1.
a.
b.
c. I O ?
pthreadcreate pthreadcreate
d. I O
fdset select select readfds select
2.:
a. a.out A.c : seteuidneweffectiveuserid
b. Saved SUID a.c root
3. dup2
: cat main.c grep main
:
1 pipeRD, WR RD WR
2 dup2WR,1
3 fork,
4 waitpid,
5 FDopenmain.c, 6 dup2FD,0,
7 dup2RD,0
4.sigprocmask ::
1 25 310 415 520 630
:
.a.out
1 21413 ID 21413
kill USR1 21413 5
kill USR1 214138
Kill USR1 21413 20 :
5.
6.
7.
8.
include stdio.h include stdlib.h include syssocket.h include netinetin.h include string.h include unistd.h
include arpainet.h
define SERVERPORT 5000 define MAXX,Y X Y ? X : Y
void prompt
printfYou ;
fflushstdout;
int main int argc, char argv
int len, rc;
int sockfd;
char sendbuf4096;
char recvbuf4096;
struct sockaddrin servaddr; struct timeval timeout; fdset masterset, selectresult; int maxsd;
ifargc!2 exit1; incorrect usage
ifsockfd socketAFINET, SOCKSTREAM, 0 0 exit2; socket creation error
memsetservaddr, 0, sizeofservaddr; servaddr.sinfamily AFINET; servaddr.sinport htonsSERVERPORT;
ifinetptonAFINET, argv1, servaddr.sinaddr0 exit3; ip adress error
ifconnectsockfd, struct sockaddr servaddr, sizeofservaddr 0 exit4; connection error
FDZEROmasterset; FDSETfilenostdin, masterset; FDSETsockfd, masterset; maxsdMAXfilenostdin, sockfd;
Initialize the timeval struct to 3 minutes. timeout.tvsec 3 60;
timeout.tvusec 0;
printfConnected to remote host. Start sending messages.n; prompt;
while1
else
closesockfd;
return 0;
rc recvsockfd, recvbuf, 4096, 0; if rc 0 exit9; recv failed
if rc 0
printfServer disconnectedn; closesockfd;
exit0;
recvbufrc0; make null terminated string printfrsn, recvbuf;
prompt;
timed out closesockfd; return 0;
QUIZ 1 memcpyselectresult,masterset,sizeofmasterset; rc selectmaxsd1,selectresult,NULL,NULL,NULL;
ifFDISSET0,selectresultQuiz2
getssendbuf;
sendsockfd, sendbuf, strlensendbuf, 0; prompt;
else ifsockfd,selectresultQuiz3
select
int main
…….
if connectsockfd, struct sockaddr servaddr, sizeofservaddr 0
exit4; pthreadt a, b;
pthreadcreatea, NULL, threadA, NULL; pthreadcreateb, NULL, threadB, NULL;
pthreadjoina, NULL; pthreadjoinb,NULL; closesockfd;
ifn 0
exit5;
threadA threadB
9.Which of the followings are shared among multiple threadsprocesses? : code, register, stack, data, heap, file, address space
a multiple threads:
b multiple processes