390 lines
10 KiB
C
390 lines
10 KiB
C
/* Mail alias file parser in nss_files module.
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Copyright (C) 1996-2022 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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<https://www.gnu.org/licenses/>. */
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#include <aliases.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 <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <kernel-features.h>
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#include "nsswitch.h"
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#include <nss_files.h>
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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 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 = __nss_files_fopen ("/etc/aliases");
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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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_nss_files_setaliasent (void)
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{
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return __nss_files_data_setent (nss_file_aliasent, "/etc/aliases");
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}
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libc_hidden_def (_nss_files_setaliasent)
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enum nss_status
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_nss_files_endaliasent (void)
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{
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return __nss_files_data_endent (nss_file_aliasent);
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}
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libc_hidden_def (_nss_files_endaliasent)
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/* Parsing the database file into `struct aliasent' data structures. */
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static enum nss_status
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get_next_alias (FILE *stream, const char *match, struct aliasent *result,
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char *buffer, size_t buflen, int *errnop)
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{
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enum nss_status status = NSS_STATUS_NOTFOUND;
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int ignore = 0;
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result->alias_members_len = 0;
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while (1)
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{
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/* Now we are ready to process the input. We have to read a
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line and all its continuations and construct the array of
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string pointers. This pointers and the names itself have to
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be placed in BUFFER. */
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char *first_unused = buffer;
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size_t room_left = buflen - (buflen % __alignof__ (char *));
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char *line;
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/* Check whether the buffer is large enough for even trying to
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read something. */
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if (room_left < 2)
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goto no_more_room;
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/* Read the first line. It must contain the alias name and
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possibly some alias names. */
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first_unused[room_left - 1] = '\xff';
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line = __fgets_unlocked (first_unused, room_left, stream);
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if (line == NULL)
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/* Nothing to read. */
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break;
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else if (first_unused[room_left - 1] != '\xff')
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{
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/* The line is too long for our buffer. */
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no_more_room:
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*errnop = ERANGE;
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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else
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{
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char *cp;
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/* If we are in IGNORE mode and the first character in the
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line is a white space we ignore the line and start
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reading the next. */
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if (ignore && isspace (*first_unused))
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continue;
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/* Terminate the line for any case. */
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cp = strpbrk (first_unused, "#\n");
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if (cp != NULL)
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*cp = '\0';
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/* Skip leading blanks. */
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while (isspace (*line))
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++line;
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result->alias_name = first_unused;
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while (*line != '\0' && *line != ':')
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*first_unused++ = *line++;
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if (*line == '\0' || result->alias_name == first_unused)
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/* No valid name. Ignore the line. */
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continue;
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*first_unused++ = '\0';
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if (room_left < (size_t) (first_unused - result->alias_name))
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goto no_more_room;
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room_left -= first_unused - result->alias_name;
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++line;
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/* When we search for a specific alias we can avoid all the
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difficult parts and compare now with the name we are
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looking for. If it does not match we simply ignore all
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lines until the next line containing the start of a new
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alias is found. */
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ignore = (match != NULL
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&& __strcasecmp (result->alias_name, match) != 0);
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while (! ignore)
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{
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while (isspace (*line))
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++line;
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cp = first_unused;
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while (*line != '\0' && *line != ',')
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*first_unused++ = *line++;
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if (first_unused != cp)
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{
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/* OK, we can have a regular entry or an include
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request. */
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if (*line != '\0')
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++line;
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*first_unused++ = '\0';
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if (strncmp (cp, ":include:", 9) != 0)
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{
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if (room_left < (first_unused - cp) + sizeof (char *))
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goto no_more_room;
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room_left -= (first_unused - cp) + sizeof (char *);
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++result->alias_members_len;
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}
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else
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{
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/* Oh well, we have to read the addressed file. */
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FILE *listfile;
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char *old_line = NULL;
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first_unused = cp;
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listfile = __nss_files_fopen (&cp[9]);
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/* If the file does not exist we simply ignore
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the statement. */
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if (listfile != NULL
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&& (old_line = __strdup (line)) != NULL)
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{
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while (! __feof_unlocked (listfile))
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{
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if (room_left < 2)
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{
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free (old_line);
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fclose (listfile);
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goto no_more_room;
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}
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first_unused[room_left - 1] = '\xff';
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line = __fgets_unlocked (first_unused, room_left,
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listfile);
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if (line == NULL)
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break;
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if (first_unused[room_left - 1] != '\xff')
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{
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free (old_line);
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fclose (listfile);
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goto no_more_room;
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}
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/* Parse the line. */
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cp = strpbrk (line, "#\n");
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if (cp != NULL)
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*cp = '\0';
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do
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{
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while (isspace (*line))
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++line;
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cp = first_unused;
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while (*line != '\0' && *line != ',')
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*first_unused++ = *line++;
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if (*line != '\0')
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++line;
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if (first_unused != cp)
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{
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*first_unused++ = '\0';
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if (room_left < ((first_unused - cp)
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+ __alignof__ (char *)))
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{
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free (old_line);
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fclose (listfile);
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goto no_more_room;
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}
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room_left -= ((first_unused - cp)
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+ __alignof__ (char *));
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++result->alias_members_len;
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}
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}
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while (*line != '\0');
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}
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fclose (listfile);
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first_unused[room_left - 1] = '\0';
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strncpy (first_unused, old_line, room_left);
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free (old_line);
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line = first_unused;
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if (first_unused[room_left - 1] != '\0')
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goto no_more_room;
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}
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}
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}
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if (*line == '\0')
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{
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/* Get the next line. But we must be careful. We
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must not read the whole line at once since it
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might belong to the current alias. Simply read
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the first character. If it is a white space we
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have a continuation line. Otherwise it is the
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beginning of a new alias and we can push back the
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just read character. */
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int ch;
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ch = __getc_unlocked (stream);
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if (ch == EOF || ch == '\n' || !isspace (ch))
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{
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size_t cnt;
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/* Now prepare the return. Provide string
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pointers for the currently selected aliases. */
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if (ch != EOF)
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ungetc (ch, stream);
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/* Adjust the pointer so it is aligned for
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storing pointers. */
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first_unused += __alignof__ (char *) - 1;
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first_unused -= ((first_unused - (char *) 0)
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% __alignof__ (char *));
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result->alias_members = (char **) first_unused;
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/* Compute addresses of alias entry strings. */
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cp = result->alias_name;
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for (cnt = 0; cnt < result->alias_members_len; ++cnt)
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{
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cp = strchr (cp, '\0') + 1;
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result->alias_members[cnt] = cp;
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}
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status = (result->alias_members_len == 0
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? NSS_STATUS_RETURN : NSS_STATUS_SUCCESS);
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break;
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}
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/* The just read character is a white space and so
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can be ignored. */
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first_unused[room_left - 1] = '\xff';
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line = __fgets_unlocked (first_unused, room_left, stream);
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if (line == NULL)
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{
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/* Continuation line without any data and
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without a newline at the end. Treat it as an
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empty line and retry, reaching EOF once
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more. */
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line = first_unused;
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*line = '\0';
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continue;
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}
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if (first_unused[room_left - 1] != '\xff')
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goto no_more_room;
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cp = strpbrk (line, "#\n");
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if (cp != NULL)
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*cp = '\0';
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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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/* We read something. In any case break here. */
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break;
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}
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return status;
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}
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enum nss_status
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_nss_files_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
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int *errnop)
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{
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/* Return next entry in host file. */
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struct nss_files_per_file_data *data;
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enum nss_status status = __nss_files_data_open (&data, nss_file_aliasent,
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"/etc/aliases", errnop, NULL);
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if (status != NSS_STATUS_SUCCESS)
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return status;
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result->alias_local = 1;
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/* Read lines until we get a definite result. */
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do
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status = get_next_alias (data->stream, NULL, result, buffer, buflen,
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errnop);
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while (status == NSS_STATUS_RETURN);
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__nss_files_data_put (data);
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return status;
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}
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libc_hidden_def (_nss_files_getaliasent_r)
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enum nss_status
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_nss_files_getaliasbyname_r (const char *name, struct aliasent *result,
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char *buffer, size_t buflen, int *errnop)
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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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FILE *stream = NULL;
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if (name == NULL)
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{
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__set_errno (EINVAL);
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return NSS_STATUS_UNAVAIL;
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}
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/* Open the stream. */
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status = internal_setent (&stream);
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if (status == NSS_STATUS_SUCCESS)
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{
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result->alias_local = 1;
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/* Read lines until we get a definite result. */
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do
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status = get_next_alias (stream, name, result, buffer, buflen, errnop);
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while (status == NSS_STATUS_RETURN);
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fclose (stream);
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}
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return status;
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}
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libc_hidden_def (_nss_files_getaliasbyname_r)
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