Crash when logging invalid characters

[bagage]

Using master version, tests are crashing consistently when invoked from Jenkins using XCode7.2 (SDK 9:2). Before updating to master, I was getting crashes similar to #555 and #650. I am/was also affected by #623 hence I had to strip XML after xctool completed, so there was always an issue with bad characters I am dumping in logs. Any clue? (except of removing logs!).

xctool[40242:16271961] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
*** First throw call stack:
(
    0   CoreFoundation                      0x00007fff8e17503c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff8f30676e objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff8e020329 -[__NSArrayM insertObject:atIndex:] + 1033
    3   xctool                              0x0000000101a4cdd4 __ReadOutputsAndFeedOuputLinesToBlockOnQueue_block_invoke15 + 578
    4   xctool                              0x0000000101a4d056 __ReadOutputsAndFeedOuputLinesToBlockOnQueue_block_invoke_239 + 178
    5   libdispatch.dylib                   0x00007fff854cf7ab ___dispatch_operation_deliver_data_block_invoke + 118
    6   libdispatch.dylib                   0x00007fff854bc323 _dispatch_call_block_and_release + 12
    7   libdispatch.dylib                   0x00007fff854b7c13 _dispatch_client_callout + 8
    8   libdispatch.dylib                   0x00007fff854bb365 _dispatch_queue_drain + 1100
    9   libdispatch.dylib                   0x00007fff854bcecc _dispatch_queue_invoke + 202
    10  libdispatch.dylib                   0x00007fff854bb154 _dispatch_queue_drain + 571
    11  libdispatch.dylib                   0x00007fff854bcecc _dispatch_queue_invoke + 202
    12  libdispatch.dylib                   0x00007fff854ba6b7 _dispatch_root_queue_drain + 463
    13  libdispatch.dylib                   0x00007fff854c8fe4 _dispatch_worker_thread3 + 91
    14  libsystem_pthread.dylib             0x00007fff83db8a9d _pthread_wqthread + 729
    15  libsystem_pthread.dylib             0x00007fff83db63dd start_wqthread + 13
)
libc++abi.dylib: terminating with uncaught exception of type NSException

[ExtremeMan]

Can you write a simple test case which will cause this crash? I would really appreciate so I can iterate on it and fix xctool eventually.

[ExtremeMan]

But most likely crash is hit at this line: https://github.com/facebook/xctool/blob/master/Common/TaskUtil.m#L127.
Can you try wrapping it into if (line) { [lines addObject:line]; }

[bagage]

Thanks for the hint @ExtremeMan . A few notes:

• bug is not 100% reproducible. Probably because it depends on the characters I am dumping which vary from time to time (dumping ZIP network data). I get exceptions around 40% of the time.
• I cannot reproduce the bug if I attach Xcode debugger to xctool. So that's a bit annoying... :(
• The bug seems only present on one of my 2 machines.
• Your work-around fixes the issue, indeed line is nil.

I will continue my investigation until I catch the string causing the exception, but at least there is a work-around for now. I'll let you know when I have a simple test for it.

[bagage]

I am able to reproduce the bug with this quick&dirty test:

static void dummy_test(void){
    FILE*fp = fopen("/tmp/test.txt", "r");
    if (fp) {
        char *line = NULL;
        size_t linecap = 0;
        ssize_t linelen;
        while ((linelen = getline(&line, &linecap, fp)) > 0)
            fprintf(stderr, "%s\n", line);
        fclose(fp);
    }
}

With test.txt.

Interesting enough: copying/pasting file content in a variable and escaping quotes lead to no exception.

[ExtremeMan]

Thanks for the example. I am able to reproduce locally. iconv fails actually. I will have some workaround for such use cases but most likely xctool will just print empty string in that case.

[ExtremeMan]

Can you try this branch for me - https://github.com/facebook/xctool/tree/nekto/utf8_handling?

[bagage]

Yep, it solves the issue!