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e19af3803b
fclose will call free, invoking its hook, then fprintf which would indirectly try to allocate a buffer, and this can cause malloc to be used (thus its hook to be invoked) if libio uses malloc instead of mmap; given any malloc/free hook locks the internal lock, this leads to a deadlock. To prevent this hook roundtrip at muntrace, first unset MALLSTREAM and the hooks, and only after that close the trace file.
380 lines
9.6 KiB
C
380 lines
9.6 KiB
C
/* More debugging hooks for `malloc'.
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Copyright (C) 1991-2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Written April 2, 1991 by John Gilmore of Cygnus Support.
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Based on mcheck.c by Mike Haertel.
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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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<http://www.gnu.org/licenses/>. */
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#ifndef _MALLOC_INTERNAL
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#define _MALLOC_INTERNAL
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#include <malloc.h>
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#include <mcheck.h>
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#include <bits/libc-lock.h>
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#endif
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#include <dlfcn.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <_itoa.h>
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#include <libc-internal.h>
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#include <libio/iolibio.h>
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#define setvbuf(s, b, f, l) _IO_setvbuf (s, b, f, l)
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#define fwrite(buf, size, count, fp) _IO_fwrite (buf, size, count, fp)
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#include <kernel-features.h>
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#ifndef attribute_hidden
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# define attribute_hidden
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#endif
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#define TRACE_BUFFER_SIZE 512
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static FILE *mallstream;
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static const char mallenv[]= "MALLOC_TRACE";
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static char *malloc_trace_buffer;
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__libc_lock_define_initialized (static, lock);
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/* Address to breakpoint on accesses to... */
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__ptr_t mallwatch;
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/* Old hook values. */
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static void (*tr_old_free_hook) (__ptr_t ptr, const __ptr_t);
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static __ptr_t (*tr_old_malloc_hook) (__malloc_size_t size, const __ptr_t);
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static __ptr_t (*tr_old_realloc_hook) (__ptr_t ptr, __malloc_size_t size,
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const __ptr_t);
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static __ptr_t (*tr_old_memalign_hook) (__malloc_size_t __alignment,
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__malloc_size_t __size,
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const __ptr_t);
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/* This function is called when the block being alloc'd, realloc'd, or
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freed has an address matching the variable "mallwatch". In a debugger,
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set "mallwatch" to the address of interest, then put a breakpoint on
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tr_break. */
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extern void tr_break (void) __THROW;
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libc_hidden_proto (tr_break)
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void
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tr_break ()
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{
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}
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libc_hidden_def (tr_break)
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static void tr_where (const __ptr_t, Dl_info *) __THROW internal_function;
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static void
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internal_function
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tr_where (caller, info)
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const __ptr_t caller;
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Dl_info *info;
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{
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if (caller != NULL)
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{
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if (info != NULL)
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{
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char *buf = (char *) "";
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if (info->dli_sname != NULL)
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{
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size_t len = strlen (info->dli_sname);
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buf = alloca (len + 6 + 2 * sizeof (void *));
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buf[0] = '(';
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__stpcpy (_fitoa (caller >= (const __ptr_t) info->dli_saddr
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? caller - (const __ptr_t) info->dli_saddr
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: (const __ptr_t) info->dli_saddr - caller,
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__stpcpy (__mempcpy (buf + 1, info->dli_sname,
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len),
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caller >= (__ptr_t) info->dli_saddr
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? "+0x" : "-0x"),
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16, 0),
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")");
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}
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fprintf (mallstream, "@ %s%s%s[%p] ",
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info->dli_fname ?: "", info->dli_fname ? ":" : "",
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buf, caller);
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}
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else
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fprintf (mallstream, "@ [%p] ", caller);
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}
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}
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static Dl_info *
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lock_and_info (const __ptr_t caller, Dl_info *mem)
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{
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if (caller == NULL)
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return NULL;
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Dl_info *res = _dl_addr (caller, mem, NULL, NULL) ? mem : NULL;
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__libc_lock_lock (lock);
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return res;
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}
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static void tr_freehook (__ptr_t, const __ptr_t) __THROW;
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static void
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tr_freehook (ptr, caller)
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__ptr_t ptr;
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const __ptr_t caller;
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{
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if (ptr == NULL)
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return;
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Dl_info mem;
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Dl_info *info = lock_and_info (caller, &mem);
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tr_where (caller, info);
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/* Be sure to print it first. */
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fprintf (mallstream, "- %p\n", ptr);
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if (ptr == mallwatch)
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{
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__libc_lock_unlock (lock);
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tr_break ();
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__libc_lock_lock (lock);
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}
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__free_hook = tr_old_free_hook;
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if (tr_old_free_hook != NULL)
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(*tr_old_free_hook) (ptr, caller);
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else
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free (ptr);
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__free_hook = tr_freehook;
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__libc_lock_unlock (lock);
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}
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static __ptr_t tr_mallochook (__malloc_size_t, const __ptr_t) __THROW;
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static __ptr_t
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tr_mallochook (size, caller)
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__malloc_size_t size;
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const __ptr_t caller;
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{
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__ptr_t hdr;
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Dl_info mem;
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Dl_info *info = lock_and_info (caller, &mem);
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__malloc_hook = tr_old_malloc_hook;
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if (tr_old_malloc_hook != NULL)
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hdr = (__ptr_t) (*tr_old_malloc_hook) (size, caller);
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else
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hdr = (__ptr_t) malloc (size);
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__malloc_hook = tr_mallochook;
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tr_where (caller, info);
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/* We could be printing a NULL here; that's OK. */
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fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
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__libc_lock_unlock (lock);
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if (hdr == mallwatch)
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tr_break ();
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return hdr;
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}
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static __ptr_t tr_reallochook (__ptr_t, __malloc_size_t, const __ptr_t)
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__THROW;
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static __ptr_t
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tr_reallochook (ptr, size, caller)
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__ptr_t ptr;
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__malloc_size_t size;
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const __ptr_t caller;
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{
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__ptr_t hdr;
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if (ptr == mallwatch)
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tr_break ();
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Dl_info mem;
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Dl_info *info = lock_and_info (caller, &mem);
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__free_hook = tr_old_free_hook;
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__malloc_hook = tr_old_malloc_hook;
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__realloc_hook = tr_old_realloc_hook;
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if (tr_old_realloc_hook != NULL)
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hdr = (__ptr_t) (*tr_old_realloc_hook) (ptr, size, caller);
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else
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hdr = (__ptr_t) realloc (ptr, size);
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__free_hook = tr_freehook;
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__malloc_hook = tr_mallochook;
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__realloc_hook = tr_reallochook;
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tr_where (caller, info);
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if (hdr == NULL)
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/* Failed realloc. */
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fprintf (mallstream, "! %p %#lx\n", ptr, (unsigned long int) size);
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else if (ptr == NULL)
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fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
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else
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{
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fprintf (mallstream, "< %p\n", ptr);
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tr_where (caller, info);
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fprintf (mallstream, "> %p %#lx\n", hdr, (unsigned long int) size);
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}
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__libc_lock_unlock (lock);
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if (hdr == mallwatch)
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tr_break ();
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return hdr;
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}
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static __ptr_t tr_memalignhook (__malloc_size_t, __malloc_size_t,
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const __ptr_t) __THROW;
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static __ptr_t
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tr_memalignhook (alignment, size, caller)
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__malloc_size_t alignment, size;
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const __ptr_t caller;
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{
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__ptr_t hdr;
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Dl_info mem;
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Dl_info *info = lock_and_info (caller, &mem);
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__memalign_hook = tr_old_memalign_hook;
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__malloc_hook = tr_old_malloc_hook;
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if (tr_old_memalign_hook != NULL)
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hdr = (__ptr_t) (*tr_old_memalign_hook) (alignment, size, caller);
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else
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hdr = (__ptr_t) memalign (alignment, size);
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__memalign_hook = tr_memalignhook;
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__malloc_hook = tr_mallochook;
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tr_where (caller, info);
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/* We could be printing a NULL here; that's OK. */
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fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
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__libc_lock_unlock (lock);
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if (hdr == mallwatch)
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tr_break ();
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return hdr;
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}
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#ifdef _LIBC
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/* This function gets called to make sure all memory the library
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allocates get freed and so does not irritate the user when studying
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the mtrace output. */
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static void __libc_freeres_fn_section
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release_libc_mem (void)
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{
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/* Only call the free function if we still are running in mtrace mode. */
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if (mallstream != NULL)
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__libc_freeres ();
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}
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#endif
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/* We enable tracing if either the environment variable MALLOC_TRACE
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is set, or if the variable mallwatch has been patched to an address
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that the debugging user wants us to stop on. When patching mallwatch,
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don't forget to set a breakpoint on tr_break! */
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void
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mtrace ()
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{
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#ifdef _LIBC
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static int added_atexit_handler;
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#endif
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char *mallfile;
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/* Don't panic if we're called more than once. */
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if (mallstream != NULL)
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return;
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#ifdef _LIBC
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/* When compiling the GNU libc we use the secure getenv function
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which prevents the misuse in case of SUID or SGID enabled
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programs. */
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mallfile = __libc_secure_getenv (mallenv);
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#else
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mallfile = getenv (mallenv);
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#endif
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if (mallfile != NULL || mallwatch != NULL)
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{
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char *mtb = malloc (TRACE_BUFFER_SIZE);
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if (mtb == NULL)
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return;
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mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "wce");
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if (mallstream != NULL)
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{
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#ifndef __ASSUME_O_CLOEXEC
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/* Make sure we close the file descriptor on exec. */
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int flags = __fcntl (fileno (mallstream), F_GETFD, 0);
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if (flags >= 0)
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{
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flags |= FD_CLOEXEC;
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__fcntl (fileno (mallstream), F_SETFD, flags);
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}
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#endif
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/* Be sure it doesn't malloc its buffer! */
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malloc_trace_buffer = mtb;
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setvbuf (mallstream, malloc_trace_buffer, _IOFBF, TRACE_BUFFER_SIZE);
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fprintf (mallstream, "= Start\n");
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tr_old_free_hook = __free_hook;
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__free_hook = tr_freehook;
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tr_old_malloc_hook = __malloc_hook;
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__malloc_hook = tr_mallochook;
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tr_old_realloc_hook = __realloc_hook;
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__realloc_hook = tr_reallochook;
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tr_old_memalign_hook = __memalign_hook;
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__memalign_hook = tr_memalignhook;
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#ifdef _LIBC
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if (!added_atexit_handler)
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{
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extern void *__dso_handle __attribute__ ((__weak__));
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added_atexit_handler = 1;
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__cxa_atexit ((void (*) (void *)) release_libc_mem, NULL,
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&__dso_handle ? __dso_handle : NULL);
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}
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#endif
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}
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else
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free (mtb);
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}
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}
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void
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muntrace ()
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{
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if (mallstream == NULL)
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return;
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/* Do the reverse of what done in mtrace: first reset the hooks and
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MALLSTREAM, and only after that write the trailer and close the
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file. */
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FILE *f = mallstream;
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mallstream = NULL;
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__free_hook = tr_old_free_hook;
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__malloc_hook = tr_old_malloc_hook;
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__realloc_hook = tr_old_realloc_hook;
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__memalign_hook = tr_old_memalign_hook;
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fprintf (f, "= End\n");
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fclose (f);
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}
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