:p :confused: 关于linux网络编程方面的一个问题：设计了一个服务端和客户端。客户端通过指定ip与服务器端建立连接，当有两个连接跟服务器连接时，服务器就新建一个进程，负责转发这两个客户端的会话（即服务器作为一个基站使用），现在有一个问题：当有两个客户端连接后，后发送数据的客户端总是无法发送数据，甚至连键盘输入的数据都检测不到。这是什么原因呢？
# @, E0 l5 l! B; k现在我把代码写下面：(附件中有代码）
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$ i3 |, L! m. [( w6 P9 Mclient.c
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/*本程序模拟一个聊天工具*/
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/*运行client serverip*/
! s, ?3 Y- i, B) ^#include <stdio.h>
6 R& B8 w& |, R0 d# @5 e
#include<sys/socket.h>
) Q& P% A- V- q) l* c#include<arpa/inet.h>
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#include<netinet/in.h>
. z8 b4 J) [$ X7 _: A, e/ G#include<errno.h>
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#include<stdio.h>
% w9 w1 G9 s/ x& ^ d#include<string.h>
$ p/ H+ [- s( t3 k; q#define MAXLINE 4096
2 d! z# `& ]- Q1 R2 d7 }#define LISTENQ 1024
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#include "talk.h"
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int main(int argc, char *argv[])
( ]5 b3 v& R/ \- A4 v+ S( S( i& D{
* D- ~* Q7 {; u3 K) z- l int sockfd,n;
; l# {% u# j L/ c4 t# Y char recvline[MAXLINE+1];
9 L* Y5 m- I* B4 U) S1 w4 s
struct sockaddr_in servaddr;
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if(argc != 2)
& l0 ^" b3 i7 _7 {4 r1 z) Q {
( W7 ~! K+ J& o" k printf("usage:filename<IP address>");
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exit(0);
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* _1 ]" B2 w* @7 g1 e" y7 I, ?, d if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
' Q& f6 a* B( ?1 e7 w0 ]8 Y
{
& n5 i( q4 G U printf("socket call error\n");
4 w6 x6 o1 E- D1 C, n6 f7 a exit(0);
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}
% V8 a' a; H' ]
bzero(&servaddr,sizeof(servaddr));
# L9 d" Z' j; V- |& Z* c* `, L) t" h5 l servaddr.sin_family = AF_INET;
" H( [: v7 ?5 n+ @ o servaddr.sin_port = htons(14);
& P" z+ J, e; j/ H( Z0 N if(inet_pton(AF_INET,argv[1],&servaddr.sin_addr) <= 0)
' [2 ~0 V8 ?6 d- |" e {
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printf("inet_pton call error for %s\n",argv[1]);
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exit(0);
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1 ~. G; x- Z' _0 j; U if(connect(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr)) < 0)
5 n9 l; K2 b6 h& `$ | {
- F% l9 J3 k; Z$ n! a8 W4 ~$ P9 @- J printf("connect error\n");
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exit(0);
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}
6 V' A) O) d) T: i* J9 R talk(fileno(stdin),sockfd);
k. j& G! C/ \1 j
exit(0);
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+ [2 w; d' \) e' G, A( |/ P3 B # H, C6 e% i5 Z& L& z3 d
\" Y0 p. P2 Nserver.c
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! V( y8 i0 f# W- F' l/*本程序用聊天服务器，支持多个用户连接，采用子进程**/
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#include <stdio.h>
1 s! f4 q m( @6 A/ }) [#include<sys/socket.h>
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#include<arpa/inet.h>
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#include<netinet/in.h>
; E ]) \# d$ z/ Y#include<errno.h>
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#include<stdio.h>
3 U5 \6 ^1 j4 q( u- S" o* C3 E6 ~#include<sys/wait.h>
1 O7 W" F/ w2 A$ j2 S `2 l9 L#include<unistd.h>
( L( ?. k d7 O L2 P# ?. i#include<signal.h>
: [ z" ^) b! x% O* i8 t+ I: I& e9 C#include<time.h>
C% V$ X8 T" h8 W- c
#include<signal.h>
0 q$ V7 u8 M; L. C8 N#include<sys/types.h>
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#include<unistd.h>
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#include "talk.h"
; H9 D; X, H6 `3 y#define LISTENQ 1024
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void sig_chld(int signo);
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int main(int argc, char *argv[])
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{
+ V$ ~% B# g/ C" _ int listenfd,connfd,connfd1;
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socklen_t len;
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pid_t childpid;
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char buff[MAXLINE];
! h' x C2 g' p int tag;
9 ~, E2 p" k/ \+ Y struct sockaddr_in servaddr,cliaddr;
; G2 F0 o% t {% h# f time_t currenttime;
, j/ V& W" p. d len = sizeof(cliaddr);
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tag = 0;
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listenfd = socket(AF_INET,SOCK_STREAM,0);
* x0 {6 @; s4 n5 Y c9 X% ~9 ?- z bzero(&servaddr,sizeof(servaddr));
: ?9 d i5 l; k: t% c8 A5 v, H servaddr.sin_family = AF_INET;
9 L5 D8 t% E3 R- @4 F6 U servaddr.sin_port = htons(14);
" R9 L/ u7 M4 J# @* h servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
) ]0 \. }* \' m3 S; f+ h bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
, X$ B9 i4 J% |/ Q; y, K. { listen(listenfd,LISTENQ);
4 a& ~! v4 L; ]" R; `9 |1 ~+ A signal(SIGCHLD,sig_chld);
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while(1)
2 ^8 P9 F8 _. t2 h {
' D W& U0 a" j connfd = accept(listenfd,(struct sockaddr *)&cliaddr,&len);
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connfd1 = accept(listenfd,(struct sockaddr *)&cliaddr,&len);
# Y/ e0 |9 |5 m- r0 H' R* w if((childpid = fork()) == 0)
# o# ]/ K6 |( e
{
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close(listenfd);
/ a* O, [; b! D transfer(connfd,connfd1);
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close(connfd);
( G1 t+ Z- j9 z8 K% x+ n close(connfd1);
- F0 {0 {% ^! p# n4 Y0 E' Y" z exit(0);
) |- \; s4 ]$ s7 b4 ]. p' T" T5 B }
) r# _3 y5 E$ h* `$ ~2 L8 P$ s close(connfd);
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close(connfd1);
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}
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3 U' ?2 ~ H) j; Fsig_chld.c
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#include <stdio.h>
6 S/ f& Q: l$ n7 Y" }
#include<sys/wait.h>
) r7 A) F8 R/ K$ U4 Z& _#include<sys/types.h>
( ?' F, W( G+ N! ~* \1 s& G$ o+ vvoid sig_chld(int signo)
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{
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pid_t pid;
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int stat;
# e( \- I1 q4 a9 Y Y while((pid = waitpid(-1,&stat,WNOHANG)) > 0);
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return;
( Q' R, Q3 O% n8 o" u}
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talk.c
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#include "talk.h"
4 y( ^% D/ t( p) R% ?#include<sys/select.h>
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#include<stdio.h>
' g) a' }' v' Y% ?8 U) z* i. Tvoid talk(int input,int socket)
v$ a0 y0 p, Y& z! E+ o{
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char buffer[MAXLINE];
! [: B4 g( V5 w3 o int maxfd;
4 V0 h+ ~" {7 `+ ^! ?" m/ t) G3 W fd_set fdset;
) p7 R, B7 ]# a4 j maxfd = max(input,socket) + 1;
, c8 { q# W. L- W3 z while(1)
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{
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FD_ZERO(&fdset);
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FD_SET(input,&fdset);
8 k$ y2 S5 c! U FD_SET(socket,&fdset);
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select(maxfd,&fdset,NULL,NULL,NULL);
3 g/ a7 k; K p1 H: ^ |. K, `4 \ if(FD_ISSET(input,&fdset))
h! j/ y, A T8 V) b {
# ?" `! F* S7 m4 d/ `# r5 S if(readLine(input,buffer,MAXLINE) == 0)
' j0 }% V: A T; {
{
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printf("input error\n");
& I1 X8 G6 {* ^+ B5 [ exit(0);
# N0 Y, l; H: d" W }
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printf("read from keyboard:%s",buffer);
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writen(socket,buffer,strlen(buffer));
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}
) S0 S$ T! _1 { if(FD_ISSET(socket,&fdset))
: e1 k2 q3 a' B; ? {
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if(readn(socket,buffer,MAXLINE) == 0)
- a) W* F: K' \ {
6 p, j5 ~6 g- @ e1 B7 q printf("error server\n");
6 v5 z. _! x0 R% ~) L5 y' [3 j* `
exit(0);
9 k- B- O/ K" C. W }
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printf("receve from socket %d: %s\n",socket,buffer);
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c# a) A( {8 C! F$ D! k }
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}
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# T9 q8 T% h9 m# u! u* Ltalk.h
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#define MAXLINE 4096
# A: v$ O* L& P. M r6 T#define max(a,b) (a) > (b) ? (a) : (b)
7 s$ U' V5 e0 _( F* x* F. @. F* q" b
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transfer.c
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/ V$ X0 \4 E, T- j#include <stdio.h>
7 |9 t. @, i) [* d9 V# P7 q5 c#include "talk.h"
/ \1 t7 B7 ?6 h: m( f#include<string.h>
0 w3 k" v! u& E$ ?, ?+ F2 g2 u#include<sys/select.h>
+ ~$ U5 d$ {: ]: u. ^void transfer(int socket1,int socket2)
& a8 c2 ? y' R& F9 J{
" g. P) t2 K/ x7 p! ] int maxfd;
: g: d# `9 `/ r# y
int nchar;
# r# I, A/ Z( P: {, t* l- t fd_set fdset;
! z5 B! B( C3 A char buffer[MAXLINE + 1];
7 K, l9 h; G2 {: K
S$ C( T; }, R* O; e t3 G
maxfd = max(socket1,socket2) + 1;
$ `6 g+ a* f3 ]0 ~" E5 f printf("transfering ...\n%d %d %d\n",socket1,socket2,maxfd);
1 t* C" `. R* j8 X- Q& f
while(1)
9 F I- k6 d; w {
: M' ~; [- I7 d, c FD_ZERO(&fdset);
, }- ~! _% h+ }4 L6 n+ x
FD_SET(socket1,&fdset);
5 B0 M" `# S# R! f6 Y
FD_SET(socket2,&fdset);
5 U1 s% Z& X# c& q select(maxfd,&fdset,NULL,NULL,NULL);
4 o4 d0 U+ \4 `0 Q printf("read...\n");
" ^% N' I/ H3 L$ H) O4 H
if(FD_ISSET(socket1,&fdset))
: c9 {! ~: x+ x7 I$ P% f0 y6 }
{
/ J5 [3 A1 r, R$ b
if((nchar = read(socket1,buffer,MAXLINE)) == 0)
5 o; k2 D4 Y- t4 W# S/ _) C {
8 O, n9 H7 k+ C. C% _; Y# `
strcpy(buffer,"bye bye\n");
7 w9 r& p3 j/ l) W
write(socket2,buffer,9);
. G# ?! b$ S1 P% a o" k
printf("read...err\n");
6 a$ U' M Y/ `4 {2 x' r
return;
4 S/ ^0 m& f# q! F u
}
+ ?+ P: v6 w6 l E6 K; P8 O
printf("read.from socket1..\n%s %d \n",buffer,nchar);
+ |9 k0 {- I; N6 v4 b4 W
writen(socket2,buffer,nchar);
" k/ _9 A4 V. D) K8 [ J% F
writen(socket1,buffer,nchar);
' [ Z% M$ [ o) {; V9 H9 B) G * r/ M' {& g3 R8 [+ U: A& d. ?& l" y; _
}
2 H3 u9 J% f: [- N
if(FD_ISSET(socket2,&fdset))
- w$ g2 d. S& e
{
' `9 G+ q$ z* ^5 p& }' x& u
if((nchar = read(socket2,buffer,MAXLINE)) == 0)
& o. a$ v+ o! m+ c7 r& Z- d C5 }( V
{
& | u" ?9 t# ^) r" s6 M( t
strcpy(buffer,"bye bye\n");
0 \, Z c9 X" y0 U( B# Q write(socket1,buffer,9);
N6 q1 R: D4 q. x: c
printf("read...err\n");
Z' F/ B+ t, n% T Z2 p; K return;
8 Q a: R; s( z- z4 G7 N9 [4 L
}
" u7 h* @* b! M" U$ a% m8 b
printf("read..from socket 2.%s %d\n",buffer,nchar);
# n F2 _1 k% Z writen(socket1,buffer,nchar);
: w" G2 k! t( }8 s0 H4 t* x1 P+ u1 @
writen(socket2,buffer,nchar);
$ K. o% _4 M2 \# {0 r7 K! |
) G& ^) Q# j9 K6 v6 x; ?( f }
+ K9 G7 a- c% y/ J! Q& }7 A
}
4 l. ?3 |' D% V1 I+ z}
8 C L. Q: R4 L1 c
7 \/ n4 P" o. Q1 l0 H- N' d
e3 \; ]; l! k$ _/ U
4 g& [( O* U' Q z3 ^0 n
, k! E) Q) D! dmakefile
3 z. Y9 a( `, x) t5 ]0 ~ # m6 \# y) E4 J4 x
all:server client
9 D" h* l5 K4 ]3 T
server:server.o transfer.o sig_chld.o fileoperate.o
$ b$ f) O' ~; d; E4 ]" Y- A6 a
cc -o server $^
% \# S0 @" U# N. w" T! f/ @
client:client.o talk.o fileoperate.o
( \6 c) X4 {* Z& ]+ I i
cc -o client $^
% A3 y, s G! k1 L- otransfer.o server.o client.o talk.o:talk.h
2 C: l1 h* \$ B; |/ D
.PHONY : clean
9 r8 T; `% B. F: Rclean:
2 i1 d, v8 j' }+ y rm *.o
8 O& J0 Y; u0 }0 L- y" Z: M$ U
$ s- p) Y5 K5 {" jfileoperate.c
3 F) V$ T) O/ c- g8 R# Z
( a8 { f1 B l5 \& \#include<stdio.h>
% p! @$ n- B" `0 D/ c1 h2 \& H
#include<errno.h>
8 F8 e& H, D1 ]7 p( c
#include<sys/types.h>
9 |- |- o$ z C* A9 f% }" m( L" g
ssize_t readn(int fd,void *vptr,size_t n)
% _$ z8 f) {7 p6 ~{
4 c E2 \; X& }$ h( k9 @& R8 C
ssize_t nleft;
: h1 _( a0 d6 S# w2 ` ssize_t nread;
: c; I. U. G( W( R) E2 u) A' P% L char *ptr = vptr;
' e/ V+ J0 S* R nleft = n;
4 {# I9 t" H* T1 h. S1 `$ c while(nleft > 0)
9 @4 c1 S; @' A/ N% b: }# {
{
" e- L" v* i1 i
if((nread = read(fd,ptr,nleft)) < 0)
! S, w0 r% l, Y' ^. s4 Z7 A& v7 p
{
) l* c( B2 i8 u* R7 Y
if(errno ==EINTR)
; Z% X) p. ~3 d4 C: a nread = 0;
; @( i) x# F0 X9 o else return(-1);
* Q" n1 u5 R# C! r8 O" V }
E- N. f, c" q" O) _) Z else if(nread == 0)
; L3 K3 S6 U2 E/ S; Y! @
break;
" h+ V' O5 \, i" m' a7 x" |, g
nleft = nleft - nread;
4 g [6 @ y& k8 b8 O' Q8 S, j ptr += nread;
+ R: o* e& G2 x) L5 T }
7 B/ b8 x. l6 _7 q0 j2 J; j return(n - nleft);
8 l" X: k/ X6 e4 B* D, M* I9 F/ F8 l1 Q
}
% y# n: O( j4 U! M9 N; `; dssize_t writen(int fd,const void *vptr,size_t n)
( A/ G9 Q6 p6 Y{
! s/ a' ]/ D5 G7 ]
ssize_t nleft;
& T8 `/ N" W1 _" a+ j
ssize_t nwrite;
" z5 ~2 q' Q ~% @$ h* _9 A F
const char *ptr = vptr;
, `/ T7 R( b% d( R+ ~; j
nleft =n;
' [" A! _3 H5 T7 ~- Q7 Q5 p1 d: D" j4 J
while(nleft > 0)
9 H, ^$ `) }1 o {
2 X3 _& s- [/ Z( }- O0 F
if((nwrite = write(fd,ptr,nleft)) < 0)
( T2 ?( |* e1 D! R: [0 P {
- W( B" \% e0 M* G" _ if(errno == EINTR)
/ |+ c% }' X" T I" v: C4 d nwrite = 0;
7 r8 a( @! m# O1 M N0 V else
; J3 l- S" Y' u) o" z! ?8 n return -1;
8 k# C/ `4 ^% ?0 e, y1 a }
& h8 q7 K; z4 c0 ]! Z* L
nleft = nleft - nwrite;
+ R+ \0 v2 W% S" v/ H+ ~ ptr += nwrite;
/ V8 Q- f" ?" R a9 v$ b+ m2 m
printf("writing...\n");
C( d J4 Z3 b' l4 r& Z! T
}
$ G2 c; @9 W) S9 ~" _ f4 ?
printf("write ok\n");
4 N8 ^0 [, L2 { return(n - nleft);
4 a5 U+ y. `& i9 S I2 N: A
}
- A+ p( |- [' k% x& v& k
ssize_t readLine(int fd,const void *vptr,size_t maxlen)
. L/ D( o# ?1 m& t/ @; h {
{
* ^ K& s9 F% @# j2 {" H
ssize_t n,rc;
/ ?. G8 A: Q( V1 c
char c,*ptr = vptr;
: k$ l9 q6 d8 P
for(n = 1; n<maxlen; n ++)
7 W: a* j( Z: [1 z {
8 E0 C% _- l, h9 Z3 S# n X
if((rc = read(fd,&c,1)) == 1)
$ i* R" X9 ]9 f8 H0 p
{
. k0 t% q. U) u; L% R *ptr++ = c;
1 L, b+ S! ?) f4 A" A( v
if(c =='\n')
( B3 h* P- n5 c& `4 ~1 S break;
& |# ]/ o. m" M
}
: |+ g% H4 [; S: L4 k& g0 F0 v else if(rc == 0)
; j9 j, K" V4 G2 q. f {
- h( f7 Y& T' l8 v. \$ S; N4 Y5 k if(n == 1)
2 H, h8 q. W" D; s& X" b return(0);
" w7 a2 Z& z$ x; l% {
else
& H) w$ R. L* p p, ~/ X3 I& ]2 Z$ c break;
+ @% s, o) h) l) J: y) w/ p8 ^ }
8 T0 i' G& M7 `6 T2 e( b/ y
else
! B& Z; t1 C8 f$ K5 u1 }) S; B
{
2 r B6 E. I* ` if(errno == EINTR)
3 ]5 k8 C1 t" Z4 L9 [+ A continue;
8 n0 t0 N: s8 ]6 s+ @4 R/ n return -1;
' b [: h. O# a! J* l
}
* D( O8 F3 c/ g3 l }
0 T. a7 I0 \4 z! S! w7 G
*ptr = '\0';
4 |7 U1 b5 n0 C7 m/ z) C
return(n);
" g2 j- O9 |0 ~9 b# H- r. F/ V
}
