Refactor MemoryMappingLayout::Next to use a single struct instead of output parameters. NFC.

Summary:
This is the first in a series of patches to refactor sanitizer_procmaps
to allow MachO section information to be exposed on darwin.

In addition, grouping all segment information in a single struct is
cleaner than passing it through a large set of output parameters, and
avoids the need for annotations of NULL parameters for unneeded
information.

The filename string is optional and must be managed and supplied by the
calling function. This is to allow the MemoryMappedSegment struct to be
stored on the stack without causing overly large stack sizes.

Reviewers: alekseyshl, kubamracek, glider

Subscribers: emaste, llvm-commits

Differential Revision: https://reviews.llvm.org/D35135

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@307688 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 7 insertions, 9 deletions

diff --git a/lib/lsan/lsan_common.cc b/lib/lsan/lsan_common.cc
index db42ead83..4ffa91568 100644
--- a/lib/lsan/lsan_common.cc
+++ b/lib/lsan/lsan_common.cc
@@ -305,11 +305,10 @@ static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
 }
 
 void ScanRootRegion(Frontier *frontier, const RootRegion &root_region,
-                    uptr region_begin, uptr region_end, uptr prot) {
+                    uptr region_begin, uptr region_end, bool is_readable) {
   uptr intersection_begin = Max(root_region.begin, region_begin);
   uptr intersection_end = Min(region_end, root_region.begin + root_region.size);
   if (intersection_begin >= intersection_end) return;
-  bool is_readable = prot & MemoryMappingLayout::kProtectionRead;
   LOG_POINTERS("Root region %p-%p intersects with mapped region %p-%p (%s)\n",
                root_region.begin, root_region.begin + root_region.size,
                region_begin, region_end,
@@ -322,11 +321,10 @@ void ScanRootRegion(Frontier *frontier, const RootRegion &root_region,
 static void ProcessRootRegion(Frontier *frontier,
                               const RootRegion &root_region) {
   MemoryMappingLayout proc_maps(/*cache_enabled*/ true);
-  uptr begin, end, prot;
-  while (proc_maps.Next(&begin, &end,
-                        /*offset*/ nullptr, /*filename*/ nullptr,
-                        /*filename_size*/ 0, &prot)) {
-    ScanRootRegion(frontier, root_region, begin, end, prot);
+  MemoryMappedSegment segment;
+  while (proc_maps.Next(&segment)) {
+    ScanRootRegion(frontier, root_region, segment.start, segment.end,
+                   segment.IsReadable());
   }
 }
 
diff --git a/lib/lsan/lsan_common.h b/lib/lsan/lsan_common.h
index beb31d6f4..d93ac1b10 100644
--- a/lib/lsan/lsan_common.h
+++ b/lib/lsan/lsan_common.h
@@ -127,7 +127,7 @@ struct RootRegion {
 
 InternalMmapVector<RootRegion> const *GetRootRegions();
 void ScanRootRegion(Frontier *frontier, RootRegion const &region,
-                    uptr region_begin, uptr region_end, uptr prot);
+                    uptr region_begin, uptr region_end, bool is_readable);
 // Run stoptheworld while holding any platform-specific locks.
 void DoStopTheWorld(StopTheWorldCallback callback, void* argument);
 
diff --git a/lib/lsan/lsan_common_mac.cc b/lib/lsan/lsan_common_mac.cc
index adde3a1b4..f87c6b7e0 100644
--- a/lib/lsan/lsan_common_mac.cc
+++ b/lib/lsan/lsan_common_mac.cc
@@ -156,7 +156,7 @@ void ProcessPlatformSpecificAllocations(Frontier *frontier) {
     if (flags()->use_root_regions) {
       for (uptr i = 0; i < root_regions->size(); i++) {
         ScanRootRegion(frontier, (*root_regions)[i], address, end_address,
-                       info.protection);
+                       info.protection & kProtectionRead);
       }
     }