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fff94fa224
When the malloc subsystem detects some kind of memory corruption, depending on the configuration it prints the error, a backtrace, a memory map and then aborts the process. In this process, the backtrace() call may result in a call to malloc, resulting in various kinds of problematic behavior. In one case, the malloc it calls may detect a corruption and call backtrace again, and a stack overflow may result due to the infinite recursion. In another case, the malloc it calls may deadlock on an arena lock with the malloc (or free, realloc, etc.) that detected the corruption. In yet another case, if the program is linked with pthreads, backtrace may do a pthread_once initialization, which deadlocks on itself. In all these cases, the program exit is not as intended. This is avoidable by marking the arena that malloc detected a corruption on, as unusable. The following patch does that. Features of this patch are as follows: - A flag is added to the mstate struct of the arena to indicate if the arena is corrupt. - The flag is checked whenever malloc functions try to get a lock on an arena. If the arena is unusable, a NULL is returned, causing the malloc to use mmap or try the next arena. - malloc_printerr sets the corrupt flag on the arena when it detects a corruption - free does not concern itself with the flag at all. It is not important since the backtrace workflow does not need free. A free in a parallel thread may cause another corruption, but that's not new - The flag check and set are not atomic and may race. This is fine since we don't care about contention during the flag check. We want to make sure that the malloc call in the backtrace does not trip on itself and all that action happens in the same thread and not across threads. I verified that the test case does not show any regressions due to this patch. I also ran the malloc benchmarks and found an insignificant difference in timings (< 2%). * malloc/Makefile (tests): New test case tst-malloc-backtrace. * malloc/arena.c (arena_lock): Check if arena is corrupt. (reused_arena): Find a non-corrupt arena. (heap_trim): Pass arena to unlink. * malloc/hooks.c (malloc_check_get_size): Pass arena to malloc_printerr. (top_check): Likewise. (free_check): Likewise. (realloc_check): Likewise. * malloc/malloc.c (malloc_printerr): Add arena argument. (unlink): Likewise. (munmap_chunk): Adjust. (ARENA_CORRUPTION_BIT): New macro. (arena_is_corrupt): Likewise. (set_arena_corrupt): Likewise. (sysmalloc): Use mmap if there are no usable arenas. (_int_malloc): Likewise. (__libc_malloc): Don't fail if arena_get returns NULL. (_mid_memalign): Likewise. (__libc_calloc): Likewise. (__libc_realloc): Adjust for additional argument to malloc_printerr. (_int_free): Likewise. (malloc_consolidate): Likewise. (_int_realloc): Likewise. (_int_memalign): Don't touch corrupt arenas. * malloc/tst-malloc-backtrace.c: New test case.
948 lines
27 KiB
C
948 lines
27 KiB
C
/* Malloc implementation for multiple threads without lock contention.
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Copyright (C) 2001-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
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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 License as
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published by the Free Software Foundation; either version 2.1 of the
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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; see the file COPYING.LIB. If
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not, see <http://www.gnu.org/licenses/>. */
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#include <stdbool.h>
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/* Compile-time constants. */
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#define HEAP_MIN_SIZE (32 * 1024)
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#ifndef HEAP_MAX_SIZE
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# ifdef DEFAULT_MMAP_THRESHOLD_MAX
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# define HEAP_MAX_SIZE (2 * DEFAULT_MMAP_THRESHOLD_MAX)
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# else
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# define HEAP_MAX_SIZE (1024 * 1024) /* must be a power of two */
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# endif
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#endif
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/* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps
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that are dynamically created for multi-threaded programs. The
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maximum size must be a power of two, for fast determination of
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which heap belongs to a chunk. It should be much larger than the
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mmap threshold, so that requests with a size just below that
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threshold can be fulfilled without creating too many heaps. */
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/***************************************************************************/
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#define top(ar_ptr) ((ar_ptr)->top)
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/* A heap is a single contiguous memory region holding (coalesceable)
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malloc_chunks. It is allocated with mmap() and always starts at an
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address aligned to HEAP_MAX_SIZE. */
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typedef struct _heap_info
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{
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mstate ar_ptr; /* Arena for this heap. */
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struct _heap_info *prev; /* Previous heap. */
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size_t size; /* Current size in bytes. */
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size_t mprotect_size; /* Size in bytes that has been mprotected
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PROT_READ|PROT_WRITE. */
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/* Make sure the following data is properly aligned, particularly
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that sizeof (heap_info) + 2 * SIZE_SZ is a multiple of
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MALLOC_ALIGNMENT. */
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char pad[-6 * SIZE_SZ & MALLOC_ALIGN_MASK];
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} heap_info;
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/* Get a compile-time error if the heap_info padding is not correct
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to make alignment work as expected in sYSMALLOc. */
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extern int sanity_check_heap_info_alignment[(sizeof (heap_info)
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+ 2 * SIZE_SZ) % MALLOC_ALIGNMENT
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? -1 : 1];
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/* Thread specific data */
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static tsd_key_t arena_key;
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static mutex_t list_lock = MUTEX_INITIALIZER;
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static size_t narenas = 1;
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static mstate free_list;
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/* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
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static unsigned long arena_mem;
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/* Already initialized? */
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int __malloc_initialized = -1;
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/**************************************************************************/
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/* arena_get() acquires an arena and locks the corresponding mutex.
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First, try the one last locked successfully by this thread. (This
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is the common case and handled with a macro for speed.) Then, loop
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once over the circularly linked list of arenas. If no arena is
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readily available, create a new one. In this latter case, `size'
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is just a hint as to how much memory will be required immediately
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in the new arena. */
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#define arena_get(ptr, size) do { \
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arena_lookup (ptr); \
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arena_lock (ptr, size); \
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} while (0)
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#define arena_lookup(ptr) do { \
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void *vptr = NULL; \
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ptr = (mstate) tsd_getspecific (arena_key, vptr); \
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} while (0)
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#define arena_lock(ptr, size) do { \
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if (ptr && !arena_is_corrupt (ptr)) \
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(void) mutex_lock (&ptr->mutex); \
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else \
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ptr = arena_get2 (ptr, (size), NULL); \
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} while (0)
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/* find the heap and corresponding arena for a given ptr */
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#define heap_for_ptr(ptr) \
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((heap_info *) ((unsigned long) (ptr) & ~(HEAP_MAX_SIZE - 1)))
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#define arena_for_chunk(ptr) \
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(chunk_non_main_arena (ptr) ? heap_for_ptr (ptr)->ar_ptr : &main_arena)
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/**************************************************************************/
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#ifndef NO_THREADS
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/* atfork support. */
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static void *(*save_malloc_hook)(size_t __size, const void *);
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static void (*save_free_hook) (void *__ptr, const void *);
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static void *save_arena;
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# ifdef ATFORK_MEM
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ATFORK_MEM;
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# endif
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/* Magic value for the thread-specific arena pointer when
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malloc_atfork() is in use. */
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# define ATFORK_ARENA_PTR ((void *) -1)
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/* The following hooks are used while the `atfork' handling mechanism
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is active. */
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static void *
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malloc_atfork (size_t sz, const void *caller)
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{
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void *vptr = NULL;
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void *victim;
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tsd_getspecific (arena_key, vptr);
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if (vptr == ATFORK_ARENA_PTR)
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{
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/* We are the only thread that may allocate at all. */
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if (save_malloc_hook != malloc_check)
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{
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return _int_malloc (&main_arena, sz);
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}
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else
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{
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if (top_check () < 0)
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return 0;
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victim = _int_malloc (&main_arena, sz + 1);
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return mem2mem_check (victim, sz);
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}
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}
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else
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{
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/* Suspend the thread until the `atfork' handlers have completed.
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By that time, the hooks will have been reset as well, so that
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mALLOc() can be used again. */
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(void) mutex_lock (&list_lock);
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(void) mutex_unlock (&list_lock);
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return __libc_malloc (sz);
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}
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}
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static void
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free_atfork (void *mem, const void *caller)
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{
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void *vptr = NULL;
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mstate ar_ptr;
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mchunkptr p; /* chunk corresponding to mem */
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if (mem == 0) /* free(0) has no effect */
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return;
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p = mem2chunk (mem); /* do not bother to replicate free_check here */
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if (chunk_is_mmapped (p)) /* release mmapped memory. */
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{
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munmap_chunk (p);
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return;
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}
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ar_ptr = arena_for_chunk (p);
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tsd_getspecific (arena_key, vptr);
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_int_free (ar_ptr, p, vptr == ATFORK_ARENA_PTR);
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}
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/* Counter for number of times the list is locked by the same thread. */
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static unsigned int atfork_recursive_cntr;
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/* The following two functions are registered via thread_atfork() to
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make sure that the mutexes remain in a consistent state in the
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fork()ed version of a thread. Also adapt the malloc and free hooks
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temporarily, because the `atfork' handler mechanism may use
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malloc/free internally (e.g. in LinuxThreads). */
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static void
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ptmalloc_lock_all (void)
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{
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mstate ar_ptr;
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if (__malloc_initialized < 1)
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return;
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if (mutex_trylock (&list_lock))
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{
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void *my_arena;
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tsd_getspecific (arena_key, my_arena);
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if (my_arena == ATFORK_ARENA_PTR)
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/* This is the same thread which already locks the global list.
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Just bump the counter. */
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goto out;
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/* This thread has to wait its turn. */
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(void) mutex_lock (&list_lock);
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}
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for (ar_ptr = &main_arena;; )
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{
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(void) mutex_lock (&ar_ptr->mutex);
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ar_ptr = ar_ptr->next;
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if (ar_ptr == &main_arena)
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break;
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}
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save_malloc_hook = __malloc_hook;
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save_free_hook = __free_hook;
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__malloc_hook = malloc_atfork;
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__free_hook = free_atfork;
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/* Only the current thread may perform malloc/free calls now. */
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tsd_getspecific (arena_key, save_arena);
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tsd_setspecific (arena_key, ATFORK_ARENA_PTR);
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out:
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++atfork_recursive_cntr;
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}
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static void
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ptmalloc_unlock_all (void)
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{
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mstate ar_ptr;
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if (__malloc_initialized < 1)
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return;
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if (--atfork_recursive_cntr != 0)
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return;
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tsd_setspecific (arena_key, save_arena);
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__malloc_hook = save_malloc_hook;
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__free_hook = save_free_hook;
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for (ar_ptr = &main_arena;; )
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{
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(void) mutex_unlock (&ar_ptr->mutex);
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ar_ptr = ar_ptr->next;
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if (ar_ptr == &main_arena)
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break;
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}
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(void) mutex_unlock (&list_lock);
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}
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# ifdef __linux__
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/* In NPTL, unlocking a mutex in the child process after a
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fork() is currently unsafe, whereas re-initializing it is safe and
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does not leak resources. Therefore, a special atfork handler is
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installed for the child. */
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static void
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ptmalloc_unlock_all2 (void)
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{
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mstate ar_ptr;
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if (__malloc_initialized < 1)
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return;
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tsd_setspecific (arena_key, save_arena);
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__malloc_hook = save_malloc_hook;
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__free_hook = save_free_hook;
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free_list = NULL;
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for (ar_ptr = &main_arena;; )
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{
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mutex_init (&ar_ptr->mutex);
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if (ar_ptr != save_arena)
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{
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ar_ptr->next_free = free_list;
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free_list = ar_ptr;
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}
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ar_ptr = ar_ptr->next;
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if (ar_ptr == &main_arena)
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break;
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}
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mutex_init (&list_lock);
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atfork_recursive_cntr = 0;
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}
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# else
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# define ptmalloc_unlock_all2 ptmalloc_unlock_all
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# endif
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#endif /* !NO_THREADS */
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/* Initialization routine. */
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#include <string.h>
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extern char **_environ;
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static char *
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internal_function
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next_env_entry (char ***position)
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{
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char **current = *position;
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char *result = NULL;
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while (*current != NULL)
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{
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if (__builtin_expect ((*current)[0] == 'M', 0)
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&& (*current)[1] == 'A'
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&& (*current)[2] == 'L'
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&& (*current)[3] == 'L'
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&& (*current)[4] == 'O'
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&& (*current)[5] == 'C'
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&& (*current)[6] == '_')
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{
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result = &(*current)[7];
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/* Save current position for next visit. */
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*position = ++current;
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break;
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}
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++current;
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}
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return result;
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}
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#ifdef SHARED
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static void *
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__failing_morecore (ptrdiff_t d)
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{
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return (void *) MORECORE_FAILURE;
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}
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extern struct dl_open_hook *_dl_open_hook;
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libc_hidden_proto (_dl_open_hook);
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#endif
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static void
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ptmalloc_init (void)
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{
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if (__malloc_initialized >= 0)
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return;
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__malloc_initialized = 0;
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#ifdef SHARED
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/* In case this libc copy is in a non-default namespace, never use brk.
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Likewise if dlopened from statically linked program. */
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Dl_info di;
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struct link_map *l;
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if (_dl_open_hook != NULL
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|| (_dl_addr (ptmalloc_init, &di, &l, NULL) != 0
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&& l->l_ns != LM_ID_BASE))
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__morecore = __failing_morecore;
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#endif
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tsd_key_create (&arena_key, NULL);
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tsd_setspecific (arena_key, (void *) &main_arena);
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thread_atfork (ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2);
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const char *s = NULL;
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if (__glibc_likely (_environ != NULL))
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{
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char **runp = _environ;
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char *envline;
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while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL,
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0))
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{
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size_t len = strcspn (envline, "=");
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if (envline[len] != '=')
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/* This is a "MALLOC_" variable at the end of the string
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without a '=' character. Ignore it since otherwise we
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will access invalid memory below. */
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continue;
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switch (len)
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{
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case 6:
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if (memcmp (envline, "CHECK_", 6) == 0)
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s = &envline[7];
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break;
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case 8:
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if (!__builtin_expect (__libc_enable_secure, 0))
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{
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if (memcmp (envline, "TOP_PAD_", 8) == 0)
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__libc_mallopt (M_TOP_PAD, atoi (&envline[9]));
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else if (memcmp (envline, "PERTURB_", 8) == 0)
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__libc_mallopt (M_PERTURB, atoi (&envline[9]));
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}
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break;
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case 9:
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if (!__builtin_expect (__libc_enable_secure, 0))
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{
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if (memcmp (envline, "MMAP_MAX_", 9) == 0)
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__libc_mallopt (M_MMAP_MAX, atoi (&envline[10]));
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else if (memcmp (envline, "ARENA_MAX", 9) == 0)
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__libc_mallopt (M_ARENA_MAX, atoi (&envline[10]));
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}
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break;
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case 10:
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if (!__builtin_expect (__libc_enable_secure, 0))
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{
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if (memcmp (envline, "ARENA_TEST", 10) == 0)
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__libc_mallopt (M_ARENA_TEST, atoi (&envline[11]));
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}
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break;
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case 15:
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if (!__builtin_expect (__libc_enable_secure, 0))
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{
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if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
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__libc_mallopt (M_TRIM_THRESHOLD, atoi (&envline[16]));
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else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
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__libc_mallopt (M_MMAP_THRESHOLD, atoi (&envline[16]));
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}
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break;
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|
default:
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break;
|
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}
|
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}
|
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}
|
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if (s && s[0])
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{
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__libc_mallopt (M_CHECK_ACTION, (int) (s[0] - '0'));
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if (check_action != 0)
|
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__malloc_check_init ();
|
|
}
|
|
void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
|
|
if (hook != NULL)
|
|
(*hook)();
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__malloc_initialized = 1;
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|
}
|
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|
|
/* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
|
|
#ifdef thread_atfork_static
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|
thread_atfork_static (ptmalloc_lock_all, ptmalloc_unlock_all, \
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ptmalloc_unlock_all2)
|
|
#endif
|
|
|
|
|
|
|
|
/* Managing heaps and arenas (for concurrent threads) */
|
|
|
|
#if MALLOC_DEBUG > 1
|
|
|
|
/* Print the complete contents of a single heap to stderr. */
|
|
|
|
static void
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dump_heap (heap_info *heap)
|
|
{
|
|
char *ptr;
|
|
mchunkptr p;
|
|
|
|
fprintf (stderr, "Heap %p, size %10lx:\n", heap, (long) heap->size);
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|
ptr = (heap->ar_ptr != (mstate) (heap + 1)) ?
|
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(char *) (heap + 1) : (char *) (heap + 1) + sizeof (struct malloc_state);
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|
p = (mchunkptr) (((unsigned long) ptr + MALLOC_ALIGN_MASK) &
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|
~MALLOC_ALIGN_MASK);
|
|
for (;; )
|
|
{
|
|
fprintf (stderr, "chunk %p size %10lx", p, (long) p->size);
|
|
if (p == top (heap->ar_ptr))
|
|
{
|
|
fprintf (stderr, " (top)\n");
|
|
break;
|
|
}
|
|
else if (p->size == (0 | PREV_INUSE))
|
|
{
|
|
fprintf (stderr, " (fence)\n");
|
|
break;
|
|
}
|
|
fprintf (stderr, "\n");
|
|
p = next_chunk (p);
|
|
}
|
|
}
|
|
#endif /* MALLOC_DEBUG > 1 */
|
|
|
|
/* If consecutive mmap (0, HEAP_MAX_SIZE << 1, ...) calls return decreasing
|
|
addresses as opposed to increasing, new_heap would badly fragment the
|
|
address space. In that case remember the second HEAP_MAX_SIZE part
|
|
aligned to HEAP_MAX_SIZE from last mmap (0, HEAP_MAX_SIZE << 1, ...)
|
|
call (if it is already aligned) and try to reuse it next time. We need
|
|
no locking for it, as kernel ensures the atomicity for us - worst case
|
|
we'll call mmap (addr, HEAP_MAX_SIZE, ...) for some value of addr in
|
|
multiple threads, but only one will succeed. */
|
|
static char *aligned_heap_area;
|
|
|
|
/* Create a new heap. size is automatically rounded up to a multiple
|
|
of the page size. */
|
|
|
|
static heap_info *
|
|
internal_function
|
|
new_heap (size_t size, size_t top_pad)
|
|
{
|
|
size_t pagesize = GLRO (dl_pagesize);
|
|
char *p1, *p2;
|
|
unsigned long ul;
|
|
heap_info *h;
|
|
|
|
if (size + top_pad < HEAP_MIN_SIZE)
|
|
size = HEAP_MIN_SIZE;
|
|
else if (size + top_pad <= HEAP_MAX_SIZE)
|
|
size += top_pad;
|
|
else if (size > HEAP_MAX_SIZE)
|
|
return 0;
|
|
else
|
|
size = HEAP_MAX_SIZE;
|
|
size = ALIGN_UP (size, pagesize);
|
|
|
|
/* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
|
|
No swap space needs to be reserved for the following large
|
|
mapping (on Linux, this is the case for all non-writable mappings
|
|
anyway). */
|
|
p2 = MAP_FAILED;
|
|
if (aligned_heap_area)
|
|
{
|
|
p2 = (char *) MMAP (aligned_heap_area, HEAP_MAX_SIZE, PROT_NONE,
|
|
MAP_NORESERVE);
|
|
aligned_heap_area = NULL;
|
|
if (p2 != MAP_FAILED && ((unsigned long) p2 & (HEAP_MAX_SIZE - 1)))
|
|
{
|
|
__munmap (p2, HEAP_MAX_SIZE);
|
|
p2 = MAP_FAILED;
|
|
}
|
|
}
|
|
if (p2 == MAP_FAILED)
|
|
{
|
|
p1 = (char *) MMAP (0, HEAP_MAX_SIZE << 1, PROT_NONE, MAP_NORESERVE);
|
|
if (p1 != MAP_FAILED)
|
|
{
|
|
p2 = (char *) (((unsigned long) p1 + (HEAP_MAX_SIZE - 1))
|
|
& ~(HEAP_MAX_SIZE - 1));
|
|
ul = p2 - p1;
|
|
if (ul)
|
|
__munmap (p1, ul);
|
|
else
|
|
aligned_heap_area = p2 + HEAP_MAX_SIZE;
|
|
__munmap (p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
|
|
}
|
|
else
|
|
{
|
|
/* Try to take the chance that an allocation of only HEAP_MAX_SIZE
|
|
is already aligned. */
|
|
p2 = (char *) MMAP (0, HEAP_MAX_SIZE, PROT_NONE, MAP_NORESERVE);
|
|
if (p2 == MAP_FAILED)
|
|
return 0;
|
|
|
|
if ((unsigned long) p2 & (HEAP_MAX_SIZE - 1))
|
|
{
|
|
__munmap (p2, HEAP_MAX_SIZE);
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
if (__mprotect (p2, size, PROT_READ | PROT_WRITE) != 0)
|
|
{
|
|
__munmap (p2, HEAP_MAX_SIZE);
|
|
return 0;
|
|
}
|
|
h = (heap_info *) p2;
|
|
h->size = size;
|
|
h->mprotect_size = size;
|
|
LIBC_PROBE (memory_heap_new, 2, h, h->size);
|
|
return h;
|
|
}
|
|
|
|
/* Grow a heap. size is automatically rounded up to a
|
|
multiple of the page size. */
|
|
|
|
static int
|
|
grow_heap (heap_info *h, long diff)
|
|
{
|
|
size_t pagesize = GLRO (dl_pagesize);
|
|
long new_size;
|
|
|
|
diff = ALIGN_UP (diff, pagesize);
|
|
new_size = (long) h->size + diff;
|
|
if ((unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE)
|
|
return -1;
|
|
|
|
if ((unsigned long) new_size > h->mprotect_size)
|
|
{
|
|
if (__mprotect ((char *) h + h->mprotect_size,
|
|
(unsigned long) new_size - h->mprotect_size,
|
|
PROT_READ | PROT_WRITE) != 0)
|
|
return -2;
|
|
|
|
h->mprotect_size = new_size;
|
|
}
|
|
|
|
h->size = new_size;
|
|
LIBC_PROBE (memory_heap_more, 2, h, h->size);
|
|
return 0;
|
|
}
|
|
|
|
/* Shrink a heap. */
|
|
|
|
static int
|
|
shrink_heap (heap_info *h, long diff)
|
|
{
|
|
long new_size;
|
|
|
|
new_size = (long) h->size - diff;
|
|
if (new_size < (long) sizeof (*h))
|
|
return -1;
|
|
|
|
/* Try to re-map the extra heap space freshly to save memory, and make it
|
|
inaccessible. See malloc-sysdep.h to know when this is true. */
|
|
if (__glibc_unlikely (check_may_shrink_heap ()))
|
|
{
|
|
if ((char *) MMAP ((char *) h + new_size, diff, PROT_NONE,
|
|
MAP_FIXED) == (char *) MAP_FAILED)
|
|
return -2;
|
|
|
|
h->mprotect_size = new_size;
|
|
}
|
|
else
|
|
__madvise ((char *) h + new_size, diff, MADV_DONTNEED);
|
|
/*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/
|
|
|
|
h->size = new_size;
|
|
LIBC_PROBE (memory_heap_less, 2, h, h->size);
|
|
return 0;
|
|
}
|
|
|
|
/* Delete a heap. */
|
|
|
|
#define delete_heap(heap) \
|
|
do { \
|
|
if ((char *) (heap) + HEAP_MAX_SIZE == aligned_heap_area) \
|
|
aligned_heap_area = NULL; \
|
|
__munmap ((char *) (heap), HEAP_MAX_SIZE); \
|
|
} while (0)
|
|
|
|
static int
|
|
internal_function
|
|
heap_trim (heap_info *heap, size_t pad)
|
|
{
|
|
mstate ar_ptr = heap->ar_ptr;
|
|
unsigned long pagesz = GLRO (dl_pagesize);
|
|
mchunkptr top_chunk = top (ar_ptr), p, bck, fwd;
|
|
heap_info *prev_heap;
|
|
long new_size, top_size, top_area, extra, prev_size, misalign;
|
|
|
|
/* Can this heap go away completely? */
|
|
while (top_chunk == chunk_at_offset (heap, sizeof (*heap)))
|
|
{
|
|
prev_heap = heap->prev;
|
|
prev_size = prev_heap->size - (MINSIZE - 2 * SIZE_SZ);
|
|
p = chunk_at_offset (prev_heap, prev_size);
|
|
/* fencepost must be properly aligned. */
|
|
misalign = ((long) p) & MALLOC_ALIGN_MASK;
|
|
p = chunk_at_offset (prev_heap, prev_size - misalign);
|
|
assert (p->size == (0 | PREV_INUSE)); /* must be fencepost */
|
|
p = prev_chunk (p);
|
|
new_size = chunksize (p) + (MINSIZE - 2 * SIZE_SZ) + misalign;
|
|
assert (new_size > 0 && new_size < (long) (2 * MINSIZE));
|
|
if (!prev_inuse (p))
|
|
new_size += p->prev_size;
|
|
assert (new_size > 0 && new_size < HEAP_MAX_SIZE);
|
|
if (new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
|
|
break;
|
|
ar_ptr->system_mem -= heap->size;
|
|
arena_mem -= heap->size;
|
|
LIBC_PROBE (memory_heap_free, 2, heap, heap->size);
|
|
delete_heap (heap);
|
|
heap = prev_heap;
|
|
if (!prev_inuse (p)) /* consolidate backward */
|
|
{
|
|
p = prev_chunk (p);
|
|
unlink (ar_ptr, p, bck, fwd);
|
|
}
|
|
assert (((unsigned long) ((char *) p + new_size) & (pagesz - 1)) == 0);
|
|
assert (((char *) p + new_size) == ((char *) heap + heap->size));
|
|
top (ar_ptr) = top_chunk = p;
|
|
set_head (top_chunk, new_size | PREV_INUSE);
|
|
/*check_chunk(ar_ptr, top_chunk);*/
|
|
}
|
|
|
|
/* Uses similar logic for per-thread arenas as the main arena with systrim
|
|
by preserving the top pad and at least a page. */
|
|
top_size = chunksize (top_chunk);
|
|
top_area = top_size - MINSIZE - 1;
|
|
if (top_area <= pad)
|
|
return 0;
|
|
|
|
extra = ALIGN_DOWN(top_area - pad, pagesz);
|
|
if ((unsigned long) extra < mp_.trim_threshold)
|
|
return 0;
|
|
|
|
/* Try to shrink. */
|
|
if (shrink_heap (heap, extra) != 0)
|
|
return 0;
|
|
|
|
ar_ptr->system_mem -= extra;
|
|
arena_mem -= extra;
|
|
|
|
/* Success. Adjust top accordingly. */
|
|
set_head (top_chunk, (top_size - extra) | PREV_INUSE);
|
|
/*check_chunk(ar_ptr, top_chunk);*/
|
|
return 1;
|
|
}
|
|
|
|
/* Create a new arena with initial size "size". */
|
|
|
|
static mstate
|
|
_int_new_arena (size_t size)
|
|
{
|
|
mstate a;
|
|
heap_info *h;
|
|
char *ptr;
|
|
unsigned long misalign;
|
|
|
|
h = new_heap (size + (sizeof (*h) + sizeof (*a) + MALLOC_ALIGNMENT),
|
|
mp_.top_pad);
|
|
if (!h)
|
|
{
|
|
/* Maybe size is too large to fit in a single heap. So, just try
|
|
to create a minimally-sized arena and let _int_malloc() attempt
|
|
to deal with the large request via mmap_chunk(). */
|
|
h = new_heap (sizeof (*h) + sizeof (*a) + MALLOC_ALIGNMENT, mp_.top_pad);
|
|
if (!h)
|
|
return 0;
|
|
}
|
|
a = h->ar_ptr = (mstate) (h + 1);
|
|
malloc_init_state (a);
|
|
/*a->next = NULL;*/
|
|
a->system_mem = a->max_system_mem = h->size;
|
|
arena_mem += h->size;
|
|
|
|
/* Set up the top chunk, with proper alignment. */
|
|
ptr = (char *) (a + 1);
|
|
misalign = (unsigned long) chunk2mem (ptr) & MALLOC_ALIGN_MASK;
|
|
if (misalign > 0)
|
|
ptr += MALLOC_ALIGNMENT - misalign;
|
|
top (a) = (mchunkptr) ptr;
|
|
set_head (top (a), (((char *) h + h->size) - ptr) | PREV_INUSE);
|
|
|
|
LIBC_PROBE (memory_arena_new, 2, a, size);
|
|
tsd_setspecific (arena_key, (void *) a);
|
|
mutex_init (&a->mutex);
|
|
(void) mutex_lock (&a->mutex);
|
|
|
|
(void) mutex_lock (&list_lock);
|
|
|
|
/* Add the new arena to the global list. */
|
|
a->next = main_arena.next;
|
|
atomic_write_barrier ();
|
|
main_arena.next = a;
|
|
|
|
(void) mutex_unlock (&list_lock);
|
|
|
|
return a;
|
|
}
|
|
|
|
|
|
static mstate
|
|
get_free_list (void)
|
|
{
|
|
mstate result = free_list;
|
|
if (result != NULL)
|
|
{
|
|
(void) mutex_lock (&list_lock);
|
|
result = free_list;
|
|
if (result != NULL)
|
|
free_list = result->next_free;
|
|
(void) mutex_unlock (&list_lock);
|
|
|
|
if (result != NULL)
|
|
{
|
|
LIBC_PROBE (memory_arena_reuse_free_list, 1, result);
|
|
(void) mutex_lock (&result->mutex);
|
|
tsd_setspecific (arena_key, (void *) result);
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/* Lock and return an arena that can be reused for memory allocation.
|
|
Avoid AVOID_ARENA as we have already failed to allocate memory in
|
|
it and it is currently locked. */
|
|
static mstate
|
|
reused_arena (mstate avoid_arena)
|
|
{
|
|
mstate result;
|
|
static mstate next_to_use;
|
|
if (next_to_use == NULL)
|
|
next_to_use = &main_arena;
|
|
|
|
result = next_to_use;
|
|
do
|
|
{
|
|
if (!arena_is_corrupt (result) && !mutex_trylock (&result->mutex))
|
|
goto out;
|
|
|
|
result = result->next;
|
|
}
|
|
while (result != next_to_use);
|
|
|
|
/* Avoid AVOID_ARENA as we have already failed to allocate memory
|
|
in that arena and it is currently locked. */
|
|
if (result == avoid_arena)
|
|
result = result->next;
|
|
|
|
/* Make sure that the arena we get is not corrupted. */
|
|
mstate begin = result;
|
|
while (arena_is_corrupt (result) || result == avoid_arena)
|
|
{
|
|
result = result->next;
|
|
if (result == begin)
|
|
break;
|
|
}
|
|
|
|
/* We could not find any arena that was either not corrupted or not the one
|
|
we wanted to avoid. */
|
|
if (result == begin || result == avoid_arena)
|
|
return NULL;
|
|
|
|
/* No arena available without contention. Wait for the next in line. */
|
|
LIBC_PROBE (memory_arena_reuse_wait, 3, &result->mutex, result, avoid_arena);
|
|
(void) mutex_lock (&result->mutex);
|
|
|
|
out:
|
|
LIBC_PROBE (memory_arena_reuse, 2, result, avoid_arena);
|
|
tsd_setspecific (arena_key, (void *) result);
|
|
next_to_use = result->next;
|
|
|
|
return result;
|
|
}
|
|
|
|
static mstate
|
|
internal_function
|
|
arena_get2 (mstate a_tsd, size_t size, mstate avoid_arena)
|
|
{
|
|
mstate a;
|
|
|
|
static size_t narenas_limit;
|
|
|
|
a = get_free_list ();
|
|
if (a == NULL)
|
|
{
|
|
/* Nothing immediately available, so generate a new arena. */
|
|
if (narenas_limit == 0)
|
|
{
|
|
if (mp_.arena_max != 0)
|
|
narenas_limit = mp_.arena_max;
|
|
else if (narenas > mp_.arena_test)
|
|
{
|
|
int n = __get_nprocs ();
|
|
|
|
if (n >= 1)
|
|
narenas_limit = NARENAS_FROM_NCORES (n);
|
|
else
|
|
/* We have no information about the system. Assume two
|
|
cores. */
|
|
narenas_limit = NARENAS_FROM_NCORES (2);
|
|
}
|
|
}
|
|
repeat:;
|
|
size_t n = narenas;
|
|
/* NB: the following depends on the fact that (size_t)0 - 1 is a
|
|
very large number and that the underflow is OK. If arena_max
|
|
is set the value of arena_test is irrelevant. If arena_test
|
|
is set but narenas is not yet larger or equal to arena_test
|
|
narenas_limit is 0. There is no possibility for narenas to
|
|
be too big for the test to always fail since there is not
|
|
enough address space to create that many arenas. */
|
|
if (__glibc_unlikely (n <= narenas_limit - 1))
|
|
{
|
|
if (catomic_compare_and_exchange_bool_acq (&narenas, n + 1, n))
|
|
goto repeat;
|
|
a = _int_new_arena (size);
|
|
if (__glibc_unlikely (a == NULL))
|
|
catomic_decrement (&narenas);
|
|
}
|
|
else
|
|
a = reused_arena (avoid_arena);
|
|
}
|
|
return a;
|
|
}
|
|
|
|
/* If we don't have the main arena, then maybe the failure is due to running
|
|
out of mmapped areas, so we can try allocating on the main arena.
|
|
Otherwise, it is likely that sbrk() has failed and there is still a chance
|
|
to mmap(), so try one of the other arenas. */
|
|
static mstate
|
|
arena_get_retry (mstate ar_ptr, size_t bytes)
|
|
{
|
|
LIBC_PROBE (memory_arena_retry, 2, bytes, ar_ptr);
|
|
if (ar_ptr != &main_arena)
|
|
{
|
|
(void) mutex_unlock (&ar_ptr->mutex);
|
|
ar_ptr = &main_arena;
|
|
(void) mutex_lock (&ar_ptr->mutex);
|
|
}
|
|
else
|
|
{
|
|
/* Grab ar_ptr->next prior to releasing its lock. */
|
|
mstate prev = ar_ptr->next ? ar_ptr : 0;
|
|
(void) mutex_unlock (&ar_ptr->mutex);
|
|
ar_ptr = arena_get2 (prev, bytes, ar_ptr);
|
|
}
|
|
|
|
return ar_ptr;
|
|
}
|
|
|
|
static void __attribute__ ((section ("__libc_thread_freeres_fn")))
|
|
arena_thread_freeres (void)
|
|
{
|
|
void *vptr = NULL;
|
|
mstate a = tsd_getspecific (arena_key, vptr);
|
|
tsd_setspecific (arena_key, NULL);
|
|
|
|
if (a != NULL)
|
|
{
|
|
(void) mutex_lock (&list_lock);
|
|
a->next_free = free_list;
|
|
free_list = a;
|
|
(void) mutex_unlock (&list_lock);
|
|
}
|
|
}
|
|
text_set_element (__libc_thread_subfreeres, arena_thread_freeres);
|
|
|
|
/*
|
|
* Local variables:
|
|
* c-basic-offset: 2
|
|
* End:
|
|
*/
|