Git 1.6.5-rc git clone unhandled exception using http protocol

> Hi,
> 
> On Sat, Oct 10, 2009 at 10:51 PM, eduard stefan <eduard.stefan@gmail.com> wrote:
>> I attached three screenshots of the msys shell,
>> it doesn't matter what url is used,
>> and git remote-curl doesn't crash when run in a non-git repository,
>> but as soon as I create an empty repo, it crashes just like git clone http://...
> 
> that's not how you use remote-curl.
> 
> Cloning a bogus repository (http://test.com/sample.git) isn't a good idea too.

> I suspect, as you do, it's got to do with remote-curl.
> 
> Could you try this command?
> 
>   echo list | git remote-curl http://github.com/loudej/spark.git

> Tay Ray Chuan wrote:
>> I suspect, as you do, it's got to do with remote-curl.
>>
>> Could you try this command?
>>
>>   echo list | git remote-curl http://github.com/loudej/spark.git
>
> Inside an empty repository it crashes the same way,
> without any additional information.
> "git remote-curl" crashes in the same way,
> but "git remote-curl --help" tries to launch the browser.

> just to check, running
> 
>   echo list | git remote-curl http://github.com/loudej/spark.git
> 
> and
> 
>   git clone http://github.com/loudej/spark.git
> 
> both gives the same error message:
> 
>   An unhandled win32 exception occurred in git-remote-curl.exe [5820].
>   Just-In-Time debugging this exception failed with the following
>   error: No installed debugger has Just-In-Time debugging enabled. In
>   Visual Studio, Just-In-Time debugging can be enabled from
>   Tools/Options/Debugging/Just-In-Time.
> 
>   Check the documentation index for 'Just-in-time debugging, errors'
>   for more information.
> 
> in a dialog?
> 
>> Is there any way to obtain more information from this crash?
>> Some debug mode?
> 
> I'm assuming you're using the Microsoft Visual Studio development
> tools to compile git from the source. I'm cc'ing this to the msysgit
> mailing list, perhaps someone familiar with them can advise you
> further.
> 

> Git was compiled with msysGit, the errors are generated inside msysGit shell,
> and VS2008 debugger gives this message:
> 
> "Unhandled exception at 0x00420354 in git-remote-curl.exe:
>  0xC0000005: Access violation reading location 0x00000000."

> Tay Ray Chuan wrote:
>> I suspect, as you do, it's got to do with remote-curl.
>>
>> Could you try this command?
>>
>>   echo list | git remote-curl http://github.com/loudej/spark.git
>
> Inside an empty repository it crashes the same way,
> without any additional information.
> "git remote-curl" crashes in the same way,
> but "git remote-curl --help" tries to launch the browser.
>
> Is there any way to obtain more information from this crash?
> Some debug mode?

> Using the above repository, I see the same crash with msysGit at git
> revision 1.6.5. Using windbg as the post-mortem debugger, the
> following information is captured:
> 
>   (a14.e8c): Access violation - code c0000005 (!!! second chance !!!)
>   eax=00000000 ebx=00000000 ecx=ffffffff edx=0046cc00 esi=0046f98f edi=00000000
>   eip=00420354 esp=0022fd80 ebp=0022fda8 iopl=0         nv up ei pl zr na pe nc
>   cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246
> 
> ...and the faulting instruction is:
> 
>   git_remote_curl+0x20354:
>   00420354 f2ae            repne scas byte ptr es:[edi]
> 
> so, a NULL dereference. The initial disassembly of the function is this:
> 
>   0:000> u 0042033C
>   git_remote_curl+0x2033c:
>   0042033c 55              push    ebp
>   0042033d 89e5            mov     ebp,esp
>   0042033f 57              push    edi
>   00420340 56              push    esi
>   00420341 53              push    ebx
>   00420342 83ec1c          sub     esp,1Ch
>   00420345 8b5d08          mov     ebx,dword ptr [ebp+8]
>   00420348 8b750c          mov     esi,dword ptr [ebp+0Ch]
>   0042034b 31c0            xor     eax,eax
>   0042034d b9ffffffff      mov     ecx,0FFFFFFFFh
>   00420352 89df            mov     edi,ebx
>   00420354 f2ae            repne scas byte ptr es:[edi]
>   00420356 f7d1            not     ecx
>   00420358 8d51ff          lea     edx,[ecx-1]
>   0042035b b9ffffffff      mov     ecx,0FFFFFFFFh
>   00420360 89f7            mov     edi,esi
>   00420362 f2ae            repne scas byte ptr es:[edi]
>   00420364 f7d1            not     ecx
>   00420366 49              dec     ecx
>   00420367 7466            je      git_remote_curl+0x203cf (004203cf)
>   00420369 85d2            test    edx,edx
>   0042036b 0f84b1000000    je      git_remote_curl+0x20422 (00420422)
>   00420371 89f7            mov     edi,esi
>   00420373 89de            mov     esi,ebx
>   ...
> 
> So its the first parameter that is NULL. The second parameter is:
> 
>   0:000> da poi(ebp+c)
>   0046f98f  "libexec/git-core"
> 
> I don't know how to build msysGit so that symbols are generated so
> I've attempted to reconstruct the source code; which ends up looking
> something like the following:
> 
>   int some_unknown_func(char *arg1, char *arg2)
>   {
>       len1 = strlen(arg1) - 1;  // <- crash here
>       len2 = strlen(arg2);
>       len3 = len2 - 1;
> 
>       if (len2 != 1) {
>           if (!len1)
>               return 0;
>           for (;;) {
>               x = arg1[len1 - 1];
> 
>               if (x != '/' && x != '\\') {
>                   --len1;
>                   --len3;
>                   if (arg1[len1] != arg2[len3])
>                       return 0;
>               } else {
>                   ...
>               }
>           }
>       }
>   }
> 
> Perhaps those more familiar with git's sources might recognise code
> that looks similar to the above sequence.

> Michael Wookey schrieb:
>> Using the above repository, I see the same crash with msysGit at git
>> revision 1.6.5. Using windbg as the post-mortem debugger, the
>> following information is captured:
>> [ ... snip ... ]
> Wow, this is great work, thank you very much! The function is
> strip_path_suffix(). And here is a patch that fixes the crash.
>
> --- >8 ---
> From: Johannes Sixt <j6t@kdbg.org>
> Subject: [PATCH] remote-curl: add missing initialization of argv0_path
>
> All programs, in particular also the stand-alone programs (non-builtins)
> must call git_extract_argv0_path(argv[0]) in order to help builds that
> derive the installation prefix at runtime, such as the MinGW build.
> Without this call, the program segfaults (or raises an assertion
> failure).
>
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
>  remote-curl.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/remote-curl.c b/remote-curl.c
> index ad6a163..d8d276a 100644
> --- a/remote-curl.c
> +++ b/remote-curl.c
> @@ -82,6 +82,7 @@ int main(int argc, const char **argv)
>        const char *url;
>        struct walker *walker = NULL;
>
> +       git_extract_argv0_path(argv[0]);
>        setup_git_directory();
>        if (argc < 2) {
>                fprintf(stderr, "Remote needed\n");
> --
> 1.6.5.1024.g31034.dirty

> 2009/10/13 Johannes Sixt <j.sixt@viscovery.net>:
>> Michael Wookey schrieb:
>>> Using the above repository, I see the same crash with msysGit at git
>>> revision 1.6.5. Using windbg as the post-mortem debugger, the
>>> following information is captured:
>>> [ ... snip ... ]
>> Wow, this is great work, thank you very much! The function is
>> strip_path_suffix(). And here is a patch that fixes the crash.
>>
>> --- >8 ---
>> From: Johannes Sixt <j6t@kdbg.org>
>> Subject: [PATCH] remote-curl: add missing initialization of argv0_path
>>
>> All programs, in particular also the stand-alone programs (non-builtins)
>> must call git_extract_argv0_path(argv[0]) in order to help builds that
>> derive the installation prefix at runtime, such as the MinGW build.
>> Without this call, the program segfaults (or raises an assertion
>> failure).
>>
>> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
>> ---
>>  remote-curl.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/remote-curl.c b/remote-curl.c
>> index ad6a163..d8d276a 100644
>> --- a/remote-curl.c
>> +++ b/remote-curl.c
>> @@ -82,6 +82,7 @@ int main(int argc, const char **argv)
>>        const char *url;
>>        struct walker *walker = NULL;
>>
>> +       git_extract_argv0_path(argv[0]);
>>        setup_git_directory();
>>        if (argc < 2) {
>>                fprintf(stderr, "Remote needed\n");
>> --
>> 1.6.5.1024.g31034.dirty
>
> No more crashes for me :)