Git 1.6.5-rc git clone unhandled exception using http protocol

 How can I obtain more information about the error?

Hi,

Quoted 4 lines · eduard stefan

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.

Could you show me the screenshot of you cloning
http://github.com/loudej/spark.git?

I was just trying to point that the URL used is not relevant, as long as the protocol used is URL, then it crashes.

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

Quoted 5 lines · Tay Ray Chuan

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?

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?

Quoted 2 lines

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."

Quoted 5 lines · Tay Ray Chuan

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.

Quoted 4 lines · Michael Wookey

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 <[email protected]>
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 <[email protected]>

---
 remote-curl.c |    1 +

 1 files changed, 1 insertions(+), 0 deletions(-)

remote-curl.c +1 -1

index ad6a163..d8d276a 100644
@@ -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 <[email protected]>:

Quoted 31 lines

Quoted 4 lines · Michael Wookey

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 <[email protected]>
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 <[email protected]>

---
 remote-curl.c |    1 +

 1 files changed, 1 insertions(+), 0 deletions(-)

remote-curl.c +0 -0

index ad6a163..d8d276a 100644
@@ -82,6 +82,7 @@ int main(int argc, const char **argv)
        const char *url;
        struct walker *walker = NULL;
 

Quoted 6 lines

remote-curl.c +1 -1

+       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 :)