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301 lines
7.8 KiB
C
301 lines
7.8 KiB
C
/* Common code for file-based databases in nss_files module.
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Copyright (C) 1996-2017 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 <stdio.h>
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <libc-lock.h>
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#include "nsswitch.h"
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#include <kernel-features.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 -- string of the database file's name ("hosts", "passwd").
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NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
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Also see files-parse.c.
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*/
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#define ENTNAME_r CONCAT(ENTNAME,_r)
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#define DATAFILE "/etc/" DATABASE
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#ifdef NEED_H_ERRNO
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# include <netdb.h>
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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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#ifndef EXTRA_ARGS
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# define EXTRA_ARGS
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# define EXTRA_ARGS_DECL
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# define EXTRA_ARGS_VALUE
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#endif
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/* Locks the static variables in this file. */
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__libc_lock_define_initialized (static, lock)
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/* Maintenance of the stream open on the database file. For getXXent
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operations the stream needs to be held open across calls, the other
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getXXbyYY operations all use their own stream. */
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static FILE *stream;
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/* Open database file if not already opened. */
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static enum nss_status
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internal_setent (FILE **stream)
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{
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enum nss_status status = NSS_STATUS_SUCCESS;
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if (*stream == NULL)
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{
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*stream = fopen (DATAFILE, "rce");
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if (*stream == NULL)
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status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
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}
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else
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rewind (*stream);
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return status;
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}
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/* Thread-safe, exported version of that. */
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enum nss_status
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CONCAT(_nss_files_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 (&stream);
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__libc_lock_unlock (lock);
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return status;
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}
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/* Close the database file. */
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static void
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internal_endent (FILE **stream)
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{
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if (*stream != NULL)
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{
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fclose (*stream);
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*stream = NULL;
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}
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}
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/* Thread-safe, exported version of that. */
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enum nss_status
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CONCAT(_nss_files_end,ENTNAME) (void)
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{
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__libc_lock_lock (lock);
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internal_endent (&stream);
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__libc_lock_unlock (lock);
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return NSS_STATUS_SUCCESS;
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}
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typedef enum
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{
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gcr_ok = 0,
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gcr_error = -1,
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gcr_overflow = -2
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} get_contents_ret;
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/* Hack around the fact that fgets only accepts int sizes. */
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static get_contents_ret
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get_contents (char *linebuf, size_t len, FILE *stream)
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{
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size_t remaining_len = len;
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char *curbuf = linebuf;
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do
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{
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int curlen = ((remaining_len > (size_t) INT_MAX) ? INT_MAX
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: remaining_len);
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/* Terminate the line so that we can test for overflow. */
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((unsigned char *) curbuf)[curlen - 1] = 0xff;
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char *p = fgets_unlocked (curbuf, curlen, stream);
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/* EOF or read error. */
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if (p == NULL)
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return gcr_error;
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/* Done reading in the line. */
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if (((unsigned char *) curbuf)[curlen - 1] == 0xff)
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return gcr_ok;
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/* Drop the terminating '\0'. */
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remaining_len -= curlen - 1;
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curbuf += curlen - 1;
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}
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/* fgets copies one less than the input length. Our last iteration is of
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REMAINING_LEN and once that is done, REMAINING_LEN is decremented by
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REMAINING_LEN - 1, leaving the result as 1. */
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while (remaining_len > 1);
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/* This means that the current buffer was not large enough. */
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return gcr_overflow;
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}
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/* Parsing the database file into `struct STRUCTURE' data structures. */
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static enum nss_status
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internal_getent (FILE *stream, struct STRUCTURE *result,
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char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO
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EXTRA_ARGS_DECL)
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{
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char *p;
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struct parser_data *data = (void *) buffer;
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size_t linebuflen = buffer + buflen - data->linebuffer;
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int parse_result;
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if (buflen < sizeof *data + 2)
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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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do
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{
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get_contents_ret r = get_contents (data->linebuffer, linebuflen, stream);
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if (r == gcr_error)
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{
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/* End of file or read error. */
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H_ERRNO_SET (HOST_NOT_FOUND);
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return NSS_STATUS_NOTFOUND;
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}
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if (r == gcr_overflow)
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{
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/* The line is too long. Give the user the opportunity to
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enlarge the buffer. */
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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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/* Everything OK. Now skip leading blanks. */
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p = data->linebuffer;
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while (isspace (*p))
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++p;
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}
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while (*p == '\0' || *p == '#' /* Ignore empty and comment lines. */
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/* Parse the line. If it is invalid, loop to get the next
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line of the file to parse. */
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|| ! (parse_result = parse_line (p, result, data, buflen, errnop
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EXTRA_ARGS)));
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if (__glibc_unlikely (parse_result == -1))
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{
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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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/* Filled in RESULT with the next entry from the database file. */
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return NSS_STATUS_SUCCESS;
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}
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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_files_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 = NSS_STATUS_SUCCESS;
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__libc_lock_lock (lock);
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/* Be prepared that the set*ent function was not called before. */
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if (stream == NULL)
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{
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int save_errno = errno;
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status = internal_setent (&stream);
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__set_errno (save_errno);
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}
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if (status == NSS_STATUS_SUCCESS)
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status = internal_getent (stream, result, buffer, buflen, errnop
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H_ERRNO_ARG EXTRA_ARGS_VALUE);
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__libc_lock_unlock (lock);
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return status;
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}
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/* Macro for defining lookup functions for this file-based database.
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NAME is the name of the lookup; e.g. `hostbyname'.
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DB_CHAR, KEYPATTERN, KEYSIZE are ignored here but used by db-XXX.c
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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_files_get##name##_r (proto, \
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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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enum nss_status status; \
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FILE *stream = NULL; \
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\
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/* Open file. */ \
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status = internal_setent (&stream); \
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\
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if (status == NSS_STATUS_SUCCESS) \
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{ \
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while ((status = internal_getent (stream, result, buffer, buflen, errnop \
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H_ERRNO_ARG EXTRA_ARGS_VALUE)) \
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== NSS_STATUS_SUCCESS) \
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{ break_if_match } \
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\
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internal_endent (&stream); \
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} \
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\
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return status; \
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}
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