What's going on with my file descriptors ?

[Martin Baulig <martin home-of-linux org>]

Hi guys,

so, there's something totally weird going on with my file descriptors.

- I start gdb /gnome/head/INSTALL/bin/guile and hit run

This opens the following file descriptors:

====
[martin einstein bonobo-extra]$ dir /proc/18791/fd/
total 0
lrwx------    1 martin   martin         64 Aug 13 18:03 0 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:03 1 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:03 2 -> /dev/pts/3
lr-x------    1 martin   martin         64 Aug 13 18:03 3 -> /gnome/head/INSTALL/bin/guile
lr-x------    1 martin   martin         64 Aug 13 18:03 4 -> /gnome/head/INSTALL/bin/guile
lrwx------    1 martin   martin         64 Aug 13 18:03 5 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:03 6 -> /dev/pts/3
====

- now I do some stuff in guile, read the ORBit imodule files and I have:

====
[martin einstein bonobo-extra]$ dir /proc/18791/fd/
total 0
lrwx------    1 martin   martin         64 Aug 13 18:04 0 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:04 1 -> /dev/pts/3
l-wx------    1 martin   martin         64 Aug 13 18:04 10 -> pipe:[358849]
lrwx------    1 martin   martin         64 Aug 13 18:04 11 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:04 2 -> /dev/pts/3
lr-x------    1 martin   martin         64 Aug 13 18:04 3 -> /gnome/head/INSTALL/bin/guile
lr-x------    1 martin   martin         64 Aug 13 18:04 4 -> /gnome/head/INSTALL/bin/guile
lrwx------    1 martin   martin         64 Aug 13 18:04 5 -> /dev/pts/3
lr-x------    1 martin   martin         64 Aug 13 18:04 6 -> pipe:[358845]
l-wx------    1 martin   martin         64 Aug 13 18:04 7 -> pipe:[358845]
lr-x------    1 martin   martin         64 Aug 13 18:04 8 -> /dev/urandom
lr-x------    1 martin   martin         64 Aug 13 18:04 9 -> pipe:[358849]
====

- stopped guile in gdb, backtraced and found out that fd 5 is the current
  input file descriptor

- now I do a bonobo_get_object ("config:", "IDL:Bonobo/PropertyBag:1.0", &ev),
  any other bonobo_get_object() call does the same.

Looking at the file descriptors, I have:

====
lrwx------    1 martin   martin         64 Aug 13 18:08 0 -> socket:[358985]
lrwx------    1 martin   martin         64 Aug 13 18:08 1 -> /dev/pts/3
l-wx------    1 martin   martin         64 Aug 13 18:08 10 -> pipe:[358849]
lrwx------    1 martin   martin         64 Aug 13 18:08 11 -> socket:[358965]
lrwx------    1 martin   martin         64 Aug 13 18:08 12 -> socket:[358990]
lrwx------    1 martin   martin         64 Aug 13 18:08 13 -> socket:[358985]
lrwx------    1 martin   martin         64 Aug 13 18:08 14 -> socket:[359078]
lrwx------    1 martin   martin         64 Aug 13 18:08 15 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:08 2 -> /dev/pts/3
lr-x------    1 martin   martin         64 Aug 13 18:08 3 -> /gnome/head/INSTALL/bin/guile
lr-x------    1 martin   martin         64 Aug 13 18:08 4 -> /gnome/head/INSTALL/bin/guile
lrwx------    1 martin   martin         64 Aug 13 18:08 5 -> socket:[358992]
lr-x------    1 martin   martin         64 Aug 13 18:08 6 -> pipe:[358845]
l-wx------    1 martin   martin         64 Aug 13 18:08 7 -> pipe:[358845]
lr-x------    1 martin   martin         64 Aug 13 18:08 8 -> /dev/urandom
lr-x------    1 martin   martin         64 Aug 13 18:08 9 -> pipe:[358849]
====

- guile correctly prints the return value of the (successful) bonobo_get_object()
  call and then it hangs.

- gdb shows me that it's hanging in read() - and it assumes that 5 is still
  its input file descriptor.

Now tried the same again, but with readline disabled:

====
[martin einstein bonobo-extra]$ dir /proc/19132/fd/
total 0
lrwx------    1 martin   martin         64 Aug 13 18:16 0 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:16 1 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:16 2 -> /dev/pts/3
lr-x------    1 martin   martin         64 Aug 13 18:16 4 -> pipe:[378644]
l-wx------    1 martin   martin         64 Aug 13 18:16 5 -> pipe:[378644]
lr-x------    1 martin   martin         64 Aug 13 18:16 6 -> /dev/urandom
lr-x------    1 martin   martin         64 Aug 13 18:16 7 -> pipe:[378648]
l-wx------    1 martin   martin         64 Aug 13 18:16 8 -> pipe:[378648]
====

Now doing to bonobo_get_object() and then

===
[martin einstein bonobo-extra]$ dir /proc/19132/fd/
total 0
lrwx------    1 martin   martin         64 Aug 13 18:16 0 -> socket:[379003]
lrwx------    1 martin   martin         64 Aug 13 18:16 1 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:16 10 -> socket:[379008]
lrwx------    1 martin   martin         64 Aug 13 18:16 11 -> socket:[379057]
lrwx------    1 martin   martin         64 Aug 13 18:16 12 -> socket:[379062]
lrwx------    1 martin   martin         64 Aug 13 18:16 2 -> /dev/pts/3
lrwx------    1 martin   martin         64 Aug 13 18:16 3 -> socket:[379010]
lr-x------    1 martin   martin         64 Aug 13 18:16 4 -> pipe:[378644]
l-wx------    1 martin   martin         64 Aug 13 18:16 5 -> pipe:[378644]
lr-x------    1 martin   martin         64 Aug 13 18:16 6 -> /dev/urandom
lr-x------    1 martin   martin         64 Aug 13 18:16 7 -> pipe:[378648]
l-wx------    1 martin   martin         64 Aug 13 18:16 8 -> pipe:[378648]
lrwx------    1 martin   martin         64 Aug 13 18:16 9 -> socket:[378983]
===

So, what the fuck is this doing with my input file descriptor ?

-- 
Martin Baulig
martin gnome org (private)
baulig suse de (work)