[PATCH] D91221: [MachO] Allow the LC_IDENT load command

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.
vsk added reviewers: JDevlieghere, lhames, jasonmolenda.
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xnu coredumps include an LC_IDENT load command. It's helpful to be able
to just ignore these. IIUC an interested client can grab the identifier
using the MachOObjectFile::load_commands() API.

The status quo is that llvm bails out when it finds an LC_IDENT because
the command is obsolete (see isLoadCommandObsolete).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91221

Files:
  llvm/lib/Object/MachOObjectFile.cpp
  llvm/test/ObjectYAML/MachO/lc-ident.yaml


Index: llvm/test/ObjectYAML/MachO/lc-ident.yaml
===================================================================
--- /dev/null
+++ llvm/test/ObjectYAML/MachO/lc-ident.yaml
@@ -0,0 +1,22 @@
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
+
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x80000003
+  filetype:        0x00000002
+  ncmds:           1
+  sizeofcmds:      16
+  flags:           0x00218085
+  reserved:        0x00000000
+LoadCommands:
+  - cmd:             LC_IDENT
+    cmdsize:         16
+    PayloadBytes:    [ 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7 ]
+...
+
+# CHECK: LoadCommands:
+# CHECK-NEXT:   - cmd:             LC_IDENT
+# CHECK-NEXT:     cmdsize:         16
+# CHECK-NEXT:     PayloadBytes:    [ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 ]
Index: llvm/lib/Object/MachOObjectFile.cpp
===================================================================
--- llvm/lib/Object/MachOObjectFile.cpp
+++ llvm/lib/Object/MachOObjectFile.cpp
@@ -1596,6 +1596,9 @@
        if ((Err = checkTwoLevelHintsCommand(*this, Load, I,
                                             &TwoLevelHintsLoadCmd, Elements)))
          return;
+    } else if (Load.C.cmd == MachO::LC_IDENT) {
+      // Note: LC_IDENT is ignored.
+      continue;
     } else if (isLoadCommandObsolete(Load.C.cmd)) {
       Err = malformedError("load command " + Twine(I) + " for cmd value of: " +
                            Twine(Load.C.cmd) + " is obsolete and not "


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