1 files changed, 238 insertions, 0 deletions
diff --git a/memory/replace/logalloc/LogAlloc.cpp b/memory/replace/logalloc/LogAlloc.cpp
new file mode 100644
index 0000000000..a976b0c674
--- /dev/null
+++ b/memory/replace/logalloc/LogAlloc.cpp
@@ -0,0 +1,238 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <cstdlib>
+#include <fcntl.h>
+
+#ifdef _WIN32
+#  include <windows.h>
+#  include <io.h>
+#  include <process.h>
+#else
+#  include <unistd.h>
+#  include <pthread.h>
+#endif
+
+#include "replace_malloc.h"
+#include "FdPrintf.h"
+#include "Mutex.h"
+
+static malloc_table_t sFuncs;
+static intptr_t sFd = 0;
+static bool sStdoutOrStderr = false;
+
+static Mutex sMutex MOZ_UNANNOTATED;
+
+#ifndef _WIN32
+static void prefork() MOZ_NO_THREAD_SAFETY_ANALYSIS { sMutex.Lock(); }
+static void postfork_parent() MOZ_NO_THREAD_SAFETY_ANALYSIS { sMutex.Unlock(); }
+static void postfork_child() { sMutex.Init(); }
+#endif
+
+static size_t GetPid() { return size_t(getpid()); }
+
+static size_t GetTid() {
+#if defined(_WIN32)
+  return size_t(GetCurrentThreadId());
+#else
+  return size_t(pthread_self());
+#endif
+}
+
+#ifdef ANDROID
+/* Android doesn't have pthread_atfork defined in pthread.h */
+extern "C" MOZ_EXPORT int pthread_atfork(void (*)(void), void (*)(void),
+                                         void (*)(void));
+#endif
+
+class LogAllocBridge : public ReplaceMallocBridge {
+  virtual void InitDebugFd(mozilla::DebugFdRegistry& aRegistry) override {
+    if (!sStdoutOrStderr) {
+      aRegistry.RegisterHandle(sFd);
+    }
+  }
+};
+
+/* Do a simple, text-form, log of all calls to replace-malloc functions.
+ * Use locking to guarantee that an allocation that did happen is logged
+ * before any other allocation/free happens.
+ */
+
+static void* replace_malloc(size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* ptr = sFuncs.malloc(aSize);
+  FdPrintf(sFd, "%zu %zu malloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr);
+  return ptr;
+}
+
+static int replace_posix_memalign(void** aPtr, size_t aAlignment,
+                                  size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  int ret = sFuncs.posix_memalign(aPtr, aAlignment, aSize);
+  FdPrintf(sFd, "%zu %zu posix_memalign(%zu,%zu)=%p\n", GetPid(), GetTid(),
+           aAlignment, aSize, (ret == 0) ? *aPtr : nullptr);
+  return ret;
+}
+
+static void* replace_aligned_alloc(size_t aAlignment, size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* ptr = sFuncs.aligned_alloc(aAlignment, aSize);
+  FdPrintf(sFd, "%zu %zu aligned_alloc(%zu,%zu)=%p\n", GetPid(), GetTid(),
+           aAlignment, aSize, ptr);
+  return ptr;
+}
+
+static void* replace_calloc(size_t aNum, size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* ptr = sFuncs.calloc(aNum, aSize);
+  FdPrintf(sFd, "%zu %zu calloc(%zu,%zu)=%p\n", GetPid(), GetTid(), aNum, aSize,
+           ptr);
+  return ptr;
+}
+
+static void* replace_realloc(void* aPtr, size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* new_ptr = sFuncs.realloc(aPtr, aSize);
+  FdPrintf(sFd, "%zu %zu realloc(%p,%zu)=%p\n", GetPid(), GetTid(), aPtr, aSize,
+           new_ptr);
+  return new_ptr;
+}
+
+static void replace_free(void* aPtr) {
+  MutexAutoLock lock(sMutex);
+  FdPrintf(sFd, "%zu %zu free(%p)\n", GetPid(), GetTid(), aPtr);
+  sFuncs.free(aPtr);
+}
+
+static void* replace_memalign(size_t aAlignment, size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* ptr = sFuncs.memalign(aAlignment, aSize);
+  FdPrintf(sFd, "%zu %zu memalign(%zu,%zu)=%p\n", GetPid(), GetTid(),
+           aAlignment, aSize, ptr);
+  return ptr;
+}
+
+static void* replace_valloc(size_t aSize) {
+  MutexAutoLock lock(sMutex);
+  void* ptr = sFuncs.valloc(aSize);
+  FdPrintf(sFd, "%zu %zu valloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr);
+  return ptr;
+}
+
+static void replace_jemalloc_stats(jemalloc_stats_t* aStats,
+                                   jemalloc_bin_stats_t* aBinStats) {
+  MutexAutoLock lock(sMutex);
+  sFuncs.jemalloc_stats_internal(aStats, aBinStats);
+  FdPrintf(sFd, "%zu %zu jemalloc_stats()\n", GetPid(), GetTid());
+}
+
+void replace_init(malloc_table_t* aTable, ReplaceMallocBridge** aBridge) {
+  /* Initialize output file descriptor from the MALLOC_LOG environment
+   * variable. Numbers up to 9999 are considered as a preopened file
+   * descriptor number. Other values are considered as a file name. */
+#ifdef _WIN32
+  wchar_t* log = _wgetenv(L"MALLOC_LOG");
+#else
+  char* log = getenv("MALLOC_LOG");
+#endif
+  if (log && *log) {
+    int fd = 0;
+    const auto* fd_num = log;
+    while (*fd_num) {
+      /* Reject non digits. */
+      if (*fd_num < '0' || *fd_num > '9') {
+        fd = -1;
+        break;
+      }
+      fd = fd * 10 + (*fd_num - '0');
+      /* Reject values >= 10000. */
+      if (fd >= 10000) {
+        fd = -1;
+        break;
+      }
+      fd_num++;
+    }
+    if (fd == 1 || fd == 2) {
+      sStdoutOrStderr = true;
+    }
+#ifdef _WIN32
+    // See comment in FdPrintf.h as to why CreateFile is used.
+    HANDLE handle;
+    if (fd > 0) {
+      handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+    } else {
+      handle =
+          CreateFileW(log, FILE_APPEND_DATA, FILE_SHARE_READ | FILE_SHARE_WRITE,
+                      nullptr, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, nullptr);
+    }
+    if (handle != INVALID_HANDLE_VALUE) {
+      sFd = reinterpret_cast<intptr_t>(handle);
+    }
+#else
+    if (fd == -1) {
+      fd = open(log, O_WRONLY | O_CREAT | O_APPEND, 0644);
+    }
+    if (fd > 0) {
+      sFd = fd;
+    }
+#endif
+  }
+
+  // Don't initialize if we weren't passed a valid MALLOC_LOG.
+  if (sFd == 0) {
+    return;
+  }
+
+  sMutex.Init();
+  static LogAllocBridge bridge;
+  sFuncs = *aTable;
+#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE
+#define MALLOC_DECL(name, ...) aTable->name = replace_##name;
+#include "malloc_decls.h"
+  aTable->jemalloc_stats_internal = replace_jemalloc_stats;
+  if (!getenv("MALLOC_LOG_MINIMAL")) {
+    aTable->posix_memalign = replace_posix_memalign;
+    aTable->aligned_alloc = replace_aligned_alloc;
+    aTable->valloc = replace_valloc;
+  }
+  *aBridge = &bridge;
+
+#ifndef _WIN32
+  /* When another thread has acquired a lock before forking, the child
+   * process will inherit the lock state but the thread, being nonexistent
+   * in the child process, will never release it, leading to a dead-lock
+   * whenever the child process gets the lock. We thus need to ensure no
+   * other thread is holding the lock before forking, by acquiring it
+   * ourselves, and releasing it after forking in the parent process and
+   * resetting it to its initial state in the child process. The latter is
+   * important because some implementations (notably macOS) prevent a lock from
+   * being unlocked by a different thread than the one which locked it in the
+   * first place.
+   * Windows doesn't have this problem since there is no fork().
+   * The real allocator, however, might be doing the same thing (jemalloc
+   * does). But pthread_atfork `prepare` handlers (first argument) are
+   * processed in reverse order they were established. But replace_init
+   * runs before the real allocator has had any chance to initialize and
+   * call pthread_atfork itself. This leads to its prefork running before
+   * ours. This leads to a race condition that can lead to a deadlock like
+   * the following:
+   *   - thread A forks.
+   *   - libc calls real allocator's prefork, so thread A holds the real
+   *     allocator lock.
+   *   - thread B calls malloc, which calls our replace_malloc.
+   *   - consequently, thread B holds our lock.
+   *   - thread B then proceeds to call the real allocator's malloc, and
+   *     waits for the real allocator's lock, which thread A holds.
+   *   - libc calls our prefork, so thread A waits for our lock, which
+   *     thread B holds.
+   * To avoid this race condition, the real allocator's prefork must be
+   * called after ours, which means it needs to be registered before ours.
+   * So trick the real allocator into initializing itself without more side
+   * effects by calling malloc with a size it can't possibly allocate. */
+  sFuncs.malloc(-1);
+  pthread_atfork(prefork, postfork_parent, postfork_child);
+#endif
+}