* include/stdio.h (__builtin_fwrite, __builtin_fwrite_unlocked):
[glibc/pb-stable.git] / sysdeps / i386 / backtrace.c
blobcf3b2719b9e95fef1dc237e8e6429a81581294af
1 /* Return backtrace of current program state.
2 Copyright (C) 1998, 2000, 2003-2005, 2007 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 02111-1307 USA. */
21 #include <bits/libc-lock.h>
22 #include <dlfcn.h>
23 #include <execinfo.h>
24 #include <stdlib.h>
25 #include <unwind.h>
27 struct trace_arg
29 void **array;
30 int cnt, size;
31 void *lastebp, *lastesp;
34 #ifdef SHARED
35 static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
36 static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
37 static _Unwind_Ptr (*unwind_getcfa) (struct _Unwind_Context *);
38 static _Unwind_Ptr (*unwind_getgr) (struct _Unwind_Context *, int);
39 static void *libgcc_handle;
41 static void
42 init (void)
44 libgcc_handle = __libc_dlopen ("libgcc_s.so.1");
46 if (libgcc_handle == NULL)
47 return;
49 unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
50 unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
51 unwind_getcfa = __libc_dlsym (libgcc_handle, "_Unwind_GetCFA");
52 unwind_getgr = __libc_dlsym (libgcc_handle, "_Unwind_GetGR");
53 if (unwind_getip == NULL || unwind_getgr == NULL || unwind_getcfa == NULL)
55 unwind_backtrace = NULL;
56 __libc_dlclose (libgcc_handle);
57 libgcc_handle = NULL;
60 #else
61 # define unwind_backtrace _Unwind_Backtrace
62 # define unwind_getip _Unwind_GetIP
63 # define unwind_getcfa _Unwind_GetCFA
64 # define unwind_getgr _Unwind_GetGR
65 #endif
67 static _Unwind_Reason_Code
68 backtrace_helper (struct _Unwind_Context *ctx, void *a)
70 struct trace_arg *arg = a;
72 /* We are first called with address in the __backtrace function.
73 Skip it. */
74 if (arg->cnt != -1)
75 arg->array[arg->cnt] = (void *) unwind_getip (ctx);
76 if (++arg->cnt == arg->size)
77 return _URC_END_OF_STACK;
79 /* %ebp is DWARF2 register 5 on IA-32. */
80 arg->lastebp = (void *) unwind_getgr (ctx, 5);
81 arg->lastesp = (void *) unwind_getcfa (ctx);
82 return _URC_NO_REASON;
86 /* This is a global variable set at program start time. It marks the
87 highest used stack address. */
88 extern void *__libc_stack_end;
91 /* This is the stack layout we see with every stack frame
92 if not compiled without frame pointer.
94 +-----------------+ +-----------------+
95 %ebp -> | %ebp last frame--------> | %ebp last frame--->...
96 | | | |
97 | return address | | return address |
98 +-----------------+ +-----------------+
100 First try as far to get as far as possible using
101 _Unwind_Backtrace which handles -fomit-frame-pointer
102 as well, but requires .eh_frame info. Then fall back to
103 walking the stack manually. */
105 struct layout
107 struct layout *ebp;
108 void *ret;
113 __backtrace (array, size)
114 void **array;
115 int size;
117 struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
118 #ifdef SHARED
119 __libc_once_define (static, once);
121 __libc_once (once, init);
122 if (unwind_backtrace == NULL)
123 return 0;
124 #endif
126 if (size >= 1)
127 unwind_backtrace (backtrace_helper, &arg);
129 if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
130 --arg.cnt;
131 else if (arg.cnt < size)
133 struct layout *ebp = (struct layout *) arg.lastebp;
135 while (arg.cnt < size)
137 /* Check for out of range. */
138 if ((void *) ebp < arg.lastesp || (void *) ebp > __libc_stack_end
139 || ((long) ebp & 3))
140 break;
142 array[arg.cnt++] = ebp->ret;
143 ebp = ebp->ebp;
146 return arg.cnt != -1 ? arg.cnt : 0;
148 weak_alias (__backtrace, backtrace)
149 libc_hidden_def (__backtrace)
152 #ifdef SHARED
153 /* Free all resources if necessary. */
154 libc_freeres_fn (free_mem)
156 unwind_backtrace = NULL;
157 if (libgcc_handle != NULL)
159 __libc_dlclose (libgcc_handle);
160 libgcc_handle = NULL;
163 #endif