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Merged
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Apr 28, 2021
Merged

Read machO sections section by section #37092

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42 changes: 7 additions & 35 deletions include/swift/Reflection/ReflectionContext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -205,36 +205,7 @@ class ReflectionContext
return false;

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 *>(
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 + Slide;
RangeEnd = S->addr + S->size + Slide;
continue;
}
RangeStart = std::min(RangeStart, (uint64_t)S->addr + Slide);
RangeEnd = std::max(RangeEnd, (uint64_t)(S->addr + S->size + Slide));
// Keep the range rounded to 8 byte alignment on both ends so we don't
// introduce misaligned pointers mapping between local and remote
// address space.
RangeStart = RangeStart & ~7;
RangeEnd = RangeEnd + 7 & ~7;
}

if (RangeStart == UINT64_MAX && RangeEnd == UINT64_MAX)
return false;

auto SectBuf = this->getReader().readBytes(RemoteAddress(RangeStart),
RangeEnd - RangeStart);
if (!SectBuf)
return false;

auto findMachOSectionByName = [&](llvm::StringRef Name)
-> std::pair<RemoteRef<void>, uint64_t> {
Expand All @@ -244,11 +215,13 @@ class ReflectionContext
if (strncmp(S->sectname, Name.data(), strlen(Name.data())) != 0)
continue;
auto RemoteSecStart = S->addr + Slide;
auto SectBufData = reinterpret_cast<const char *>(SectBuf.get());
auto LocalSectStart =
reinterpret_cast<const char *>(SectBufData + RemoteSecStart - RangeStart);

auto StartRef = RemoteRef<void>(RemoteSecStart, LocalSectStart);
auto LocalSectBuf =
this->getReader().readBytes(RemoteAddress(RemoteSecStart), S->size);
if (!LocalSectBuf)
return {nullptr, 0};

auto StartRef = RemoteRef<void>(RemoteSecStart, LocalSectBuf.get());
savedBuffers.push_back(std::move(LocalSectBuf));
return {StartRef, S->size};
}
return {nullptr, 0};
Expand Down Expand Up @@ -307,7 +280,6 @@ class ReflectionContext
}

savedBuffers.push_back(std::move(Buf));
savedBuffers.push_back(std::move(SectBuf));
savedBuffers.push_back(std::move(Sections));
return true;
}
Expand Down