zero size buf in output(Bug?)

[Andre Jaenisch]

2012/10/10 Maxim Dounin <mdounin at mdounin.ru>:
> Hello!
>
> Unfortunately, backtrace is completely unreadable.

GooglePlus shows the following as attachment:


Core was generated by `nginx: worker process                   '.
Program terminated with signal 11, Segmentation fault.
#0  0x000000000040ab19 in ngx_vslprintf (buf=0x7fffefda6605 "",
last=0x7fffefda6dd0 "\020", fmt=<value optimized out>,
args=0x7fffefda65b0)
    at src/core/ngx_string.c:178
178	            while (*fmt >= '0' && *fmt <= '9') {
(gdb) bt
#0  0x000000000040ab19 in ngx_vslprintf (buf=0x7fffefda6605 "",
last=0x7fffefda6dd0 "\020", fmt=<value optimized out>,
args=0x7fffefda65b0)
    at src/core/ngx_string.c:178
#1  0x000000000040692e in ngx_log_error_core (level=3, log=0x14143930,
err=14, fmt=0x473e4a "\307", <incomplete sequence \320>)
    at src/core/ngx_log.c:108
#2  0x000000000040dfb2 in ngx_conf_set_path_slot (cf=0x14224fe8,
cmd=<value optimized out>, conf=<value optimized out>)
    at src/core/ngx_file.c:267
#3  0x00000000141439b8 in ?? ()
#4  0x0000000014225850 in ?? ()
#5  0x00002b87720e8250 in ?? ()
#6  0x0000000014154770 in ?? ()
#7  0x0000000000449e6f in ngx_http_upstream_send_response (r=0x0,
u=0x1) at src/http/ngx_http_upstream.c:2124
#8  ngx_http_upstream_process_header (r=0x0, u=0x1) at
src/http/ngx_http_upstream.c:1644
#9  0x00000000141439b8 in ?? ()
#10 0x0000000000000078 in ?? ()
#11 0x4a8da000006b3500 in ?? ()
#12 0x0000000050757962 in ?? ()
#13 0x00000000141439b8 in ?? ()
#14 0x00000000141439b8 in ?? ()
#15 0xfffffffffffffffe in ?? ()
#16 0x0000000000000078 in ?? ()
#17 0x00000000141d7828 in ?? ()
#18 0x0000000050757962 in ?? ()
#19 0x000000000045106a in ngx_http_file_cache_exists (cache=0x4742a1,
c=0x40aa1c) at src/http/ngx_http_file_cache.c:690
#20 0x0000000300000010 in ?? ()
#21 0x0000000014143930 in ?? ()
#22 0x000000000068c2c0 in ?? ()
#23 0x00000000141439b8 in ?? ()
#24 0x0000000014224c80 in ?? ()
#25 0x00000000141439b8 in ?? ()
#26 0x0000000014224a00 in ?? ()
#27 0x00002b87720e8250 in ?? ()
#28 0x00000000141d6798 in ?? ()
#29 0x0000000000000001 in ?? ()
#30 0x00000000004409d6 in ngx_http_variable_sent_keep_alive (r=<value
optimized out>, v=0x78, data=<value optimized out>)
    at src/http/ngx_http_variables.c:1654
#31 0x000000000000012e in ?? ()
#32 0x0000000014224c80 in ?? ()
#33 0x0000000014224c80 in ?? ()
#34 0x00000000141439b8 in ?? ()
#35 0x00000000141439b8 in ?? ()
#36 0x00002b87720e8250 in ?? ()
#37 0x00000000141d6798 in ?? ()
#38 0x0000000014224a00 in ?? ()
#39 0x0000000014224c80 in ?? ()
#40 0x00000000141439b8 in ?? ()
#41 0x00002b87720e8250 in ?? ()
#42 0x00000000141d6798 in ?? ()
#43 0x000000000044321c in ngx_http_script_regex_start_code (e=0x1) at
src/http/ngx_http_script.c:974
#44 0x00000000140610d0 in ?? ()
#45 0x00000000004762c9 in ngx_http_modern_browser (cf=0x7fffefda6605,
cmd=0x0, conf=0x7fffefda6e00)
    at src/http/modules/ngx_http_browser_module.c:553
#46 0x0000000000000089 in ?? ()
---Type <return> to continue, or q <return> to quit---
#47 0x00000000000019b0 in ?? ()
#48 0xfffffffffffffffc in ?? ()
#49 0x000000000041fee0 in ngx_event_pipe_read_upstream (p=0x0,
do_write=<value optimized out>) at src/event/ngx_event_pipe.c:382
#50 ngx_event_pipe (p=0x0, do_write=<value optimized out>) at
src/event/ngx_event_pipe.c:49
#51 0x0000000000001260 in ?? ()
#52 0x0000000000000062 in ?? ()
#53 0x00000000004220e9 in ngx_signal_handler (signo=25593) at
src/os/unix/ngx_process.c:316
#54 0x0000000000000000 in ?? ()


Not unreadable, but a little bit confusing to me.

Andre Jaenisch