meminfo: Add Smaps(), showmap and friends.

Needed by showmap and also android_s_Debug to classify each allocation
into multiple heaps.

The APIs added are:
ForEachVmaFromFile - Global API to parse a file expected to be in the
same format as /proc/<pid>/smaps and make a callback for each VMA found.
ProcMemInfo::ForEachVma - Same as 'ForEachVmaFromFile' but for a
ProcMemInfo object corresponding to a process(pid).
ProcMemInfo::Smaps - Wrapper to ProcMemInfo::ForEachVma, except the
function collects 'struct Vma' in a member vector and returns the
reference for the same.

Added showmap2 using the APIs and the corresponding tests the same time.

Bug: 111694435
Test: showmap_test.sh
Test: libmeminfo_test 1

Change-Id: I3065809cf94ecf3da88529809701035c47a8ce34
Signed-off-by: Sandeep Patil <sspatil@google.com>

2 files changed, 25 insertions, 1 deletions

diff --git a/libmeminfo/include/meminfo/meminfo.h b/libmeminfo/include/meminfo/meminfo.h
index 21e0af4af..5ee32d45f 100644
--- a/libmeminfo/include/meminfo/meminfo.h
+++ b/libmeminfo/include/meminfo/meminfo.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <string.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -66,10 +67,16 @@ struct Vma {
     uint16_t flags;
     std::string name;
 
+    Vma() : start(0), end(0), offset(0), flags(0), name("") {}
     Vma(uint64_t s, uint64_t e, uint64_t off, uint16_t f, const char* n)
         : start(s), end(e), offset(off), flags(f), name(n) {}
     ~Vma() = default;
 
+    void clear() {
+        memset(&usage, 0, sizeof(usage));
+        memset(&wss, 0, sizeof(wss));
+    }
+
     // Memory usage of this mapping.
     MemUsage usage;
     // Working set within this mapping.
diff --git a/libmeminfo/include/meminfo/procmeminfo.h b/libmeminfo/include/meminfo/procmeminfo.h
index 4aafd7713..0bfd80f2f 100644
--- a/libmeminfo/include/meminfo/procmeminfo.h
+++ b/libmeminfo/include/meminfo/procmeminfo.h
@@ -26,6 +26,8 @@
 namespace android {
 namespace meminfo {
 
+using VmaCallback = std::function<void(const Vma&)>;
+
 class ProcMemInfo final {
     // Per-process memory accounting
   public:
@@ -38,6 +40,18 @@ class ProcMemInfo final {
     const MemUsage& Usage();
     const MemUsage& Wss();
 
+    // Collect all 'vma' or 'maps' from /proc/<pid>/smaps and store them in 'maps_'. Returns a
+    // constant reference to the vma vector after the collection is done.
+    //
+    // Each 'struct Vma' is *fully* populated by this method (unlike SmapsOrRollup).
+    const std::vector<Vma>& Smaps(const std::string& path = "");
+
+    // This method reads /proc/<pid>/smaps and calls the callback() for each
+    // vma or map that it finds. The map is converted to 'struct Vma' object which is then
+    // passed to the callback.
+    // Returns 'false' if the file is malformed.
+    bool ForEachVma(const VmaCallback& callback);
+
     // Used to parse either of /proc/<pid>/{smaps, smaps_rollup} and record the process's
     // Pss and Private memory usage in 'stats'.  In particular, the method only populates the fields
     // of the MemUsage structure that are intended to be used by Android's periodic Pss collection.
@@ -49,7 +63,6 @@ class ProcMemInfo final {
     //   private_clean
     //   private_dirty
     //   SwapPss
-    //
     // All other fields of MemUsage are zeroed.
     bool SmapsOrRollup(bool use_rollup, MemUsage* stats) const;
 
@@ -73,6 +86,10 @@ class ProcMemInfo final {
     std::vector<uint16_t> swap_offsets_;
 };
 
+// Makes callback for each 'vma' or 'map' found in file provided. The file is expected to be in the
+// same format as /proc/<pid>/smaps. Returns 'false' if the file is malformed.
+bool ForEachVmaFromFile(const std::string& path, const VmaCallback& callback);
+
 // Same as ProcMemInfo::SmapsOrRollup but reads the statistics directly
 // from a file. The file MUST be in the same format as /proc/<pid>/smaps
 // or /proc/<pid>/smaps_rollup