usr/src/usr.bin/pascal/px_header/px_header.c

#include <pagsiz.h>
#include <sys/types.h>
#include <a.out.h>
#include "whoami.h"
#include "objfmt.h"

/*
 * pxheader - program to sit in front of interpreter code to make shell mods
 *            unnecessary to make Pascal obj's look like real programs.
 *
 * This program lives in /usr/lib/px_header
 * Bill Joy UCB February 6, 1978
 */
static  char *sccsid = "@(#)px_header.c 1.1 (Berkeley) %G%";

extern  errno;

#define BUFSIZ  BSIZE
#define ETXTBSY 26
#define ADDR_LC HEADER_BYTES - sizeof (struct exec) - sizeof (struct pxhdr)

main(argc, argv)
        register int argc;
        register char *argv[];
{
        register int i, j;
        register unsigned short *ip;
        char *largv[512];
        int pv[2];

        if (argc > 510) {
                error("Too many arguments.\n");
                exit(1);
        }
        largv[0] = argv[0];
        largv[1] = "-";
        for (i = 1; i < argc; i++)
                largv[i + 1] = argv[i];
        largv[argc + 1] = 0;
        pipe(pv);
        i = fork();
        if (i == -1)
                error("Try again.\n");
        if (i == 0) {
                close(pv[0]);
                ip = (unsigned short *) (ADDR_LC);
                i = ((struct pxhdr *)(ADDR_LC))->objsize + sizeof(struct pxhdr);
                while (i != 0) {
                        j = (i > 0 && i < BUFSIZ) ? i : BUFSIZ;
                        write(pv[1], ip, j);
                        ip += BUFSIZ / sizeof ( unsigned short );
                        i -= j;
                }
                exit(1);
        }
        close(pv[1]);
        if (pv[0] != 3) {
                close(3);
                dup(pv[0]);
                close(pv[0]);
        }
        for (;;) {
                execv(PX_INTRP, largv);
                if (errno != ETXTBSY)
                        break;
                sleep(2);
        }
        error("Px not found.\n");
}

error(cp)
        register char *cp;
{
        register int i;
        register char *dp;

        dp = cp;
        i = 0;
        while (*dp++)
                i++;
        write(2, cp, i);
        exit(1);
}

exit(i)
{
        _exit(i);
}