/*
 * Make histogram showing distribution of filesizes in a directory.
 *
 * Command-line arguments:
 *    directory path D
 *    blocksize B
 *    maximum number of blocks N
 *
 * Examines all the files in D and its subdirectories and prints
 * how many have size <= B, how many have size > B and <= 2*B, 
 * etc., with the last category being files with size > N*B.
 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

/*
 * Main function.
 */
int main(int argc, char* argv[]) {
    int blocksize;
    int maxblocks;
    char * ending_char; /* for strtol error checking */
    char * current_dir;

    int* hist; /* the histogram */
    int i;

    /* parse command-line arguments */
    if (argc < 4) {
        fprintf(stderr, "Usage:  %s directorypath blocksize maxblocks\n",
                argv[0]);
        return EXIT_FAILURE;
    }
    blocksize = strtol(argv[2], &ending_char, 10);
    if ((*ending_char != '\0') || (blocksize <= 0)) {
        fprintf(stderr, "invalid blocksize\n");
        return EXIT_FAILURE;
    }
    maxblocks = strtol(argv[3], &ending_char, 10);
    if ((*ending_char != '\0') || (maxblocks <= 0)) {
        fprintf(stderr, "invalid maxblocks\n");
        return EXIT_FAILURE;
    }

    /* change to specified directory */
    if (chdir(argv[1]) != 0) {
        fprintf(stderr, "Unable to access %s:  %s\n", argv[1], strerror(errno));
        return EXIT_FAILURE;
    }

    /* initialize histogram */
    hist = malloc((maxblocks+1) * sizeof(int));
    if (hist == NULL) {
        fprintf(stderr, "Not enough memory\n");
        return EXIT_FAILURE;
    }
    for (i = 0; i < maxblocks+1; ++i)
        hist[i] = 0;

    /* YOUR CODE GOES HERE */

    /* print results */
    fprintf(stdout, "Results for directory %s with blocksize %d:\n\n", 
            (current_dir = getcwd(NULL, 0)), blocksize);
    for (i = 0; i < maxblocks; ++i) {
        fprintf(stdout, "%20d files of size %10d blocks\n",
                hist[i], i+1);
    }
    fprintf(stdout, "%20d files of size %10d blocks or more\n", 
            hist[maxblocks], maxblocks+1);

    free(current_dir);
    free(hist);
    return EXIT_SUCCESS;

}