/****************************************************************************
 * bfs                                                                      *
 * Copyright (C) 2016-2018 Tavian Barnes <tavianator@tavianator.com>        *
 *                                                                          *
 * Permission to use, copy, modify, and/or distribute this software for any *
 * purpose with or without fee is hereby granted.                           *
 *                                                                          *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
 ****************************************************************************/

#include "util.h"
#include "bftw.h"
#include "dstring.h"
#include <errno.h>
#include <fcntl.h>
#include <langinfo.h>
#include <regex.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#if BFS_HAS_SYS_ACL
#	include <sys/acl.h>
#endif

#if BFS_HAS_POSIX1E_CAPABILITIES
#	include <sys/capability.h>
#endif

#if BFS_HAS_SYS_PARAM
#	include <sys/param.h>
#endif

#if BFS_HAS_SYS_SYSMACROS
#	include <sys/sysmacros.h>
#elif BFS_HAS_SYS_MKDEV
#	include <sys/mkdev.h>
#endif

int xreaddir(DIR *dir, struct dirent **de) {
	errno = 0;
	*de = readdir(dir);
	if (!*de && errno != 0) {
		return -1;
	} else {
		return 0;
	}
}

char *xreadlinkat(int fd, const char *path, size_t size) {
	++size; // NUL-terminator
	ssize_t len;
	char *name = NULL;

	while (true) {
		char *new_name = realloc(name, size);
		if (!new_name) {
			goto error;
		}
		name = new_name;

		len = readlinkat(fd, path, name, size);
		if (len < 0) {
			goto error;
		} else if (len >= size) {
			size *= 2;
		} else {
			break;
		}
	}

	name[len] = '\0';
	return name;

error:
	free(name);
	return NULL;
}

bool isopen(int fd) {
	return fcntl(fd, F_GETFD) >= 0 || errno != EBADF;
}

int redirect(int fd, const char *path, int flags, ...) {
	close(fd);

	mode_t mode = 0;
	if (flags & O_CREAT) {
		va_list args;
		va_start(args, flags);

		// Use int rather than mode_t, because va_arg must receive a
		// fully-promoted type
		mode = va_arg(args, int);

		va_end(args);
	}

	int ret = open(path, flags, mode);

	if (ret >= 0 && ret != fd) {
		int other = ret;
		ret = dup2(other, fd);
		if (close(other) != 0) {
			ret = -1;
		}
	}

	return ret;
}

int dup_cloexec(int fd) {
#ifdef F_DUPFD_CLOEXEC
	return fcntl(fd, F_DUPFD_CLOEXEC, 0);
#else
	int ret = dup(fd);
	if (ret < 0) {
		return -1;
	}

	if (fcntl(ret, F_SETFD, FD_CLOEXEC) == -1) {
		close(ret);
		return -1;
	}

	return ret;
#endif
}

int pipe_cloexec(int pipefd[2]) {
#if __linux__ || (BSD && !__APPLE__)
	return pipe2(pipefd, O_CLOEXEC);
#else
	if (pipe(pipefd) != 0) {
		return -1;
	}

	if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1 || fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1) {
		int error = errno;
		close(pipefd[1]);
		close(pipefd[0]);
		errno = error;
		return -1;
	}

	return 0;
#endif
}

char *xregerror(int err, const regex_t *regex) {
	size_t len = regerror(err, regex, NULL, 0);
	char *str = malloc(len);
	if (str) {
		regerror(err, regex, str, len);
	}
	return str;
}

int xlocaltime(const time_t *timep, struct tm *result) {
	// Should be called before localtime_r() according to POSIX.1-2004
	tzset();

	if (localtime_r(timep, result)) {
		return 0;
	} else {
		return -1;
	}
}

void format_mode(mode_t mode, char str[11]) {
	strcpy(str, "----------");

	switch (bftw_mode_typeflag(mode)) {
	case BFTW_BLK:
		str[0] = 'b';
		break;
	case BFTW_CHR:
		str[0] = 'c';
		break;
	case BFTW_DIR:
		str[0] = 'd';
		break;
	case BFTW_DOOR:
		str[0] = 'D';
		break;
	case BFTW_FIFO:
		str[0] = 'p';
		break;
	case BFTW_LNK:
		str[0] = 'l';
		break;
	case BFTW_SOCK:
		str[0] = 's';
		break;
	default:
		break;
	}

	if (mode & 00400) {
		str[1] = 'r';
	}
	if (mode & 00200) {
		str[2] = 'w';
	}
	if ((mode & 04100) == 04000) {
		str[3] = 'S';
	} else if (mode & 04000) {
		str[3] = 's';
	} else if (mode & 00100) {
		str[3] = 'x';
	}

	if (mode & 00040) {
		str[4] = 'r';
	}
	if (mode & 00020) {
		str[5] = 'w';
	}
	if ((mode & 02010) == 02000) {
		str[6] = 'S';
	} else if (mode & 02000) {
		str[6] = 's';
	} else if (mode & 00010) {
		str[6] = 'x';
	}

	if (mode & 00004) {
		str[7] = 'r';
	}
	if (mode & 00002) {
		str[8] = 'w';
	}
	if ((mode & 01001) == 01000) {
		str[9] = 'T';
	} else if (mode & 01000) {
		str[9] = 't';
	} else if (mode & 00001) {
		str[9] = 'x';
	}
}

const char *xbasename(const char *path) {
	const char *i;

	// Skip trailing slashes
	for (i = path + strlen(path); i > path && i[-1] == '/'; --i);

	// Find the beginning of the name
	for (; i > path && i[-1] != '/'; --i);

	// Skip leading slashes
	for (; i[0] == '/' && i[1]; ++i);

	return i;
}

int xfaccessat(int fd, const char *path, int amode) {
	int ret = faccessat(fd, path, amode, 0);

#ifdef AT_EACCESS
	// Some platforms, like Hurd, only support AT_EACCESS.  Other platforms,
	// like Android, don't support AT_EACCESS at all.
	if (ret != 0 && (errno == EINVAL || errno == ENOTSUP)) {
		ret = faccessat(fd, path, amode, AT_EACCESS);
	}
#endif

	return ret;
}

bool is_nonexistence_error(int error) {
	return error == ENOENT || errno == ENOTDIR;
}

/** Read a line from standard input. */
static char *xgetline() {
	char *line = dstralloc(0);
	if (!line) {
		return NULL;
	}

	while (true) {
		int c = getchar();
		if (c == '\n' || c == EOF) {
			break;
		}

		if (dstrapp(&line, c) != 0) {
			goto error;
		}
	}

	return line;

error:
	dstrfree(line);
	return NULL;
}

/** Compile and execute a regular expression for xrpmatch(). */
static int xrpregex(nl_item item, const char *response) {
	const char *pattern = nl_langinfo(item);
	if (!pattern) {
		return REG_BADPAT;
	}

	regex_t regex;
	int ret = regcomp(&regex, pattern, REG_EXTENDED);
	if (ret != 0) {
		return ret;
	}

	ret = regexec(&regex, response, 0, NULL, 0);
	regfree(&regex);
	return ret;
}

/** Check if a response is affirmative or negative. */
static int xrpmatch(const char *response) {
	int ret = xrpregex(NOEXPR, response);
	if (ret == 0) {
		return 0;
	} else if (ret != REG_NOMATCH) {
		return -1;
	}

	ret = xrpregex(YESEXPR, response);
	if (ret == 0) {
		return 1;
	} else if (ret != REG_NOMATCH) {
		return -1;
	}

	// Failsafe: always handle y/n
	char c = response[0];
	if (c == 'n' || c == 'N') {
		return 0;
	} else if (c == 'y' || c == 'Y') {
		return 1;
	} else {
		return -1;
	}
}

int ynprompt() {
	fflush(stderr);

	char *line = xgetline();
	int ret = line ? xrpmatch(line) : -1;
	dstrfree(line);
	return ret;
}

dev_t bfs_makedev(int ma, int mi) {
#ifdef makedev
	return makedev(ma, mi);
#else
	return (ma << 8) | mi;
#endif
}

int bfs_major(dev_t dev) {
#ifdef major
	return major(dev);
#else
	return dev >> 8;
#endif
}

int bfs_minor(dev_t dev) {
#ifdef minor
	return minor(dev);
#else
	return dev & 0xFF;
#endif
}

#if BFS_HAS_SYS_ACL || BFS_HAS_POSIX1E_CAPABILITIES

static const char *open_path(const struct BFTW *ftwbuf, int *fd) {
#ifdef O_PATH
	// The POSIX.1e APIS predate the *at() family of functions.  We'd still
	// like to do something to avoid path re-traversals and limit races
	// though.  Ideally we could just do openat(..., O_PATH) (since we may
	// not have read access) and pass that fd to something like cap_get_fd()
	// but that will fail since fgetxattr() needs read access to the file.
	// The workaround is to use O_PATH to open an fd and then pass
	// /proc/self/fd/<fd> to cap_get_path().  Inspired by
	// https://android.googlesource.com/platform/bionic/+/2825f10b7f61558c264231a536cf3affc0d84204
	int flags = O_PATH;
	if (ftwbuf->at_flags & AT_SYMLINK_NOFOLLOW) {
		flags |= O_NOFOLLOW;
	}

	*fd = openat(ftwbuf->at_fd, ftwbuf->at_path, flags);
	if (*fd < 0) {
		return NULL;
	}

	size_t size = strlen("/proc/self/fd/") + CHAR_BIT*sizeof(int) + 1;
	char *path = malloc(size);
	if (!path) {
		close(*fd);
		*fd = -1;
		return NULL;
	}

	snprintf(path, size, "/proc/self/fd/%d", *fd);
	return path;
#else
	*fd = -1;
	return ftwbuf->path;
#endif
}

static void close_path(const struct BFTW *ftwbuf, const char *path, int fd) {
	if (path && path != ftwbuf->path) {
		free((void *)path);
	}
	if (fd >= 0) {
		close(fd);
	}
}

#endif // BFS_HAS_SYS_ACL || BFS_HAS_POSIX1E_CAPABILITIES

#if BFS_HAS_SYS_ACL

/** Check if any ACLs of the given type are non-trivial. */
static bool bfs_check_acl_type(const char *path, acl_type_t type) {
	acl_t acl = acl_get_file(path, type);
	if (!acl) {
		return false;
	}

	bool ret = false;
	acl_entry_t entry;
	for (int status = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
	     status > 0;
	     status = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry)) {
#if defined(ACL_USER_OBJ) && defined(ACL_GROUP_OBJ) && defined(ACL_OTHER)
		acl_tag_t tag;
		if (acl_get_tag_type(entry, &tag) != 0) {
			continue;
		}
		if (tag != ACL_USER_OBJ && tag != ACL_GROUP_OBJ && tag != ACL_OTHER) {
			ret = true;
			break;
		}
#else
		ret = true;
		break;
#endif
	}

	acl_free(acl);
	return ret;
}

bool bfs_check_acl(const struct BFTW *ftwbuf) {
	if (ftwbuf->typeflag == BFTW_LNK) {
		return false;
	}

	int fd;
	const char *path = open_path(ftwbuf, &fd);
	if (!path) {
		return false;
	}

	bool ret = false;
	if (bfs_check_acl_type(path, ACL_TYPE_ACCESS)) {
		ret = true;
	} else if (bfs_check_acl_type(path, ACL_TYPE_DEFAULT)) {
		ret = true;
#ifdef ACL_TYPE_EXTENDED
	} else if (bfs_check_acl_type(path, ACL_TYPE_EXTENDED)) {
		ret = true;
#endif
	}

	close_path(ftwbuf, path, fd);
	return ret;
}

#else // !BFS_HAS_SYS_ACL

bool bfs_check_acl(const struct BFTW *ftwbuf) {
	return false;
}

#endif

#if BFS_HAS_POSIX1E_CAPABILITIES

bool bfs_check_capabilities(const struct BFTW *ftwbuf) {
	bool ret = false;

	if (ftwbuf->typeflag == BFTW_LNK) {
		goto out;
	}

	int fd;
	const char *path = open_path(ftwbuf, &fd);
	if (!path) {
		goto out;
	}

	cap_t caps = cap_get_file(path);
	if (!caps) {
		goto out_close;
	}

	// TODO: Any better way to check for a non-empty capability set?
	char *text = cap_to_text(caps, NULL);
	if (!text) {
		goto out_free_caps;
	}
	ret = text[0];

	cap_free(text);
out_free_caps:
	cap_free(caps);
out_close:
	close_path(ftwbuf, path, fd);
out:
	return ret;
}

#else // !BFS_HAS_POSIX1E_CAPABILITIES

bool bfs_check_capabilities(const struct BFTW *ftwbuf) {
	return false;
}

#endif