On Wed, Oct 24, 2012 at 7:46 PM, Ian Lance Taylor <i...@google.com> wrote: > On Wed, Oct 24, 2012 at 9:34 AM, Uros Bizjak <ubiz...@gmail.com> wrote: >> >> Continuing. >> [New Thread 0x2000307b280 (LWP 8059)] >> >> Breakpoint 18, 0x0000020002e378c0 in socketpair () from /lib/libc.so.6.1 >> >> Continuing. >> [New Thread 0x20003083280 (LWP 8065)] >> [Switching to Thread 0x20003083280 (LWP 8065)] >> >> [...] >> >> The first call with relevant FD is from: >> >> Breakpoint 21, 0x0000020002e243f8 in close () from /lib/libc.so.6.1 >> (gdb) i r a0 >> a0 0x8 8 > > Does this mean that this is a call to close file descriptor 8? > According to the strace log, the file descriptor we care about is 4. > Although it is also true that I don't see a close of file descriptor 8 > at all in the strace log. Or is the change from 4 to 8 due somehow to > running the program under gdb?
Yes, I am running under gdb and all FDs are offset by +4 for some reason. So, FD 8 corresponds to FD4 in the strace log. > >> (gdb) bt >> #0 0x0000020002e243f8 in close () from /lib/libc.so.6.1 >> #1 0x000000012003559c in syscall.Close (fd=<optimized out>) at >> libcalls.go:271 >> #2 0x00000200005d3cfc in os.close.pN7_os.file (file=0xf840414b70) at >> ../../../gcc-svn/trunk/libgo/go/os/file_unix.go:106 >> #3 0x0000020000888f18 in ffi_call_osf () at >> ../../../gcc-svn/trunk/libffi/src/alpha/osf.S:79 >> #4 0x00000200008889c4 in ffi_call (cif=<optimized out>, fn=<optimized >> out>, rvalue=<optimized out>, avalue=0xf840c87fe8) >> at ../../../gcc-svn/trunk/libffi/src/alpha/ffi.c:169 >> #5 0x0000020000558204 in reflect.call (func_type=0x200009e9650 >> <__go_td_FppN7_os.fileerN5_erroree>, >> func_addr=0x200005d3c60 <os.close.pN7_os.file>, >> is_interface=<optimized out>, is_method=<optimized out>, >> params=0xf840c87fe0, results=0x0) at >> ../../../gcc-svn/trunk/libgo/runtime/go-reflect-call.c:498 >> #6 0x00000200005620b8 in runfinq (dummy=<optimized out>) at >> ../../../gcc-svn/trunk/libgo/runtime/mgc0.c:1168 >> #7 0x0000020000566b20 in kickoff () at >> ../../../gcc-svn/trunk/libgo/runtime/proc.c:338 >> #8 0x0000020002d8d024 in ?? () from /lib/libc.so.6.1 > > If this is indeed the file descriptor we care about, then this is > interesting, because it is being closed by a finalizer run by the > garbage collector. That implies that the garbage collector collected > the local variable readFile in TestPassFD in passfd_test.go, which > would be clearly wrong. Unfortunately this could be rather difficult > to debug. Yes, this is correct descriptor. For added fun, a descriptor that corresponds to writeFile closes through the same mechanism. Uros.
