commit 3841accba82b47087647d023e670219ac3627710
author Yabin Cui <yabinc@google.com> Thu May 10 17:19:12 2018 -0700
committer Yabin Cui <yabinc@google.com> Mon May 14 14:00:18 2018 -0700
tree 2e5d901771563dded16721f694530b3ddc53e8ed
parent 3607fe672a1aa0fa775df01b60d18d287e7f8686

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

libbacktrace/BacktraceMap.cpp

diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index bdae140..399721d 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -28,6 +28,9 @@
 #include <backtrace/Backtrace.h>
 #include <backtrace/BacktraceMap.h>
 #include <backtrace/backtrace_constants.h>
+#if defined(__linux__)
+#include <procinfo/process_map.h>
+#endif
 
 #include "thread_utils.h"
 
@@ -60,27 +63,19 @@
   *map = {};
 }
 
-bool BacktraceMap::ParseLine(const char* line, backtrace_map_t* map) {
+#if defined(__APPLE__)
+static bool ParseLine(const char* line, backtrace_map_t* map) {
   uint64_t start;
   uint64_t end;
   char permissions[5];
   int name_pos;
 
-#if defined(__APPLE__)
 // Mac OS vmmap(1) output:
 // __TEXT                 0009f000-000a1000 [    8K     8K] r-x/rwx SM=COW  /Volumes/android/dalvik-dev/out/host/darwin-x86/bin/libcorkscrew_test\n
 // 012345678901234567890123456789012345678901234567890123456789
 // 0         1         2         3         4         5
   if (sscanf(line, "%*21c %" SCNx64 "-%" SCNx64 " [%*13c] %3c/%*3c SM=%*3c  %n",
              &start, &end, permissions, &name_pos) != 3) {
-#else
-// Linux /proc/<pid>/maps lines:
-// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
-// 012345678901234567890123456789012345678901234567890123456789
-// 0         1         2         3         4         5
-  if (sscanf(line, "%" SCNx64 "-%" SCNx64 " %4s %*x %*x:%*x %*d %n",
-             &start, &end, permissions, &name_pos) != 3) {
-#endif
     return false;
   }
 
@@ -107,24 +102,15 @@
         map->flags, map->name.c_str());
   return true;
 }
+#endif  // defined(__APPLE__)
 
 bool BacktraceMap::Build() {
 #if defined(__APPLE__)
   char cmd[sizeof(pid_t)*3 + sizeof("vmmap -w -resident -submap -allSplitLibs -interleaved ") + 1];
-#else
-  char path[sizeof(pid_t)*3 + sizeof("/proc//maps") + 1];
-#endif
   char line[1024];
-
-#if defined(__APPLE__)
   // cmd is guaranteed to always be big enough to hold this string.
   snprintf(cmd, sizeof(cmd), "vmmap -w -resident -submap -allSplitLibs -interleaved %d", pid_);
   FILE* fp = popen(cmd, "r");
-#else
-  // path is guaranteed to always be big enough to hold this string.
-  snprintf(path, sizeof(path), "/proc/%d/maps", pid_);
-  FILE* fp = fopen(path, "r");
-#endif
   if (fp == nullptr) {
     return false;
   }
@@ -135,13 +121,19 @@
       maps_.push_back(map);
     }
   }
-#if defined(__APPLE__)
   pclose(fp);
-#else
-  fclose(fp);
-#endif
-
   return true;
+#else
+  return android::procinfo::ReadProcessMaps(
+      pid_, [&](uint64_t start, uint64_t end, uint16_t flags, uint64_t, const char* name) {
+        maps_.resize(maps_.size() + 1);
+        backtrace_map_t& map = maps_.back();
+        map.start = start;
+        map.end = end;
+        map.flags = flags;
+        map.name = name;
+      });
+#endif
 }
 
 #if defined(__APPLE__)