backtrace.c

/*
 * Copyright (c) 2007, 2008 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

#include <TargetConditionals.h>
#include <mach/vm_types.h>
#include <sys/uio.h>
#include <errno.h>
#include <mach-o/dyld_priv.h>
#include <stdint.h>
#include <stdlib.h>
#include <uuid/uuid.h>
#include "execinfo.h"

extern void _thread_stack_pcs(vm_address_t *buffer, unsigned max,
		unsigned *nb, unsigned skip, void *startfp);

int backtrace(void** buffer, int size) {
	unsigned int num_frames;
	_thread_stack_pcs((vm_address_t*)buffer, size, &num_frames, 1, NULL);
	while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
	return num_frames;
}

extern unsigned int _thread_stack_async_pcs(vm_address_t *buffer, unsigned max,
		unsigned *nb, unsigned skip, void *startfp);

size_t backtrace_async(void** buffer, size_t size, uint32_t *task_id_ptr) {
	unsigned int num_frames;
	uint32_t task_id = _thread_stack_async_pcs((vm_address_t*)buffer, size, &num_frames, 1, NULL);
	while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
	if (task_id_ptr) *task_id_ptr = task_id;
	return num_frames;
}


int
backtrace_from_fp(void *startfp, void **buffer, int size)
{
	unsigned int num_frames;
	_thread_stack_pcs((vm_address_t*)buffer, size, &num_frames, 1, startfp);
	while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
	return num_frames;
}

#if !TARGET_OS_DRIVERKIT

#include <dlfcn.h>
#include <stdio.h>
#include <string.h>
#include "stack_logging.h"

#if __LP64__
#define _BACKTRACE_FORMAT "%-4d%-35s 0x%016lx %s + %lu"
#define _BACKTRACE_FORMAT_SIZE 83 /* %lu can take up to 20, does not include %s, includes NUL */
#define _BACKTRACE_ADDRESS_LEN 18 /* 0x + 16 (no NUL) */
#else
#define _BACKTRACE_FORMAT "%-4d%-35s 0x%08lx %s + %lu"
#define _BACKTRACE_FORMAT_SIZE 65 /* %lu can take up to 10, does not include %s, includes NUL */
#define _BACKTRACE_ADDRESS_LEN 10 /* 0x + 8 (no NUL) */
#endif
#define _BACKTRACE_IMAGE_LEN 35
#define _BACKTRACE_UUID_LEN 36

static int _backtrace_snprintf(char* buf, size_t size, int frame, const void* addr, const Dl_info* info) {
	char addrbuf[_BACKTRACE_ADDRESS_LEN + 1];
	char imagebuf[_BACKTRACE_IMAGE_LEN + 1];
	uuid_string_t uuidbuf;
	const char* image = "???";
	const char* symbol = "0x0";
	uintptr_t symbol_offset = 0;

	if (info->dli_fname) {
		const char *tmp = strrchr(info->dli_fname, '/');
		if (tmp == NULL) {
			strlcpy(imagebuf, info->dli_fname, sizeof(imagebuf));
		} else {
			strlcpy(imagebuf, tmp + 1, sizeof(imagebuf));
		}
		image = imagebuf;
	}

	if (info->dli_sname) {
		uuid_t uuid;
		if (strcmp(info->dli_sname, "<redacted>") == 0 &&
				_dyld_get_image_uuid(info->dli_fbase, uuid)) {
			/*
			 * dyld returns <redacted> when the symbol name has been elided in
			 * the shared cache.  To enable symbolication later, we provide the
			 * UUID and UUID-offset instead.
			 */
			uuid_unparse(uuid, uuidbuf);
			symbol = uuidbuf;
			symbol_offset = (uintptr_t)addr - (uintptr_t)info->dli_fbase;
		} else {
			symbol = info->dli_sname;
			symbol_offset = (uintptr_t)addr - (uintptr_t)info->dli_saddr;
		}
	} else if (info->dli_fname) {
		symbol = image;
		symbol_offset = (uintptr_t)addr - (uintptr_t)info->dli_fbase;
	} else if (0 < snprintf(addrbuf, sizeof(addrbuf), "0x%lx",
			(uintptr_t)info->dli_saddr)) {
		symbol = addrbuf;
		symbol_offset = (uintptr_t)addr - (uintptr_t)info->dli_saddr;
	} else {
		symbol_offset = (uintptr_t)addr;
	}

	return snprintf(buf, size, _BACKTRACE_FORMAT, frame, image,
			(uintptr_t)addr, symbol, symbol_offset);
}

static size_t symbol_length(Dl_info *info)
{
	if (info->dli_sname) {
		if (strcmp(info->dli_sname, "<redacted>") == 0) {
			return _BACKTRACE_UUID_LEN;
		} else {
			return strlen(info->dli_sname);
		}
	} else if (info->dli_fname) {
		const char *tmp = strrchr(info->dli_fname, '/');
		if (tmp == NULL) {
			return strlen(info->dli_fname);
		} else {
			return strlen(tmp + 1);
		}
	} else {
		return _BACKTRACE_ADDRESS_LEN;
	}
}

char** backtrace_symbols(void* const* buffer, int size) {
	int i;
	size_t total_bytes;
	char** result;
	char** ptrs;
	intptr_t strs, end;
	Dl_info* info = calloc(size, sizeof (Dl_info));

	if (info == NULL) return NULL;

	// Compute the total size for the block that is returned.
	// The block will contain size number of pointers to the
	// symbol descriptions.

	total_bytes = sizeof(char*) * size;

	// Plus each symbol description
	for (i = 0 ; i < size; ++i) {
		dladdr(buffer[i], &info[i]);
		total_bytes += _BACKTRACE_FORMAT_SIZE;
		total_bytes += symbol_length(&info[i]);
	}

	result = (char**)malloc(total_bytes);
	if (result == NULL) {
		goto error;
	}
	end = (intptr_t)result + total_bytes;

	// Fill in the array of pointers and append the strings for
	// each symbol description.

	ptrs = result;
	strs = ((intptr_t)result) + sizeof(char*) * size;

	for (i = 0; i < size; ++i) {
		int chk = _backtrace_snprintf((char*)strs, end - (intptr_t)strs, i, buffer[i], &info[i]);
		if (chk < 0) {
			goto error;
		}

		ptrs[i] = (char*)strs;
		strs += chk + 1; // Step over the '\0'
	}

	free(info);
	return result;

error:
	free(info);
	free(result);
	return NULL;
}

void backtrace_symbols_fd(void* const* buffer, int size, int fd) {
	int i;
	char buf[BUFSIZ];
	Dl_info info;
	struct iovec iov[2];

	iov[0].iov_base = buf;

	iov[1].iov_base = "\n";
	iov[1].iov_len = 1;

	for (i = 0; i < size; ++i) {
		memset(&info, 0, sizeof(info));
		dladdr(buffer[i], &info);

		iov[0].iov_len = _backtrace_snprintf(buf, sizeof(buf), i, buffer[i], &info);

		writev(fd, iov, 2);
	}
}

#endif // !TARGET_OS_DRIVERKIT

void
backtrace_image_offsets(void* const* buffer, struct image_offset *imgoffs, int size)
{
	struct dyld_image_uuid_offset infos[size];
	_dyld_images_for_addresses(size, (const void **)buffer, infos);

	for (int i = 0; i < size; i++) {
		uuid_copy(imgoffs[i].uuid, infos[i].uuid);
		imgoffs[i].offset = infos[i].offsetInImage;
	};
}