[macho] Minor install_name fixes

[Jean-Daniel]

Summary

Fix the binary file reader to properly read dyld version info.
Update the install_name test case to properly test the binary reader. We can't use '-print_atoms' as the output format is 'native' yaml and it does not contains the dyld current and compatibility versions.

Also change the timestamp value of LD_ID_DYLD to match the one generated by ld64.
The dynamic linker (dyld) used to expects different values for timestamp in LD_ID_DYLD and LD_LOAD_DYLD for prebound images. While prebinding is deprecated, we should probably keep it safe and match ld64.

[kledzik]

LGTM

lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp

case LC_SYMTAB: {
             f->localSymbols.push_back(sout);
         }
       }
       }
       break;
     case LC_ID_DYLIB: {
       const dylib_command *dl = reinterpret_cast<const dylib_command*>(lc);
       f->installName = lc + read32(&dl->dylib.name, isBig);
+      f->currentVersion = read32(&dl->dylib.current_version, isBig);
+      f->compatVersion = read32(&dl->dylib.compatibility_version, isBig);
       }
       break;
     case LC_DATA_IN_CODE: {
       const linkedit_data_command *ldc =
                             reinterpret_cast<const linkedit_data_command*>(lc);
       dataInCode = reinterpret_cast<const data_in_code_entry *>(
           start + read32(&ldc->dataoff, isBig));
       dataInCodeSize = read32(&ldc->datasize, isBig);

lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp

if (_file.fileType == llvm::MachO::MH_OBJECT) {
     // Add LC_ID_DYLIB command for dynamic libraries.
     if (_file.fileType == llvm::MachO::MH_DYLIB) {
       dylib_command *dc = reinterpret_cast<dylib_command*>(lc);
       StringRef path = _file.installName;
       uint32_t size = sizeof(dylib_command) + pointerAlign(path.size() + 1);
       dc->cmd                         = LC_ID_DYLIB;
       dc->cmdsize                     = size;
       dc->dylib.name                  = sizeof(dylib_command); // offset
-      dc->dylib.timestamp             = 2;
+      // needs to be some constant value different than the one in LC_LOAD_DYLIB
+      dc->dylib.timestamp             = 1;
       dc->dylib.current_version       = _file.currentVersion;
       dc->dylib.compatibility_version = _file.compatVersion;
       if (_swap)
         swapStruct(*dc);
       memcpy(lc + sizeof(dylib_command), path.begin(), path.size());
       lc[sizeof(dylib_command) + path.size()] = '\0';
       lc += size;
     }
if (_file.fileType == llvm::MachO::MH_OBJECT) {
 
     // Add LC_LOAD_DYLIB commands
     for (const DependentDylib &dep : _file.dependentDylibs) {
       dylib_command* dc = reinterpret_cast<dylib_command*>(lc);
       uint32_t size = sizeof(dylib_command) + pointerAlign(dep.path.size()+1);
       dc->cmd                         = dep.kind;
       dc->cmdsize                     = size;
       dc->dylib.name                  = sizeof(dylib_command); // offset
+      // needs to be some constant value different than the one in LC_ID_DYLIB
       dc->dylib.timestamp             = 2;
       dc->dylib.current_version       = dep.currentVersion;
       dc->dylib.compatibility_version = dep.compatVersion;
       if (_swap)
         swapStruct(*dc);
       memcpy(lc+sizeof(dylib_command), dep.path.begin(), dep.path.size());
       lc[sizeof(dylib_command)+dep.path.size()] = '\0';
       lc += size;

lld/trunk/test/mach-o/dylib-install-names.yaml

 # Check we accept -install_name correctly:
 # RUN: lld -flavor darwin -arch x86_64 -install_name libwibble.dylib -dylib \
 # RUN:     -compatibility_version 2.0 -current_version 5.3 \
 # RUN:     %p/Inputs/libSystem.yaml %s -o %t.dylib
-# RUN: macho-dump %t.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
+# RUN: llvm-objdump -private-headers %t.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
 
 # Check we read LC_ID_DYLIB correctly:
 # RUN: lld -flavor darwin -arch x86_64 %p/Inputs/use-dylib-install-names.yaml \
-# RUN:      %t.dylib -r -print_atoms | FileCheck %s --check-prefix=CHECK-BINARY-READ
+# RUN:      %p/Inputs/libSystem.yaml %t.dylib -dylib -o %t2.dylib
+# RUN: llvm-objdump -private-headers %t2.dylib | FileCheck %s --check-prefix=CHECK-BINARY-READ
 
 # Check we default the install-name to the output file:
 # RUN: lld -flavor darwin -arch x86_64 -dylib %s -o libwibble.dylib \
 # RUN:     -compatibility_version 2.0 -current_version 5.3 \
 # RUN:     %p/Inputs/libSystem.yaml
-# RUN: macho-dump libwibble.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
+# RUN: llvm-objdump -private-headers libwibble.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
 # RUN: rm -f libwibble.dylib
 
 # Check -single_module does nothing
 # RUN: lld -flavor darwin -arch x86_64 -dylib %s -install_name libwibble.dylib \
 # RUN:     -compatibility_version 2.0 -current_version 5.3 \
 # RUN:     -single_module -o %t2.dylib %p/Inputs/libSystem.yaml
-# RUN: macho-dump %t2.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
+# RUN: llvm-objdump -private-headers %t2.dylib | FileCheck %s --check-prefix=CHECK-BINARY-WRITE
 
 --- !mach-o
 arch:            x86_64
 file-type:       MH_OBJECT
 flags:           [ MH_SUBSECTIONS_VIA_SYMBOLS ]
 has-UUID:        false
 OS:              unknown
 sections:
global-symbols:
   - name:            _myGlobal
     type:            N_SECT
     scope:           [ N_EXT ]
     sect:            1
     value:           0x0000000000000001
 ...
 
 
-# CHECK-BINARY-WRITE: (('command', 13)
-# CHECK-BINARY-WRITE-NEXT:  ('size', 40)
-# CHECK-BINARY-WRITE-NEXT:  ('install_name', 'libwibble.dylib')
-# CHECK-BINARY-WRITE-NEXT:    ('timestamp,
-# CHECK-BINARY-WRITE-NEXT:    ('cur_version, 328448)
-# CHECK-BINARY-WRITE-NEXT:    ('compat_version, 131072)
-
-# CHECK-BINARY-READ: shared-library-atoms:
-# CHECK-BINARY-READ:     - name:          _myGlobal
-# CHECK-BINARY-READ:       load-name:     libwibble.dylib
+# CHECK-BINARY-WRITE: cmd LC_ID_DYLIB
+# CHECK-BINARY-WRITE-NEXT: cmdsize 40
+# CHECK-BINARY-WRITE-NEXT:  name libwibble.dylib (offset 24)
+# CHECK-BINARY-WRITE-NEXT:  time stamp 1
+# CHECK-BINARY-WRITE-NEXT:  current version 5.3.0
+# CHECK-BINARY-WRITE-NEXT:  compatibility version 2.0.0
+
+# CHECK-BINARY-READ: cmd LC_LOAD_DYLIB
+# CHECK-BINARY-READ-NEXT: cmdsize 56
+# CHECK-BINARY-READ-NEXT:  name /usr/lib/libSystem.B.dylib (offset 24)
+# CHECK-BINARY-READ-NEXT:  time stamp 2
+# CHECK-BINARY-READ-NEXT:  current version 0.16.0
+# CHECK-BINARY-READ-NEXT:  compatibility version 0.16.0
+
+# CHECK-BINARY-READ: cmd LC_LOAD_DYLIB
+# CHECK-BINARY-READ-NEXT: cmdsize 40
+# CHECK-BINARY-READ-NEXT:  name libwibble.dylib (offset 24)
+# CHECK-BINARY-READ-NEXT:  time stamp 2
+# CHECK-BINARY-READ-NEXT:  current version 5.3.0
+# CHECK-BINARY-READ-NEXT:  compatibility version 2.0.0