Bug#98071: symlink to itself hangs

[Marcus Brinkmann]

Package: hurd

Hi,

the following doesn't return:

$ cd /tmp
$ ln -s /tmp/x x
$ ls x

The variant "ln -s x x" does not show such errornous behaviour.
Filesystem is ext2fs. It is sufficient to do "ls".

Here is a backtrace:

Script started on Sun May 20 02:23:35 2001
marcus@ulysses:/tmp$ gdb /b bin/ls 17841
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This GDB was configured as "i386-unknown-gnu0.2"...
(no debugging symbols found)...
/tmp/17841: No such file or directory.
Attaching to program `/bin/ls', pid 17841
Reading symbols from /lib/debug/libc.so.0.2...done.
Loaded symbols for /lib/debug/libc.so.0.2
Reading symbols from /lib/ld.so...done.
Loaded symbols for /lib/ld.so
Reading symbols from /lib/debug/libmachuser.so.1...done.
Loaded symbols for /lib/debug/libmachuser.so.1
Reading symbols from /lib/debug/libhurduser.so.0.0...done.
Loaded symbols for /lib/debug/libhurduser.so.0.0
[Switching to thread 17841.1]
(gdb) bt full
#0  0x105af11 in _hurd_intr_rpc_msg_in_trap () at intr-msg.c:118
        err = 0
        ss = (struct hurd_sigstate *) 0x11aa808
        user_option = 3
        user_timeout = 0
        m = (union msg *) 0x1020c28
        msgh_bits = 5395
        remote_port = 22
        msgid = 20018
        save_data = {i = {335546380, 795897204}}
#1  0x119bfbb in __dir_lookup (start_dir=22, file_name=0x102165d "tmp/x", 
    flags=0, mode=0, do_retry=0x1021610, retry_name=0x102165c "/tmp/x", 
    result=0x1021a98)
    at 
/mnt/marcus/gnu/hurd/glibc/glibc-2.2.2/i386-gnu/obj/hurd/RPC_dir_lookup.c:183
        flags = 0
        do_retry = (retry_type *) 0x11aa808
        result = (mach_port_t *) 0x0
        Mess = {In = {Head = {msgh_bits = 2147488256, msgh_size = 1076, 
      msgh_remote_port = 0, msgh_local_port = 43, msgh_seqno = 241946, 
      msgh_id = 20118}, file_nameType = {msgt_name = 2, msgt_size = 32, 
      msgt_number = 1, msgt_inline = 1, msgt_longform = 0, 
      msgt_deallocate = 0, msgt_unused = 0}, 
    file_name = "\000\000\000\000\002 
\001\020\003\000\000\000\f\b\000\024/tmp/x---Type <return> to continue, or q 
<return> to quit---
", '\000' <repeats 1001 times>, flagsType = {msgt_name = 2, msgt_size = 32, 
      msgt_number = 1, msgt_inline = 1, msgt_longform = 0, 
      msgt_deallocate = 0, msgt_unused = 0}, flags = 0, modeType = {
      msgt_name = 2, msgt_size = 32, msgt_number = 1, msgt_inline = 1, 
      msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}, mode = 0}, 
  Out = {Head = {msgh_bits = 2147488256, msgh_size = 1076, 
      msgh_remote_port = 0, msgh_local_port = 43, msgh_seqno = 241946, 
      msgh_id = 20118}, RetCodeType = {msgt_name = 2, msgt_size = 32, 
      msgt_number = 1, msgt_inline = 1, msgt_longform = 0, 
      msgt_deallocate = 0, msgt_unused = 0}, RetCode = 0, do_retryType = {
      msgt_name = 2, msgt_size = 32, msgt_number = 1, msgt_inline = 1, 
      msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}, 
    do_retry = FS_RETRY_MAGICAL, retry_nameType = {msgt_name = 12, 
      msgt_size = 8, msgt_number = 1024, msgt_inline = 1, msgt_longform = 0, 
      msgt_deallocate = 0, msgt_unused = 0}, 
    retry_name = "/tmp/x", '\000' <repeats 1002 times>, "\002 
\001\020\000\000\000\000\002 \001\020\000\000\000", resultType = {msgt_name = 
17, 
      msgt_size = 32, msgt_number = 1, msgt_inline = 1, msgt_longform = 0, 
      msgt_deallocate = 0, msgt_unused = 0}, result = 0}}
        OutP = (Reply *) 0x1020c28
        msg_result = 0
        msgh_simple = 0
        msgh_size = 18524168
        file_nameType = {msgt_name = 12, msgt_size = 8, msgt_number = 1024, 
---Type <return> to continue, or q <return> to quit---
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        flagsType = {msgt_name = 2, msgt_size = 32, msgt_number = 1, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        modeType = {msgt_name = 2, msgt_size = 32, msgt_number = 1, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        RetCodeCheck = {msgt_name = 2, msgt_size = 32, msgt_number = 1, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        do_retryCheck = {msgt_name = 2, msgt_size = 32, msgt_number = 1, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        retry_nameCheck = {msgt_name = 12, msgt_size = 8, msgt_number = 1024, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
        resultCheck = {msgt_name = 17, msgt_size = 32, msgt_number = 1, 
  msgt_inline = 1, msgt_longform = 0, msgt_deallocate = 0, msgt_unused = 0}
#2  0x1047b18 in lookup_op (startdir=22) at hurdlookup.c:128
        error = 0
#3  0x1046b74 in _hurd_ports_use (which=1, operate=0x1021150) at hurdinit.c:42
        port = (struct hurd_port *) 0x11a9f94
        __p = (struct hurd_port *) 0x11a9f94
        __link = {resource = {next = 0x0, prevp = 0x11a9f98}, thread = {
    next = 0x0, prevp = 0x11aac5c}, cleanup = 0x1065f3c <_hurd_port_cleanup>, 
  cleanup_data = 0x16}
        __result = 0
        which = 0
#4  0x104830f in __hurd_file_name_lookup_retry (
---Type <return> to continue, or q <return> to quit---
    use_init_port=0x10469a0 <_hurd_ports_use>, 
    get_dtable_port=0x105e1e0 <__getdport>, lookup=0x119bf10 <__dir_lookup>, 
    doretry=FS_RETRY_MAGICAL, retryname=0x102165c "/tmp/x", flags=0, mode=0, 
    result=0x1021a98) at hurdlookup.c:376
        startdir = 0
        dirport = 1
        err = 0
        file_name = 0x102165d "tmp/x"
        nloops = 0
#5  0x1047ab6 in __hurd_file_name_lookup (
    use_init_port=0x10469a0 <_hurd_ports_use>, 
    get_dtable_port=0x105e1e0 <__getdport>, lookup=0x119bf10 <__dir_lookup>, 
    file_name=0x80578e1 "tmp/x", flags=0, mode=0, result=0x1021a98)
    at hurdlookup.c:97
        err = 0
        doretry = FS_RETRY_MAGICAL
        retryname = "/tmp/x", '\000' <repeats 1017 times>
        startport = 1
#6  0x10485e9 in __file_name_lookup (file_name=0x80578e0 "/tmp/x", flags=0, 
    mode=0) at hurdlookup.c:514
        err = 0
        result = 0
#7  0x1105be0 in __xstat (vers=0, file=0x80578e0 "/tmp/x", buf=0x1021b1c)
    at ../sysdeps/mach/hurd/xstat.c:34
---Type <return> to continue, or q <return> to quit---
        err = EKERN_PROTECTION_FAILURE
        port = 16915228
#8  0x804b0e2 in strcpy () at ../sysdeps/generic/strcpy.c:31
No symbol table info available.
#9  0x8049822 in strcpy () at ../sysdeps/generic/strcpy.c:31
No symbol table info available.
#10 0x1067720 in __libc_start_main (main=0x8049658 <strcpy+480>, argc=2, 
    ubp_av=0x1021c30, 
    init=0x8049020 <_hurdsig_fault_exc_server_routines+116003704>, 
    fini=0x804f83c <__umoddi3+460>, rtld_fini=0xe6a0 <_dl_fini>, 
    stack_end=0x1021c2c) at ../sysdeps/generic/libc-start.c:129
        fini = (void (*)()) 0x1021b1c
        rtld_fini = (void (*)()) 0x1020b94
        ubp_ev = (char **) 0x0
(gdb) quit
The program is running.  Quit anyway (and detach it)? (y or n) y
Detaching from program `/bin/ls' pid 17841
marcus@ulysses:/tmp$ exit

Script done on Sun May 20 02:24:02 2001