read-all-the-ports.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <sys/io.h>
#ifdef __GLIBC__
#include <sys/perm.h>
#endif

#define PORT_FILE "/dev/port"

char* progname;

#ifdef __i386__
static int read_and_print_one(unsigned int port, int size) {
    static int iopldone = 0;

    if (port > 1024) {
        if (!iopldone && iopl(3)) {
            fprintf(stderr, "%s: iopl(): %s\n", progname, strerror(errno));
            return 1;
        }
        iopldone++;
    } else if (ioperm(port, size, 1)) {
        fprintf(stderr, "%s: ioperm(%x): %s\n", progname, port, strerror(errno));
        return 1;
    }

    if (size == 4) printf("%04x: %08x\n", port, inl(port));
    else if (size == 2) printf("%04x: %04x\n", port, inw(port));
    else printf("%04x: %02x\n", port, inb(port));
    return 0;
}
#else
static int read_and_print_one(unsigned int port, int size) {
    static int fd = -1;
    unsigned char b;
    unsigned short w;
    unsigned int l;

    if (fd < 0) fd = open(PORT_FILE, O_RDONLY);
    if (fd < 0) {
        fprintf(stderr, "%s: %s: %s\n", progname, PORT_FILE, strerror(errno));
        return 1;
    }
    lseek(fd, port, SEEK_SET);

    if (size == 4) {
        read(fd, &l, 4);
        printf("%04x: 0x%08x\n", port, l);
    } else if (size == 2) {
        read(fd, &w, 2);
        printf("%04x: 0x%04x\n", port, w & 0xffff);
    } else {
        read(fd, &b, 1);
        printf("%04x: 0x%02x\n", port, b & 0xff);
    }

    return 0;
}
#endif

int main(int argc, char** argv) {
    unsigned int i, n, port, size, error = 0;

    progname = argv[0];
    switch (progname[strlen(progname)-1]) {
    case 'w':
        size = 2; break;
    case 'l':
        size = 4; break;
    case 'b':
    case 'p':
    default:
        size = 1;
    }

    setuid(0);
    for (i = 1; i < argc; ++i) {
        if (sscanf(argv[i], "%x%n", &port, &n) < 1 || n != strlen(argv[i])) {
            fprintf(stderr, "%s: argument '%s' is not a hex number\n", argv[0], argv[i]);
            ++error;
            continue;
        }
        if (port & (size-1)) {
            fprintf(stderr, "%s: argument '%s' is not properly aligned\n", argv[0], argv[i]);
            ++error;
            continue;
        }
        error += read_and_print_one(port, size);
    }

    exit(error ? 1 : 0);
}