/* Recursively scan a directory tree for all dirs, and fork off a process for
 * each dir to read all the files in that dir
 *
 * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
#include <sys/wait.h>
#include <sys/stat.h>

static char *prog, *exefile;

/*
 *
 */
static __attribute__((noreturn))
void clean_up_and_exit(int ret)
{
	pid_t pid;
	int wstatus;

	for (;;) {
		pid = wait(&wstatus);
		if (pid == -1) {
			switch (errno) {
			case ECHILD:
				exit(ret);
			default:
				exit(1);
			}
		}

		if (WIFEXITED(wstatus)) {
			if (WEXITSTATUS(wstatus) == 0)
				continue;
			if (ret > 0)
				ret = WEXITSTATUS(wstatus);
			continue;
		}

		if (WIFSIGNALED(wstatus)) {
			ret = WTERMSIG(wstatus) + 128;
			continue;
		}

		ret = 126;
	}
}

/*
 *
 */
static void read_file(char *filename, int depth)
{
	ssize_t size;
	char buf[4096];
	int fd;

	printf("%*.*sread %s\n", depth, depth, "", filename);

	fd = open(filename, O_RDONLY, 0);
	if (fd == -1)
		clean_up_and_exit(4);

	for (;;) {
		size = read(fd, buf, sizeof(buf));
		if (size == 0)
			return;
		if (size == -1)
			clean_up_and_exit(5);
	}
}

/*
 *
 */
static int dot_filter(const struct dirent *entry)
{
	return entry->d_name[0] != '.';
}

/*
 *
 */
static __attribute__((noreturn))
void scan_directory(char *dirname, int depth)
{
	struct dirent **entries, *entry;
	struct stat st;
	int nent, loop;

	if (depth == 30)
		clean_up_and_exit(0);

	printf("%*.*sscan %s\n", depth, depth, "", dirname);

	nent = scandir(".", &entries, dot_filter, alphasort);
	if (nent == -1)
		clean_up_and_exit(1);

	/* firstly deal with all the subdirs */
	for (loop = 0; loop < nent; loop++) {
		entry = entries[loop];
		if (stat(entry->d_name, &st) == -1) {
			if (errno == ENOENT)
				continue;
			clean_up_and_exit(2);
		}
		if (S_ISDIR(st.st_mode))
			if (fork() == 0) {
				char dbuf[16];
				sprintf(dbuf, "%d", depth + 1);
				if (chdir(entry->d_name) < 0) {
					perror(entry->d_name);
					clean_up_and_exit(8);
				}
				execl(exefile, prog,
				      "--exec-done", entry->d_name, dbuf, NULL);
				perror(prog);
				clean_up_and_exit(9);
			}
	}

	/* then read all the regular files in that directory */
	for (loop = 0; loop < nent; loop++) {
		entry = entries[loop];
		if (stat(entry->d_name, &st) == -1) {
			if (errno == ENOENT)
				continue;
			clean_up_and_exit(3);
		}
		if (S_ISREG(st.st_mode))
			read_file(entry->d_name, depth + 1);
	}

	clean_up_and_exit(0);
}

/*
 *
 */
int main(int argc, char **argv)
{
	prog = argv[0];

	if (argv[0][0] == '/')
		exefile = argv[0];
	else
		exefile = "/proc/self/exe";

	if (argc == 4 && strcmp(argv[1], "--exec-done") == 0) {
		scan_directory(argv[2], atoi(argv[3]));
	} else {
		for (argv++; *argv; argv++) {
			if (fork() == 0) {
				if (chdir(*argv) < 0) {
					perror(*argv);
					clean_up_and_exit(8);
				}
				execl(exefile, prog,
				      "--exec-done", *argv, "0", NULL);
				perror(prog);
				clean_up_and_exit(9);
			}
		}
	}
	clean_up_and_exit(0);
}