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/* Copyright 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#include "mongo/config.h"
#if !defined(_WIN32)
#if defined(__sun) || !defined(MONGO_CONFIG_HAVE_EXECINFO_BACKTRACE)
#include "mongo/platform/backtrace.h"
#include <boost/smart_ptr/scoped_array.hpp>
#include <cstdio>
#include <dlfcn.h>
#include <string>
#include <ucontext.h>
#include <vector>
#include "mongo/base/init.h"
#include "mongo/base/status.h"
using std::string;
using std::vector;
namespace mongo {
namespace pal {
namespace {
class WalkcontextCallback {
public:
WalkcontextCallback(uintptr_t* array, int size)
: _position(0),
_count(size),
_addresses(array) {}
// This callback function is called from C code, and so must not throw exceptions
//
static int callbackFunction(uintptr_t address,
int signalNumber,
WalkcontextCallback* thisContext) {
if (thisContext->_position < thisContext->_count) {
thisContext->_addresses[thisContext->_position++] = address;
return 0;
}
return 1;
}
int getCount() const { return static_cast<int>(_position); }
private:
size_t _position;
size_t _count;
uintptr_t* _addresses;
};
// This function emulates a Solaris function that was added to Solaris 11 at the same time
// that the backtrace* functions were added. It is not important to match the function name
// or interface for this code, but this is a fine interface for our purposes and following
// an existing model seems potentially helpful ... hence the all-lowercase name with no
// underscores. The formatting of the output matches what Solaris 11 does; this is similar
// to Linux's display, but slightly different.
//
int addrtosymstr(void* address, char* outputBuffer, int outputBufferSize) {
Dl_info_t symbolInfo;
if (dladdr(address, &symbolInfo) == 0) { // no info: "[address]"
return snprintf(outputBuffer, outputBufferSize, "[0x%p]", address);
}
if (symbolInfo.dli_sname == NULL) {
return snprintf(outputBuffer, // no symbol: "filename'offset [address]"
outputBufferSize,
"%s'0x%p [0x%p]",
symbolInfo.dli_fname,
reinterpret_cast<char*>(reinterpret_cast<char*>(address) -
reinterpret_cast<char*>(symbolInfo.dli_fbase)),
address);
}
return snprintf(outputBuffer, // symbol: "filename'symbol+offset [address]"
outputBufferSize,
"%s'%s+0x%p [0x%p]",
symbolInfo.dli_fname,
symbolInfo.dli_sname,
reinterpret_cast<char*>(reinterpret_cast<char*>(address) -
reinterpret_cast<char*>(symbolInfo.dli_saddr)),
address);
}
} // namespace
typedef int (*WalkcontextCallbackFunc)(uintptr_t address, int signalNumber, void* thisContext);
int backtrace_emulation(void** array, int size) {
WalkcontextCallback walkcontextCallback(reinterpret_cast<uintptr_t*>(array), size);
ucontext_t context;
if (getcontext(&context) != 0) {
return 0;
}
int wcReturn = walkcontext(
&context,
reinterpret_cast<WalkcontextCallbackFunc>(WalkcontextCallback::callbackFunction),
static_cast<void*>(&walkcontextCallback));
if (wcReturn == 0) {
return walkcontextCallback.getCount();
}
return 0;
}
// The API for backtrace_symbols() specifies that the caller must call free() on the char**
// returned by this function, and must *not* call free on the individual strings.
// In order to support this API, we allocate a single block of memory containing both the
// array of pointers to the strings and the strings themselves. Constructing this block
// requires two passes: one to collect the strings and calculate the required size of the
// combined single memory block; and a second pass to copy the strings into the block and
// set their pointers.
// The result is that we return a single memory block (allocated with malloc()) which begins
// with an array of pointers to strings (of count 'size'). This array is immediately
// followed by the strings themselves, each NUL terminated.
//
char** backtrace_symbols_emulation(void* const* array, int size) {
vector<string> stringVector;
vector<size_t> stringLengths;
size_t blockSize = size * sizeof(char*);
size_t blockPtr = blockSize;
const size_t kBufferSize = 8 * 1024;
boost::scoped_array<char> stringBuffer(new char[kBufferSize]);
for (int i = 0; i < size; ++i) {
size_t thisLength = 1 + addrtosymstr(array[i], stringBuffer.get(), kBufferSize);
stringVector.push_back(string(stringBuffer.get()));
stringLengths.push_back(thisLength);
blockSize += thisLength;
}
char** singleBlock = static_cast<char**>(malloc(blockSize));
if (singleBlock == NULL) {
return NULL;
}
for (int i = 0; i < size; ++i) {
singleBlock[i] = reinterpret_cast<char*>(singleBlock) + blockPtr;
strncpy(singleBlock[i], stringVector[i].c_str(), stringLengths[i]);
blockPtr += stringLengths[i];
}
return singleBlock;
}
void backtrace_symbols_fd_emulation(void* const* array, int size, int fd) {
const int kBufferSize = 4 * 1024;
char stringBuffer[kBufferSize];
for (int i = 0; i < size; ++i) {
int len = addrtosymstr(array[i], stringBuffer, kBufferSize);
if (len > kBufferSize - 1) {
len = kBufferSize - 1;
}
stringBuffer[len] = '\n';
write(fd, stringBuffer, len + 1);
}
}
typedef int (*BacktraceFunc)(void** array, int size);
static BacktraceFunc backtrace_switcher =
pal::backtrace_emulation;
typedef char** (*BacktraceSymbolsFunc)(void* const* array, int size);
static BacktraceSymbolsFunc backtrace_symbols_switcher =
pal::backtrace_symbols_emulation;
typedef void (*BacktraceSymbolsFdFunc)(void* const* array, int size, int fd);
static BacktraceSymbolsFdFunc backtrace_symbols_fd_switcher =
pal::backtrace_symbols_fd_emulation;
int backtrace(void** array, int size) {
return backtrace_switcher(array, size);
}
char** backtrace_symbols(void* const* array, int size) {
return backtrace_symbols_switcher(array, size);
}
void backtrace_symbols_fd(void* const* array, int size, int fd) {
backtrace_symbols_fd_switcher(array, size, fd);
}
} // namespace pal
// 'backtrace()', 'backtrace_symbols()' and 'backtrace_symbols_fd()' on Solaris will call
// emulation functions if the symbols are not found
//
MONGO_INITIALIZER_GENERAL(SolarisBacktrace,
MONGO_NO_PREREQUISITES,
("default"))(InitializerContext* context) {
void* functionAddress = dlsym(RTLD_DEFAULT, "backtrace");
if (functionAddress != NULL) {
pal::backtrace_switcher =
reinterpret_cast<pal::BacktraceFunc>(functionAddress);
}
functionAddress = dlsym(RTLD_DEFAULT, "backtrace_symbols");
if (functionAddress != NULL) {
pal::backtrace_symbols_switcher =
reinterpret_cast<pal::BacktraceSymbolsFunc>(functionAddress);
}
functionAddress = dlsym(RTLD_DEFAULT, "backtrace_symbols_fd");
if (functionAddress != NULL) {
pal::backtrace_symbols_fd_switcher =
reinterpret_cast<pal::BacktraceSymbolsFdFunc>(functionAddress);
}
return Status::OK();
}
} // namespace mongo
#endif // #if defined(__sun)
#endif // #if !defined(_WIN32)
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