Working with the Unix OS

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Interprocess Communication Server socket() | bind() | recvfrom() | Client blocks until connection from client socket() | | | connect() | | process request| | | | sendto() recvfrom() ! Socket system calls connectionless protocol Unix Domain Protocols Provide a feature that is not currently provided by any other protocol family: the ability to pass access rights from one process to another. The name space used by unix domain protocols consists of pathnames, for example: { unixstr, 0 /tmp/log.1528, 0, /dev/logfile } unixstr unix stream connection oriented 0 local address /tmp/log.1528 local process 0 remote address 0 /dev/logfile remote process Socket Addresses /* defined in */ struct sockaddr { u_short sa_family; /* address family: AF_xxx */ char sa_data[14];} /* protocol specific addr */ /* defined in */ struct in_addr { u_long s_addr; /* 32-bit netid/hostid */ }; /* network byte ordered */ struct sockaddr_in { short sin_family; /* AF_INET * / u_short sin-port; /* 16-bit port number */ struct in_addr sin_addr; /* netid/hostid */ char sin_zero[8]; /* unused */ }; /* defined in */ struct sockaddr_un { short sun_family; /* AF_UNIX */ char sun_path[108]; /* pathname */ }; Socket address structures struct sockaddr_in struct sockaddr_un family family 2 byte port 4 byte net ID, host ID pathname (unused) (upto 108 bytes) struct sockaddr_in serv_addr; 165
… connect(sockfd,(struct sockaddr*) & serv_addr, sizeof(serv_addr)); Socket System Calls #include #include int socket(int family, int type, int protocol); Interprocess Communication family AF_UNIX AF_INET unix internal protocols internet protocols type SOCK_STREAM stream socket } SOCK_DGRAM datagram socket} VALID SOCK_RAW raw socket } SOCK_SEQPACKET sequenced packet socket SOCK_RDM reliably delivered message protocol IPPROTO_UDP } IPPROTO_TCP } AF _INET family IPPROTO_ICMP} IPPROTO_RAW } For an association (5-tuple): {protocol, local-addr, local-process, remote-addr, remote-process} socketpair System Call - only for Unix domain #include #include int socketpair(int family, int type, int protocol, int sockvec[2]); similar to the "pipe" system call, but bidirectional int rc, sockfd[2]; rc = socketpair(AF_UNIX, SOCK_STREAM, 0, sockfd); bind System Call - assigns a name to an unnamed socket #include #include int bind(int sockfd, struct sockaddr *myaddr, int addrlen); connect System Call - establish connection with a server #include #include int connect(int sockfd, struct sockaddr *servaddr, int addrlen); listen System Call - server is willing to receive connections int listen(int sockfd, int backlog); accept System Call #include #include int accept(int sockfd, struct sockaddr *peer, int *addrlen); accept takes the first connection request on the queue and creates another socket with the same properties as sockfd. If there are no connection requests pending, this call blocks the caller until one arrives. int sockfd, newsocketfd; 166
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UNIVERSITY OF ATHENS DEPARTMENT OF
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Figure 27. Driver Entry Points.....
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Introduction to Unix ! Execution ma
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Introduction to Unix It works in th
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Introduction to Unix * matches 0 or
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Introduction to Unix vi file-name s
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Introduction to Unix 1,$s/^/>>/ 1,$
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Introduction to Unix ! Special Devi
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Introduction to Unix Working with F
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Introduction to Unix ! Communicatio
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Unix Shells 2. UNIX SHELLS Back Quo
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Unix Shells ! CASE Statement case t
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Unix Shells two lines !Y@Y@Z@Z@ZY c
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Unix Shells if $append then tee -a
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C Programming - Basics main() { int
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C Programming - Basics e.g. i += 2
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External Variables A C program cons
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C Programming - Basics main.c #incl
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C Programming - Basics default: pri
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C Programming - Basics struct tnode
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Unix Tools 4. UNIX TOOLS Tools of t
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Unix Tools Korn shell ! .profile HI
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Unix Tools grep "$name" $PHONEBOOK
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Unix Tools awk '$3 > 0 { print $1,
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Unix Tools END { print max, maxline
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Unix Tools Let an example input fil
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Unix Tools Brown eqn 1 # output Jon
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Development Tools Make looks at the
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Development Tools /* compute size o
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Development Tools #endif #line cons
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Development Tools 1.1 5 lines Retri
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Development Tools In Emacs, you may
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Development Tools */ %{ #define YYS
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C Libraries 6. C LIBRARIES Input an
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C Libraries } while (!feof(fp1)) pu
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C Libraries } free(p); /* what is w
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C Libraries } if ((fp->flag&( _READ
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C Libraries /* dirwalk: apply fcn t
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C Libraries } switch (pid=fork()){
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C Libraries What is curses? - libra
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C Libraries } if ((fd=fopen(argv[1]
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Introduction to kernel 7. INTRODUCT
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82 Introduction to kernel Programs
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Introduction to kernel } { printf("
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Introduction to kernel The kernel r
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Introduction to kernel UNIX Interna
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Introduction to kernel File System
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Introduction to kernel Every proces
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Processes I Process States 1. Execu
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Processes I } printf("%d %s\n", cnt
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Processes I dup (and other similar
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Processes I The u area contains - p
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Processes I The Context of a Proces
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Processes I Process Control use and
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Processes I Although the processes
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Processes I Handling Signals - proc
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Processes I USER=neville PATH=/user
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Processes I ! Shadow Password /etc/
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Page 119 and 120: Processes I F_SETFL set status flag
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Page 125 and 126: Processes II 9. PROCESSES (II) FORK
Page 127 and 128: Processes II /* background.c */ #in
Page 129 and 130: Processes II } while (1){ printf("p
Page 131 and 132: Processes II } /* child */ signal (
Page 133 and 134: Processes II int readline(int fd, c
Page 135 and 136: Processes II { } char process_name[
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Page 139 and 140: Processes II System V IPC - message
Page 141 and 142: Processes II int msgctl(int msqid,
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Page 145 and 146: Processes II /* client loop */ mesg
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Page 149 and 150: I/O Subsystem Terminal Drivers - In
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Page 153 and 154: I/O Subsystem Raw Mode Raw mode is
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Page 157 and 158: Interprocess Communication } { ptra
Page 159 and 160: Interprocess Communication T ID KEY
Page 161 and 162: Interprocess Communication }; int m
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Page 165 and 166: Interprocess Communication /* struc
Page 167: Interprocess Communication ! Compar
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Page 173 and 174: Process Scheduling Page Tables and
Page 176 and 177: Figure 49. Tie breaker rule Process
Page 178 and 179: Process Scheduling Clock - restart
Page 180 and 181: Process Scheduling Figure 57. Mappi
Page 182 and 183: Figure 62. Sequence of Swapping Ope
Page 184 and 185: Buffer Cache The kernel takes buffe
Page 186 and 187: Buffer Cache The kernel places the
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Page 192 and 193: Unix Administration Example output
Page 194 and 195: Unix Administration *) IN=-mtime -2
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Page 206 and 207: Unix Security $ crypt < exam320.Z >
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