pagecount.c

unix环境高级编程的源代码

#include    "lprps.h"

/* PostScript program to fetch the printer's pagecount.
 * Notice that the string returned by the printer:
 *        %%[ pagecount: N ]%%
 * will be parsed by proc_msg(). */

static char    pagecount_string[] =
    "(%%[ pagecount: ) print "    /* print writes to current output file */
    "statusdict begin pagecount end "    /* push pagecount onto stack */
    "20 string "        /* creates a string of length 20 */
    "cvs "                /* convert to string */
    "print "            /* write to current output file */
    "( ]%%) print "
    "flush\n";            /* flush current output file */

/* Read the starting or ending pagecount from the printer.
 * The argument is either &start_page or &end_page. */

void
get_page(int *ptrcount)
{
    set_alrm(30);            /* 30 second timeout to read pagecount */

    tty_flush();
    block_write(pagecount_string, sizeof(pagecount_string) - 1);
                            /* send query to printer */
    init_input(0);
    *ptrcount = -1;
    while (*ptrcount < 0)
        proc_some_input();    /* read results from printer */

    block_write(&eofc, 1);    /* send EOF to printer */
    proc_upto_eof(0);        /* wait for EOF from printer */

    clear_alrm();
}