/*
    clsync - file tree sync utility based on inotify
    
    Copyright (C) 2013  Dmitry Yu Okunev <dyokunev@ut.mephi.ru> 0x8E30679C
    
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "common.h"

#include "port-hacks.h"

#include "error.h"
#include "malloc.h"


char *fd2fpath_malloc(int fd) {
#if __linux__
	stat64_t st64;

	if(fd <= 0) {
		error("Invalid file descriptor supplied: fd2fpath_malloc(%i).", fd);
		errno = EINVAL;
		return NULL;
	}

	char *fpath = xmalloc((1<<8) + 2);
	sprintf(fpath, "/proc/self/fd/%i", fd);

	if(lstat64(fpath, &st64)) {
		error("Cannot lstat64(\"%s\", st64).", fpath);
		return NULL;
	}

	ssize_t fpathlen = st64.st_size;

	if(fpathlen > (1<<8))
		fpath = xrealloc(fpath, fpathlen+2);

	debug(3, "Getting file path from symlink \"%s\". Path length is: %i.", fpath, fpathlen);
	if((fpathlen = readlink(fpath, fpath, fpathlen+1)) < 0) {
		error("Cannot readlink(\"%s\", fpath, bufsize).", fpath);
		return NULL;
	}
	debug(3, "The path is: \"%s\"", fpath);

	fpath[fpathlen] = 0;
	return fpath;
#else
	critical("Function fd2fpath_malloc() is not supported in this OS");
	return NULL;
#endif
}

/**
 * @brief 			Copies file
 * 
 * @param[in] 	path_from 	Source file path
 * @param[in] 	path_to		Destination file path
 *
 * @retval	zero 		Successfully copied
 * @retval	non-zero 	Got error, while copying
 * 
 */

int fileutils_copy(const char *path_from, const char *path_to) {
	char buf[BUFSIZ];
	FILE *from, *to;

	from = fopen(path_from, "r");
	if(from == NULL) {
		error("fileutils_copy(\"%s\", \"%s\"): Cannot open file \"%s\" for reading", 
			path_from, path_to, path_from);
		return errno;
	}

	to   = fopen(path_to,   "w");
	if(to == NULL) {
		error("fileutils_copy(\"%s\", \"%s\"): Cannot open file \"%s\" for writing", 
			path_from, path_to, path_to);
		return errno;
	}

	while(!feof(from)) {
		int err;
		size_t r, w;

		r =  fread(buf, 1, BUFSIZ, from);
		if((err=ferror(from))) {
			error("fileutils_copy(\"%s\", \"%s\"): Cannot read from file \"%s\"",
				path_from, path_to, path_from);
			return errno;	// CHECK: Is the "errno" should be used in fread() case?
		}

		w = fwrite(buf, 1, r,      to);
		if((err=ferror(to))) {
			error("fileutils_copy(\"%s\", \"%s\"): Cannot write to file \"%s\"",
				path_from, path_to, path_to);
			return errno;	// CHECK: is the "errno" should be used in fwrite() case?
		}
		if(r != w) {
			error("fileutils_copy(\"%s\", \"%s\"): Got error while writing to file \"%s\" (%u != %u)",
				path_from, path_to, path_to, r, w);
			return errno;	// CHECK: is the "errno" should be used in case "r != w"?
		}
	}

	return 0;
}


/**
 * @brief 				Calculates directory level of a canonized path (actually it just counts "/"-s)
 * 
 * @param[in] 	path 			Canonized path (with realpath())
 *
 * @retval	zero or prositive	Direcory level
 * @retval	negative 		Got error, while calculation. Error-code is placed to errno.
 * 
 */

short int fileutils_calcdirlevel(const char *path) {
	short int dirlevel = 0;
	const char *ptr = path;

	if(path == NULL) {
		error("path is NULL.");
		errno=EINVAL;
		return -1;
	}

	if(*path == 0) {
		error("path has zero length.");
		errno=EINVAL;
		return -2;
	}

	if(*path != '/') {
		error("path \"%s\" is not canonized.", path);
		errno=EINVAL;
		return -3;
	}

	while(*(ptr++))
		if(*ptr == '/')
			dirlevel++;

	return dirlevel;
}

/**
 * @brief 			Combination of mkdirat() and openat()
 * 
 * @param[in]	dir_path	Path to directory to create and open
 @ @param[in]	dirfd_parent	File descriptor of directory for relative paths
 @ @param[in]	dir_mode	Modes for newly created directory (e.g. 750)
 * 
 * @retval	dirfd		File descriptor to newly created directory
 * @retval	NULL		On error
 * 
 */
int mkdirat_open(const char *const dir_path, int dirfd_parent, mode_t dir_mode) {
	int dirfd;

	debug(5, "mkdirat(%u, \"%s\", %o)", dirfd_parent, dir_path, dir_mode);
	if (mkdirat(dirfd_parent, dir_path, dir_mode))
		return -1;

	debug(5, "openat(%u, \"%s\", %x)", dirfd_parent, dir_path, O_RDWR|O_DIRECTORY|O_PATH);
	dirfd = openat(dirfd_parent, dir_path, O_RDWR|O_DIRECTORY|O_PATH);
	if (dirfd == -1)
		return -1;

	return dirfd;
}