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Implement core dump to minidump conversion.

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This patch is part of a bigger patch that helps merging the breakpad code
with the modified version in Chromium OS.

Specifically, this patch makes the following changes:
1. Turn the LinuxDumper class into a base class and move ptrace related
   code into a new derived class, LinuxPtraceDumper.
2. Add a LinuxCoreDumper class, which is derived from LinuxDumper, to
   extract information from a crashed process via a core dump file instead
   of ptrace.
3. Add a WriteMinidumpFromCore function to
     src/client/linux/minidump_writer/minidump_writer.h,
   which uses LinuxCoreDumper to extract information from a core dump file.
4. Add a core2md utility, which simply wraps WriteMinidumpFromCore, for
   converting a core dump to a minidump.

BUG=455
TEST=Tested the following:
1. Build on 32-bit and 64-bit Linux with gcc 4.4.3 and gcc 4.6.
2. Build on Mac OS X 10.6.8 with gcc 4.2 and clang 3.0 (with latest gmock).
3. All unit tests pass.
4. Run Chromium OS tests to test core2md.
Review URL: http://breakpad.appspot.com/343001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@905 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
benchan@chromium.org
2012-01-19 07:14:51 +00:00
parent 3822e36b20
commit 30566abed8
16 changed files with 1277 additions and 430 deletions
Download Patch File Download Diff File Expand all files Collapse all files

275
src/client/linux/minidump_writer/linux_dumper.cc
View File

@@ -27,6 +27,9 @@
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// linux_dumper.cc: Implement google_breakpad::LinuxDumper.
// See linux_dumper.h for details.
// This code deals with the mechanics of getting information about a crashed
// process. Since this code may run in a compromised address space, the same
// rules apply as detailed at the top of minidump_writer.h: no libc calls and
@@ -34,25 +37,12 @@
#include "client/linux/minidump_writer/linux_dumper.h"
#include <asm/ptrace.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#if !defined(__ANDROID__)
#include <link.h>
#endif
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <unistd.h>
#include <algorithm>
#include "client/linux/minidump_writer/directory_reader.h"
#include "client/linux/minidump_writer/line_reader.h"
#include "common/linux/file_id.h"
#include "common/linux/linux_libc_support.h"
@@ -63,48 +53,6 @@
static const char kMappedFileUnsafePrefix[] = "/dev/";
static const char kDeletedSuffix[] = " (deleted)";
// Suspend a thread by attaching to it.
static bool SuspendThread(pid_t pid) {
// This may fail if the thread has just died or debugged.
errno = 0;
if (sys_ptrace(PTRACE_ATTACH, pid, NULL, NULL) != 0 &&
errno != 0) {
return false;
}
while (sys_waitpid(pid, NULL, __WALL) < 0) {
if (errno != EINTR) {
sys_ptrace(PTRACE_DETACH, pid, NULL, NULL);
return false;
}
}
#if defined(__i386) || defined(__x86_64)
// On x86, the stack pointer is NULL or -1, when executing trusted code in
// the seccomp sandbox. Not only does this cause difficulties down the line
// when trying to dump the thread's stack, it also results in the minidumps
// containing information about the trusted threads. This information is
// generally completely meaningless and just pollutes the minidumps.
// We thus test the stack pointer and exclude any threads that are part of
// the seccomp sandbox's trusted code.
user_regs_struct regs;
if (sys_ptrace(PTRACE_GETREGS, pid, NULL, &regs) == -1 ||
#if defined(__i386)
!regs.esp
#elif defined(__x86_64)
!regs.rsp
#endif
) {
sys_ptrace(PTRACE_DETACH, pid, NULL, NULL);
return false;
}
#endif
return true;
}
// Resume a thread by detaching from it.
static bool ResumeThread(pid_t pid) {
return sys_ptrace(PTRACE_DETACH, pid, NULL, NULL) >= 0;
}
inline static bool IsMappedFileOpenUnsafe(
const google_breakpad::MappingInfo& mapping) {
// It is unsafe to attempt to open a mapped file that lives under /dev,
@@ -123,7 +71,6 @@ LinuxDumper::LinuxDumper(pid_t pid)
crash_address_(0),
crash_signal_(0),
crash_thread_(0),
threads_suspended_(false),
threads_(&allocator_, 8),
mappings_(&allocator_) {
}
@@ -135,80 +82,6 @@ bool LinuxDumper::Init() {
return EnumerateThreads() && EnumerateMappings();
}
bool LinuxDumper::ThreadsSuspend() {
if (threads_suspended_)
return true;
for (size_t i = 0; i < threads_.size(); ++i) {
if (!SuspendThread(threads_[i])) {
// If the thread either disappeared before we could attach to it, or if
// it was part of the seccomp sandbox's trusted code, it is OK to
// silently drop it from the minidump.
memmove(&threads_[i], &threads_[i+1],
(threads_.size() - i - 1) * sizeof(threads_[i]));
threads_.resize(threads_.size() - 1);
--i;
}
}
threads_suspended_ = true;
return threads_.size() > 0;
}
bool LinuxDumper::ThreadsResume() {
if (!threads_suspended_)
return false;
bool good = true;
for (size_t i = 0; i < threads_.size(); ++i)
good &= ResumeThread(threads_[i]);
threads_suspended_ = false;
return good;
}
void
LinuxDumper::BuildProcPath(char* path, pid_t pid, const char* node) const {
assert(path);
if (!path) {
return;
}
path[0] = '\0';
const unsigned pid_len = my_int_len(pid);
assert(node);
if (!node) {
return;
}
size_t node_len = my_strlen(node);
assert(node_len < NAME_MAX);
if (node_len >= NAME_MAX) {
return;
}
assert(node_len > 0);
if (node_len == 0) {
return;
}
assert(pid > 0);
if (pid <= 0) {
return;
}
const size_t total_length = 6 + pid_len + 1 + node_len;
assert(total_length < NAME_MAX);
if (total_length >= NAME_MAX) {
return;
}
memcpy(path, "/proc/", 6);
my_itos(path + 6, pid, pid_len);
memcpy(path + 6 + pid_len, "/", 1);
memcpy(path + 6 + pid_len + 1, node, node_len);
path[total_length] = '\0';
}
bool
LinuxDumper::ElfFileIdentifierForMapping(const MappingInfo& mapping,
bool member,
@@ -261,10 +134,8 @@ LinuxDumper::ElfFileIdentifierForMapping(const MappingInfo& mapping,
void*
LinuxDumper::FindBeginningOfLinuxGateSharedLibrary(const pid_t pid) const {
char auxv_path[NAME_MAX];
BuildProcPath(auxv_path, pid, "auxv");
// If BuildProcPath errors out due to invalid input, we'll handle it when
// we try to sys_open the file.
if (!BuildProcPath(auxv_path, pid, "auxv"))
return NULL;
// Find the AT_SYSINFO_EHDR entry for linux-gate.so
// See http://www.trilithium.com/johan/2005/08/linux-gate/ for more
@@ -290,7 +161,8 @@ LinuxDumper::FindBeginningOfLinuxGateSharedLibrary(const pid_t pid) const {
bool LinuxDumper::EnumerateMappings() {
char maps_path[NAME_MAX];
BuildProcPath(maps_path, pid_, "maps");
if (!BuildProcPath(maps_path, pid_, "maps"))
return false;
// linux_gate_loc is the beginning of the kernel's mapping of
// linux-gate.so in the process. It doesn't actually show up in the
@@ -359,118 +231,6 @@ bool LinuxDumper::EnumerateMappings() {
return !mappings_.empty();
}
// Parse /proc/$pid/task to list all the threads of the process identified by
// pid.
bool LinuxDumper::EnumerateThreads() {
char task_path[NAME_MAX];
BuildProcPath(task_path, pid_, "task");
const int fd = sys_open(task_path, O_RDONLY | O_DIRECTORY, 0);
if (fd < 0)
return false;
DirectoryReader* dir_reader = new(allocator_) DirectoryReader(fd);
// The directory may contain duplicate entries which we filter by assuming
// that they are consecutive.
int last_tid = -1;
const char* dent_name;
while (dir_reader->GetNextEntry(&dent_name)) {
if (my_strcmp(dent_name, ".") &&
my_strcmp(dent_name, "..")) {
int tid = 0;
if (my_strtoui(&tid, dent_name) &&
last_tid != tid) {
last_tid = tid;
threads_.push_back(tid);
}
}
dir_reader->PopEntry();
}
sys_close(fd);
return true;
}
// Read thread info from /proc/$pid/status.
// Fill out the |tgid|, |ppid| and |pid| members of |info|. If unavailable,
// these members are set to -1. Returns true iff all three members are
// available.
bool LinuxDumper::GetThreadInfoByIndex(size_t index, ThreadInfo* info) {
if (index >= threads_.size())
return false;
pid_t tid = threads_[index];
assert(info != NULL);
char status_path[NAME_MAX];
BuildProcPath(status_path, tid, "status");
const int fd = sys_open(status_path, O_RDONLY, 0);
if (fd < 0)
return false;
LineReader* const line_reader = new(allocator_) LineReader(fd);
const char* line;
unsigned line_len;
info->ppid = info->tgid = -1;
while (line_reader->GetNextLine(&line, &line_len)) {
if (my_strncmp("Tgid:\t", line, 6) == 0) {
my_strtoui(&info->tgid, line + 6);
} else if (my_strncmp("PPid:\t", line, 6) == 0) {
my_strtoui(&info->ppid, line + 6);
}
line_reader->PopLine(line_len);
}
if (info->ppid == -1 || info->tgid == -1)
return false;
if (sys_ptrace(PTRACE_GETREGS, tid, NULL, &info->regs) == -1) {
return false;
}
#if !defined(__ANDROID__)
if (sys_ptrace(PTRACE_GETFPREGS, tid, NULL, &info->fpregs) == -1) {
return false;
}
#endif
#if defined(__i386)
if (sys_ptrace(PTRACE_GETFPXREGS, tid, NULL, &info->fpxregs) == -1)
return false;
#endif
#if defined(__i386) || defined(__x86_64)
for (unsigned i = 0; i < ThreadInfo::kNumDebugRegisters; ++i) {
if (sys_ptrace(
PTRACE_PEEKUSER, tid,
reinterpret_cast<void*> (offsetof(struct user,
u_debugreg[0]) + i *
sizeof(debugreg_t)),
&info->dregs[i]) == -1) {
return false;
}
}
#endif
const uint8_t* stack_pointer;
#if defined(__i386)
memcpy(&stack_pointer, &info->regs.esp, sizeof(info->regs.esp));
#elif defined(__x86_64)
memcpy(&stack_pointer, &info->regs.rsp, sizeof(info->regs.rsp));
#elif defined(__ARM_EABI__)
memcpy(&stack_pointer, &info->regs.ARM_sp, sizeof(info->regs.ARM_sp));
#else
#error "This code hasn't been ported to your platform yet."
#endif
return GetStackInfo(&info->stack, &info->stack_len,
(uintptr_t) stack_pointer);
}
// Get information about the stack, given the stack pointer. We don't try to
// walk the stack since we might not have all the information needed to do
// unwind. So we just grab, up to, 32k of stack.
@@ -497,24 +257,6 @@ bool LinuxDumper::GetStackInfo(const void** stack, size_t* stack_len,
return true;
}
void LinuxDumper::CopyFromProcess(void* dest, pid_t child, const void* src,
size_t length) {
unsigned long tmp = 55;
size_t done = 0;
static const size_t word_size = sizeof(tmp);
uint8_t* const local = (uint8_t*) dest;
uint8_t* const remote = (uint8_t*) src;
while (done < length) {
const size_t l = length - done > word_size ? word_size : length - done;
if (sys_ptrace(PTRACE_PEEKDATA, child, remote + done, &tmp) == -1) {
tmp = 0;
}
memcpy(local + done, &tmp, l);
done += l;
}
}
// Find the mapping which the given memory address falls in.
const MappingInfo* LinuxDumper::FindMapping(const void* address) const {
const uintptr_t addr = (uintptr_t) address;
@@ -544,7 +286,8 @@ bool LinuxDumper::HandleDeletedFileInMapping(char* path) const {
// Check |path| against the /proc/pid/exe 'symlink'.
char exe_link[NAME_MAX];
char new_path[NAME_MAX];
BuildProcPath(exe_link, pid_, "exe");
if (!BuildProcPath(exe_link, pid_, "exe"))
return false;
if (!SafeReadLink(exe_link, new_path))
return false;
if (my_strcmp(path, new_path) != 0)