linux c 编程

(gdb) p gr->gr_name

$19 = 0x4dbffff4 <Address 0x4dbffff4 out of bounds>

我试了一下 由于第2此循环得到的指针不对

把这句话去掉就没问题了

//printf("%-10s",gr->gr_name)

所以你看看你上面的 gr=getgrgid(IFo.st_gid)函数调用是不是有问题

比较忙 没仔细给你调试

你要多用gdb哦

客户端

#include <stdio.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <time.h>

#include <errno.h>

#define SERVER_PORT_ID 6081

#define CLIENT_PORT_ID 6086

#define SERVER_HOST_ADDR "128.119.40.186"

/* gaia.cs.umass.edu */

#define MAXSIZE 512

#define ACK 2

#define NACK 3

#define REQUESTFILE 100

#define COMMANDNOTSUPPORTED 150

#define COMMANDSUPPORTED 160

#define BADFILENAME 200

#define FILENAMEOK 400

#define STARTTRANSFER 500

int readn(int sd,char *ptr,int size)

int writen(int sd,char *ptr,int size)

main(int argc,char *argv[])

{

int sockid, newsockid,i,getfile,ack,msg,msg_2,c,len

int no_writen,start_xfer, num_blks,num_last_blk

struct sockaddr_in my_addr, server_addr

FILE *fp

char in_buf[MAXSIZE]

if(argc != 2)

no_writen = 0

num_blks = 0

num_last_blk = 0

len = strlen(argv[1])

printf("client: creating socket\n")

if ((sockid = socket(AF_INET,SOCK_STREAM,0)) < 0)

{ printf("client: socket error : %d\n", errno) exit(0)

}

printf("client: binding my local socket\n")

bzero((char *) &my_addr,sizeof(my_addr))

my_addr.sin_family = AF_INET

my_addr.sin_addr.s_addr = htonl(INADDR_ANY)

my_addr.sin_port = htons(CLIENT_PORT_ID)

if (bind(sockid ,(struct sockaddr *) &my_addr,sizeof(my_addr)) < 0)

{printf("client: bind error :%d\n", errno) exit(0)

}

printf("client: starting connect\n")

bzero((char *) &server_addr,sizeof(server_addr))

server_addr.sin_family = AF_INET

server_addr.sin_addr.s_addr = inet_addr(SERVER_HOST_ADDR)

server_addr.sin_port = htons(SERVER_PORT_ID)

if (connect(sockid ,(struct sockaddr *) &server_addr,

sizeof(server_addr)) < 0)

{printf("client: connect error :%d\n", errno) exit(0)

}

/* Once we are here, we've got a connection to the server */

/* tell server that we want to get a file */

getfile = htons(REQUESTFILE)

printf("client: sending command request to ftp server\n")

if((writen(sockid,(char *)&getfile,sizeof(getfile))) < 0)

/* want for go-ahead from server */

msg = 0

if((readn(sockid,(char *)&msg,sizeof(msg)))< 0)

msg = ntohs(msg)

if (msg==COMMANDNOTSUPPORTED) {

printf("client: server refused command. goodbye\n")

exit(0)

}

else

printf("client: server replied %d, command supported\n",msg)

/* send file name to server */

printf("client: sending filename\n")

if ((writen(sockid,argv[1],len))< 0)

/* see if server replied that file name is OK */

msg_2 = 0

if ((readn(sockid,(char *)&msg_2,sizeof(msg_2)))< 0)

msg_2 = ntohs(msg_2)

if (msg_2 == BADFILENAME) {

printf("client: server reported bad file name. goodbye.\n")

exit(0)

}

else

printf("client: server replied %d, filename OK\n",msg_2)

/* CLIENT KNOWS SERVER HAS BEEN ABLE TO OPEN THE FILE IN READ

MODE AND IS ASKING FOR GO-AHEAD*/

/* CLIENT NOW OPENS A COPY OF THE FILE IN WRITE MODE AND SENDS

THE GOAHEAD TO SERVER*/

printf("client: sending start transfer command\n")

start_xfer = STARTTRANSFER

start_xfer = htons(start_xfer)

if ((writen(sockid,(char *)&start_xfer,sizeof(start_xfer)))< 0)

{printf("client: write error :%d\n", errno) exit(0)

}

if ((fp = fopen(argv[1],"w")) == NULL)

/*NOW THE CLIENT IS READING INFORMATION FROM THE SERVER REGARDING HOW MANY

FULL BLOCKS OF SIZE MAXSIZE IT CAN EXPECT. IT ALSO RECEIVES THE NUMBER

OF BYTES REMAINING IN THE LAST PARTIALLY FILLED BLOCK, IF ANY */

if((readn(sockid,(char *)&num_blks,sizeof(num_blks))) < 0)

num_blks = ntohs(num_blks)

printf("client: server responded: %d blocks in file\n",num_blks)

ack = ACK

ack = htons(ack)

if((writen(sockid,(char *)&ack,sizeof(ack))) < 0)

{printf("client: ack write error :%d\n",errno)exit(0)

}

if((readn(sockid,(char *)&num_last_blk,sizeof(num_last_blk))) < 0)

num_last_blk = ntohs(num_last_blk)

printf("client: server responded: %d bytes last blk\n",num_last_blk)

if((writen(sockid,(char *)&ack,sizeof(ack))) < 0)

{printf("client: ack write error :%d\n",errno)exit(0)

}

/* BEGIN READING BLOCKS BEING SENT BY SERVER */

printf("client: starting to get file contents\n")

for(i= 0 i < num_blks i ++) {

if((readn(sockid,in_buf,MAXSIZE)) < 0)

no_writen = fwrite(in_buf,sizeof(char),MAXSIZE,fp)

if (no_writen == 0)

if (no_writen != MAXSIZE)

/* send an ACK for this block */

if((writen(sockid,(char *)&ack,sizeof(ack))) < 0)

printf(" %d...",i)

}

/*IF THERE IS A LAST PARTIALLY FILLED BLOCK, READ IT */

if (num_last_blk > 0) {

printf("%d\n",num_blks)

if((readn(sockid,in_buf,num_last_blk)) < 0)

no_writen = fwrite(in_buf,sizeof(char),num_last_blk,fp)

if (no_writen == 0)

if (no_writen != num_last_blk)

if((writen(sockid,(char *)&ack,sizeof(ack))) < 0)

}

else printf("\n")

/*FILE TRANSFER ENDS. CLIENT TERMINATES AFTER CLOSING ALL ITS FILES

AND SOCKETS*/

fclose(fp)

printf("client: FILE TRANSFER COMPLETE\n")

close(sockid)

}

/* DUE TO THE FACT THAT BUFFER LIMITS IN KERNEL FOR THE SOCKET MAY BE

REACHED, IT IS POSSIBLE THAT READ AND WRITE MAY RETURN A POSITIVE VALUE

LESS THAN THE NUMBER REQUESTED. HENCE WE CALL THE TWO PROCEDURES

BELOW TO TAKE CARE OF SUCH EXIGENCIES */

int readn(int sd,char *ptr,int size)

{ int no_left,no_read

no_left = size

while (no_left > 0)

{ no_read = read(sd,ptr,no_left)

if(no_read <0) return(no_read)

if (no_read == 0) break

no_left -= no_read

ptr += no_read

}

return(size - no_left)

}

int writen(int sd,char *ptr,int size)

{ int no_left,no_written

no_left = size

while (no_left > 0)

{ no_written = write(sd,ptr,no_left)

if(no_written <=0) return(no_written)

no_left -= no_written

ptr += no_written

}

return(size - no_left)

}

服务端

#include <stdio.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <time.h>

#include <errno.h>

#define MY_PORT_ID 6081

#define MAXLINE 256

#define MAXSIZE 512

#define ACK 2

#define NACK 3

#define REQUESTFILE 100

#define COMMANDNOTSUPPORTED 150

#define COMMANDSUPPORTED 160

#define BADFILENAME 200

#define FILENAMEOK 400

int writen(int sd,char *ptr,int size)

int readn(int sd,char *ptr,int size)

main() {

int sockid, newsd, pid, clilen

struct sockaddr_in my_addr, client_addr

printf("server: creating socket\n")

if ((sockid = socket(AF_INET,SOCK_STREAM,0)) < 0)

printf("server: binding my local socket\n")

bzero((char *) &my_addr,sizeof(my_addr))

my_addr.sin_family = AF_INET

my_addr.sin_port = htons(MY_PORT_ID)

my_addr.sin_addr.s_addr = htons(INADDR_ANY)

if (bind(sockid ,(struct sockaddr *) &my_addr,sizeof(my_addr)) < 0)

printf("server: starting listen \n")

if (listen(sockid,5) < 0)

while(1==1) {

/* ACCEPT A CONNECTION AND THEN CREATE A CHILD TO DO THE WORK */

/* LOOP BACK AND WAIT FOR ANOTHER CONNECTION */

printf("server: starting accept\n")

if ((newsd = accept(sockid ,(struct sockaddr *) &client_addr,

&clilen)) < 0)

printf("server: return from accept, socket for this ftp: %d\n",

newsd)

if ( (pid=fork()) == 0) {

/* CHILD PROC STARTS HERE. IT WILL DO ACTUAL FILE TRANSFER */

close(sockid) /* child shouldn't do an accept */

doftp(newsd)

close (newsd)

exit(0) /* child all done with work */

}

/* PARENT CONTINUES BELOW HERE */

close(newsd)/* parent all done with client, only child */

} /* will communicate with that client from now on */

}

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