Linux: Add Breakpad client.

breakpad/linux/linux_dumper.cc

Index: breakpad/linux/linux_dumper.cc
diff --git a/breakpad/linux/linux_dumper.cc b/breakpad/linux/linux_dumper.cc
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+// Copyright (c) 2009, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// 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
+// use the alternative allocator.
+
+#include "breakpad/linux/linux_dumper.h"
+
+#include <assert.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+
+#include "breakpad/linux/directory_reader.h"
+#include "breakpad/linux/line_reader.h"
+#include "breakpad/linux/linux_libc_support.h"
+#include "breakpad/linux/linux_syscall_support.h"
+
+// 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;
+    }
+  }
+  return true;
+}
+
+// Resume a thread by detaching from it.
+static bool ResumeThread(pid_t pid) {
+  return sys_ptrace(PTRACE_DETACH, pid, NULL, NULL) >= 0;
+}
+
+namespace google_breakpad {
+
+LinuxDumper::LinuxDumper(int pid)
+    : pid_(pid),
+      threads_suspened_(false),
+      threads_(&allocator_, 8),
+      mappings_(&allocator_) {
+}
+
+bool LinuxDumper::Init() {
+  return EnumerateThreads(&threads_) &&
+         EnumerateMappings(&mappings_);
+}
+
+bool LinuxDumper::ThreadsSuspend() {
+  if (threads_suspened_)
+    return true;
+  bool good = true;
+  for (size_t i = 0; i < threads_.size(); ++i)
+    good &= SuspendThread(threads_[i]);
+  threads_suspened_ = true;
+  return good;
+}
+
+bool LinuxDumper::ThreadsResume() {
+  if (!threads_suspened_)
+    return false;
+  bool good = true;
+  for (size_t i = 0; i < threads_.size(); ++i)
+    good &= ResumeThread(threads_[i]);
+  threads_suspened_ = false;
+  return good;
+}
+
+bool
+LinuxDumper::EnumerateMappings(wasteful_vector<MappingInfo*> *result) const {
+  char maps_path[80];
+  memcpy(maps_path, "/proc/", 6);
+  const unsigned pid_len = my_int_len(pid_);
+  my_itos(maps_path + 6, pid_, pid_len);
+  memcpy(maps_path + 6 + pid_len, "/maps", 6);
+
+  const int fd = sys_open(maps_path, O_RDONLY, 0);
+  if (fd < 0)
+    return false;
+  LineReader *const line_reader = new(allocator_) LineReader(fd);
+
+  const char *line;
+  unsigned line_len;
+  while (line_reader->GetNextLine(&line, &line_len)) {
+    uintptr_t start_addr;
+    uintptr_t end_addr;
+
+    const char* i1 = my_read_hex_ptr(&start_addr, line);
+    if (*i1 == '-') {
+      const char *i2 = my_read_hex_ptr(&end_addr, i1 + 1);
+      if (*i2 == ' ') {
+        MappingInfo *const module = new(allocator_) MappingInfo;
+        memset(module, 0, sizeof(MappingInfo));
+        module->start_addr = start_addr;
+        module->size = end_addr - start_addr;
+        const char *name = NULL;
+        // Only copy name if the name is a valid path name.
+        if ((name = my_strchr(line, '/')) != NULL) {
+          const unsigned l = my_strlen(name);
+          if (l < sizeof(module->name))
+            memcpy(module->name, name, l);
+        }
+
+        result->push_back(module);
+      }
+    }
+
+    line_reader->PopLine(line_len);
+  }
+
+  sys_close(fd);
+  return result->size() > 0;
+}
+
+// Parse /proc/$pid/task to list all the threads of the process identified by
+// pid.
+bool LinuxDumper::EnumerateThreads(wasteful_vector<pid_t> *result) const {
+  char task_path[80];
+  memcpy(task_path, "/proc/", 6);
+  const unsigned pid_len = my_int_len(pid_);
+  my_itos(task_path + 6, pid_, pid_len);
+  memcpy(task_path + 6 + pid_len, "/task", 6);
+
+  const int fd = sys_open(task_path, O_RDONLY | O_DIRECTORY, 0);
+  if (fd < 0)
+    return false;
+  DirectoryReader *dir_reader = new(allocator_) DirectoryReader(fd);
+
+  // The directory may contain duplicate entries which we filter by assuming
+  // that they are consecutive 
+  int last_tid = -1;
+  const char *dent_name;
+  while (dir_reader->GetNextEntry(&dent_name)) {
+    if (my_strcmp(dent_name, ".") &&
+        my_strcmp(dent_name, "..")) {
+      int tid = 0;
+      if (my_strtoui(&tid, dent_name) &&
+          last_tid != tid) {
+        last_tid = tid;
+        result->push_back(tid);
+      }
+    }
+    dir_reader->PopEntry();
+  }
+
+  sys_close(fd);
+  return true;
+}
+
+// Read thread info from /proc/$pid/status.
+// Fill out the |tgid|, |ppid| and |pid| members of |info|. If unavailible,
+// these members are set to -1. Returns true iff all three members are
+// availible.
+bool LinuxDumper::ThreadInfoGet(pid_t tid, ThreadInfo *info) {
+  assert(info != NULL);
+  char status_path[80];
+  memcpy(status_path, "/proc/", 6);
+  const unsigned tid_len = my_int_len(tid);
+  my_itos(status_path + 6, tid, tid_len);
+  memcpy(status_path + 6 + tid_len, "/status", 8);
+  const int fd = open(status_path, O_RDONLY);
+  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 ||
+      sys_ptrace(PTRACE_GETFPREGS, tid, NULL, &info->fpregs) == -1) {
+    return false;
+  }
+
+#if defined(__i386) || defined(__x86_64)
+  if (sys_ptrace(PTRACE_GETFPXREGS, tid, NULL, &info->fpxregs) == -1)
+    return false;
+
+  for (unsigned i = 0; i < ThreadInfo::kNumDebugRegisters; ++i) {
+    if (sys_ptrace(
+        PTRACE_PEEKUSER, tid,
+        (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));
+#else
+#error "This code hasn't been ported to your platform yet."
+#endif
+
+  if (!GetStackInfo(&info->stack, &info->stack_len,
+                    (uintptr_t) stack_pointer))
+    return false;
+
+  return true;
+}
+
+// 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.
+bool LinuxDumper::GetStackInfo(const void** stack, size_t* stack_len,
+                               uintptr_t int_stack_pointer) {
+#if defined(__i386) || defined(__x86_64)
+  static const bool stack_grows_down = true;
+  static const uintptr_t page_size = 4096;
+#else
+#error "This code has not been ported to your platform yet."
+#endif
+  // Move the stack pointer to the bottom of the page that it's in.
+  uint8_t* const stack_pointer =
+      (uint8_t *) (int_stack_pointer & ~(page_size - 1));
+
+  // The number of bytes of stack which we try to capture.
+  static unsigned kStackToCapture = 32 * 1024;
+
+  const MappingInfo *mapping = FindMapping(stack_pointer);
+  if (!mapping)
+    return false;
+  if (stack_grows_down) {
+    const ptrdiff_t offset = stack_pointer - (uint8_t*) mapping->start_addr;
+    const ptrdiff_t distance_to_end =
+        static_cast<ptrdiff_t>(mapping->size) - offset;
+    *stack_len = distance_to_end > kStackToCapture ?
+                 kStackToCapture : distance_to_end;
+    *stack = stack_pointer;
+  } else {
+    const ptrdiff_t offset = stack_pointer - (uint8_t*) mapping->start_addr;
+    *stack_len = offset > kStackToCapture ? kStackToCapture : offset;
+    *stack = stack_pointer - *stack_len;
+  }
+
+  return true;
+}
+
+// static
+void LinuxDumper::CopyFromProcess(void* dest, pid_t child, const void* src,
+                                  size_t length) {
+  unsigned long tmp;
+  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;
+
+  for (size_t i = 0; i < mappings_.size(); ++i) {
+    const uintptr_t start = static_cast<uintptr_t>(mappings_[i]->start_addr);
+    if (addr >= start && addr - start < mappings_[i]->size)
+      return mappings_[i];
+  }
+
+  return NULL;
+}
+
+}  // namespace google_breakpad