/*-
 * Public Domain 2014-2016 MongoDB, Inc.
 * Public Domain 2008-2014 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include "wt_internal.h"

/*
 * __posix_sync --
 *	Underlying support function to flush a file handle.
 */
static int
__posix_sync(
    WT_SESSION_IMPL *session, int fd, const char *name, const char *func)
{
	WT_DECL_RET;

#if defined(F_FULLFSYNC)
	/*
	 * OS X fsync documentation:
	 * "Note that while fsync() will flush all data from the host to the
	 * drive (i.e. the "permanent storage device"), the drive itself may
	 * not physically write the data to the platters for quite some time
	 * and it may be written in an out-of-order sequence. For applications
	 * that require tighter guarantees about the integrity of their data,
	 * Mac OS X provides the F_FULLFSYNC fcntl. The F_FULLFSYNC fcntl asks
	 * the drive to flush all buffered data to permanent storage."
	 *
	 * OS X F_FULLFSYNC fcntl documentation:
	 * "This is currently implemented on HFS, MS-DOS (FAT), and Universal
	 * Disk Format (UDF) file systems."
	 */
	WT_SYSCALL_RETRY(fcntl(fd, F_FULLFSYNC, 0), ret);
	if (ret == 0)
		return (0);
	/*
	 * Assume F_FULLFSYNC failed because the file system doesn't support it
	 * and fallback to fsync.
	 */
#endif
#if defined(HAVE_FDATASYNC)
	WT_SYSCALL_RETRY(fdatasync(fd), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret, "%s: %s: fdatasync", name, func);
#else
	WT_SYSCALL_RETRY(fsync(fd), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret, "%s: %s: fsync", name, func);
#endif
}

#ifdef __linux__
/*
 * __posix_directory_sync --
 *	Flush a directory to ensure file creation is durable.
 */
static int
__posix_directory_sync(
    WT_FILE_SYSTEM *file_system, WT_SESSION *wt_session, const char *path)
{
	WT_DECL_RET;
	WT_SESSION_IMPL *session;
	int fd, tret;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	WT_SYSCALL_RETRY((
	    (fd = open(path, O_RDONLY, 0444)) == -1 ? 1 : 0), ret);
	if (ret != 0)
		WT_RET_MSG(session, ret, "%s: directory-sync: open", path);

	ret = __posix_sync(session, fd, path, "directory-sync");

	WT_SYSCALL_RETRY(close(fd), tret);
	if (tret != 0) {
		__wt_err(session, tret, "%s: directory-sync: close", path);
		if (ret == 0)
			ret = tret;
	}
	return (ret);
}
#endif

/*
 * __posix_fs_exist --
 *	Return if the file exists.
 */
static int
__posix_fs_exist(WT_FILE_SYSTEM *file_system,
    WT_SESSION *wt_session, const char *name, bool *existp)
{
	struct stat sb;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	WT_SYSCALL_RETRY(stat(name, &sb), ret);
	if (ret == 0) {
		*existp = true;
		return (0);
	}
	if (ret == ENOENT) {
		*existp = false;
		return (0);
	}
	WT_RET_MSG(session, ret, "%s: file-exist: stat", name);
}

/*
 * __posix_fs_remove --
 *	Remove a file.
 */
static int
__posix_fs_remove(
    WT_FILE_SYSTEM *file_system, WT_SESSION *wt_session, const char *name)
{
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	WT_SYSCALL_RETRY(remove(name), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret, "%s: file-remove: remove", name);
}

/*
 * __posix_fs_rename --
 *	Rename a file.
 */
static int
__posix_fs_rename(WT_FILE_SYSTEM *file_system,
    WT_SESSION *wt_session, const char *from, const char *to)
{
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	WT_SYSCALL_RETRY(rename(from, to), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret, "%s to %s: file-rename: rename", from, to);
}

/*
 * __posix_fs_size --
 *	Get the size of a file in bytes, by file name.
 */
static int
__posix_fs_size(WT_FILE_SYSTEM *file_system,
    WT_SESSION *wt_session, const char *name, wt_off_t *sizep)
{
	struct stat sb;
	WT_DECL_RET;
	WT_SESSION_IMPL *session;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	WT_SYSCALL_RETRY(stat(name, &sb), ret);
	if (ret == 0) {
		*sizep = sb.st_size;
		return (0);
	}
	WT_RET_MSG(session, ret, "%s: file-size: stat", name);
}

#if defined(HAVE_POSIX_FADVISE)
/*
 * __posix_file_advise --
 *	POSIX fadvise.
 */
static int
__posix_file_advise(WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session,
    wt_off_t offset, wt_off_t len, int advice)
{
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	WT_SYSCALL_RETRY(posix_fadvise(pfh->fd, offset, len, advice), ret);
	if (ret == 0)
		return (0);

	/*
	 * Treat EINVAL as not-supported, some systems don't support some flags.
	 * Quietly fail, callers expect not-supported failures, and reset the
	 * handle method to prevent future calls.
	 */
	if (ret == EINVAL) {
		file_handle->fh_advise = NULL;
		return (ENOTSUP);
	}

	WT_RET_MSG(session, ret,
	    "%s: handle-advise: posix_fadvise", file_handle->name);

}
#endif

/*
 * __posix_file_close --
 *	ANSI C close.
 */
static int
__posix_file_close(WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session)
{
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	/* Close the file handle. */
	if (pfh->fd != -1) {
		WT_SYSCALL_RETRY(close(pfh->fd), ret);
		if (ret != 0)
			__wt_err(session, ret,
			    "%s: handle-close: close", file_handle->name);
	}

	__wt_free(session, file_handle->name);
	__wt_free(session, pfh);
	return (ret);
}

/*
 * __posix_file_lock --
 *	Lock/unlock a file.
 */
static int
__posix_file_lock(
    WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session, bool lock)
{
	struct flock fl;
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	/*
	 * WiredTiger requires this function be able to acquire locks past
	 * the end of file.
	 *
	 * Note we're using fcntl(2) locking: all fcntl locks associated with a
	 * file for a given process are removed when any file descriptor for the
	 * file is closed by the process, even if a lock was never requested for
	 * that file descriptor.
	 */
	fl.l_start = 0;
	fl.l_len = 1;
	fl.l_type = lock ? F_WRLCK : F_UNLCK;
	fl.l_whence = SEEK_SET;

	WT_SYSCALL_RETRY(fcntl(pfh->fd, F_SETLK, &fl), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret, "%s: handle-lock: fcntl", file_handle->name);
}

/*
 * __posix_file_read --
 *	POSIX pread.
 */
static int
__posix_file_read(WT_FILE_HANDLE *file_handle,
    WT_SESSION *wt_session, wt_off_t offset, size_t len, void *buf)
{
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;
	size_t chunk;
	ssize_t nr;
	uint8_t *addr;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	/* Assert direct I/O is aligned and a multiple of the alignment. */
	WT_ASSERT(session,
	    !pfh->direct_io ||
	    S2C(session)->buffer_alignment == 0 ||
	    (!((uintptr_t)buf &
	    (uintptr_t)(S2C(session)->buffer_alignment - 1)) &&
	    len >= S2C(session)->buffer_alignment &&
	    len % S2C(session)->buffer_alignment == 0));

	/* Break reads larger than 1GB into 1GB chunks. */
	for (addr = buf; len > 0; addr += nr, len -= (size_t)nr, offset += nr) {
		chunk = WT_MIN(len, WT_GIGABYTE);
		if ((nr = pread(pfh->fd, addr, chunk, offset)) <= 0)
			WT_RET_MSG(session, nr == 0 ? WT_ERROR : __wt_errno(),
			    "%s: handle-read: pread: failed to read %"
			    WT_SIZET_FMT " bytes at offset %" PRIuMAX,
			    file_handle->name, chunk, (uintmax_t)offset);
	}
	return (0);
}

/*
 * __posix_file_size --
 *	Get the size of a file in bytes, by file handle.
 */
static int
__posix_file_size(
    WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session, wt_off_t *sizep)
{
	struct stat sb;
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	WT_SYSCALL_RETRY(fstat(pfh->fd, &sb), ret);
	if (ret == 0) {
		*sizep = sb.st_size;
		return (0);
	}
	WT_RET_MSG(session, ret, "%s: handle-size: fstat", file_handle->name);
}

/*
 * __posix_file_sync --
 *	POSIX fsync.
 */
static int
__posix_file_sync(WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session)
{
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	return (
	    __posix_sync(session, pfh->fd, file_handle->name, "handle-sync"));
}

#ifdef HAVE_SYNC_FILE_RANGE
/*
 * __posix_file_sync_nowait --
 *	POSIX fsync.
 */
static int
__posix_file_sync_nowait(WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session)
{
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	WT_SYSCALL_RETRY(sync_file_range(pfh->fd,
	    (off64_t)0, (off64_t)0, SYNC_FILE_RANGE_WRITE), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret,
	    "%s: handle-sync-nowait: sync_file_range", file_handle->name);
}
#endif

/*
 * __posix_file_truncate --
 *	POSIX ftruncate.
 */
static int
__posix_file_truncate(
    WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session, wt_off_t len)
{
	WT_DECL_RET;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	WT_SYSCALL_RETRY(ftruncate(pfh->fd, len), ret);
	if (ret == 0)
		return (0);
	WT_RET_MSG(session, ret,
	    "%s: handle-truncate: ftruncate", file_handle->name);
}

/*
 * __posix_file_write --
 *	POSIX pwrite.
 */
static int
__posix_file_write(WT_FILE_HANDLE *file_handle, WT_SESSION *wt_session,
    wt_off_t offset, size_t len, const void *buf)
{
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;
	size_t chunk;
	ssize_t nw;
	const uint8_t *addr;

	session = (WT_SESSION_IMPL *)wt_session;
	pfh = (WT_FILE_HANDLE_POSIX *)file_handle;

	/* Assert direct I/O is aligned and a multiple of the alignment. */
	WT_ASSERT(session,
	    !pfh->direct_io ||
	    S2C(session)->buffer_alignment == 0 ||
	    (!((uintptr_t)buf &
	    (uintptr_t)(S2C(session)->buffer_alignment - 1)) &&
	    len >= S2C(session)->buffer_alignment &&
	    len % S2C(session)->buffer_alignment == 0));

	/* Break writes larger than 1GB into 1GB chunks. */
	for (addr = buf; len > 0; addr += nw, len -= (size_t)nw, offset += nw) {
		chunk = WT_MIN(len, WT_GIGABYTE);
		if ((nw = pwrite(pfh->fd, addr, chunk, offset)) < 0)
			WT_RET_MSG(session, __wt_errno(),
			    "%s: handle-write: pwrite: failed to write %"
			    WT_SIZET_FMT " bytes at offset %" PRIuMAX,
			    file_handle->name, chunk, (uintmax_t)offset);
	}
	return (0);
}

/*
 * __posix_open_file_cloexec --
 *	Prevent child access to file handles.
 */
static inline int
__posix_open_file_cloexec(WT_SESSION_IMPL *session, int fd, const char *name)
{
#if defined(HAVE_FCNTL) && defined(FD_CLOEXEC) && !defined(O_CLOEXEC)
	int f;

	/*
	 * Security:
	 * The application may spawn a new process, and we don't want another
	 * process to have access to our file handles. There's an obvious race
	 * between the open and this call, prefer the flag to open if available.
	 */
	if ((f = fcntl(fd, F_GETFD)) == -1 ||
	    fcntl(fd, F_SETFD, f | FD_CLOEXEC) == -1)
		WT_RET_MSG(session, __wt_errno(),
		    "%s: handle-open: fcntl", name);
	return (0);
#else
	WT_UNUSED(session);
	WT_UNUSED(fd);
	WT_UNUSED(name);
	return (0);
#endif
}

/*
 * __posix_open_file --
 *	Open a file handle.
 */
static int
__posix_open_file(WT_FILE_SYSTEM *file_system, WT_SESSION *wt_session,
    const char *name, WT_OPEN_FILE_TYPE file_type, uint32_t flags,
    WT_FILE_HANDLE **file_handlep)
{
	WT_CONNECTION_IMPL *conn;
	WT_DECL_RET;
	WT_FILE_HANDLE *file_handle;
	WT_FILE_HANDLE_POSIX *pfh;
	WT_SESSION_IMPL *session;
	mode_t mode;
	int f;

	WT_UNUSED(file_system);

	*file_handlep = NULL;

	session = (WT_SESSION_IMPL *)wt_session;
	conn = S2C(session);

	WT_RET(__wt_calloc_one(session, &pfh));

	/* Set up error handling. */
	pfh->fd = -1;

	if (file_type == WT_OPEN_FILE_TYPE_DIRECTORY) {
		f = O_RDONLY;
#ifdef O_CLOEXEC
		/*
		 * Security:
		 * The application may spawn a new process, and we don't want
		 * another process to have access to our file handles.
		 */
		f |= O_CLOEXEC;
#endif
		WT_SYSCALL_RETRY((
		    (pfh->fd = open(name, f, 0444)) == -1 ? 1 : 0), ret);
		if (ret != 0)
			WT_ERR_MSG(session, ret, "%s: handle-open: open", name);
		WT_ERR(__posix_open_file_cloexec(session, pfh->fd, name));
		goto directory_open;
	}

	f = LF_ISSET(WT_OPEN_READONLY) ? O_RDONLY : O_RDWR;
	if (LF_ISSET(WT_OPEN_CREATE)) {
		f |= O_CREAT;
		if (LF_ISSET(WT_OPEN_EXCLUSIVE))
			f |= O_EXCL;
		mode = 0666;
	} else
		mode = 0;

#ifdef O_BINARY
	/* Windows clones: we always want to treat the file as a binary. */
	f |= O_BINARY;
#endif
#ifdef O_CLOEXEC
	/*
	 * Security:
	 * The application may spawn a new process, and we don't want another
	 * process to have access to our file handles.
	 */
	f |= O_CLOEXEC;
#endif
#ifdef O_DIRECT
	/* Direct I/O. */
	if (LF_ISSET(WT_OPEN_DIRECTIO)) {
		f |= O_DIRECT;
		pfh->direct_io = true;
	} else
		pfh->direct_io = false;
#endif
#ifdef O_NOATIME
	/* Avoid updating metadata for read-only workloads. */
	if (file_type == WT_OPEN_FILE_TYPE_DATA)
		f |= O_NOATIME;
#endif

	if (file_type == WT_OPEN_FILE_TYPE_LOG &&
	    FLD_ISSET(conn->txn_logsync, WT_LOG_DSYNC)) {
#ifdef O_DSYNC
		f |= O_DSYNC;
#elif defined(O_SYNC)
		f |= O_SYNC;
#else
		WT_ERR_MSG(session, ENOTSUP,
		    "unsupported log sync mode configured");
#endif
	}

	WT_SYSCALL_RETRY(((pfh->fd = open(name, f, mode)) == -1 ? 1 : 0), ret);
	if (ret != 0)
		WT_ERR_MSG(session, ret,
		    pfh->direct_io ?
		    "%s: handle-open: open: failed with direct I/O configured, "
		    "some filesystem types do not support direct I/O" :
		    "%s: handle-open: open", name);
	WT_ERR(__posix_open_file_cloexec(session, pfh->fd, name));

#if defined(HAVE_POSIX_FADVISE)
	/*
	 * Disable read-ahead on trees: it slows down random read workloads.
	 * Ignore fadvise when doing direct I/O, the kernel cache isn't
	 * interesting.
	 */
	if (!pfh->direct_io && file_type == WT_OPEN_FILE_TYPE_DATA) {
		WT_SYSCALL_RETRY(
		    posix_fadvise(pfh->fd, 0, 0, POSIX_FADV_RANDOM), ret);
		if (ret != 0)
			WT_ERR_MSG(session, ret,
			    "%s: handle-open: posix_fadvise", name);
	}
#endif

directory_open:
	/* Initialize public information. */
	file_handle = (WT_FILE_HANDLE *)pfh;
	WT_ERR(__wt_strdup(session, name, &file_handle->name));

	file_handle->close = __posix_file_close;
#if defined(HAVE_POSIX_FADVISE)
	/*
	 * Ignore fadvise when doing direct I/O, the kernel cache isn't
	 * interesting.
	 */
	if (!pfh->direct_io)
		file_handle->fh_advise = __posix_file_advise;
#endif
	file_handle->fh_allocate = __wt_posix_file_fallocate;
	file_handle->fh_lock = __posix_file_lock;
#ifdef WORDS_BIGENDIAN
	/*
	 * The underlying objects are little-endian, mapping objects isn't
	 * currently supported on big-endian systems.
	 */
#else
	file_handle->fh_map = __wt_posix_map;
#ifdef HAVE_POSIX_MADVISE
	file_handle->fh_map_discard = __wt_posix_map_discard;
	file_handle->fh_map_preload = __wt_posix_map_preload;
#endif
	file_handle->fh_unmap = __wt_posix_unmap;
#endif
	file_handle->fh_read = __posix_file_read;
	file_handle->fh_size = __posix_file_size;
	file_handle->fh_sync = __posix_file_sync;
#ifdef HAVE_SYNC_FILE_RANGE
	file_handle->fh_sync_nowait = __posix_file_sync_nowait;
#endif
	file_handle->fh_truncate = __posix_file_truncate;
	file_handle->fh_write = __posix_file_write;

	*file_handlep = file_handle;

	return (0);

err:	WT_TRET(__posix_file_close((WT_FILE_HANDLE *)pfh, wt_session));
	return (ret);
}

/*
 * __posix_terminate --
 *	Terminate a POSIX configuration.
 */
static int
__posix_terminate(WT_FILE_SYSTEM *file_system, WT_SESSION *wt_session)
{
	WT_SESSION_IMPL *session;

	WT_UNUSED(file_system);

	session = (WT_SESSION_IMPL *)wt_session;

	__wt_free(session, file_system);
	return (0);
}

/*
 * __wt_os_posix --
 *	Initialize a POSIX configuration.
 */
int
__wt_os_posix(WT_SESSION_IMPL *session)
{
	WT_CONNECTION_IMPL *conn;
	WT_FILE_SYSTEM *file_system;

	conn = S2C(session);

	WT_RET(__wt_calloc_one(session, &file_system));

	/* Initialize the POSIX jump table. */
	file_system->fs_directory_list = __wt_posix_directory_list;
	file_system->fs_directory_list_free = __wt_posix_directory_list_free;
#ifdef __linux__
	file_system->fs_directory_sync = __posix_directory_sync;
#endif
	file_system->fs_exist = __posix_fs_exist;
	file_system->fs_open_file = __posix_open_file;
	file_system->fs_remove = __posix_fs_remove;
	file_system->fs_rename = __posix_fs_rename;
	file_system->fs_size = __posix_fs_size;
	file_system->terminate = __posix_terminate;

	/* Switch it into place. */
	conn->file_system = file_system;

	return (0);
}