libprocinfo: add functions reading process map file.

Add test and benchmark.
Also switch libbacktrace, libunwindstack, libmemunreachable
to use libprocinfo for map file reading.
The benchmark shows using libprocinfo speeds up map file reading
in libbacktrace and libunwindstack 18% - 36% on walleye.

Bug: http://b/79118393
Test: run procinfo_test.
Test: run libunwindstack_test.
Test: run libbacktrace_test.
Test: run memunreachable_test.

Change-Id: Icf281c352f4103fc8d4ba6732c5c07b943330ca1

5 files changed, 28 insertions, 140 deletions

diff --git a/libmemunreachable/Android.bp b/libmemunreachable/Android.bp
index f164a19e0..248a9d25c 100644
--- a/libmemunreachable/Android.bp
+++ b/libmemunreachable/Android.bp
@@ -29,7 +29,6 @@ cc_library {
         "HeapWalker.cpp",
         "LeakFolding.cpp",
         "LeakPipe.cpp",
-        "LineBuffer.cpp",
         "MemUnreachable.cpp",
         "ProcessMappings.cpp",
         "PtracerThread.cpp",
@@ -38,6 +37,7 @@ cc_library {
 
     static_libs: [
         "libc_malloc_debug_backtrace",
+        "libprocinfo",
     ],
     // Only need this for arm since libc++ uses its own unwind code that
     // doesn't mix with the other default unwind code.
diff --git a/libmemunreachable/LineBuffer.cpp b/libmemunreachable/LineBuffer.cpp
deleted file mode 100644
index 4ea0542c7..000000000
--- a/libmemunreachable/LineBuffer.cpp
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright (C) 2015 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.
- */
-
-// Copied from system/extras/memory_replay/LineBuffer.cpp
-// TODO(ccross): find a way to share between libmemunreachable and memory_replay?
-
-#include <errno.h>
-#include <string.h>
-#include <unistd.h>
-
-#include "LineBuffer.h"
-
-namespace android {
-
-LineBuffer::LineBuffer(int fd, char* buffer, size_t buffer_len)
-    : fd_(fd), buffer_(buffer), buffer_len_(buffer_len) {}
-
-bool LineBuffer::GetLine(char** line, size_t* line_len) {
-  while (true) {
-    if (bytes_ > 0) {
-      char* newline = reinterpret_cast<char*>(memchr(buffer_ + start_, '\n', bytes_));
-      if (newline != nullptr) {
-        *newline = '\0';
-        *line = buffer_ + start_;
-        start_ = newline - buffer_ + 1;
-        bytes_ -= newline - *line + 1;
-        *line_len = newline - *line;
-        return true;
-      }
-    }
-    if (start_ > 0) {
-      // Didn't find anything, copy the current to the front of the buffer.
-      memmove(buffer_, buffer_ + start_, bytes_);
-      start_ = 0;
-    }
-    ssize_t bytes = TEMP_FAILURE_RETRY(read(fd_, buffer_ + bytes_, buffer_len_ - bytes_ - 1));
-    if (bytes <= 0) {
-      if (bytes_ > 0) {
-        // The read data might not contain a nul terminator, so add one.
-        buffer_[bytes_] = '\0';
-        *line = buffer_ + start_;
-        *line_len = bytes_;
-        bytes_ = 0;
-        start_ = 0;
-        return true;
-      }
-      return false;
-    }
-    bytes_ += bytes;
-  }
-}
-
-}  // namespace android
diff --git a/libmemunreachable/LineBuffer.h b/libmemunreachable/LineBuffer.h
deleted file mode 100644
index cc6cd0c6a..000000000
--- a/libmemunreachable/LineBuffer.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright (C) 2015 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.
- */
-
-#ifndef _LIBMEMUNREACHABLE_LINE_BUFFER_H
-#define _LIBMEMUNREACHABLE_LINE_BUFFER_H
-
-#include <stdint.h>
-
-namespace android {
-
-class LineBuffer {
- public:
-  LineBuffer(int fd, char* buffer, size_t buffer_len);
-
-  bool GetLine(char** line, size_t* line_len);
-
- private:
-  int fd_;
-  char* buffer_ = nullptr;
-  size_t buffer_len_ = 0;
-  size_t start_ = 0;
-  size_t bytes_ = 0;
-};
-
-}  // namespace android
-
-#endif  // _LIBMEMUNREACHABLE_LINE_BUFFER_H
diff --git a/libmemunreachable/ProcessMappings.cpp b/libmemunreachable/ProcessMappings.cpp
index 9a0687052..701ce1670 100644
--- a/libmemunreachable/ProcessMappings.cpp
+++ b/libmemunreachable/ProcessMappings.cpp
@@ -14,21 +14,30 @@
  * limitations under the License.
  */
 
+#include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <string.h>
 #include <unistd.h>
 
 #include <android-base/unique_fd.h>
+#include <procinfo/process_map.h>
 
-#include "LineBuffer.h"
 #include "ProcessMappings.h"
-#include "log.h"
 
 namespace android {
 
-// This function is not re-entrant since it uses a static buffer for
-// the line data.
+struct ReadMapCallback {
+  ReadMapCallback(allocator::vector<Mapping>& mappings) : mappings_(mappings) {}
+
+  void operator()(uint64_t start, uint64_t end, uint16_t flags, uint64_t, const char* name) const {
+    mappings_.emplace_back(start, end, flags & PROT_READ, flags & PROT_WRITE, flags & PROT_EXEC,
+                           name);
+  }
+
+  allocator::vector<Mapping>& mappings_;
+};
+
 bool ProcessMappings(pid_t pid, allocator::vector<Mapping>& mappings) {
   char map_buffer[1024];
   snprintf(map_buffer, sizeof(map_buffer), "/proc/%d/maps", pid);
@@ -36,35 +45,13 @@ bool ProcessMappings(pid_t pid, allocator::vector<Mapping>& mappings) {
   if (fd == -1) {
     return false;
   }
-
-  LineBuffer line_buf(fd, map_buffer, sizeof(map_buffer));
-  char* line;
-  size_t line_len;
-  while (line_buf.GetLine(&line, &line_len)) {
-    int name_pos;
-    char perms[5];
-    Mapping mapping{};
-    if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR " %4s %*x %*x:%*x %*d %n", &mapping.begin,
-               &mapping.end, perms, &name_pos) == 3) {
-      if (perms[0] == 'r') {
-        mapping.read = true;
-      }
-      if (perms[1] == 'w') {
-        mapping.write = true;
-      }
-      if (perms[2] == 'x') {
-        mapping.execute = true;
-      }
-      if (perms[3] == 'p') {
-        mapping.priv = true;
-      }
-      if ((size_t)name_pos < line_len) {
-        strlcpy(mapping.name, line + name_pos, sizeof(mapping.name));
-      }
-      mappings.emplace_back(mapping);
-    }
+  allocator::string content(mappings.get_allocator());
+  ssize_t n;
+  while ((n = TEMP_FAILURE_RETRY(read(fd, map_buffer, sizeof(map_buffer)))) > 0) {
+    content.append(map_buffer, n);
   }
-  return true;
+  ReadMapCallback callback(mappings);
+  return android::procinfo::ReadMapFileContent(&content[0], callback);
 }
 
 }  // namespace android
diff --git a/libmemunreachable/ProcessMappings.h b/libmemunreachable/ProcessMappings.h
index a0e97e9fc..94da69b11 100644
--- a/libmemunreachable/ProcessMappings.h
+++ b/libmemunreachable/ProcessMappings.h
@@ -17,6 +17,8 @@
 #ifndef LIBMEMUNREACHABLE_PROCESS_MAPPING_H_
 #define LIBMEMUNREACHABLE_PROCESS_MAPPING_H_
 
+#include <string.h>
+
 #include "Allocator.h"
 
 namespace android {
@@ -27,8 +29,13 @@ struct Mapping {
   bool read;
   bool write;
   bool execute;
-  bool priv;
   char name[96];
+
+  Mapping() {}
+  Mapping(uintptr_t begin, uintptr_t end, bool read, bool write, bool execute, const char* name)
+      : begin(begin), end(end), read(read), write(write), execute(execute) {
+    strlcpy(this->name, name, sizeof(this->name));
+  }
 };
 
 // This function is not re-entrant since it uses a static buffer for