progress in c

c_progress.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int progress(char *buf, ssize_t bufsize,
        int completed, int length,
        char cell, char empty,
        char begin, char end)
{
    int i = 0;
    char *p = buf;
    char *bufend;

    if (bufsize < 2 + length + 1) return -1;

    bufend = buf + bufsize - 1;
    cell = cell == '\0' ? '-' : cell;
    empty = empty == '\0' ? '|' : empty;
    completed = completed <= length ? completed : length;

    if (begin != '\0' && p < bufend)
        *p++ = begin;

    for (i = 0; i < completed && p < bufend; i++)
        *p++ = cell;

    for (; i < length && p < bufend; i++)
        *p++ = empty;

    if (end != '\0' && p < bufend)
        *p++ = end;

    *p++ = '\0';
    return p - buf;
}

void assest(int i, char *msg)
{
    if (!i) {
        dprintf(2, "assest error %s\n", msg);
        exit(-1);
    }
}

int main()
{
    char buf[512];
    assest(-1 == progress(buf, 1, 20, 100, '*', ' ', '[', ']'), "");
    assest(-1 == progress(buf, 50, 20, 100, '*', ' ', '[', ']'), "");
    assest(53 == progress(buf, 53, 20, 50, '*', ' ', '[', ']'), "");
    assest(51 == progress(buf, 53, 20, 50, '*', ' ', '\0', '\0'), "");
    assest(51 == progress(buf, 53, 100, 50, '*', ' ', '\0', '\0'), "");

    for (int i = 0; i <= 100; i++) {
        int l = progress(buf, sizeof(buf), i, 100, '\0', '\0', '[', ']');
        assest(l != -1, "");
        dprintf(1, "\r%s", buf);
        usleep(1 * 10e4);
    }
}