]> andersk Git - nss_nonlocal.git/blame - walk_nss.h
Guard one-time initialization with memory barriers
[nss_nonlocal.git] / walk_nss.h
CommitLineData
cbb0e3ea
AK
1/*
2 * walk_nss.h
3 * NSS walking template for nss_nonlocal proxy
4 *
5 * Copyright © 2011 Anders Kaseorg <andersk@mit.edu> and Tim Abbott
6 * <tabbott@mit.edu>
7 *
8 * This file is part of nss_nonlocal.
9 *
10 * nss_nonlocal is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public License
12 * as published by the Free Software Foundation; either version 2.1 of
13 * the License, or (at your option) any later version.
14 *
15 * nss_nonlocal is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with nss_nonlocal; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
23 * 02110-1301 USA
24 */
25
26{
48939704
AK
27 static bool initialized = false;
28 static service_user *startp;
29 static void *fct_start;
cbb0e3ea
AK
30
31 service_user *nip;
32 union {
33 __typeof__(self) l;
34 void *ptr;
35 } fct;
36 int old_errno = errno;
37
48939704
AK
38 if (!initialized) {
39 if (w.lookup(&startp, w.fct_name, &fct_start) != 0) {
40 *w.status = NSS_STATUS_UNAVAIL;
41 goto walk_nss_out;
42 }
43 __sync_synchronize();
44 initialized = true;
cbb0e3ea
AK
45 }
46
47 nip = startp;
48 fct.ptr = fct_start;
49
50 if (w.buf != NULL) {
51 *w.buf = malloc(*w.buflen);
52 errno = old_errno;
53 if (*w.buf == NULL) {
54 *w.status = NSS_STATUS_TRYAGAIN;
55 *w.errnop = ENOMEM;
56 goto walk_nss_out;
57 }
58 }
59
60 do {
61 walk_nss_morebuf:
62 if (fct.ptr == NULL)
63 *w.status = NSS_STATUS_UNAVAIL;
64 else if (self != NULL && fct.l == self)
65 *w.status = NSS_STATUS_NOTFOUND;
66 else
67 *w.status = DL_CALL_FCT(fct.l, args);
68 if (*w.status == NSS_STATUS_TRYAGAIN &&
69 w.errnop != NULL && *w.errnop == ERANGE) {
70 if (w.buf == NULL)
71 break;
72 free(*w.buf);
73 *w.buflen *= 2;
74 *w.buf = malloc(*w.buflen);
75 errno = old_errno;
76 if (*w.buf == NULL) {
77 *w.errnop = ENOMEM;
78 goto walk_nss_out;
79 }
80 goto walk_nss_morebuf;
81 }
82 } while (__nss_next(&nip, w.fct_name, &fct.ptr, *w.status, 0) == 0);
83
84 if (w.buf != NULL && *w.status != NSS_STATUS_SUCCESS) {
85 free(*w.buf);
86 *w.buf = NULL;
87 }
88
89 walk_nss_out:
90 ;
91}
This page took 0.052736 seconds and 5 git commands to generate.