Add function definitions for MapInfo.

Bug: 23762183

Test: All new unit tests pass.
Change-Id: I26a1f6e84bf1a02447eff48ff6e35068554330fe

libunwindstack/Android.bp

@@ -54,6 +54,7 @@ cc_defaults {
         "ElfInterfaceArm.cpp",
         "Log.cpp",
         "Regs.cpp",
+        "MapInfo.cpp",
         "Maps.cpp",
         "Memory.cpp",
         "Symbols.cpp",
@@ -98,6 +99,7 @@ cc_defaults {
         "tests/ElfInterfaceTest.cpp",
         "tests/ElfTest.cpp",
         "tests/LogFake.cpp",
+        "tests/MapInfoTest.cpp",
         "tests/MapsTest.cpp",
         "tests/MemoryFake.cpp",
         "tests/MemoryFileTest.cpp",

libunwindstack/MapInfo.cpp

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+
+#include "Elf.h"
+#include "MapInfo.h"
+#include "Maps.h"
+#include "Memory.h"
+
+Memory* MapInfo::CreateMemory(pid_t pid) {
+  if (end <= start) {
+    return nullptr;
+  }
+
+  elf_offset = 0;
+
+  // First try and use the file associated with the info.
+  if (!name.empty()) {
+    // Fail on device maps.
+    if (flags & MAPS_FLAGS_DEVICE_MAP) {
+      return nullptr;
+    }
+
+    std::unique_ptr<MemoryFileAtOffset> file_memory(new MemoryFileAtOffset);
+    uint64_t map_size;
+    if (offset != 0) {
+      // Only map in a piece of the file.
+      map_size = end - start;
+    } else {
+      map_size = UINT64_MAX;
+    }
+    if (file_memory->Init(name, offset, map_size)) {
+      // It's possible that a non-zero offset might not be pointing to
+      // valid elf data. Check if this is a valid elf, and if not assume
+      // that this was meant to incorporate the entire file.
+      if (offset != 0 && !Elf::IsValidElf(file_memory.get())) {
+        // Don't bother checking the validity that will happen on the elf init.
+        if (file_memory->Init(name, 0)) {
+          elf_offset = offset;
+          return file_memory.release();
+        }
+        // Fall through if the init fails.
+      } else {
+        return file_memory.release();
+      }
+    }
+  }
+
+  Memory* memory = nullptr;
+  if (pid == getpid()) {
+    memory = new MemoryLocal();
+  } else {
+    memory = new MemoryRemote(pid);
+  }
+  return new MemoryRange(memory, start, end);
+}
+
+Elf* MapInfo::GetElf(pid_t pid, bool) {
+  if (elf) {
+    return elf;
+  }
+
+  elf = new Elf(CreateMemory(pid));
+  elf->Init();
+  // If the init fails, keep the elf around as an invalid object so we
+  // don't try to reinit the object.
+  return elf;
+}

libunwindstack/MapInfo.h

@@ -39,6 +39,7 @@ struct MapInfo {
   uint64_t elf_offset;
 
   Memory* CreateMemory(pid_t pid);
+  Elf* GetElf(pid_t pid, bool init_gnu_debugdata = false);
 };
 
 #endif  // _LIBUNWINDSTACK_MAP_INFO_H

libunwindstack/tests/MapInfoTest.cpp

@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <elf.h>
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <memory>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/test_utils.h>
+#include <gtest/gtest.h>
+
+#include "Elf.h"
+#include "MapInfo.h"
+#include "Memory.h"
+
+class MapInfoTest : public ::testing::Test {
+ protected:
+  static void SetUpTestCase() {
+    std::vector<uint8_t> buffer(1024);
+    memcpy(buffer.data(), ELFMAG, SELFMAG);
+    for (size_t i = SELFMAG; i < buffer.size(); i++) {
+      buffer[i] = i / 256 + 1;
+    }
+    ASSERT_TRUE(android::base::WriteFully(elf_.fd, buffer.data(), buffer.size()));
+
+    for (size_t i = 0; i < 0x100; i++) {
+      buffer[i] = i / 256 + 1;
+    }
+    memcpy(&buffer[0x100], ELFMAG, SELFMAG);
+    for (size_t i = 0x100 + SELFMAG; i < buffer.size(); i++) {
+      buffer[i] = i / 256 + 1;
+    }
+    ASSERT_TRUE(android::base::WriteFully(elf_at_100_.fd, buffer.data(), buffer.size()));
+  }
+
+  static TemporaryFile elf_;
+
+  static TemporaryFile elf_at_100_;
+};
+TemporaryFile MapInfoTest::elf_;
+TemporaryFile MapInfoTest::elf_at_100_;
+
+TEST_F(MapInfoTest, end_le_start) {
+  MapInfo info{.start = 0x100, .end = 0x100, .offset = 0, .name = elf_.path};
+
+  std::unique_ptr<Memory> memory;
+  memory.reset(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() == nullptr);
+
+  info.end = 0xff;
+  memory.reset(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() == nullptr);
+
+  // Make sure this test is valid.
+  info.end = 0x101;
+  memory.reset(info.CreateMemory(getpid()));
+  ASSERT_FALSE(info.CreateMemory(getpid()) == nullptr);
+}
+
+// Verify that if the offset is non-zero but there is no elf at the offset,
+// that the full file is used.
+TEST_F(MapInfoTest, create_memory_file_backed_non_zero_offset_full_file) {
+  MapInfo info{.start = 0x100, .end = 0x200, .offset = 0x100, .name = elf_.path};
+
+  std::unique_ptr<Memory> memory(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() != nullptr);
+  ASSERT_EQ(0x100U, info.elf_offset);
+
+  // Read the entire file.
+  std::vector<uint8_t> buffer(1024);
+  ASSERT_TRUE(memory->Read(0, buffer.data(), 1024));
+  ASSERT_TRUE(memcmp(buffer.data(), ELFMAG, SELFMAG) == 0);
+  for (size_t i = SELFMAG; i < buffer.size(); i++) {
+    ASSERT_EQ(i / 256 + 1, buffer[i]) << "Failed at byte " << i;
+  }
+
+  ASSERT_FALSE(memory->Read(1024, buffer.data(), 1));
+}
+
+// Verify that if the offset is non-zero and there is an elf at that
+// offset, that only part of the file is used.
+TEST_F(MapInfoTest, create_memory_file_backed_non_zero_offset_partial_file) {
+  MapInfo info{.start = 0x100, .end = 0x200, .offset = 0x100, .name = elf_at_100_.path};
+
+  std::unique_ptr<Memory> memory(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() != nullptr);
+  ASSERT_EQ(0U, info.elf_offset);
+
+  // Read the valid part of the file.
+  std::vector<uint8_t> buffer(0x100);
+  ASSERT_TRUE(memory->Read(0, buffer.data(), 0x100));
+  ASSERT_TRUE(memcmp(buffer.data(), ELFMAG, SELFMAG) == 0);
+  for (size_t i = SELFMAG; i < buffer.size(); i++) {
+    ASSERT_EQ(2, buffer[i]) << "Failed at byte " << i;
+  }
+
+  ASSERT_FALSE(memory->Read(0x100, buffer.data(), 1));
+}
+
+// Verify that device file names will never result in Memory object creation.
+TEST_F(MapInfoTest, create_memory_check_device_maps) {
+  // Set up some memory so that a valid local memory object would
+  // be returned if the file mapping fails, but the device check is incorrect.
+  std::vector<uint8_t> buffer(1024);
+  MapInfo info;
+  info.start = reinterpret_cast<uint64_t>(buffer.data());
+  info.end = info.start + buffer.size();
+  info.offset = 0;
+  std::unique_ptr<Memory> memory;
+
+  info.flags = 0x8000;
+  info.name = "/dev/something";
+  memory.reset(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() == nullptr);
+}
+
+TEST_F(MapInfoTest, create_memory_local_memory) {
+  // Set up some memory for a valid local memory object.
+  std::vector<uint8_t> buffer(1024);
+  for (size_t i = 0; i < buffer.size(); i++) {
+    buffer[i] = i % 256;
+  }
+
+  MapInfo info;
+  info.start = reinterpret_cast<uint64_t>(buffer.data());
+  info.end = info.start + buffer.size();
+  info.offset = 0;
+
+  std::unique_ptr<Memory> memory;
+  memory.reset(info.CreateMemory(getpid()));
+  ASSERT_TRUE(memory.get() != nullptr);
+
+  std::vector<uint8_t> read_buffer(1024);
+  ASSERT_TRUE(memory->Read(0, read_buffer.data(), read_buffer.size()));
+  for (size_t i = 0; i < read_buffer.size(); i++) {
+    ASSERT_EQ(i % 256, read_buffer[i]) << "Failed at byte " << i;
+  }
+
+  ASSERT_FALSE(memory->Read(read_buffer.size(), read_buffer.data(), 1));
+}
+
+TEST_F(MapInfoTest, create_memory_remote_memory) {
+  std::vector<uint8_t> buffer(1024);
+  memset(buffer.data(), 0xa, buffer.size());
+
+  pid_t pid;
+  if ((pid = fork()) == 0) {
+    while (true)
+      ;
+    exit(1);
+  }
+  ASSERT_LT(0, pid);
+
+  ASSERT_TRUE(ptrace(PTRACE_ATTACH, pid, 0, 0) != -1);
+  uint64_t iterations = 0;
+  siginfo_t si;
+  while (TEMP_FAILURE_RETRY(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)) < 0 && errno == ESRCH) {
+    usleep(30);
+    iterations++;
+    ASSERT_LT(iterations, 500000000ULL);
+  }
+
+  MapInfo info;
+  info.start = reinterpret_cast<uint64_t>(buffer.data());
+  info.end = info.start + buffer.size();
+  info.offset = 0;
+
+  std::unique_ptr<Memory> memory;
+  memory.reset(info.CreateMemory(pid));
+  ASSERT_TRUE(memory.get() != nullptr);
+  // Set the local memory to a different value to guarantee we are reading
+  // from the remote process.
+  memset(buffer.data(), 0x1, buffer.size());
+  std::vector<uint8_t> read_buffer(1024);
+  ASSERT_TRUE(memory->Read(0, read_buffer.data(), read_buffer.size()));
+  for (size_t i = 0; i < read_buffer.size(); i++) {
+    ASSERT_EQ(0xaU, read_buffer[i]) << "Failed at byte " << i;
+  }
+
+  ASSERT_TRUE(ptrace(PTRACE_DETACH, pid, 0, 0) == 0);
+
+  kill(pid, SIGKILL);
+}
+
+TEST_F(MapInfoTest, get_elf) {
+  // Create a map to use as initialization data.
+  void* map = mmap(nullptr, 1024, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  ASSERT_NE(MAP_FAILED, map);
+
+  uint64_t start = reinterpret_cast<uint64_t>(map);
+  MapInfo info{.start = start, .end = start + 1024, .offset = 0, .name = ""};
+
+  // The map contains garbage, but this should still produce an elf object.
+  Elf* elf = info.GetElf(getpid(), false);
+  ASSERT_TRUE(elf != nullptr);
+  ASSERT_FALSE(elf->valid());
+
+  ASSERT_EQ(0, munmap(map, 1024));
+}