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/* $OpenBSD: table.c,v 1.19 2016/08/26 08:44:04 guenther Exp $ */ |
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/* |
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* Copyright (c) 1983 Regents of the University of California. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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/* |
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* Routines to handle insertion, deletion, etc on the table |
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* of requests kept by the daemon. Nothing fancy here, linear |
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* search on a double-linked list. A time is kept with each |
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* entry so that overly old invitations can be eliminated. |
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* |
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* Consider this a mis-guided attempt at modularity |
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*/ |
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#include <sys/queue.h> |
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#include <sys/socket.h> |
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#include <sys/time.h> |
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#include <protocols/talkd.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <syslog.h> |
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#include <unistd.h> |
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#include "talkd.h" |
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#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ |
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struct timeval tp; |
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struct timezone txp; |
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typedef struct table_entry TABLE_ENTRY; |
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struct table_entry { |
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CTL_MSG request; |
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time_t time; |
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TAILQ_ENTRY(table_entry) list; |
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}; |
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TAILQ_HEAD(, table_entry) table; |
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static void delete(TABLE_ENTRY *); |
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/* |
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* Init the table |
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*/ |
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void |
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init_table(void) |
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{ |
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TAILQ_INIT(&table); |
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} |
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/* |
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* Look in the table for an invitation that matches the current |
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* request looking for an invitation |
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*/ |
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CTL_MSG * |
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find_match(CTL_MSG *request) |
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{ |
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TABLE_ENTRY *ptr, *next; |
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time_t current_time; |
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gettimeofday(&tp, &txp); |
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current_time = tp.tv_sec; |
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if (debug) |
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print_request("find_match", request); |
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for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) { |
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next = TAILQ_NEXT(ptr, list); |
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if ((current_time - ptr->time) > MAX_LIFE) { |
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/* the entry is too old */ |
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if (debug) |
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print_request("deleting expired entry", |
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&ptr->request); |
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delete(ptr); |
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continue; |
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} |
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if (debug) |
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print_request("", &ptr->request); |
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if (ptr->request.type == LEAVE_INVITE && |
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strcmp(request->l_name, ptr->request.r_name) == 0 && |
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strcmp(request->r_name, ptr->request.l_name) == 0) |
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return (&ptr->request); |
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} |
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if (debug) |
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syslog(LOG_DEBUG, "find_match: not found"); |
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return (NULL); |
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} |
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/* |
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* Look for an identical request, as opposed to a complimentary |
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* one as find_match does |
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*/ |
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CTL_MSG * |
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find_request(CTL_MSG *request) |
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{ |
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TABLE_ENTRY *ptr, *next; |
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time_t current_time; |
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gettimeofday(&tp, &txp); |
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current_time = tp.tv_sec; |
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/* |
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* See if this is a repeated message, and check for |
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* out of date entries in the table while we are it. |
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*/ |
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if (debug) |
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print_request("find_request", request); |
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for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) { |
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next = TAILQ_NEXT(ptr, list); |
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if ((current_time - ptr->time) > MAX_LIFE) { |
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/* the entry is too old */ |
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if (debug) |
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print_request("deleting expired entry", |
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&ptr->request); |
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delete(ptr); |
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continue; |
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} |
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if (debug) |
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print_request("", &ptr->request); |
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if (request->pid == ptr->request.pid && |
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request->type == ptr->request.type && |
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strcmp(request->r_name, ptr->request.r_name) == 0 && |
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strcmp(request->l_name, ptr->request.l_name) == 0) { |
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/* update the time if we 'touch' it */ |
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ptr->time = current_time; |
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return (&ptr->request); |
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} |
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} |
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return (NULL); |
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} |
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void |
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insert_table(CTL_MSG *request, CTL_RESPONSE *response) |
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{ |
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TABLE_ENTRY *ptr; |
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time_t current_time; |
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if (debug) |
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print_request( "insert_table", request ); |
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gettimeofday(&tp, &txp); |
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current_time = tp.tv_sec; |
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request->id_num = new_id(); |
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response->id_num = htonl(request->id_num); |
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/* insert a new entry into the top of the list */ |
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ptr = malloc(sizeof(TABLE_ENTRY)); |
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if (ptr == NULL) { |
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syslog(LOG_ERR, "insert_table: Out of memory"); |
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_exit(1); |
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} |
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ptr->time = current_time; |
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ptr->request = *request; |
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TAILQ_INSERT_HEAD(&table, ptr, list); |
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} |
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/* |
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* Generate a unique non-zero sequence number |
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*/ |
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int |
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new_id(void) |
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{ |
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static int current_id = 0; |
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current_id = (current_id + 1) % MAX_ID; |
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/* 0 is reserved, helps to pick up bugs */ |
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if (current_id == 0) |
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current_id = 1; |
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return (current_id); |
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} |
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/* |
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* Delete the invitation with id 'id_num' |
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*/ |
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int |
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delete_invite(int id_num) |
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{ |
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TABLE_ENTRY *ptr; |
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if (debug) |
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syslog(LOG_DEBUG, "delete_invite(%d)", id_num); |
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TAILQ_FOREACH(ptr, &table, list) { |
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if (ptr->request.id_num == id_num) |
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break; |
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if (debug) |
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print_request("", &ptr->request); |
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} |
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if (ptr != NULL) { |
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delete(ptr); |
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return (SUCCESS); |
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} |
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return (NOT_HERE); |
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} |
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/* |
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* Classic delete from a double-linked list |
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*/ |
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static void |
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delete(TABLE_ENTRY *ptr) |
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{ |
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if (debug) |
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print_request("delete", &ptr->request); |
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TAILQ_REMOVE(&table, ptr, list); |
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free((char *)ptr); |
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} |