On Wed, Apr 25, 2012 at 02:54:07PM -0400, Chet Ramey wrote:
> On 4/25/12 2:04 PM, Greg Wooledge wrote:
>
> > Maybe it only works on boxes with a very large "open files" resource
> > limit. Perhaps the hard-coded 255 should be replaced with something
> > involving getrlimit() or similar?
>
> I see two potential fixes here. First, try changing the 255 to -1 and
> see what happens.
That broke something pretty badly.
cyclops:/var/tmp/bash/bash-4.2$ cat ~/foo
#!/bin/bash
shopt -s lastpipe
echo hi | read foo
echo "<$foo>"
cyclops:/var/tmp/bash/bash-4.2$ ./bash ~/foo
cyclops:/var/tmp/bash/bash-4.2$ ./bash -c 'shopt -s lastpipe; echo hi | read
foo; echo "<$foo>"'
<hi>
So it seems to work with -c but not when reading from a file. I'm guessing
the file descriptor move somehow made bash lose track of the file it was
reading commands from.
The move_to_high_fd part looks happier:
Breakpoint 2, move_to_high_fd (fd=0, check_new=0, maxfd=-1) at general.c:444
444 if (maxfd < 20)
(gdb) n
446 nfds = getdtablesize ();
(gdb) n
447 if (nfds <= 0)
(gdb) n
449 if (nfds > HIGH_FD_MAX)
(gdb) n
455 for (nfds--; check_new && nfds > 3; nfds--)
(gdb) n
459 if (nfds > 3 && fd != nfds && (script_fd = dup2 (fd, nfds)) != -1)
(gdb) n
461 if (check_new == 0 || fd != fileno (stderr)) /* don't close
stderr */
(gdb) n
462 close (fd);
(gdb) n
463 return (script_fd);
(gdb) print script_fd
$1 = 127
(gdb) n
469 }
(gdb) n
But after that I have no idea what's happening (or failing to happen):
execute_pipeline (command=0x209d2c260, asynchronous=0, pipe_in=-1,
pipe_out=-1, fds_to_close=0x202b8ca10) at execute_cmd.c:2209
2209 if (lstdin > 0)
(gdb) n
2211 do_piping (prev, pipe_out);
(gdb) n
2212 prev = NO_PIPE;
(gdb) n
2213 add_unwind_protect (restore_stdin, lstdin);
(gdb) n
2214 lastpipe_flag = 1;
(gdb) n
2215 freeze_jobs_list ();
(gdb) n
2216 lastpipe_jid = stop_pipeline (0, (COMMAND *)NULL); /* XXX
*/
(gdb) n
2217 add_unwind_protect (lastpipe_cleanup, lastpipe_jid);
f (cmd)
(gdb) n
2220 cmd->flags |= CMD_LASTPIPE;
(gdb) n
2222 if (prev >= 0)
(gdb) n
2226 exec_result = execute_command_internal (cmd, asynchronous, prev,
pipe_out, fds_to_close);
(gdb) n
2229 if (lstdin > 0)
(gdb) n
2230 restore_stdin (lstdin);
(gdb) n
2233 if (prev >= 0)
(gdb) n
2237 UNBLOCK_CHILD (oset);
(gdb) n
2240 QUIT;
(gdb) n
2242 if (lastpipe_flag)
(gdb) n
2245 append_process (savestring (the_printed_command),
dollar_dollar_pid, exec_result, lastpipe_jid);
(gdb) n
2247 lstdin = wait_for (lastpid);
(gdb) n
2249 exec_result = job_exit_status (lastpipe_jid);
(gdb) n
2251 unfreeze_jobs_list ();
(gdb) n
2254 discard_unwind_frame ("lastpipe-exec");
(gdb) n
2256 return (exec_result);
(gdb) n
2257 }
(gdb) n
execute_connection (command=0x209d2c260, asynchronous=0, pipe_in=-1,
pipe_out=-1, fds_to_close=0x202b8ca10) at execute_cmd.c:2338
2338 if (was_error_trap && ignore_return == 0 && invert == 0 &&
exec_result != EXECUTION_SUCCESS)
(gdb) cont
Continuing.
Program exited normally.
(gdb)
