[llvm] r225271 - Don't loop endlessly for MachO files with 0 ncmds

[Rafael Espíndola]

Nice :-)

On 6 January 2015 at 12:08, Filipe Cabecinhas <me at filcab.net> wrote:
> Author: filcab
> Date: Tue Jan  6 11:08:26 2015
> New Revision: 225271
>
> URL: http://llvm.org/viewvc/llvm-project?rev=225271&view=rev
> Log:
> Don't loop endlessly for MachO files with 0 ncmds
>
> Added:
>     llvm/trunk/test/Object/Inputs/macho-zero-ncmds
>     llvm/trunk/test/Object/objdump-macho-quirks.test
> Modified:
>     llvm/trunk/lib/Object/MachOObjectFile.cpp
>     llvm/trunk/tools/llvm-objdump/MachODump.cpp
>
> Modified: llvm/trunk/lib/Object/MachOObjectFile.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/MachOObjectFile.cpp?rev=225271&r1=225270&r2=225271&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Object/MachOObjectFile.cpp (original)
> +++ llvm/trunk/lib/Object/MachOObjectFile.cpp Tue Jan  6 11:08:26 2015
> @@ -236,6 +236,9 @@ MachOObjectFile::MachOObjectFile(MemoryB
>        DataInCodeLoadCmd(nullptr), DyldInfoLoadCmd(nullptr),
>        UuidLoadCmd(nullptr), HasPageZeroSegment(false) {
>    uint32_t LoadCommandCount = this->getHeader().ncmds;
> +  if (LoadCommandCount == 0)
> +    return;
> +
>    MachO::LoadCommandType SegmentLoadType = is64Bit() ?
>      MachO::LC_SEGMENT_64 : MachO::LC_SEGMENT;
>
>
> Added: llvm/trunk/test/Object/Inputs/macho-zero-ncmds
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/Inputs/macho-zero-ncmds?rev=225271&view=auto
> ==============================================================================
> Binary files llvm/trunk/test/Object/Inputs/macho-zero-ncmds (added) and llvm/trunk/test/Object/Inputs/macho-zero-ncmds Tue Jan  6 11:08:26 2015 differ
>
> Added: llvm/trunk/test/Object/objdump-macho-quirks.test
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/objdump-macho-quirks.test?rev=225271&view=auto
> ==============================================================================
> --- llvm/trunk/test/Object/objdump-macho-quirks.test (added)
> +++ llvm/trunk/test/Object/objdump-macho-quirks.test Tue Jan  6 11:08:26 2015
> @@ -0,0 +1,9 @@
> +RUN: llvm-objdump -private-headers %p/Inputs/macho-zero-ncmds \
> +RUN:         | FileCheck %s -check-prefix A
> +
> +// Check that we don't get an infinite loop if ncmds = 0
> +A: file format Mach-O 64-bit unknown
> +A: Mach header
> +A:      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
> +A: MH_MAGIC_64  0x00      OBJECT     0          0 0x00000000
> +
>
> Modified: llvm/trunk/tools/llvm-objdump/MachODump.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objdump/MachODump.cpp?rev=225271&r1=225270&r2=225271&view=diff
> ==============================================================================
> --- llvm/trunk/tools/llvm-objdump/MachODump.cpp (original)
> +++ llvm/trunk/tools/llvm-objdump/MachODump.cpp Tue Jan  6 11:08:26 2015
> @@ -4204,6 +4204,8 @@ static void PrintLinkEditDataCommand(Mac
>  static void PrintLoadCommands(const MachOObjectFile *Obj, uint32_t ncmds,
>                                uint32_t filetype, uint32_t cputype,
>                                bool verbose) {
> +  if (ncmds == 0)
> +    return;
>    StringRef Buf = Obj->getData();
>    MachOObjectFile::LoadCommandInfo Command = Obj->getFirstLoadCommandInfo();
>    for (unsigned i = 0;; ++i) {
>
>
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