163 lines
5.8 KiB
HTML
163 lines
5.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<!--Converted with LaTeX2HTML 96.1-c (Feb 29, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds -->
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<HTML>
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<HEAD>
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<TITLE>The Source</TITLE>
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<META NAME="description" CONTENT="The Source">
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<META NAME="keywords" CONTENT="lpg">
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<META NAME="resource-type" CONTENT="document">
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<META NAME="distribution" CONTENT="global">
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<LINK REL=STYLESHEET HREF="lpg.css">
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</HEAD>
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<BODY LANG="EN">
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<A NAME="tex2html929" HREF="node46.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME="tex2html927" HREF="node37.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME="tex2html923" HREF="node44.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME="tex2html931" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME="tex2html930" HREF="node46.html">6.4.3 Semaphores</A>
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<B>Up:</B> <A NAME="tex2html928" HREF="node37.html">msgtool: An interactive message </A>
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<B> Previous:</B> <A NAME="tex2html924" HREF="node44.html">Examples</A>
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<BR> <P>
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<H4><A NAME="SECTION00742640000000000000">The Source</A></H4>
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<P>
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The following is the source code for the <TT>msgtool</TT> facility. It should compile clean
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on any recent (decent) kernel revision that supports System V IPC. Be sure to enable
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System V IPC in your kernel when doing a rebuild!
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<P>
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On a side note, this utility will <EM>create</EM> a message queue if it does not exist, no
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matter what type of action is requested.
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<P>
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<BLOCKQUOTE> <B>NOTE:</B> <EM>Since this tool uses the ftok() function to generate IPC key values, you may
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encounter directory conflicts. If you change directories at any point in your script, it probably
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won't work. Another solution would be to hardcode a more complete path into msgtool, such as
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``/tmp/msgtool'', or possibly even allow the path to be passed on the command line, along with
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the operational arguments. </EM>
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</BLOCKQUOTE>
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<P>
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<P>
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<HR><PRE>/*****************************************************************************
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Excerpt from "Linux Programmer's Guide - Chapter 6"
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(C)opyright 1994-1995, Scott Burkett
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*****************************************************************************
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MODULE: msgtool.c
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*****************************************************************************
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A command line tool for tinkering with SysV style Message Queues
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*****************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <ctype.h>
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/msg.h>
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#define MAX_SEND_SIZE 80
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struct mymsgbuf {
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long mtype;
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char mtext[MAX_SEND_SIZE];
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};
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void send_message(int qid, struct mymsgbuf *qbuf, long type, char *text);
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void read_message(int qid, struct mymsgbuf *qbuf, long type);
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void remove_queue(int qid);
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void change_queue_mode(int qid, char *mode);
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void usage(void);
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int main(int argc, char *argv[])
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{
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key_t key;
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int msgqueue_id;
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struct mymsgbuf qbuf;
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if(argc == 1)
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usage();
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/* Create unique key via call to ftok() */
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key = ftok(".", 'm');
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/* Open the queue - create if necessary */
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if((msgqueue_id = msgget(key, IPC_CREAT|0660)) == -1) {
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perror("msgget");
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exit(1);
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}
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switch(tolower(argv[1][0]))
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{
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case 's': send_message(msgqueue_id, (struct mymsgbuf *)&qbuf,
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atol(argv[2]), argv[3]);
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break;
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case 'r': read_message(msgqueue_id, &qbuf, atol(argv[2]));
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break;
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case 'd': remove_queue(msgqueue_id);
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break;
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case 'm': change_queue_mode(msgqueue_id, argv[2]);
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break;
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default: usage();
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}
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return(0);
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}
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void send_message(int qid, struct mymsgbuf *qbuf, long type, char *text)
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{
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/* Send a message to the queue */
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printf("Sending a message ...\n");
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qbuf->mtype = type;
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strcpy(qbuf->mtext, text);
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if((msgsnd(qid, (struct msgbuf *)qbuf,
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strlen(qbuf->mtext)+1, 0)) ==-1)
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{
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perror("msgsnd");
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exit(1);
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}
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}
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void read_message(int qid, struct mymsgbuf *qbuf, long type)
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{
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/* Read a message from the queue */
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printf("Reading a message ...\n");
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qbuf->mtype = type;
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msgrcv(qid, (struct msgbuf *)qbuf, MAX_SEND_SIZE, type, 0);
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printf("Type: %ld Text: %s\n", qbuf->mtype, qbuf->mtext);
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}
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void remove_queue(int qid)
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{
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/* Remove the queue */
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msgctl(qid, IPC_RMID, 0);
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}
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void change_queue_mode(int qid, char *mode)
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{
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struct msqid_ds myqueue_ds;
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/* Get current info */
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msgctl(qid, IPC_STAT, &myqueue_ds);
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/* Convert and load the mode */
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sscanf(mode, "%ho", &myqueue_ds.msg_perm.mode);
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/* Update the mode */
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msgctl(qid, IPC_SET, &myqueue_ds);
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}
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void usage(void)
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{
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fprintf(stderr, "msgtool - A utility for tinkering with msg queues\n");
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fprintf(stderr, "\nUSAGE: msgtool (s)end <type> <messagetext>\n");
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fprintf(stderr, " (r)ecv <type>\n");
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fprintf(stderr, " (d)elete\n");
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fprintf(stderr, " (m)ode <octal mode>\n");
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exit(1);
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}</PRE>
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<HR><BR> <HR>
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<P><ADDRESS>
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<I>Converted on: <BR>
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Fri Mar 29 14:43:04 EST 1996</I>
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</ADDRESS>
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</HTML>
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