/*
 * \brief  libc file operations
 * \author Christian Prochaska
 * \author Norman Feske
 * \date   2010-01-21
 */

/*
 * Copyright (C) 2010-2013 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU General Public License version 2.
 */

/* Genode includes */
#include <base/printf.h>
#include <base/env.h>
#include <os/path.h>
#include <util/token.h>

/* Genode-specific libc interfaces */
#include <libc-plugin/fd_alloc.h>
#include <libc-plugin/plugin_registry.h>
#include <libc-plugin/plugin.h>

/* libc includes */
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

/* libc-internal includes */
#include "libc_mem_alloc.h"
#include "libc_mmap_registry.h"

using namespace Libc;


#ifdef GENODE_RELEASE
#undef PERR
#define PERR(...)
#endif /* GENODE_RELEASE */

static bool const verbose = false;
#define PDBGV(...) if (verbose) PDBG(__VA_ARGS__)


enum { INVALID_FD = -1 };


Libc::Mmap_registry *Libc::mmap_registry()
{
	static Libc::Mmap_registry registry;
	return &registry;
}


/***************
 ** Utilities **
 ***************/

/**
 * Find plugin responsible for the specified libc file descriptor
 *
 * \param func_name  function name of the caller for printing an error message
 */
inline File_descriptor *libc_fd_to_fd(int libc_fd, const char *func_name)
{
	File_descriptor *fd = file_descriptor_allocator()->find_by_libc_fd(libc_fd);
	if (!fd)
		PERR("no plugin found for %s(%d)", func_name, libc_fd);
	return fd;
}


/**
 * Generate body of wrapper function taking a file descriptor as first argument
 */
#define FD_FUNC_WRAPPER_GENERIC(result_stm, func_name, libc_fd, ...)	\
{																		\
	File_descriptor *fd = libc_fd_to_fd(libc_fd, #func_name);			\
	if (!fd || !fd->plugin)												\
		result_stm INVALID_FD;											\
	else																\
		result_stm fd->plugin->func_name(fd, ##__VA_ARGS__ ); 			\
}

#define FD_FUNC_WRAPPER(func_name, libc_fd, ...) \
	FD_FUNC_WRAPPER_GENERIC(return, func_name, libc_fd, ##__VA_ARGS__ )

/**
 * Generate body of wrapper function taking a path name as first argument
 */
#define FNAME_FUNC_WRAPPER_GENERIC(result_stm, func_name, path, ...)						\
{																							\
	Plugin *plugin  = plugin_registry()->get_plugin_for_##func_name(path, ##__VA_ARGS__);	\
	if (!plugin) {																			\
		PERR("no plugin found for %s(\"%s\")", #func_name, path);							\
		errno = ENOSYS;																		\
		result_stm -1;																		\
	} else																					\
		result_stm plugin->func_name(path, ##__VA_ARGS__);									\
}

#define FNAME_FUNC_WRAPPER(func_name, path, ...) \
	FNAME_FUNC_WRAPPER_GENERIC(return, func_name, path, ##__VA_ARGS__ )


/**
 * Current working directory
 */
static Absolute_path &cwd()
{
	static Absolute_path _cwd("/");
	return _cwd;
}

/**
 * path element token
 */

struct Scanner_policy_path_element
{
	static bool identifier_char(char c, unsigned /* i */)
	{
		return (c != '/') && (c != 0);
	}
};

typedef Genode::Token<Scanner_policy_path_element> Path_element_token;


/**
 * Resolve symbolic links in a given absolute path
 */

/* exception */
class Symlink_resolve_error { };

static void resolve_symlinks(char const *path, Absolute_path &resolved_path)
{
	PDBGV("path = %s", path);

	char path_element[PATH_MAX];
	char symlink_target[PATH_MAX];

	Absolute_path current_iteration_working_path;
	Absolute_path next_iteration_working_path(path, cwd().base());
	PDBGV("absolute_path = %s", next_iteration_working_path.base());

	enum { FOLLOW_LIMIT = 10 };
	int follow_count = 0;
	bool symlink_resolved_in_this_iteration;
	do {
		PDBGV("new iteration");
		if (follow_count++ == FOLLOW_LIMIT) {
			errno = ELOOP;
			throw Symlink_resolve_error();
		}

		current_iteration_working_path.import(next_iteration_working_path.base());
		PDBGV("current_iteration_working_path = %s", current_iteration_working_path.base());

		next_iteration_working_path.import("");
		symlink_resolved_in_this_iteration = false;

		Path_element_token t(current_iteration_working_path.base());

		while (t) {
			if (t.type() != Path_element_token::IDENT) {
					t = t.next();
					continue;
			}

			t.string(path_element, sizeof(path_element));
			PDBGV("path_element = %s", path_element);

			try {
				next_iteration_working_path.append("/");
				next_iteration_working_path.append(path_element);
			} catch (Genode::Path_base::Path_too_long) {
				errno = ENAMETOOLONG;
				throw Symlink_resolve_error();
			}

			PDBGV("working_path_new = %s", next_iteration_working_path.base());

			/*
			 * If a symlink has been resolved in this iteration, the remaining
			 * path elements get added and a new iteration starts.
			 */
			if (!symlink_resolved_in_this_iteration) {
				struct stat stat_buf;
				int res;
				FNAME_FUNC_WRAPPER_GENERIC(res = , stat, next_iteration_working_path.base(), &stat_buf);
				if (res == -1) {
					PDBGV("stat() failed for %s", next_iteration_working_path.base());
					throw Symlink_resolve_error();
				}
				if (S_ISLNK(stat_buf.st_mode)) {
					PDBGV("found symlink: %s", next_iteration_working_path.base());
					FNAME_FUNC_WRAPPER_GENERIC(res = , readlink,
					                           next_iteration_working_path.base(),
					                           symlink_target, sizeof(symlink_target));
					if (res < 1)
						throw Symlink_resolve_error();

					if (symlink_target[0] == '/')
						/* absolute target */
						next_iteration_working_path.import(symlink_target, cwd().base());
					else {
						/* relative target */
						next_iteration_working_path.strip_last_element();
						try {
							next_iteration_working_path.append(symlink_target);
						} catch (Genode::Path_base::Path_too_long) {
							errno = ENAMETOOLONG;
							throw Symlink_resolve_error();
						}
					}
					PDBGV("resolved symlink to: %s", next_iteration_working_path.base());
					symlink_resolved_in_this_iteration = true;
				}
			}

			t = t.next();
		}
		PDBGV("token end");

	} while (symlink_resolved_in_this_iteration);

	resolved_path.import(next_iteration_working_path.base());
	PDBGV("resolved_path = %s", resolved_path.base());
}


static void resolve_symlinks_except_last_element(char const *path, Absolute_path &resolved_path)
{
	PDBGV("path = %s", path);

	Absolute_path absolute_path_without_last_element(path, cwd().base());
	absolute_path_without_last_element.strip_last_element();

	resolve_symlinks(absolute_path_without_last_element.base(), resolved_path);

	/* append last element to resolved path */
	Absolute_path absolute_path_last_element(path, cwd().base());
	absolute_path_last_element.keep_only_last_element();
	try {
		resolved_path.append(absolute_path_last_element.base());
	} catch (Genode::Path_base::Path_too_long) {
		errno = ENAMETOOLONG;
		throw Symlink_resolve_error();
	}
}


/********************
 ** Libc functions **
 ********************/

extern "C" int _accept(int libc_fd, struct sockaddr *addr, socklen_t *addrlen)
{
	return accept(libc_fd, addr, addrlen);
}


extern "C" int accept(int libc_fd, struct sockaddr *addr, socklen_t *addrlen)
{
	File_descriptor *fd = libc_fd_to_fd(libc_fd, "accept");
	File_descriptor *ret_fd = (fd && fd->plugin) ? fd->plugin->accept(fd, addr, addrlen) : 0;
	return ret_fd ? ret_fd->libc_fd : INVALID_FD;
}


extern "C" int _bind(int libc_fd, const struct sockaddr *addr,
                     socklen_t addrlen)
{
	return bind(libc_fd, addr, addrlen);
}


extern "C" int bind(int libc_fd, const struct sockaddr *addr,
                    socklen_t addrlen) {
	FD_FUNC_WRAPPER(bind, libc_fd, addr, addrlen); }


extern "C" int chdir(const char *path)
{
	struct stat stat_buf;
	if ((stat(path, &stat_buf) == -1) ||
	    (!S_ISDIR(stat_buf.st_mode))) {
		errno = ENOTDIR;
		return -1;
	}
	cwd().import(path, cwd().base());
	return 0;
}


extern "C" int _close(int libc_fd) {
	FD_FUNC_WRAPPER(close, libc_fd); }


extern "C" int close(int libc_fd) { return _close(libc_fd); }


extern "C" int connect(int libc_fd, const struct sockaddr *addr,
                       socklen_t addrlen) {
	FD_FUNC_WRAPPER(connect, libc_fd, addr, addrlen); }


extern "C" int _connect(int libc_fd, const struct sockaddr *addr,
                        socklen_t addrlen)
{
    return connect(libc_fd, addr, addrlen);
}


extern "C" int _dup(int libc_fd)
{
	File_descriptor *fd = libc_fd_to_fd(libc_fd, "dup");
	File_descriptor *ret_fd = (fd && fd->plugin) ? fd->plugin->dup(fd) : 0;
	return ret_fd ? ret_fd->libc_fd : INVALID_FD;
}


extern "C" int dup(int libc_fd)
{
	return _dup(libc_fd);
}


extern "C" int _dup2(int libc_fd, int new_libc_fd)
{
	File_descriptor *fd = libc_fd_to_fd(libc_fd, "dup2");
	if (!fd || !fd->plugin)
		return INVALID_FD;

	if (libc_fd == new_libc_fd)
		return libc_fd;

	/*
	 * Check if 'new_libc_fd' is already in use. If so, close it before
	 * allocating it again.
	 */
	File_descriptor *new_fd = file_descriptor_allocator()->find_by_libc_fd(new_libc_fd);
	if (new_fd)
		close(new_libc_fd);

	new_fd = file_descriptor_allocator()->alloc(fd->plugin, 0, new_libc_fd);
	new_fd->path(fd->fd_path);
	/* new_fd->context must be assigned by the plugin implementing 'dup2' */
	return fd->plugin->dup2(fd, new_fd);
}


extern "C" int dup2(int libc_fd, int new_libc_fd)
{
	return _dup2(libc_fd, new_libc_fd);
}


extern "C" int _execve(char const *filename, char *const argv[],
                       char *const envp[])
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks(filename, resolved_path);
		FNAME_FUNC_WRAPPER(execve, resolved_path.base(), argv, envp);
	} catch (Symlink_resolve_error) {
		return -1;
	}
}


extern "C" int execve(char const *filename, char *const argv[],
                      char *const envp[])
{
	return _execve(filename, argv, envp);
}


extern "C" int fchdir(int libc_fd)
{
	File_descriptor *fd = libc_fd_to_fd(libc_fd, "fchdir");

	if (!fd)
		return INVALID_FD;

	return chdir(fd->fd_path);
}


extern "C" int fcntl(int libc_fd, int cmd, ...)
{
	va_list ap;
	int res;
	va_start(ap, cmd);
	FD_FUNC_WRAPPER_GENERIC(res =, fcntl, libc_fd, cmd, va_arg(ap, long));
	va_end(ap);
	return res;
}


extern "C" int _fcntl(int libc_fd, int cmd, long arg) {
	return fcntl(libc_fd, cmd, arg); }


extern "C" void freeaddrinfo(struct addrinfo *res)
{
	Plugin *plugin;

	plugin = plugin_registry()->get_plugin_for_freeaddrinfo(res);

	if (!plugin) {
		PERR("no plugin found for freeaddrinfo()");
		return;
	}

	plugin->freeaddrinfo(res);
}


extern "C" int _fstat(int libc_fd, struct stat *buf) {
	FD_FUNC_WRAPPER(fstat, libc_fd, buf); }


extern "C" int fstat(int libc_fd, struct stat *buf)
{
	return _fstat(libc_fd, buf);
}


extern "C" int _fstatfs(int libc_fd, struct statfs *buf) {
	FD_FUNC_WRAPPER(fstatfs, libc_fd, buf); }


extern "C" int fsync(int libc_fd) {
	FD_FUNC_WRAPPER(fsync, libc_fd); }


extern "C" int ftruncate(int libc_fd, ::off_t length) {
	FD_FUNC_WRAPPER(ftruncate, libc_fd, length); }


extern "C" int getaddrinfo(const char *node, const char *service,
                           const struct addrinfo *hints,
                           struct addrinfo **res)
{
	Plugin *plugin;

	plugin = plugin_registry()->get_plugin_for_getaddrinfo(node, service, hints, res);

	if (!plugin) {
		PERR("no plugin found for getaddrinfo()");
		return -1;
	}

	return plugin->getaddrinfo(node, service, hints, res);
}


extern "C" ssize_t _getdirentries(int libc_fd, char *buf, ::size_t nbytes, ::off_t *basep) {
	FD_FUNC_WRAPPER(getdirentries, libc_fd, buf, nbytes, basep); }



extern "C" int _getpeername(int libc_fd, struct sockaddr *addr, socklen_t *addrlen) {
	FD_FUNC_WRAPPER(getpeername, libc_fd, addr, addrlen); }


extern "C" int getpeername(int libc_fd, struct sockaddr *addr, socklen_t *addrlen)
{
	return _getpeername(libc_fd, addr, addrlen);
}


extern "C" int _getsockname(int libc_fd, struct sockaddr *addr, socklen_t *addrlen) {
	FD_FUNC_WRAPPER(getsockname, libc_fd, addr, addrlen); }


extern "C" int getsockname(int libc_fd, struct sockaddr *addr, socklen_t *addrlen)
{
	return _getsockname(libc_fd, addr, addrlen);
}


extern "C" int ioctl(int libc_fd, int request, char *argp) {
	FD_FUNC_WRAPPER(ioctl, libc_fd, request, argp); }


extern "C" int _ioctl(int libc_fd, int request, char *argp) {
	FD_FUNC_WRAPPER(ioctl, libc_fd, request, argp); }


extern "C" int _listen(int libc_fd, int backlog)
{
	return listen(libc_fd, backlog);
}


extern "C" int listen(int libc_fd, int backlog) {
	FD_FUNC_WRAPPER(listen, libc_fd, backlog); }


extern "C" ::off_t lseek(int libc_fd, ::off_t offset, int whence) {
	FD_FUNC_WRAPPER(lseek, libc_fd, offset, whence); }


extern "C" int lstat(const char *path, struct stat *buf)
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks_except_last_element(path, resolved_path);
		FNAME_FUNC_WRAPPER(stat, resolved_path.base(), buf);
	} catch (Symlink_resolve_error) {
		return -1;
	}
}


extern "C" int mkdir(const char *path, mode_t mode)
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks_except_last_element(path, resolved_path);
		FNAME_FUNC_WRAPPER(mkdir, resolved_path.base(), mode);
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" void *mmap(void *addr, ::size_t length, int prot, int flags,
                      int libc_fd, ::off_t offset)
{

	/* handle requests for anonymous memory */
	if (!addr && libc_fd == -1) {
		void *start = Libc::mem_alloc()->alloc(length, PAGE_SHIFT);
		mmap_registry()->insert(start, length, 0);
		return start;
	}

	/* lookup plugin responsible for file descriptor */
	File_descriptor *fd = libc_fd_to_fd(libc_fd, "mmap");
	if (!fd || !fd->plugin || !fd->plugin->supports_mmap()) {
		PWRN("mmap not supported for file descriptor %d", libc_fd);
		return (void *)INVALID_FD;
	}

	void *start = fd->plugin->mmap(addr, length, prot, flags, fd, offset);
	mmap_registry()->insert(start, length, fd->plugin);
	return start;
}


extern "C" int munmap(void *start, ::size_t length)
{
	if (!mmap_registry()->is_registered(start)) {
		PWRN("munmap: could not lookup plugin for address %p", start);
		errno = EINVAL;
		return -1;
	}

	/*
	 * Lookup plugin that was used for mmap
	 *
	 * If the pointer is NULL, 'start' refers to an anonymous mmap.
	 */
	Plugin *plugin = mmap_registry()->lookup_plugin_by_addr(start);

	int ret = 0;
	if (plugin)
		ret = plugin->munmap(start, length);
	else
		Libc::mem_alloc()->free(start);

	mmap_registry()->remove(start);
	return ret;
}


extern "C" int _open(const char *pathname, int flags, ::mode_t mode)
{
	PDBGV("pathname = %s", pathname);

	Absolute_path resolved_path;

	Plugin *plugin;
	File_descriptor *new_fdo;

	try {
		resolve_symlinks_except_last_element(pathname, resolved_path);
	} catch (Symlink_resolve_error) {
		return -1;
	}

	if (!(flags & O_NOFOLLOW)) {
		/* resolve last element */
		try {
			resolve_symlinks(resolved_path.base(), resolved_path);
		} catch (Symlink_resolve_error) {
			if (errno == ENOENT) {
				if (!(flags & O_CREAT))
					return -1;
			} else
				return -1;
		}
	}

	PDBGV("resolved path = %s", resolved_path.base());

	plugin = plugin_registry()->get_plugin_for_open(resolved_path.base(), flags);

	if (!plugin) {
		PERR("no plugin found for open(\"%s\", int)", pathname, flags);
		return -1;
	}

	new_fdo = plugin->open(resolved_path.base(), flags);
	if (!new_fdo) {
		PERR("plugin()->open(\"%s\") failed", pathname);
		return -1;
	}
	new_fdo->path(resolved_path.base());

	return new_fdo->libc_fd;
}


extern "C" int open(const char *pathname, int flags, ...)
{
	va_list ap;
	va_start(ap, flags);
	int res = _open(pathname, flags, va_arg(ap, unsigned));
	va_end(ap);
	return res;
}


extern "C" int pipe(int pipefd[2])
{
	Plugin *plugin;
	File_descriptor *pipefdo[2];

	plugin = plugin_registry()->get_plugin_for_pipe();

	if (!plugin) {
		PERR("no plugin found for pipe()");
		return -1;
	}

	if (plugin->pipe(pipefdo) == -1) {
		PERR("plugin()->pipe() failed");
		return -1;
	}

	pipefd[0] = pipefdo[0]->libc_fd;
	pipefd[1] = pipefdo[1]->libc_fd;

	return 0;
}


extern "C" ssize_t _read(int libc_fd, void *buf, ::size_t count) {
	FD_FUNC_WRAPPER(read, libc_fd, buf, count); }


extern "C" ssize_t read(int libc_fd, void *buf, ::size_t count)
{
	return _read(libc_fd, buf, count);
}


extern "C" ssize_t readlink(const char *path, char *buf, size_t bufsiz)
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks_except_last_element(path, resolved_path);
		FNAME_FUNC_WRAPPER(readlink, resolved_path.base(), buf, bufsiz);
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" ssize_t recv(int libc_fd, void *buf, ::size_t len, int flags) {
	FD_FUNC_WRAPPER(recv, libc_fd, buf, len, flags); }


extern "C" ssize_t _recvfrom(int libc_fd, void *buf, ::size_t len, int flags,
                              struct sockaddr *src_addr, socklen_t *addrlen) {
	FD_FUNC_WRAPPER(recvfrom, libc_fd, buf, len, flags, src_addr, addrlen); }


extern "C" ssize_t recvfrom(int libc_fd, void *buf, ::size_t len, int flags,
                              struct sockaddr *src_addr, socklen_t *addrlen)
{
	return _recvfrom(libc_fd, buf, len, flags, src_addr, addrlen);
}


extern "C" ssize_t recvmsg(int libc_fd, struct msghdr *msg, int flags) {
	FD_FUNC_WRAPPER(recvmsg, libc_fd, msg, flags); }


extern "C" int rename(const char *oldpath, const char *newpath)
{
	try {
		Absolute_path resolved_oldpath, resolved_newpath;
		resolve_symlinks_except_last_element(oldpath, resolved_oldpath);
		resolve_symlinks_except_last_element(newpath, resolved_newpath);
		FNAME_FUNC_WRAPPER(rename, resolved_oldpath.base(), resolved_newpath.base());
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" ssize_t send(int libc_fd, const void *buf, ::size_t len, int flags) {
	FD_FUNC_WRAPPER(send, libc_fd, buf, len, flags); }


extern "C" ssize_t _sendto(int libc_fd, const void *buf, ::size_t len, int flags,
                            const struct sockaddr *dest_addr, socklen_t addrlen) {
	FD_FUNC_WRAPPER(sendto, libc_fd, buf, len, flags, dest_addr, addrlen); }


extern "C" ssize_t sendto(int libc_fd, const void *buf, ::size_t len, int flags,
                            const struct sockaddr *dest_addr, socklen_t addrlen)
{
	return _sendto(libc_fd, buf, len, flags, dest_addr, addrlen);
}


extern "C" int _getsockopt(int libc_fd, int level, int optname,
                          void *optval, socklen_t *optlen)
{
	return getsockopt(libc_fd, level, optname, optval, optlen);
}


extern "C" int getsockopt(int libc_fd, int level, int optname,
                          void *optval, socklen_t *optlen) {
	FD_FUNC_WRAPPER(getsockopt, libc_fd, level, optname, optval, optlen); }


extern "C" int _setsockopt(int libc_fd, int level, int optname,
                          const void *optval, socklen_t optlen) {
	FD_FUNC_WRAPPER(setsockopt, libc_fd, level, optname, optval, optlen); }


extern "C" int setsockopt(int libc_fd, int level, int optname,
                          const void *optval, socklen_t optlen)
{
	return _setsockopt(libc_fd, level, optname, optval, optlen);
}


extern "C" int shutdown(int libc_fd, int how) {
	FD_FUNC_WRAPPER(shutdown, libc_fd, how); }

extern "C" int socket(int domain, int type, int protocol)
{
	Plugin *plugin;
	File_descriptor *new_fdo;

	plugin = plugin_registry()->get_plugin_for_socket(domain, type, protocol);

	if (!plugin) {
		PERR("no plugin found for socket()");
		return -1;
	}

	new_fdo = plugin->socket(domain, type, protocol);
	if (!new_fdo) {
		PERR("plugin()->socket() failed");
		return -1;
	}

	return new_fdo->libc_fd;
}


extern "C" int _socket(int domain, int type, int protocol)
{
	return socket(domain, type, protocol);
}


extern "C" int stat(const char *path, struct stat *buf)
{
	PDBGV("path = %s", path);
	try {
		Absolute_path resolved_path;
		resolve_symlinks(path, resolved_path);
		FNAME_FUNC_WRAPPER(stat, resolved_path.base(), buf);
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" int symlink(const char *oldpath, const char *newpath)
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks_except_last_element(newpath, resolved_path);
		FNAME_FUNC_WRAPPER(symlink, oldpath, resolved_path.base());
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" int unlink(const char *path)
{
	try {
		Absolute_path resolved_path;
		resolve_symlinks_except_last_element(path, resolved_path);
		FNAME_FUNC_WRAPPER(unlink, resolved_path.base());
	} catch(Symlink_resolve_error) {
		return -1;
	}
}


extern "C" ssize_t _write(int libc_fd, const void *buf, ::size_t count)
{
	int flags = fcntl(libc_fd, F_GETFL);

	if ((flags != -1) && (flags & O_APPEND))
		lseek(libc_fd, 0, SEEK_END);

	FD_FUNC_WRAPPER(write, libc_fd, buf, count);
}


extern "C" ssize_t write(int libc_fd, const void *buf, ::size_t count) {
	return _write(libc_fd, buf, count); }


extern "C" int __getcwd(char *dst, ::size_t dst_size)
{
	Genode::strncpy(dst, cwd().base(), dst_size);
	PDBGV("cwd = %s", dst);
	return 0;
}
