diff options
Diffstat (limited to 'hurd/alloc-fd.c')
| -rw-r--r-- | hurd/alloc-fd.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/hurd/alloc-fd.c b/hurd/alloc-fd.c new file mode 100644 index 0000000000..02a1bdfd52 --- /dev/null +++ b/hurd/alloc-fd.c @@ -0,0 +1,127 @@ +/* Copyright (C) 1994 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include <hurd.h> +#include <hurd/fd.h> +#include <hurd/resource.h> +#include <stdlib.h> +#include "hurdmalloc.h" /* XXX */ + +/* Allocate a new file descriptor and return it, locked. The new + descriptor number will be no less than FIRST_FD. If the table is full, + set errno to EMFILE and return NULL. If FIRST_FD is negative or bigger + than the size of the table, set errno to EINVAL and return NULL. */ + +struct hurd_fd * +_hurd_alloc_fd (int *fd, int first_fd) +{ + int i; + void *crit; + long int rlimit; + + if (first_fd < 0) + { + errno = EINVAL; + return NULL; + } + + crit = _hurd_critical_section_lock (); + + __mutex_lock (&_hurd_dtable_lock); + + search: + for (i = first_fd; i < _hurd_dtablesize; ++i) + { + struct hurd_fd *d = _hurd_dtable[i]; + if (d == NULL) + { + /* Allocate a new descriptor structure for this slot, + initializing its port cells to nil. The test below will catch + and return this descriptor cell after locking it. */ + d = _hurd_new_fd (MACH_PORT_NULL, MACH_PORT_NULL); + if (d == NULL) + { + __mutex_unlock (&_hurd_dtable_lock); + _hurd_critical_section_unlock (crit); + return NULL; + } + _hurd_dtable[i] = d; + } + + __spin_lock (&d->port.lock); + if (d->port.port == MACH_PORT_NULL) + { + __mutex_unlock (&_hurd_dtable_lock); + _hurd_critical_section_unlock (crit); + if (fd != NULL) + *fd = i; + return d; + } + else + __spin_unlock (&d->port.lock); + } + + __mutex_lock (&_hurd_rlimit_lock); + rlimit = _hurd_rlimits[RLIMIT_OFILE].rlim_cur; + __mutex_unlock (&_hurd_rlimit_lock); + + if (first_fd < rlimit) + { + /* The descriptor table is full. Check if we have reached the + resource limit, or only the allocated size. */ + if (_hurd_dtablesize < rlimit) + { + /* Enlarge the table. */ + int save = errno; + struct hurd_fd **new; + /* Try to double the table size (but don't exceed the limit). + If there isn't any at all, give it three slots (because + stdio will take that many anyway). */ + int size = _hurd_dtablesize ? _hurd_dtablesize * 2 : 3; + if (size > rlimit) + size = rlimit; + /* If we fail to allocate that, decrement the desired size + until we succeed in allocating it. */ + do + new = realloc (_hurd_dtable, size * sizeof (*_hurd_dtable)); + while (new == NULL && size-- > _hurd_dtablesize); + if (new != NULL) + { + /* We managed to allocate a new table. Now install it. */ + errno = save; + first_fd = _hurd_dtablesize; + /* Initialize the new slots. */ + for (i = first_fd; i < size; ++i) + new[i] = NULL; + _hurd_dtablesize = size; + _hurd_dtable = new; + /* Go back to the loop to initialize the first new slot. */ + goto search; + } + } + else + errno = EMFILE; + } + else + errno = EINVAL; /* Bogus FIRST_FD value. */ + + __mutex_unlock (&_hurd_dtable_lock); + _hurd_critical_section_unlock (crit); + + return NULL; +} |