#include <sys/types.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

enum { buf_size = 10 };

struct path_type {
    char *buffer;
    int size;
    int pos;
};

static void init_path(struct path_type *path)
{
    path->buffer = malloc(buf_size);
    path->size = buf_size;
    path->pos = 0;
}

static void copy_str(char *first, char *second, int pos)
{
    int i;
    for(i = 0; i <= pos; ++i)
        first[i] = second[i];
}

static void allocate_memory(struct path_type *path)
{
    char *tmp = malloc(path->size * 2);
    copy_str(tmp, path->buffer, path->pos);
    free(path->buffer);
    path->buffer = tmp;
    path->size *= 2;
}

static void add_dir_into_path(char *directory_name, int length,
                              struct path_type *path)
{
    int i;
    for(i = 0; i < length; ++i, ++path->pos)
        path->buffer[path->pos] = directory_name[i];
    path->buffer[path->pos] = '/';
    ++path->pos;
    path->buffer[path->pos] = '\0';
}

static void edit_path(struct path_type *path)
{
    if(path->pos == 2)
        return;
    path->pos -= 2;       /* skip '/' and '\0' */
    for( ; path->buffer[path->pos] != '/'; --path->pos)
        path->buffer[path->pos] = '\0';
    ++path->pos;
}

static void recursive_step(char *target_name, struct path_type *path)
{
    int name_length;
    char *directory_name;
    DIR *current_directory;
    struct dirent *data;
    directory_name = path->buffer;
    current_directory = opendir(directory_name);
    while((data = readdir(current_directory))) {
        if(data->d_type == DT_DIR) {
            if(!strcmp(data->d_name, target_name))
                printf("%s%s\n", path->buffer, data->d_name);
            if(!strcmp(data->d_name, ".") || !strcmp(data->d_name, ".."))
                continue;
            name_length = strlen(data->d_name);
            name_length += 2; /* slash and null character */
            while(name_length + path->pos > path->size)
                allocate_memory(path);
            add_dir_into_path(data->d_name, strlen(data->d_name), path);
            recursive_step(target_name, path);
            edit_path(path);
        } else if(!strcmp(data->d_name, target_name))
            printf("%s%s\n", path->buffer, data->d_name);
    }
    closedir(current_directory);
}

static void set_start_path(struct path_type *path)
{
    path->buffer[path->pos] = '.';
    ++path->pos;
    path->buffer[path->pos] = '/';
    ++path->pos;
    path->buffer[path->pos] = '\0';
}

int main(int argc, char **argv)
{
    struct path_type path;
    if(argc != 2) {
        perror("enter only two params");
        return 1;
    }
    init_path(&path);
    set_start_path(&path);
    recursive_step(argv[1], &path);
    free(path.buffer);
    return 0;
}