ttystrip

ttystrip.c

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

#define BUFSIZE 8192

void usage(char *prgm) {
    printf("Usage: %s [ttyrec ...]\n", prgm);
}

int min(int a, int b) {
    return (a < b) ? a : b;

}

void strip(int fd) {
    const int bufsize = BUFSIZE;
    char buf[BUFSIZE];
    int *size;
    int frame_size;
    int offset;
    int n;
    int bytes_read;
    int bytes_offset;

    frame_size = offset = n = 0;
    bytes_offset = 0;
    bytes_read = bufsize;

    while ((n = read(fd, &buf[bytes_offset], bytes_read)) > 0) {
        /* If there is data from the previous frame in the buffer,
            * output that.
            */
        if (offset > 0) {
            write(1, buf, offset);
        }
        while ((offset + 12) < (n + bytes_offset)) {
            /* Skip first eight bytes for each frame. */
            size = (int *) &buf[offset+8];
            frame_size = *size;
            write(1, &buf[offset+12], min(frame_size, n + bytes_offset - offset - 12));
            offset += frame_size + 12;
        }
        /* Check if the header was only partially in the buffer. */
        if (offset >= bufsize) {
            bytes_offset = 0;
            bytes_read = bufsize;
            offset -= bufsize;
        }
        else {
            memmove(&buf[0], &buf[offset], bufsize - offset);
            bytes_offset = bufsize - offset;
            bytes_read = offset;
            offset = 0;
        }
    }
}

int main(int argc, char **argv) {
    int fd;

    if (argc == 1) {
        strip(0);
    }
    else if (strcmp(argv[1], "-h") == 0 ||
            strcmp(argv[1], "--help") == 0) {
            usage(argv[0]);
            exit(0);
        }
    else {
        int i;
        for (i = 1; i < argc; i++) {
            if ((fd = open(argv[i], O_RDONLY)) == -1) {
                fprintf(stderr, "Unable to open %s\n", argv[1]);
                exit(1);
            }
            strip(fd);
            close(fd);
        }
    }

    return 0;
}