[llvm-obcopy][MachO] Add error for MH_PRELOAD

[keith]

Summary

Previously this would crash. Fixes https://bugs.llvm.org/show_bug.cgi?id=51877

[alexander-shaposhnikov]

llvm/test/tools/llvm-objcopy/MachO/Inputs/mh_preload.yaml

1 ↗

(On Diff #386987)

this can be reduced to just the header, no load commands, no sections

llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

393

if I am not mistaken this should be replaced with llvm::errc::not_supported

[keith]

Improve test, change error code

[alexander-shaposhnikov]

LG, thanks for the fix!

[keith]

Thanks for the super quick review!

llvm/test/tools/llvm-objcopy/MachO/mh-preload-unsupported.yaml

+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x100000C
+  cpusubtype:      0x0
+  filetype:        0x5
+  ncmds:           0
+  sizeofcmds:      0
+  flags:           0x1
+  reserved:        0x0
+...
+
+# RUN: yaml2obj %s > %t
+# RUN: not llvm-objcopy %t 2>&1 | FileCheck %s -DFILE=%t
+#
+# CHECK: error: [[FILE]]: MH_PRELOAD files are not supported

llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

Error objcopy::macho::executeObjcopyOnBinary(const CommonConfig &Config,
                                              const MachOConfig &MachOConfig,
                                              object::MachOObjectFile &In,
                                              raw_ostream &Out) {
   MachOReader Reader(In);
   Expected<std::unique_ptr<Object>> O = Reader.create();
   if (!O)
     return createFileError(Config.InputFilename, O.takeError());
 
+  if (O->get()->Header.FileType == MachO::HeaderFileType::MH_PRELOAD)
+    return createStringError(std::errc::not_supported,
+                             "%s: MH_PRELOAD files are not supported",
+                             Config.InputFilename.str().c_str());
+
   if (Error E = handleArgs(Config, MachOConfig, **O))
     return createFileError(Config.InputFilename, std::move(E));
 
   // Page size used for alignment of segment sizes in Mach-O executables and
   // dynamic libraries.
   uint64_t PageSize;
   switch (In.getArch()) {
   case Triple::ArchType::arm: