我创建了一个具有多线程的客户端 - 服务器文件共享系统。客户端代码适用于单个客户端。当我增加客户端中的线程数时，服务器代码中会出现分段错误。
当我在gdb上执行代码时，它显示发生了错误分段错误，没有这样的文件或目录。这是因为线程共享文件描述符吗？如何解决分段错误？
---------- -----------编辑 我考虑了你的所有建议。大多数错误都已解决，但是当我尝试发送＆gt; 10mb文件时，某些send-recv调用在使用线程发送时不会完全执行（它可以在单个线程中正常工作）。我相信这就是内存泄漏发生的原因，并最终导致分段错误（文件指针未关闭）。 gdb也是如此。 如何解决此发送接收阻止错误？
客户端代码
#include <time.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<string.h>
#include<stdio.h>
#include <stdlib.h>
#include<pthread.h>
#include <semaphore.h>
#define PORT 8029
#define SIZE 1024
#define SERVER_ADDR "192.168.43.158" //"10.15.36.112"
//defining number of threads
struct ser_data
{
int sockfd;
int n;
};
void *client_req(void * data){
// printf("inside thread\n");
//sleep(1);
int s,c,n,read_size,r;
//login_id and password of the user
//array to choose file names randomly
//char f_name[20][20]={"f0.txt","f1.txt","f2.txt","f3.txt","f4.txt","f5.txt","f6.txt","f7.txt","f8.txt","f9.txt","f10.txt\0","f11.txt\0","f12.txt\0" ,"f13.txt\0","f14.txt\0","f15.txt\0","f16.txt\0","f17.txt\0","f18.txt","f19.txt"};
//socket address for client and server
//used for generation of random no
time_t t;
struct sockaddr_in cli,serv;
FILE *f;
char fname[SIZE]="file_cli/";
char f_name[SIZE];
char login_id[21], pswd[21], choice[2];
//msg_cli_rec= message recieved form server
char msg_cli_rec[SIZE];
//msg_cli_send =message sent by client
char msg_cli_send[SIZE];
time_t start, stop;
int brk=0;
start = time(NULL);
s=socket(AF_INET,SOCK_STREAM,0);
bzero((char*)&serv,sizeof(cli));
cli.sin_family=AF_INET;
cli.sin_port=htons(PORT);
cli.sin_addr.s_addr = inet_addr(SERVER_ADDR);
connect(s,(struct sockaddr*)&cli,sizeof(cli));
//printf("\nConnected with server");
strcpy(choice, "1");
/*msg_cli_rec = (char *) malloc(1000* sizeof(char));
msg_cli_send = (char *) malloc(1000* sizeof(char));*/
//if user wants to login
if(strcmp(choice,"1")==0)
{
strcpy(login_id, "prach");
send(s, login_id, sizeof(login_id), 0);
strcpy(pswd, "prach");
send(s, pswd, sizeof(pswd), 0);
}
//making default choice download 1
do {
strcpy(choice, "1\0");
strcpy(msg_cli_send, choice);
//send(s, choice, sizeof(choice), 0);
send(s,msg_cli_send,sizeof(msg_cli_send),0);
//random number generation
srand((unsigned) time(NULL));
//r=((unsigned)rand()*(i++))%20;
r=15;
if(strcmp(choice,"1")==0)
{
/*if(recv(s, msg_cli_rec, sizeof(msg_cli_rec), 0))
{
//if((strcmp("end",msg_cli_rec))==0)break;
printf("\n%s", msg_cli_rec);
}*/
/*printf("\nEnter the file name you want:");
scanf("%s", msg_cli_send);*/
// to select file name with index of the random number
sprintf(f_name,"file (%d).txt",r);
strcpy(msg_cli_send, "");
strcpy(msg_cli_send,f_name);
// printf("\n%s",msg_cli_send);
// printf("\n rand =%d\n", r );
send(s,msg_cli_send,sizeof(msg_cli_send),0);
// printf("\nThe received file content is:");
//receiving the file names
f = fopen(strcat(fname,f_name),"w");
bzero( msg_cli_rec, sizeof(msg_cli_rec));
while((recv(s, msg_cli_rec, sizeof(msg_cli_rec), 0)> 0)&&(*msg_cli_rec!='\0'))
{//fflush(stdout);
if((strcmp("quit",msg_cli_rec))==0)break;
fprintf(f, "%s", msg_cli_rec);
//printf("\n%s", msg_cli_rec);
bzero( msg_cli_rec, sizeof(msg_cli_rec));
}
// printf("File recieved");
fclose(f);
strcpy(fname,"\0" );
//sem_post(&sem);
}
stop = time(NULL);
// printf("\n%s\n", ctime(&stop));
//printf("%ld", (stop-start));
//set the timer to 300 seconds
}while(*choice == '1' && (stop-start)<10);
//tell the server that we are done with sending files
strcpy(choice, "0");
send(s, choice, sizeof(choice), 0);
printf("%ld\n", (stop-start) );
/* free(msg_cli_rec);
free(msg_cli_send);*/
close(s);
//pthread_exit(NULL);
}
int main()
{
int N_Threads=2, count =0;
struct ser_data data;
/*while(N_Threads<=2)
{
pthread_t t;
pthread_create( &t , NULL , client_req , NULL);
N_Threads++;
if ( ! pthread_detach(t) )
printf("Thread detached successfully !!!\n");
//pthread_join(t, NULL);
}*/
while(count != N_Threads){
pthread_t handle;
count = count+1;
data.sockfd = count;
if(pthread_create(&handle, NULL, client_req,(void *)&data)<0)
error("Error creating thread");
else
printf("Thread allocation successful for fd: %d\n",data.sockfd);
}
pthread_exit(NULL);
}
服务器代码
#include <time.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<string.h>
#include<stdio.h>
#include<pthread.h>
#include<stdlib.h>
#include<dirent.h>
#include <mysql/mysql.h>
#include <semaphore.h>
#define PORT 8029
#define SIZE 1024
#define QUERY_SIZE 200
#define N_Threads 5
#define SERV_ADDR "192.168.43.158"
clock_t start, stop;
//login id and password of the user
int file_id=1;
/*Database variables*/
MYSQL *db_conn;
char *db_server = "localhost";
char *db_user = "root";
char *db_password = "root";
char *database = "file_db";
//for synchronization while accessing the db
sem_t sem;
/* A function which generates the and returns login query statement*/
char* query_login(char *query, char *login_id, char *pswd)
{
//generating query
strcpy(query,"SELECT * FROM user_info WHERE user_id='");
strcat(query, login_id);
strcat(query, "' AND pswd='");
strcat(query, pswd);
strcat(query, "'");
return query;
}
/* A function which generates and returns the register query statement*/
char* query_register(char *query, char *login_id, char *pswd)
{
strcpy(query, "INSERT INTO user_info VALUES ( '");
strcat(query, login_id);
strcat(query, "', '");
strcat(query, pswd);
strcat(query, "' )");
return query;
}
void *connect_client(void *socket)
{ int sock=*(int*)socket;
printf("\nFD %d",sock);
char msg_c_r[SIZE], msg_s_s[SIZE];
//for the choice given to the user to login or register
char choice='0';
char msg_serv_send[SIZE],msg_serv_rec[SIZE];
char msg_cli_rec[SIZE];
char fpath[SIZE] = "file_serv/";
char fname[SIZE];
int read_size;
int num_fields=0;
char * line = NULL;
size_t len = 0;
ssize_t read;
MYSQL_ROW row;
MYSQL_RES *db_res;
char login_id[21], pswd[21];
FILE *f;
FILE *fc;
char name[SIZE];
char query1[SIZE];
char query[QUERY_SIZE];
/*locking the database for mutual exclusion*/
//sem_wait(&sem);
//executing a query
choice = '1';
strcpy(query, "\0");
switch(choice)
{
//1 = login
case '1':
/*to find the login id and password of the user*/
bzero(login_id, sizeof(login_id));
recv(sock, login_id, sizeof(login_id), 0);
bzero(pswd, sizeof(pswd));
recv(sock, pswd, sizeof(pswd), 0);
printf("The login id is: %s\nThe Password is: %s\n", login_id, pswd);
//lock for accessing db in mutual exclusion
sem_wait(&sem);
query_login(query, login_id, pswd);
//checking the details given by client
if (mysql_query(db_conn, query)!=0) {
fprintf(stderr, "%s\n", mysql_error(db_conn));
}
strcpy(query, "\0");
strcat(query,"select * from user_info where user_id='");
strcat(query,login_id);
strcat(query,"'");
mysql_query(db_conn, query);
db_res = mysql_store_result(db_conn);
row = mysql_fetch_row(db_res);
if (row!=0) {
//send(sock,"T",sizeof("T"),0);
printf("\nT");
}
//freeing the result variable so it can be used further
mysql_free_result(db_res);
//release lock
sem_post(&sem);
break;
}//switch case
/*send(sock, "\nPlease enter your choice \n 1- File Download \n 2-File Upload\n 3-Rating\n", sizeof("\nPlease enter your choice \n 1- File Download \n 2-File Upload\n 3-Rating\n"), 0);*/
int nu=1;
do{
bzero(msg_serv_rec,sizeof(msg_serv_rec));
if(recv(sock, msg_serv_rec,sizeof(msg_serv_rec), 0)>0)
{
choice = msg_serv_rec ? *msg_serv_rec : '0';
printf("\n choice = %c\n", choice);
strcpy(query, "\0");
//printf("Client's choice is file Download\n" );
/*Sending File to the client line by line
checking the database connection*/
if(choice == '1'){
/*if(mysql_query(db_conn, "SELECT name FROM file_info")==0)
{
db_res = mysql_store_result(db_conn);
num_fields = mysql_num_fields(db_res);
if(num_fields>0)
{
while ((row = mysql_fetch_row(db_res)))
{
for(int i = 0; i < num_fields; i++)
{
char *fname1=row[i] ? row[i] : "NULL";
strcat(name,fname1);
strcat(name, "\n");
//send(sock,name,sizeof(name),0);
//printf("\n%s",name);
}
}
//sending list of all files to client
send(sock,name,sizeof(name),0);*/
/*emptying the name!!
strcpy(name, "");*/
//freeing the result variable so it can be used further
/*mysql_free_result(db_res);
sem_post(&sem);*/
bzero(msg_serv_rec,sizeof(msg_serv_rec));
if(recv(sock, msg_serv_rec,sizeof(msg_serv_rec), 0)>0)
{//which file recieved
printf("%s\n", msg_serv_rec );
// sem_wait(&sem);
f = fopen(strcat(fpath, msg_serv_rec),"r");
while(fgets(msg_serv_send, sizeof(msg_serv_send), f) !=NULL)
{
if((*msg_serv_send!=EOF || *msg_serv_send!='\n'))
{
send(sock, msg_serv_send, sizeof(msg_serv_send), 0);
//printf("\n%s", msg_serv_send);
}
else
break;
}
send(sock,"quit",sizeof("quit"),0);
fclose(f);
strcpy(fpath, "file_serv/");
//sem_post(&sem);
printf("\nFile sent to the client\n");
}
}
else if (choice == '0')
break;
strcpy(msg_serv_rec, "");
//stop = clock();
//time(NULL);
}
else
{
choice = '0';
}
}while ( choice != 'f' && choice != '0');
nu++;
/* unblocking the semaphores to allow other threads to access*/
//sem_post(&sem);
if(read_size == 0)
{
puts("\nClient disconnected\n");
fflush(stdout);
}
/*else if(read_size == -1)
{perror("recv failed");}
fclose(f);*/
close(sock);
pthread_exit(NULL);
}
int main()
{ int s,n,i, clilen;
int c;
int newsockfd;
int *new_sock;
start = clock();
//pthread_t handle;
struct sockaddr_in cli,serv;//socket address for client and server
MYSQL_ROW row;
MYSQL_RES *db_res;
//initializing the semaphore
sem_init(&sem, 0, 1);
//synchronization in DB
sem_wait(&sem);
/*Database connectivity*/
db_conn = mysql_init(NULL);
/* Connect to database */
if (!mysql_real_connect(db_conn, db_server, db_user, db_password, database, 0, NULL, 0)) {
fprintf(stderr, "%s\n", mysql_error(db_conn));
exit(1);
}
/* send SQL query */
if (mysql_query(db_conn, "show tables")) {
fprintf(stderr, "%s\n", mysql_error(db_conn));
exit(1);
}
db_res = mysql_use_result(db_conn);
/* output table name */
printf("MySQL Tables in mysql database:\n");
while ((row = mysql_fetch_row(db_res)) != NULL)
printf("%s \n", row[0]);
//freeing the result variable so it can be used further
mysql_free_result(db_res);
sem_post(&sem);
//Server socket
s=socket(AF_INET,SOCK_STREAM,0);
bzero((char*)&serv,sizeof(serv));
serv.sin_family=AF_INET;
serv.sin_port=htons(PORT);
serv.sin_addr.s_addr=inet_addr( SERV_ADDR);//"10.15.36.112");
/*printf("\nServer is waiting for client to respond");
i=0*/
//accept the incomming connections from client
bind(s,(struct sockaddr *)&serv,sizeof(serv));
printf("\nAddress bind successful");
listen(s,3000);//4 is the limit of the number of outstanding connections
n=sizeof(cli);
/*
i=0;
//accept the incomming connections from client
while( (c = accept(s, (struct sockaddr *)&cli, (socklen_t*)&n))) //&& (stop-start)<300 )
{ puts("Connection accepted\n");
pthread_t t;
printf("sock =%d\n", c);
if( pthread_create( &t , NULL , connect_client , (void*) c) < 0)
{
perror("could not create thread");
return 1;
}
i++;
/*Now detach the thread ,When a detached thread terminates, its resources are
automatically released back to the system without the need for
another thread to join with the terminated thread.*/
/* if ( ! pthread_detach(t) )
printf("Thread detached successfully !!!\n");
puts("Handler assigned");
stop = clock();
}*/
clilen=sizeof(cli);
while(newsockfd = accept(s, (struct sockaddr *) &cli, &clilen))
{
if(newsockfd < 0)
error("ERROR on accept");
else{
pthread_t handle;
new_sock = malloc(1);
*new_sock = newsockfd;
if(pthread_create(&handle, NULL,connect_client ,(void *)new_sock)<0)
error("Error creating thread");
else
printf("Thread fd: %d\n",newsockfd);
if ( ! pthread_detach(handle) )
printf("Thread detached successfully !!!\n");
}
}
/* close database connection */
mysql_free_result(db_res);
mysql_close(db_conn);
close(s);
/*destroying the mutex */
sem_destroy(&sem);
return 0;
}