From: Carlo Cabrera <carlo.antonio.cabrera@gmail.com>
Subject: `got import` segfaults on macOS (got-portable 0.85, 0.86)
To: gameoftrees@openbsd.org
Date: Wed, 15 Mar 2023 19:35:36 +0800

Hi all,

We've been having trouble updating our got package at Homebrew. (See attempts at
[1], [2].)

The following smoke test causes `got` to segfault:

    export GOT_AUTHOR="Flan Hacker <flan_hacker@openbsd.org>"
    gotadmin init repo.git
    mkdir import-dir
    touch import-dir/{haunted,house}
    got import -m "Initial commit" -r repo.git import-dir

This has been happening since got 0.85. got 0.84 does not have this problem.

Based on output from `lldb`, I believe the problem is a null pointer
dereference:

    ❯ lldb -- got import -m "initial commit" -r repo.git import-dir
    (lldb) target create "got"
    Current executable set to 'got' (x86_64).
    (lldb) settings set -- target.run-args  "import" "-m" "initial commit" "-r" "repo.git" "import-dir"
    (lldb) r
    Process 29562 launched: '/usr/local/bin/got' (x86_64)
    Process 29562 stopped
    * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
        frame #0: 0x00007ff80d07c6b2 libsystem_platform.dylib`_platform_strlen + 18
    libsystem_platform.dylib`:
    ->  0x7ff80d07c6b2 <+18>: pcmpeqb (%rdi), %xmm0
        0x7ff80d07c6b6 <+22>: pmovmskb %xmm0, %esi
        0x7ff80d07c6ba <+26>: andq   $0xf, %rcx
        0x7ff80d07c6be <+30>: orq    $-0x1, %rax
    Target 0: (got) stopped.
    (lldb) bt
    * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
      * frame #0: 0x00007ff80d07c6b2 libsystem_platform.dylib`_platform_strlen + 18
        frame #1: 0x00007ff80cf346c8 libsystem_c.dylib`strdup + 18
        frame #2: 0x0000000100001f79 got`cmd_import(argc=6, argv=0x00007ff7bfefe398) at got.c:788:13 [opt]
        frame #3: 0x0000000100001c36 got`main(argc=6, argv=0x00007ff7bfefe398) at got.c:260:11 [opt]
        frame #4: 0x00000001000c952e dyld`start + 462
    (lldb) up
    frame #1: 0x00007ff80cf346c8 libsystem_c.dylib`strdup + 18
    libsystem_c.dylib`strdup:
    ->  0x7ff80cf346c8 <+18>: movq   %rax, %rbx
        0x7ff80cf346cb <+21>: incq   %rbx
        0x7ff80cf346ce <+24>: movq   %rbx, %rdi
        0x7ff80cf346d1 <+27>: callq  0x7ff80cfb5856            ; symbol stub for: malloc
    (lldb) up
    warning: got was compiled with optimization - stepping may behave oddly; variables may not be available.
    frame #2: 0x0000000100001f79 got`cmd_import(argc=6, argv=0x00007ff7bfefe398) at got.c:788:13 [opt]
       785                                  goto done;
       786                          break;
       787                  case 'm':
    -> 788                          logmsg = strdup(optarg);
       789                          if (logmsg == NULL) {
       790                                  error = got_error_from_errno("strdup");
       791                                  goto done;

In particular, `optarg` seems to be a null pointer, but I haven't yet worked out
why this is the case.

Any assistance here would be appreciated.

Best,
Carlo

[1] https://github.com/Homebrew/homebrew-core/pull/125107
[2] https://github.com/Homebrew/homebrew-core/pull/125651