expectstr.c

unix环境高级编程的源代码

#include    "calld.h"

#define    EXPALRM        45            /* alarm time to read expect string */

static int        expalarm = EXPALRM;
static void        sig_alrm(int);
static volatile sig_atomic_t    caught_alrm;

static size_t    exp_read(int, char *);

int                        /* return 0 if got it, -1 if not */
expect_str(int fd, char *ptr)
{
    char    expstr[MAXLINE], inbuf[MAXLINE];
    char    c, *src, *dst, *inptr, *cmpptr;
    int        i, matchlen;

    if (strcmp(ptr, "\"\"") == 0)
        goto returnok;        /* special case of "" (expect nothing) */

            /* copy expect string, converting escape sequences */
    for (src = ptr, dst = expstr; (c = *src++) != 0; ) {
        if (c == '\\') {
            if (*src == 0) {
                sprintf(errmsg, "invalid expect string: %s\n", ptr);
                return(-1);
            }
            c = *src++;        /* char following backslash */
            switch (c) {
            case 'r':    c = '\r'; break;
            case 's':    c = ' '; break;
                /* room for lots more case statements ... */
            default:
                sprintf(errmsg, "unknown expect escape char: \\%s\n",
                                                        ctl_str(c));
                return(-1);
            }
        }
        *dst++ = c;
    }
    *dst = 0;
    matchlen = strlen(expstr);

    if (signal(SIGALRM, sig_alrm) == SIG_ERR)
        log_quit("signal error");
    caught_alrm = 0;
    alarm(expalarm);

    do {
        if (exp_read(fd, &c) < 0)
            return(-1);
    } while (c != expstr[0]);    /* skip until first chars equal */
    cmpptr = inptr = inbuf;
    *inptr = c;

    for (i = 1; i < matchlen; i++) {    /* read matchlen chars */
        inptr++;
        if (exp_read(fd, inptr) < 0)
            return(-1);
    }

    for ( ; ; ) {        /* keep reading until we have a match */
        if (strncmp(cmpptr, expstr, matchlen) == 0)
            break;        /* have a match */
        inptr++;
        if (exp_read(fd, inptr) < 0)
            return(-1);
        cmpptr++;
    }
returnok:
    alarm(0);
    DEBUG("\nexpect: got it");
    return(0);
}

size_t            /* read one byte, handle timeout errors & DEBUG */
exp_read(int fd, char *buf)
{
    if (caught_alrm) {    /* test flag before blocking in read */
        DEBUG("\nread timeout");
        return(-1);
    }
    if (read(fd, buf, 1) == 1) {
        DEBUG_NONL("%s", ctl_str(*buf));
        return(1);
    }
    if (errno == EINTR && caught_alrm) {
        DEBUG("\nread timeout");
        return(-1);
    }
    log_sys("read error");
}

static void
sig_alrm(int signo)
{
    caught_alrm = 1;
    return;
}