1 /* Copyright (C) 1994-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #include <hurd.h>
19 #include <hurd/fd.h>
20 #include <hurd/resource.h>
21 #include <stdlib.h>
22 #include "hurdmalloc.h" /* XXX */
23
24 /* Allocate a new file descriptor and return it, locked. The new
25 descriptor number will be no less than FIRST_FD. If the table is full,
26 set errno to EMFILE and return NULL. If FIRST_FD is negative or bigger
27 than the size of the table, set errno to EINVAL and return NULL. */
28
29 struct hurd_fd *
30 _hurd_alloc_fd (int *fd, int first_fd)
31 {
32 int i;
33 void *crit;
34 long int rlimit;
35
36 if (first_fd < 0)
37 return __hurd_fail (EINVAL), NULL;
38
39 crit = _hurd_critical_section_lock ();
40
41 __mutex_lock (&_hurd_dtable_lock);
42
43 search:
44 for (i = first_fd; i < _hurd_dtablesize; ++i)
45 {
46 struct hurd_fd *d = _hurd_dtable[i];
47 if (d == NULL)
48 {
49 /* Allocate a new descriptor structure for this slot,
50 initializing its port cells to nil. The test below will catch
51 and return this descriptor cell after locking it. */
52 d = _hurd_new_fd (MACH_PORT_NULL, MACH_PORT_NULL);
53 if (d == NULL)
54 {
55 __mutex_unlock (&_hurd_dtable_lock);
56 _hurd_critical_section_unlock (crit);
57 return NULL;
58 }
59 _hurd_dtable[i] = d;
60 }
61
62 __spin_lock (&d->port.lock);
63 if (d->port.port == MACH_PORT_NULL)
64 {
65 __mutex_unlock (&_hurd_dtable_lock);
66 _hurd_critical_section_unlock (crit);
67 if (fd != NULL)
68 *fd = i;
69 return d;
70 }
71 else
72 __spin_unlock (&d->port.lock);
73 }
74
75 __mutex_lock (&_hurd_rlimit_lock);
76 rlimit = _hurd_rlimits[RLIMIT_OFILE].rlim_cur;
77 __mutex_unlock (&_hurd_rlimit_lock);
78
79 if (first_fd < rlimit)
80 {
81 /* The descriptor table is full. Check if we have reached the
82 resource limit, or only the allocated size. */
83 if (_hurd_dtablesize < rlimit)
84 {
85 /* Enlarge the table. */
86 int save = errno;
87 struct hurd_fd **new;
88 /* Try to double the table size, but don't exceed the limit,
89 and make sure it exceeds FIRST_FD. */
90 int size = _hurd_dtablesize * 2;
91 if (size > rlimit)
92 size = rlimit;
93 else if (size <= first_fd)
94 size = first_fd + 1;
95
96 if (size * sizeof (*_hurd_dtable) < size)
97 {
98 /* Integer overflow! */
99 __hurd_fail (ENOMEM);
100 goto out;
101 }
102
103 /* If we fail to allocate that, decrement the desired size
104 until we succeed in allocating it. */
105 do
106 new = realloc (_hurd_dtable, size * sizeof (*_hurd_dtable));
107 while (new == NULL && size-- > first_fd);
108
109 if (new != NULL)
110 {
111 /* We managed to allocate a new table. Now install it. */
112 errno = save;
113 if (first_fd < _hurd_dtablesize)
114 first_fd = _hurd_dtablesize;
115 /* Initialize the new slots. */
116 for (i = _hurd_dtablesize; i < size; ++i)
117 new[i] = NULL;
118 _hurd_dtablesize = size;
119 _hurd_dtable = new;
120 /* Go back to the loop to initialize the first new slot. */
121 goto search;
122 }
123 else
124 __hurd_fail (ENOMEM);
125 }
126 else
127 __hurd_fail (EMFILE);
128 }
129 else
130 __hurd_fail (EINVAL); /* Bogus FIRST_FD value. */
131
132 out:
133 __mutex_unlock (&_hurd_dtable_lock);
134 _hurd_critical_section_unlock (crit);
135
136 return NULL;
137 }