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https://sourceware.org/git/glibc.git
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a6033052d0
Reproducer (needs to run as root):
perl -e \
'print "large❌999:" . join(",", map {"user$_"} (1 .. 135))."\n"' \
>> /etc/group
cd /var/db
make
getent -s db group
After the fix, the last command should list the "large" group.
The magic number 135 has been chosen so that the line is shorter than
1024 bytes, but the pointers required to encode the member array will
cross the threshold, triggering the bug.
306 lines
8.7 KiB
C
306 lines
8.7 KiB
C
/* Common code for DB-based databases in nss_db module.
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Copyright (C) 1996-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <dlfcn.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <libc-lock.h>
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#include "nsswitch.h"
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#include "nss_db.h"
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/* The hashing function we use. */
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#include "../intl/hash-string.h"
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/* These symbols are defined by the including source file:
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ENTNAME -- database name of the structure and functions (hostent, pwent).
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STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
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DATABASE -- database file name, ("hosts", "passwd")
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NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
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*/
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#define ENTNAME_r CONCAT(ENTNAME,_r)
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#include <paths.h>
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#define DBFILE _PATH_VARDB DATABASE ".db"
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#ifdef NEED_H_ERRNO
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# define H_ERRNO_PROTO , int *herrnop
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# define H_ERRNO_ARG , herrnop
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# define H_ERRNO_SET(val) (*herrnop = (val))
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#else
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# define H_ERRNO_PROTO
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# define H_ERRNO_ARG
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# define H_ERRNO_SET(val) ((void) 0)
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#endif
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/* State for this database. */
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static struct nss_db_map state;
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/* Lock to protect the state and global variables. */
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__libc_lock_define (static , lock);
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/* Maintenance of the shared handle open on the database. */
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static int keep_db;
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static const char *entidx;
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/* Open the database. */
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enum nss_status
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CONCAT(_nss_db_set,ENTNAME) (int stayopen)
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{
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enum nss_status status;
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__libc_lock_lock (lock);
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status = internal_setent (DBFILE, &state);
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if (status == NSS_STATUS_SUCCESS)
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{
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/* Remember STAYOPEN flag. */
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keep_db |= stayopen;
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/* Reset the sequential index. */
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entidx = (const char *) state.header + state.header->valstroffset;
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}
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__libc_lock_unlock (lock);
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return status;
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}
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/* Close it again. */
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enum nss_status
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CONCAT(_nss_db_end,ENTNAME) (void)
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{
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__libc_lock_lock (lock);
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internal_endent (&state);
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/* Reset STAYOPEN flag. */
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keep_db = 0;
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__libc_lock_unlock (lock);
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return NSS_STATUS_SUCCESS;
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}
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/* Macro for defining lookup functions for this DB-based database.
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NAME is the name of the lookup; e.g. `pwnam'.
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DB_CHAR is index indicator for the database.
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KEYPATTERN gives `printf' args to construct a key string;
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e.g. `("%d", id)'.
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KEYSIZE gives the allocation size of a buffer to construct it in;
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e.g. `1 + sizeof (id) * 4'.
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PROTO is the potentially empty list of other parameters.
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BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
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to the lookup key arguments and does `break;' if they match. */
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#define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\
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enum nss_status \
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_nss_db_get##name##_r (proto, struct STRUCTURE *result, \
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char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)\
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{ \
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struct parser_data *data = (void *) buffer; \
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\
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if (buflen < sizeof *data) \
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{ \
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*errnop = ERANGE; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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return NSS_STATUS_TRYAGAIN; \
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} \
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\
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struct nss_db_map state = { NULL, 0 }; \
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enum nss_status status = internal_setent (DBFILE, &state); \
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if (status != NSS_STATUS_SUCCESS) \
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{ \
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*errnop = errno; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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return status; \
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} \
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\
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const struct nss_db_header *header = state.header; \
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int i; \
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for (i = 0; i < header->ndbs; ++i) \
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if (header->dbs[i].id == db_char) \
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break; \
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if (i == header->ndbs) \
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{ \
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status = NSS_STATUS_UNAVAIL; \
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goto out; \
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} \
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\
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char *key; \
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if (db_char == '.') \
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key = (char *) IGNOREPATTERN keypattern; \
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else \
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{ \
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const size_t size = (keysize) + 1; \
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key = alloca (size); \
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\
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KEYPRINTF keypattern; \
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} \
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\
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const stridx_t *hashtable \
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= (const stridx_t *) ((const char *) header \
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+ header->dbs[i].hashoffset); \
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const char *valstrtab = (const char *) header + header->valstroffset; \
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uint32_t hashval = __hash_string (key); \
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size_t hidx = hashval % header->dbs[i].hashsize; \
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size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2); \
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\
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status = NSS_STATUS_NOTFOUND; \
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while (hashtable[hidx] != ~((stridx_t) 0)) \
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{ \
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const char *valstr = valstrtab + hashtable[hidx]; \
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size_t len = strlen (valstr) + 1; \
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if (len > buflen) \
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{ \
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/* No room to copy the data to. */ \
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*errnop = ERANGE; \
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H_ERRNO_SET (NETDB_INTERNAL); \
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status = NSS_STATUS_TRYAGAIN; \
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break; \
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} \
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\
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/* Copy the string to a place where it can be modified. */ \
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char *p = memcpy (buffer, valstr, len); \
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\
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int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS); \
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\
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/* Advance before break_if_match, lest it uses continue to skip
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to the next entry. */ \
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if ((hidx += hval2) >= header->dbs[i].hashsize) \
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hidx -= header->dbs[i].hashsize; \
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\
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if (err > 0) \
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{ \
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status = NSS_STATUS_SUCCESS; \
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break_if_match; \
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status = NSS_STATUS_NOTFOUND; \
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} \
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else if (err == -1) \
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{ \
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H_ERRNO_SET (NETDB_INTERNAL); \
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status = NSS_STATUS_TRYAGAIN; \
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break; \
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} \
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} \
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\
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if (status == NSS_STATUS_NOTFOUND) \
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H_ERRNO_SET (HOST_NOT_FOUND); \
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\
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out: \
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internal_endent (&state); \
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\
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return status; \
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}
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#define KEYPRINTF(pattern, args...) snprintf (key, size, pattern ,##args)
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#define IGNOREPATTERN(pattern, arg1, args...) (char *) (uintptr_t) arg1
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/* Return the next entry from the database file, doing locking. */
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enum nss_status
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CONCAT(_nss_db_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
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size_t buflen, int *errnop H_ERRNO_PROTO)
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{
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/* Return next entry in host file. */
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enum nss_status status;
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struct parser_data *data = (void *) buffer;
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if (buflen < sizeof *data)
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{
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*errnop = ERANGE;
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H_ERRNO_SET (NETDB_INTERNAL);
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return NSS_STATUS_TRYAGAIN;
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}
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__libc_lock_lock (lock);
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if (state.header == NULL)
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{
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status = internal_setent (DBFILE, &state);
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if (status != NSS_STATUS_SUCCESS)
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{
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*errnop = errno;
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H_ERRNO_SET (NETDB_INTERNAL);
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goto out;
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}
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}
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status = NSS_STATUS_UNAVAIL;
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if (state.header != MAP_FAILED)
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{
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const char *const end = ((const char *) state.header
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+ state.header->valstroffset
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+ state.header->valstrlen);
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while (entidx < end)
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{
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const char *next = rawmemchr (entidx, '\0') + 1;
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size_t len = next - entidx;
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if (len > buflen)
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{
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/* No room to copy the data to. */
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*errnop = ERANGE;
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H_ERRNO_SET (NETDB_INTERNAL);
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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/* Copy the string to a place where it can be modified. */
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char *p = memcpy (buffer, entidx, len);
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int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS);
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if (err > 0)
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{
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status = NSS_STATUS_SUCCESS;
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entidx = next;
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break;
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}
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if (err < 0)
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{
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H_ERRNO_SET (NETDB_INTERNAL);
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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/* Continue with the next record, this one is ill-formed. */
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entidx = next;
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}
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}
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out:
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__libc_lock_unlock (lock);
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return status;
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}
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