cmd.c

linux下的一个串口调试程序的源代码

#include <stdio.h>              //* printf, fgets */
#include <string.h>             //* strcpy */
#include <limits.h>             //* NAME_MAX, CHAR_MAX */
#include <stdlib.h>             //* exit */
#include <sys/types.h>          //* pid_t */
#include <unistd.h>             //* fork, fork, _exit */
#include <sys/wait.h>           //* wait */
#include <ctype.h>              //* isspace */

#include "basename.h"           //* basename */
#include "types.h"              //* INT32, INT16, P_PORT_INFO, P_PACKAGE_INFO */
#include "serial.h"             //* WriteComPort */
#include "cmd.h"
#include "prompt.h"

static char     cmd_line[NAME_MAX + 1];
static char     save_cmd_line[NAME_MAX + 1];
static pid_t    pid_recv;

static int      is_valid (char **argv);
static void     usage (void);
static void     shell (char **argv);
static void     makeargv (char **argv);

/*
 *	Function: void cmd ()
 * 	Arguments:	void;	
 */
void cmd ()
{
    static char    *argv[NAME_MAX];
    INT32           RecvData = 0;

    switch ((pid_recv = fork ())) {
    case -1:
        return;
    case 0:                    //* child */
        close (STDIN_FILENO);
        SetPortSig (&RecvData);
        while (1) {
            if (RecvData) {
            }
            sleep (1);
        }
        exit (0);
        break;
    }

    for (;;) {
        prompt ();
        fgets (cmd_line, sizeof (cmd_line), stdin);
        if (!is_valid (argv))
            break;
    }                           //* end for (;;) */
}

/* 
 * Function: 	is_valid(char **argv)
 * Arguments: 	
 *	 		argv[0] && argv[1]==NULL, invoke a subshell without any command
 *			argv[0] && argv[1], invoke a subshell to execute a command
 *			argv[0]==NULL, don't invoke a subshell
 *  		argv[0]==NULL && argv[1]==NULL, no command at all, return(1)
 *			argv[0]==NULL && argv[1], execute inner commands without subshell
 *			argv[1]=="exit" || "quit", quit sdb;
 *			argv[1]=="?", show help messages;
 *			argv[1]=="@", send messages in argv[2];
 *			argv[1]=="open", open port;
 *			argv[1]=="close", close port;
 *			argv[2], the rest arguments altogether 
 * return value: 1, continue;
 *				 0, break;
 */
static int is_valid (char **argv)
{
    makeargv (argv);
    if (argv[0] == NULL) {      //* no subshel */
        if (argv[1] == NULL) {  //* NULL, no arguments, just return */
            return (1);
        }
        else if (!strcmp ("?", argv[1]) || !strcmp ("help", argv[1])) {
            usage ();
        }
        else if (!strcmp ("exit", argv[1]) || !strcmp ("quit", argv[1])) {
            //* exit this program. */
            kill (pid_recv, SIGTERM);
            return (0);
        }
        else if (!strcmp ("@", argv[1])) {
            INT32           retval =
                WriteComPort (argv[2], strlen (argv[2]));
            if (strlen (argv[2]) != retval) {
                fprintf (stderr, "cannot send data correctly\n");
            }
        }
        else if (!strcmp ("close", argv[1])) {
            CloseComPort ();
        }
        else if (!strcmp ("open", argv[1])) {
            INT32           retval = 0;
            retval = OpenComPort (pArgs->pPortInfo);
            if (retval) {
                fprintf (stderr,
                         "Make sure /dev/ttyS%d "
                         "not in use or you have enough privilege.\n\n",
                         pArgs->pPortInfo->port);
            }
        }
        else {                  //* invalid commands */
            fprintf (stderr,
                     "Invalid command: %s\n"
                     "type \"?\" to show commands\n", argv[1]);
        }
    }
    //* argv[0] isn't a NULL pointer, which means to invoke a subshell */
    else {
        shell (argv);
    }
    return (1);
}

/*
 * Function: shell(char **argv)
 * Arguments:
 * 		argv[0]: pointer shell name
 *		argv[1]: "-c", with a command
 *				 NULL, without any commands
 */
static void shell (char **argv)
{
    switch (fork ()) {
    case -1:
        perror ("Fork failed\r\n");
        break;
    case 0:
        {
            /*
             * Fire up the shell in the child.
             */
            if (DEBUG) {
                char          **save_argv = argv;
                while (*save_argv) {
                    printf ("%s\n", *save_argv++);
                }
            }
            execvp (argv[0], argv);
            perror ("execvp");
            _exit (1);
        }
    default:
        (void) wait ((int *) 0);        //* Wait for the shell to complete */
        break;
    }
}

/*
 * Function:	makeargv (char **argv)
 * Arguments:	argv[0], NULL: don't invoke a subshell
 *				argv[0]==NULL && argv[1]==NULL, no command, just white space
 *			  	argv[0]!=NULL && argv[1]==NULL, just invoke a subshell,
 *				without commands.
 *				argv[0]!=NULL && argv[1]=="-c", invoke a subshell with a command
 */
static void makeargv (char **argv)
{
    char           *cp;
    char           *shellp = getenv ("SHELL");
    int             newword = 1;

    if (NULL == shellp)
        shellp = "/bin/sh";

    cp = cmd_line;
    strcpy (save_cmd_line, cp); //* save for shell command */
    while (*cp && isspace (*cp)) {
        cp++;
    };                          //* escape all white spaces */

    if ('!' == *cp) {           //* Special case shell escape */
        cp++;
        *argv++ = shellp;
        while (*cp && isspace (*cp)) {
            cp++;
        }
        if (*cp) {              //* with extra arguments */ 
            *argv++ = "-c";
            if (DEBUG) {
                printf ("%s\n", cp);
            }
            *argv++ = cp;
            *argv++ = NULL;
            return;
        }
        else {                  //* without extra arguments, only "!" */
            *argv++ = NULL;
            return;
        }
    }
    else if ('@' == *cp) {
        //* send message, extra arguments to be handled specially */
        cp++;
        *argv++ = NULL;
        *argv++ = "@";
        *argv++ = cp;
        *argv++ = NULL;
        return;
    }
    else {
        //* neither invoke a subshell nor send message */
        *argv++ = NULL;
    }

    while (*cp) {
        if (isspace (*cp)) {
            *cp = '\0';
            newword = !newword;
        }
        else if (newword) {
            newword = !newword;
            *argv++ = cp;
        }
        cp++;
    }
    *argv++ = NULL;
}

/*
 *	Function:	static void usage(void);
 *	Arguments:	void;
 *	Description:	show usage message;
 */
static void usage (void)
{
    fprintf (stdout,
             "Commands are:\n\n"
             "exit  \t\texit sdb\n"
             "quit  \t\texit sdb\n"
             "open  \t\topen a serail port\n"
             "close \t\tclose an open serial port\n"
             "@     \t\tsend messages\n"
             "!     \t\tinvoke a subshell\n"
             "      \t\texample: ! /bin/sh /bin/ls\n"
             "help  \t\tthis help message\n"
             "?     \t\tthis help message\n");
}