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//
// GTMStackTrace.m
//
// Copyright 2007-2008 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
#include <stdlib.h>
#include <dlfcn.h>
#include <mach-o/nlist.h>
#include "GTMStackTrace.h"
// Structure representing a small portion of a stack, starting from the saved
// frame pointer, and continuing through the saved program counter.
struct StackFrame {
void *saved_fp;
#if defined (__ppc__) || defined(__ppc64__)
void *padding;
#endif
void *saved_pc;
};
// __builtin_frame_address(0) is a gcc builtin that returns a pointer to the
// current frame pointer. We then use the frame pointer to walk the stack
// picking off program counters and other saved frame pointers. This works
// great on i386, but PPC requires a little more work because the PC (or link
// register) isn't always stored on the stack.
//
int GTMGetStackProgramCounters(void *outPcs[], int size) {
if (!outPcs || (size < 1)) return 0;
struct StackFrame *fp;
#if defined (__ppc__) || defined(__ppc64__)
outPcs[0] = __builtin_return_address(0);
fp = (struct StackFrame *)__builtin_frame_address(1);
#elif defined (__i386__) || defined(__x86_64__)
fp = (struct StackFrame *)__builtin_frame_address(0);
#else
#error architecture not supported
#endif
int level = 0;
while (level < size) {
if (fp == NULL) {
level--;
break;
}
outPcs[level] = fp->saved_pc;
level++;
fp = (struct StackFrame *)fp->saved_fp;
}
return level;
}
CFStringRef GTMStackTraceCreate(void) {
// The maximum number of stack frames that we will walk. We limit this so
// that super-duper recursive functions (or bugs) don't send us for an
// infinite loop.
static const int kMaxStackTraceDepth = 100;
void *pcs[kMaxStackTraceDepth];
int depth = kMaxStackTraceDepth;
depth = GTMGetStackProgramCounters(pcs, depth);
CFMutableStringRef trace = CFStringCreateMutable(kCFAllocatorDefault, 0);
for (int i = 0; i < depth; i++) {
Dl_info info = { NULL, NULL, NULL, NULL };
dladdr(pcs[i], &info);
const char *symbol = info.dli_sname;
const char *fname = info.dli_fname;
CFStringAppendFormat(trace, NULL,
CFSTR("#%-2d 0x%08lx %s () [%s]\n"),
i, pcs[i],
(symbol ? symbol : "??"),
(fname ? fname : "??"));
}
return trace;
}
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