[ReflectionContext] Take slide in account.

Author: Davide Italiano

include/swift/Reflection/ReflectionContext.h

@@ -139,12 +139,8 @@ class ReflectionContext
     if (!Command)
       return false;
 
-    // Read everything including the __TEXT segment.
-    // Buf = this->getReader().readBytes(ImageStart, Command->vmsize);
-    auto Start = reinterpret_cast<const char *>(Buf.get());
-
-    // Find the load command offset.
-    auto loadCmdOffset = Start + Offset + sizeof(typename T::Header);
+   // Find the load command offset.
+    auto loadCmdOffset = ImageStart.getAddressData() + Offset + sizeof(typename T::Header);
 
     // Read the load command.
     auto LoadCmdAddress = reinterpret_cast<const char *>(loadCmdOffset);
@@ -159,49 +155,43 @@ class ReflectionContext
     auto Sections = this->getReader().readBytes(
         RemoteAddress(SectAddress), NumSect * sizeof(typename T::Section));
 
+    auto Slide = ImageStart.getAddressData() - Command->vmaddr;
     std::string Prefix = "__swift5";
     uint64_t RangeStart = UINT64_MAX;
     uint64_t RangeEnd = UINT64_MAX;
+    auto SectionsBuf = reinterpret_cast<const char *>(Sections.get());
     for (unsigned I = 0; I < NumSect; ++I) {
       auto S = reinterpret_cast<typename T::Section *>(
-          SectAddress + (I * sizeof(typename T::Section)));
+          SectionsBuf + (I * sizeof(typename T::Section)));
       if (strncmp(S->sectname, Prefix.c_str(), strlen(Prefix.c_str())) != 0)
         continue;
       if (RangeStart == UINT64_MAX && RangeEnd == UINT64_MAX) {
-        RangeStart = S->addr;
-        RangeEnd = S->addr + S->size;
+        RangeStart = S->addr + Slide;
+        RangeEnd = S->addr + S->size + Slide;
         continue;
       }
-      RangeStart = std::min(RangeStart, (uint64_t)S->addr);
-      RangeEnd = std::max(RangeEnd, (uint64_t)(S->addr + S->size));
+      RangeStart = std::min(RangeStart, (uint64_t)S->addr + Slide);
+      RangeEnd = std::max(RangeEnd, (uint64_t)(S->addr + S->size + Slide));
     }
-
+ 
     if (RangeStart == UINT64_MAX && RangeEnd == UINT64_MAX)
       return false;
 
-    auto Slide = ImageStart.getAddressData() - Command->vmaddr;
     auto SectBuf = this->getReader().readBytes(RemoteAddress(RangeStart),
                                                RangeEnd - RangeStart);
 
     auto findMachOSectionByName = [&](std::string Name)
         -> std::pair<std::pair<const char *, const char *>, uint32_t> {
-      auto cmdOffset = Start + Offset + sizeof(typename T::Header);
-      auto SegCmd = reinterpret_cast<typename T::SegmentCmd *>(cmdOffset);
-      auto SectAddress = reinterpret_cast<const char *>(cmdOffset) +
-                         sizeof(typename T::SegmentCmd);
-      for (unsigned I = 0; I < SegCmd->nsects; ++I) {
+      for (unsigned I = 0; I < NumSect; ++I) {
         auto S = reinterpret_cast<typename T::Section *>(
-            SectAddress + (I * sizeof(typename T::Section)));
+            SectionsBuf + (I * sizeof(typename T::Section)));
         if (strncmp(S->sectname, Name.c_str(), strlen(Name.c_str())) != 0)
           continue;
-        auto Slide = ImageStart.getAddressData() - Command->vmaddr;
         auto RemoteSecStart = S->addr + Slide;
-        auto LocalSectBuf =
-            this->getReader().readBytes(RemoteAddress(RemoteSecStart), S->size);
+        auto SectBufData = reinterpret_cast<const char *>(SectBuf.get());
         auto LocalSectStart =
-            reinterpret_cast<const char *>(LocalSectBuf.get());
-        auto LocalSectEnd =
-            reinterpret_cast<const char *>(LocalSectBuf.get()) + S->size;
+            reinterpret_cast<const char *>(SectBufData + RemoteSecStart - RangeStart);
+        auto LocalSectEnd = reinterpret_cast<const char *>(LocalSectStart + S->size);
         return {{LocalSectStart, LocalSectEnd}, 0};
       }
       return {{nullptr, nullptr}, 0};