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//===-- sanitizer_symbolizer_mac.cpp --------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is shared between various sanitizers' runtime libraries.
//
// Implementation of Mac-specific "atos" symbolizer.
//===----------------------------------------------------------------------===//
#include "sanitizer_platform.h"
#if SANITIZER_MAC
#include "sanitizer_allocator_internal.h"
#include "sanitizer_mac.h"
#include "sanitizer_symbolizer_mac.h"
#include <dlfcn.h>
#include <errno.h>
#include <mach/mach.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#include <util.h>
namespace __sanitizer {
bool DlAddrSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
Dl_info info;
int result = dladdr((const void *)addr, &info);
if (!result) return false;
// Compute offset if possible. `dladdr()` doesn't always ensure that `addr >=
// sym_addr` so only compute the offset when this holds. Failure to find the
// function offset is not treated as a failure because it might still be
// possible to get the symbol name.
uptr sym_addr = reinterpret_cast<uptr>(info.dli_saddr);
if (addr >= sym_addr) {
stack->info.function_offset = addr - sym_addr;
}
const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
if (!demangled) return false;
stack->info.function = internal_strdup(demangled);
return true;
}
bool DlAddrSymbolizer::SymbolizeData(uptr addr, DataInfo *datainfo) {
Dl_info info;
int result = dladdr((const void *)addr, &info);
if (!result) return false;
const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
datainfo->name = internal_strdup(demangled);
datainfo->start = (uptr)info.dli_saddr;
return true;
}
#define K_ATOS_ENV_VAR "__check_mach_ports_lookup"
// This cannot live in `AtosSymbolizerProcess` because instances of that object
// are allocated by the internal allocator which under ASan is poisoned with
// kAsanInternalHeapMagic.
static char kAtosMachPortEnvEntry[] = K_ATOS_ENV_VAR "=000000000000000";
class AtosSymbolizerProcess final : public SymbolizerProcess {
public:
explicit AtosSymbolizerProcess(const char *path)
: SymbolizerProcess(path, /*use_posix_spawn*/ true) {
pid_str_[0] = '\0';
}
void LateInitialize() {
if (SANITIZER_IOSSIM) {
// `putenv()` may call malloc/realloc so it is only safe to do this
// during LateInitialize() or later (i.e. we can't do this in the
// constructor). We also can't do this in `StartSymbolizerSubprocess()`
// because in TSan we switch allocators when we're symbolizing.
// We use `putenv()` rather than `setenv()` so that we can later directly
// write into the storage without LibC getting involved to change what the
// variable is set to
int result = putenv(kAtosMachPortEnvEntry);
CHECK_EQ(result, 0);
}
}
private:
bool StartSymbolizerSubprocess() override {
// Configure sandbox before starting atos process.
// Put the string command line argument in the object so that it outlives
// the call to GetArgV.
internal_snprintf(pid_str_, sizeof(pid_str_), "%d", internal_getpid());
if (SANITIZER_IOSSIM) {
// `atos` in the simulator is restricted in its ability to retrieve the
// task port for the target process (us) so we need to do extra work
// to pass our task port to it.
mach_port_t ports[]{mach_task_self()};
kern_return_t ret =
mach_ports_register(mach_task_self(), ports, /*count=*/1);
CHECK_EQ(ret, KERN_SUCCESS);
// Set environment variable that signals to `atos` that it should look
// for our task port. We can't call `setenv()` here because it might call
// malloc/realloc. To avoid that we instead update the
// `mach_port_env_var_entry_` variable with our current PID.
uptr count = internal_snprintf(kAtosMachPortEnvEntry,
sizeof(kAtosMachPortEnvEntry),
K_ATOS_ENV_VAR "=%s", pid_str_);
CHECK_GE(count, sizeof(K_ATOS_ENV_VAR) + internal_strlen(pid_str_));
// Document our assumption but without calling `getenv()` in normal
// builds.
DCHECK(getenv(K_ATOS_ENV_VAR));
DCHECK_EQ(internal_strcmp(getenv(K_ATOS_ENV_VAR), pid_str_), 0);
}
return SymbolizerProcess::StartSymbolizerSubprocess();
}
bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
return (length >= 1 && buffer[length - 1] == '\n');
}
void GetArgV(const char *path_to_binary,
const char *(&argv)[kArgVMax]) const override {
int i = 0;
argv[i++] = path_to_binary;
argv[i++] = "-p";
argv[i++] = &pid_str_[0];
if (GetMacosAlignedVersion() == MacosVersion(10, 9)) {
// On Mavericks atos prints a deprecation warning which we suppress by
// passing -d. The warning isn't present on other OSX versions, even the
// newer ones.
argv[i++] = "-d";
}
argv[i++] = nullptr;
}
char pid_str_[16];
// Space for `\0` in `K_ATOS_ENV_VAR` is reused for `=`.
static_assert(sizeof(kAtosMachPortEnvEntry) ==
(sizeof(K_ATOS_ENV_VAR) + sizeof(pid_str_)),
"sizes should match");
};
#undef K_ATOS_ENV_VAR
static bool ParseCommandOutput(const char *str, uptr addr, char **out_name,
char **out_module, char **out_file, uptr *line,
uptr *start_address) {
// Trim ending newlines.
char *trim;
ExtractTokenUpToDelimiter(str, "\n", &trim);
// The line from `atos` is in one of these formats:
// myfunction (in library.dylib) (sourcefile.c:17)
// myfunction (in library.dylib) + 0x1fe
// myfunction (in library.dylib) + 15
// 0xdeadbeef (in library.dylib) + 0x1fe
// 0xdeadbeef (in library.dylib) + 15
// 0xdeadbeef (in library.dylib)
// 0xdeadbeef
const char *rest = trim;
char *symbol_name;
rest = ExtractTokenUpToDelimiter(rest, " (in ", &symbol_name);
if (rest[0] == '\0') {
InternalFree(symbol_name);
InternalFree(trim);
return false;
}
if (internal_strncmp(symbol_name, "0x", 2) != 0)
*out_name = symbol_name;
else
InternalFree(symbol_name);
rest = ExtractTokenUpToDelimiter(rest, ") ", out_module);
if (rest[0] == '(') {
if (out_file) {
rest++;
rest = ExtractTokenUpToDelimiter(rest, ":", out_file);
char *extracted_line_number;
rest = ExtractTokenUpToDelimiter(rest, ")", &extracted_line_number);
if (line) *line = (uptr)internal_atoll(extracted_line_number);
InternalFree(extracted_line_number);
}
} else if (rest[0] == '+') {
rest += 2;
uptr offset = internal_atoll(rest);
if (start_address) *start_address = addr - offset;
}
InternalFree(trim);
return true;
}
AtosSymbolizer::AtosSymbolizer(const char *path, LowLevelAllocator *allocator)
: process_(new (*allocator) AtosSymbolizerProcess(path)) {}
bool AtosSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
if (!process_) return false;
if (addr == 0) return false;
char command[32];
internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
const char *buf = process_->SendCommand(command);
if (!buf) return false;
uptr line;
uptr start_address = AddressInfo::kUnknown;
if (!ParseCommandOutput(buf, addr, &stack->info.function, &stack->info.module,
&stack->info.file, &line, &start_address)) {
process_ = nullptr;
return false;
}
stack->info.line = (int)line;
if (start_address == AddressInfo::kUnknown) {
// Fallback to dladdr() to get function start address if atos doesn't report
// it.
Dl_info info;
int result = dladdr((const void *)addr, &info);
if (result)
start_address = reinterpret_cast<uptr>(info.dli_saddr);
}
// Only assign to `function_offset` if we were able to get the function's
// start address and we got a sensible `start_address` (dladdr doesn't always
// ensure that `addr >= sym_addr`).
if (start_address != AddressInfo::kUnknown && addr >= start_address) {
stack->info.function_offset = addr - start_address;
}
return true;
}
bool AtosSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
if (!process_) return false;
char command[32];
internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
const char *buf = process_->SendCommand(command);
if (!buf) return false;
if (!ParseCommandOutput(buf, addr, &info->name, &info->module, nullptr,
nullptr, &info->start)) {
process_ = nullptr;
return false;
}
return true;
}
void AtosSymbolizer::LateInitialize() { process_->LateInitialize(); }
} // namespace __sanitizer
#endif // SANITIZER_MAC