static inline bool
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_dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size)
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{
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return ptr < string_table_size;
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}
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/* Compute the address of the element INDEX of the array at LIBS.
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Conceptually, this is &LIBS[INDEX], but use ENTRY_SIZE for the size
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of *LIBS. */
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static inline const struct file_entry *
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_dl_cache_file_entry (const struct file_entry *libs, size_t entry_size,
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size_t index)
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{
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return (const void *) libs + index * entry_size;
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}
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/* We use binary search since the table is sorted in the cache file.
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The first matching entry in the table is returned. It is important
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to use the same algorithm as used while generating the cache file.
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STRING_TABLE_SIZE indicates the maximum offset in STRING_TABLE at
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which data is mapped; it is not exact. */
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static const char *
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search_cache (const char *string_table, uint32_t string_table_size,
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struct file_entry *libs, uint32_t nlibs, uint32_t entry_size,
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const char *name)
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{
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int left = 0;
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int right = nlibs - 1;
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const char *best = NULL;
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#ifdef SHARED
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uint32_t best_priority = 0;
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#endif
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while (left <= right)
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{
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int middle = (left + right) / 2;
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uint32_t key = _dl_cache_file_entry (libs, entry_size, middle)->key;
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/* Make sure string table indices are not bogus before using
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them. */
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if (!_dl_cache_verify_ptr (key, string_table_size))
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return NULL;
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/* Actually compare the entry with the key. */
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int cmpres = _dl_cache_libcmp (name, string_table + key);
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if (__glibc_unlikely (cmpres == 0))
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{
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/* Found it. LEFT now marks the last entry for which we
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know the name is correct. */
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left = middle;
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/* There might be entries with this name before the one we
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found. So we have to find the beginning. */
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while (middle > 0)
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{
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key = _dl_cache_file_entry (libs, entry_size, middle - 1)->key;
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/* Make sure string table indices are not bogus before
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using them. */
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if (!_dl_cache_verify_ptr (key, string_table_size)
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/* Actually compare the entry. */
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|| _dl_cache_libcmp (name, string_table + key) != 0)
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break;
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--middle;
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}
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do
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{
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int flags;
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const struct file_entry *lib
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= _dl_cache_file_entry (libs, entry_size, middle);
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/* Only perform the name test if necessary. */
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if (middle > left
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/* We haven't seen this string so far. Test whether the
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index is ok and whether the name matches. Otherwise
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we are done. */
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&& (! _dl_cache_verify_ptr (lib->key, string_table_size)
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|| (_dl_cache_libcmp (name, string_table + lib->key)
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!= 0)))
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break;
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flags = lib->flags;
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if (_dl_cache_check_flags (flags)
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&& _dl_cache_verify_ptr (lib->value, string_table_size))
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{
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/* Named/extension hwcaps get slightly different
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treatment: We keep searching for a better
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match. */
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bool named_hwcap = false;
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if (entry_size >= sizeof (struct file_entry_new))
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{
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/* The entry is large enough to include
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HWCAP data. Check it. */
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struct file_entry_new *libnew
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= (struct file_entry_new *) lib;
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#ifdef SHARED
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named_hwcap = dl_cache_hwcap_extension (libnew);
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if (named_hwcap
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&& !dl_cache_hwcap_isa_level_compatible (libnew))
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continue;
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#endif
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/* The entries with named/extension hwcaps have
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been exhausted (they are listed before all
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other entries). Return the best match
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encountered so far if there is one. */
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if (!named_hwcap && best != NULL)
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break;
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/* Skip entries with the legacy hwcap/platform mechanism
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which was removed with glibc 2.37. */
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if (!named_hwcap && libnew->hwcap != 0)
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continue;
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#ifdef SHARED
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/* For named hwcaps, determine the priority and
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see if beats what has been found so far. */
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if (named_hwcap)
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{
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uint32_t entry_priority
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= glibc_hwcaps_priority (libnew->hwcap);
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if (entry_priority == 0)
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/* Not usable at all. Skip. */
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continue;
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else if (best == NULL
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|| entry_priority < best_priority)
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/* This entry is of higher priority
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than the previous one, or it is the
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first entry. */
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best_priority = entry_priority;
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else
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/* An entry has already been found,
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but it is a better match. */
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continue;
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}
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#endif /* SHARED */
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}
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best = string_table + lib->value;
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if (!named_hwcap && flags == _DL_CACHE_DEFAULT_ID)
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/* With named hwcaps, we need to keep searching to
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see if we find a better match. A better match
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is also possible if the flags of the current
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entry do not match the expected cache flags.
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But if the flags match, no better entry will be
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found. */
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break;
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}
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}
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while (++middle <= right);
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break;
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}
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if (cmpres < 0)
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left = middle + 1;
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else
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right = middle - 1;
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}
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return best;
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}
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int
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_dl_cache_libcmp (const char *p1, const char *p2)
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{
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while (*p1 != '\0')
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{
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if (*p1 >= '0' && *p1 <= '9')
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{
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if (*p2 >= '0' && *p2 <= '9')
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{
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/* Must compare this numerically. */
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int val1;
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int val2;
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val1 = *p1++ - '0';
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val2 = *p2++ - '0';
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while (*p1 >= '0' && *p1 <= '9')
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val1 = val1 * 10 + *p1++ - '0';
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while (*p2 >= '0' && *p2 <= '9')
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val2 = val2 * 10 + *p2++ - '0';
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if (val1 != val2)
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return val1 - val2;
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}
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else
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return 1;
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}
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else if (*p2 >= '0' && *p2 <= '9')
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return -1;
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else if (*p1 != *p2)
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return *p1 - *p2;
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else
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{
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++p1;
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++p2;
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}
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}
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return *p1 - *p2;
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}
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/* Look up NAME in ld.so.cache and return the file name stored there, or null
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if none is found. The cache is loaded if it was not already. If loading
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the cache previously failed there will be no more attempts to load it.
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The caller is responsible for freeing the returned string. The ld.so.cache
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may be unmapped at any time by a completing recursive dlopen and
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this function must take care that it does not return references to
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any data in the mapping. */
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char *
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_dl_load_cache_lookup (const char *name)
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{
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/* Print a message if the loading of libs is traced. */
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
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_dl_debug_printf (" search cache=%s\n", LD_SO_CACHE);
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if (cache == NULL)
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{
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/* Read the contents of the file. */
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void *file = _dl_sysdep_read_whole_file (LD_SO_CACHE, &cachesize,
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PROT_READ);
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/* We can handle three different cache file formats here:
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- only the new format
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- the old libc5/glibc2.0/2.1 format
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- the old format with the new format in it
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The following checks if the cache contains any of these formats. */
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if (file != MAP_FAILED && cachesize > sizeof *cache_new
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&& memcmp (file, CACHEMAGIC_VERSION_NEW,
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sizeof CACHEMAGIC_VERSION_NEW - 1) == 0
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/* Check for corruption, avoiding overflow. */
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&& ((cachesize - sizeof *cache_new) / sizeof (struct file_entry_new)
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>= ((struct cache_file_new *) file)->nlibs))
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{
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if (! cache_file_new_matches_endian (file))
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{
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__munmap (file, cachesize);
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file = (void *) -1;
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}
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cache_new = file;
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cache = file;
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}
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else if (file != MAP_FAILED && cachesize > sizeof *cache
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&& memcmp (file, CACHEMAGIC, sizeof CACHEMAGIC - 1) == 0
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/* Check for corruption, avoiding overflow. */
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&& ((cachesize - sizeof *cache) / sizeof (struct file_entry)
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>= ((struct cache_file *) file)->nlibs))
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{
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size_t offset;
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/* Looks ok. */
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cache = file;
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/* Check for new version. */
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offset = ALIGN_CACHE (sizeof (struct cache_file)
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+ cache->nlibs * sizeof (struct file_entry));
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cache_new = (struct cache_file_new *) ((void *) cache + offset);
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if (cachesize < (offset + sizeof (struct cache_file_new))
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|| memcmp (cache_new->magic, CACHEMAGIC_VERSION_NEW,
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sizeof CACHEMAGIC_VERSION_NEW - 1) != 0)
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cache_new = (void *) -1;
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else
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{
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if (! cache_file_new_matches_endian (cache_new))
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{
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/* The old-format part of the cache is bogus as well
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if the endianness does not match. (But it is
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unclear how the new header can be located if the
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endianness does not match.) */
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cache = (void *) -1;
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cache_new = (void *) -1;
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__munmap (file, cachesize);
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}
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}
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}
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else
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{
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if (file != MAP_FAILED)
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__munmap (file, cachesize);
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cache = (void *) -1;
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}
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assert (cache != NULL);
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}
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if (cache == (void *) -1)
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/* Previously looked for the cache file and didn't find it. */
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return NULL;
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const char *best;
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if (cache_new != (void *) -1)
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{
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const char *string_table = (const char *) cache_new;
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best = search_cache (string_table, cachesize,
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&cache_new->libs[0].entry, cache_new->nlibs,
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sizeof (cache_new->libs[0]), name);
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}
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else
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{
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const char *string_table = (const char *) &cache->libs[cache->nlibs];
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uint32_t string_table_size
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= (const char *) cache + cachesize - string_table;
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best = search_cache (string_table, string_table_size,
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&cache->libs[0], cache->nlibs,
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sizeof (cache->libs[0]), name);
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}
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/* Print our result if wanted. */
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if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, 0)
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&& best != NULL)
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_dl_debug_printf (" trying file=%s\n", best);
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if (best == NULL)
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return NULL;
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/* The double copy is *required* since malloc may be interposed
|
|
and call dlopen itself whose completion would unmap the data
|
|
we are accessing. Therefore we must make the copy of the
|
|
mapping data without using malloc. */
|
|
char *temp;
|
|
size_t best_len = strlen (best) + 1;
|
|
temp = alloca (best_len);
|
|
memcpy (temp, best, best_len);
|
|
return __strdup (temp);
|
|
}
|
|
|
|
#ifndef MAP_COPY
|
|
/* If the system does not support MAP_COPY we cannot leave the file open
|
|
all the time since this would create problems when the file is replaced.
|
|
Therefore we provide this function to close the file and open it again
|
|
once needed. */
|
|
void
|
|
_dl_unload_cache (void)
|
|
{
|
|
if (cache != NULL && cache != (struct cache_file *) -1)
|
|
{
|
|
__munmap (cache, cachesize);
|
|
cache = NULL;
|
|
}
|
|
#ifdef SHARED
|
|
/* This marks the glibc_hwcaps_priorities array as out-of-date. */
|
|
glibc_hwcaps_priorities_length = 0;
|
|
#endif
|
|
}
|
|
#endif
|