Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party

xz/src/xz/file_io.c

Index: xz/src/xz/file_io.c
===================================================================
--- xz/src/xz/file_io.c	(revision 0)
+++ xz/src/xz/file_io.c	(revision 0)
@@ -0,0 +1,957 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       file_io.c
+/// \brief      File opening, unlinking, and closing
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "private.h"
+
+#include <fcntl.h>
+
+#ifdef TUKLIB_DOSLIKE
+#	include <io.h>
+#else
+static bool warn_fchown;
+#endif
+
+#if defined(HAVE_FUTIMES) || defined(HAVE_FUTIMESAT) || defined(HAVE_UTIMES)
+#	include <sys/time.h>
+#elif defined(HAVE_UTIME)
+#	include <utime.h>
+#endif
+
+#include "tuklib_open_stdxxx.h"
+
+#ifndef O_BINARY
+#	define O_BINARY 0
+#endif
+
+#ifndef O_NOCTTY
+#	define O_NOCTTY 0
+#endif
+
+
+/// If true, try to create sparse files when decompressing.
+static bool try_sparse = true;
+
+#ifndef TUKLIB_DOSLIKE
+/// File status flags of standard output. This is used by io_open_dest()
+/// and io_close_dest().
+static int stdout_flags = 0;
+#endif
+
+
+static bool io_write_buf(file_pair *pair, const uint8_t *buf, size_t size);
+
+
+extern void
+io_init(void)
+{
+	// Make sure that stdin, stdout, and and stderr are connected to
+	// a valid file descriptor. Exit immediately with exit code ERROR
+	// if we cannot make the file descriptors valid. Maybe we should
+	// print an error message, but our stderr could be screwed anyway.
+	tuklib_open_stdxxx(E_ERROR);
+
+#ifndef TUKLIB_DOSLIKE
+	// If fchown() fails setting the owner, we warn about it only if
+	// we are root.
+	warn_fchown = geteuid() == 0;
+#endif
+
+#ifdef __DJGPP__
+	// Avoid doing useless things when statting files.
+	// This isn't important but doesn't hurt.
+	_djstat_flags = _STAT_INODE | _STAT_EXEC_EXT
+			| _STAT_EXEC_MAGIC | _STAT_DIRSIZE;
+#endif
+
+	return;
+}
+
+
+extern void
+io_no_sparse(void)
+{
+	try_sparse = false;
+	return;
+}
+
+
+/// \brief      Unlink a file
+///
+/// This tries to verify that the file being unlinked really is the file that
+/// we want to unlink by verifying device and inode numbers. There's still
+/// a small unavoidable race, but this is much better than nothing (the file
+/// could have been moved/replaced even hours earlier).
+static void
+io_unlink(const char *name, const struct stat *known_st)
+{
+#if defined(TUKLIB_DOSLIKE)
+	// On DOS-like systems, st_ino is meaningless, so don't bother
+	// testing it. Just silence a compiler warning.
+	(void)known_st;
+#else
+	struct stat new_st;
+
+	// If --force was used, use stat() instead of lstat(). This way
+	// (de)compressing symlinks works correctly. However, it also means
+	// that xz cannot detect if a regular file foo is renamed to bar
+	// and then a symlink foo -> bar is created. Because of stat()
+	// instead of lstat(), xz will think that foo hasn't been replaced
+	// with another file. Thus, xz will remove foo even though it no
+	// longer is the same file that xz used when it started compressing.
+	// Probably it's not too bad though, so this doesn't need a more
+	// complex fix.
+	const int stat_ret = opt_force
+			? stat(name, &new_st) : lstat(name, &new_st);
+
+	if (stat_ret
+#	ifdef __VMS
+			// st_ino is an array, and we don't want to
+			// compare st_dev at all.
+			|| memcmp(&new_st.st_ino, &known_st->st_ino,
+				sizeof(new_st.st_ino)) != 0
+#	else
+			// Typical POSIX-like system
+			|| new_st.st_dev != known_st->st_dev
+			|| new_st.st_ino != known_st->st_ino
+#	endif
+			)
+		// TRANSLATORS: When compression or decompression finishes,
+		// and xz is going to remove the source file, xz first checks
+		// if the source file still exists, and if it does, does its
+		// device and inode numbers match what xz saw when it opened
+		// the source file. If these checks fail, this message is
+		// shown, %s being the filename, and the file is not deleted.
+		// The check for device and inode numbers is there, because
+		// it is possible that the user has put a new file in place
+		// of the original file, and in that case it obviously
+		// shouldn't be removed.
+		message_error(_("%s: File seems to have been moved, "
+				"not removing"), name);
+	else
+#endif
+		// There's a race condition between lstat() and unlink()
+		// but at least we have tried to avoid removing wrong file.
+		if (unlink(name))
+			message_error(_("%s: Cannot remove: %s"),
+					name, strerror(errno));
+
+	return;
+}
+
+
+/// \brief      Copies owner/group and permissions
+///
+/// \todo       ACL and EA support
+///
+static void
+io_copy_attrs(const file_pair *pair)
+{
+	// Skip chown and chmod on Windows.
+#ifndef TUKLIB_DOSLIKE
+	// This function is more tricky than you may think at first.
+	// Blindly copying permissions may permit users to access the
+	// destination file who didn't have permission to access the
+	// source file.
+
+	// Try changing the owner of the file. If we aren't root or the owner
+	// isn't already us, fchown() probably doesn't succeed. We warn
+	// about failing fchown() only if we are root.
+	if (fchown(pair->dest_fd, pair->src_st.st_uid, -1) && warn_fchown)
+		message_warning(_("%s: Cannot set the file owner: %s"),
+				pair->dest_name, strerror(errno));
+
+	mode_t mode;
+
+	if (fchown(pair->dest_fd, -1, pair->src_st.st_gid)) {
+		message_warning(_("%s: Cannot set the file group: %s"),
+				pair->dest_name, strerror(errno));
+		// We can still safely copy some additional permissions:
+		// `group' must be at least as strict as `other' and
+		// also vice versa.
+		//
+		// NOTE: After this, the owner of the source file may
+		// get additional permissions. This shouldn't be too bad,
+		// because the owner would have had permission to chmod
+		// the original file anyway.
+		mode = ((pair->src_st.st_mode & 0070) >> 3)
+				& (pair->src_st.st_mode & 0007);
+		mode = (pair->src_st.st_mode & 0700) | (mode << 3) | mode;
+	} else {
+		// Drop the setuid, setgid, and sticky bits.
+		mode = pair->src_st.st_mode & 0777;
+	}
+
+	if (fchmod(pair->dest_fd, mode))
+		message_warning(_("%s: Cannot set the file permissions: %s"),
+				pair->dest_name, strerror(errno));
+#endif
+
+	// Copy the timestamps. We have several possible ways to do this, of
+	// which some are better in both security and precision.
+	//
+	// First, get the nanosecond part of the timestamps. As of writing,
+	// it's not standardized by POSIX, and there are several names for
+	// the same thing in struct stat.
+	long atime_nsec;
+	long mtime_nsec;
+
+#	if defined(HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC)
+	// GNU and Solaris
+	atime_nsec = pair->src_st.st_atim.tv_nsec;
+	mtime_nsec = pair->src_st.st_mtim.tv_nsec;
+
+#	elif defined(HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC)
+	// BSD
+	atime_nsec = pair->src_st.st_atimespec.tv_nsec;
+	mtime_nsec = pair->src_st.st_mtimespec.tv_nsec;
+
+#	elif defined(HAVE_STRUCT_STAT_ST_ATIMENSEC)
+	// GNU and BSD without extensions
+	atime_nsec = pair->src_st.st_atimensec;
+	mtime_nsec = pair->src_st.st_mtimensec;
+
+#	elif defined(HAVE_STRUCT_STAT_ST_UATIME)
+	// Tru64
+	atime_nsec = pair->src_st.st_uatime * 1000;
+	mtime_nsec = pair->src_st.st_umtime * 1000;
+
+#	elif defined(HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC)
+	// UnixWare
+	atime_nsec = pair->src_st.st_atim.st__tim.tv_nsec;
+	mtime_nsec = pair->src_st.st_mtim.st__tim.tv_nsec;
+
+#	else
+	// Safe fallback
+	atime_nsec = 0;
+	mtime_nsec = 0;
+#	endif
+
+	// Construct a structure to hold the timestamps and call appropriate
+	// function to set the timestamps.
+#if defined(HAVE_FUTIMENS)
+	// Use nanosecond precision.
+	struct timespec tv[2];
+	tv[0].tv_sec = pair->src_st.st_atime;
+	tv[0].tv_nsec = atime_nsec;
+	tv[1].tv_sec = pair->src_st.st_mtime;
+	tv[1].tv_nsec = mtime_nsec;
+
+	(void)futimens(pair->dest_fd, tv);
+
+#elif defined(HAVE_FUTIMES) || defined(HAVE_FUTIMESAT) || defined(HAVE_UTIMES)
+	// Use microsecond precision.
+	struct timeval tv[2];
+	tv[0].tv_sec = pair->src_st.st_atime;
+	tv[0].tv_usec = atime_nsec / 1000;
+	tv[1].tv_sec = pair->src_st.st_mtime;
+	tv[1].tv_usec = mtime_nsec / 1000;
+
+#	if defined(HAVE_FUTIMES)
+	(void)futimes(pair->dest_fd, tv);
+#	elif defined(HAVE_FUTIMESAT)
+	(void)futimesat(pair->dest_fd, NULL, tv);
+#	else
+	// Argh, no function to use a file descriptor to set the timestamp.
+	(void)utimes(pair->dest_name, tv);
+#	endif
+
+#elif defined(HAVE_UTIME)
+	// Use one-second precision. utime() doesn't support using file
+	// descriptor either. Some systems have broken utime() prototype
+	// so don't make this const.
+	struct utimbuf buf = {
+		.actime = pair->src_st.st_atime,
+		.modtime = pair->src_st.st_mtime,
+	};
+
+	// Avoid warnings.
+	(void)atime_nsec;
+	(void)mtime_nsec;
+
+	(void)utime(pair->dest_name, &buf);
+#endif
+
+	return;
+}
+
+
+/// Opens the source file. Returns false on success, true on error.
+static bool
+io_open_src_real(file_pair *pair)
+{
+	// There's nothing to open when reading from stdin.
+	if (pair->src_name == stdin_filename) {
+		pair->src_fd = STDIN_FILENO;
+#ifdef TUKLIB_DOSLIKE
+		setmode(STDIN_FILENO, O_BINARY);
+#endif
+		return false;
+	}
+
+	// Symlinks are not followed unless writing to stdout or --force
+	// was used.
+	const bool follow_symlinks = opt_stdout || opt_force;
+
+	// We accept only regular files if we are writing the output
+	// to disk too. bzip2 allows overriding this with --force but
+	// gzip and xz don't.
+	const bool reg_files_only = !opt_stdout;
+
+	// Flags for open()
+	int flags = O_RDONLY | O_BINARY | O_NOCTTY;
+
+#ifndef TUKLIB_DOSLIKE
+	// If we accept only regular files, we need to be careful to avoid
+	// problems with special files like devices and FIFOs. O_NONBLOCK
+	// prevents blocking when opening such files. When we want to accept
+	// special files, we must not use O_NONBLOCK, or otherwise we won't
+	// block waiting e.g. FIFOs to become readable.
+	if (reg_files_only)
+		flags |= O_NONBLOCK;
+#endif
+
+#if defined(O_NOFOLLOW)
+	if (!follow_symlinks)
+		flags |= O_NOFOLLOW;
+#elif !defined(TUKLIB_DOSLIKE)
+	// Some POSIX-like systems lack O_NOFOLLOW (it's not required
+	// by POSIX). Check for symlinks with a separate lstat() on
+	// these systems.
+	if (!follow_symlinks) {
+		struct stat st;
+		if (lstat(pair->src_name, &st)) {
+			message_error("%s: %s", pair->src_name,
+					strerror(errno));
+			return true;
+
+		} else if (S_ISLNK(st.st_mode)) {
+			message_warning(_("%s: Is a symbolic link, "
+					"skipping"), pair->src_name);
+			return true;
+		}
+	}
+#else
+	// Avoid warnings.
+	(void)follow_symlinks;
+#endif
+
+	// Try to open the file. If we are accepting non-regular files,
+	// unblock the caught signals so that open() can be interrupted
+	// if it blocks e.g. due to a FIFO file.
+	if (!reg_files_only)
+		signals_unblock();
+
+	// Maybe this wouldn't need a loop, since all the signal handlers for
+	// which we don't use SA_RESTART set user_abort to true. But it
+	// doesn't hurt to have it just in case.
+	do {
+		pair->src_fd = open(pair->src_name, flags);
+	} while (pair->src_fd == -1 && errno == EINTR && !user_abort);
+
+	if (!reg_files_only)
+		signals_block();
+
+	if (pair->src_fd == -1) {
+		// If we were interrupted, don't display any error message.
+		if (errno == EINTR) {
+			// All the signals that don't have SA_RESTART
+			// set user_abort.
+			assert(user_abort);
+			return true;
+		}
+
+#ifdef O_NOFOLLOW
+		// Give an understandable error message in if reason
+		// for failing was that the file was a symbolic link.
+		//
+		// Note that at least Linux, OpenBSD, Solaris, and Darwin
+		// use ELOOP to indicate if O_NOFOLLOW was the reason
+		// that open() failed. Because there may be
+		// directories in the pathname, ELOOP may occur also
+		// because of a symlink loop in the directory part.
+		// So ELOOP doesn't tell us what actually went wrong.
+		//
+		// FreeBSD associates EMLINK with O_NOFOLLOW and
+		// Tru64 uses ENOTSUP. We use these directly here
+		// and skip the lstat() call and the associated race.
+		// I want to hear if there are other kernels that
+		// fail with something else than ELOOP with O_NOFOLLOW.
+		bool was_symlink = false;
+
+#	if defined(__FreeBSD__) || defined(__DragonFly__)
+		if (errno == EMLINK)
+			was_symlink = true;
+
+#	elif defined(__digital__) && defined(__unix__)
+		if (errno == ENOTSUP)
+			was_symlink = true;
+
+#	elif defined(__NetBSD__)
+		// FIXME? As of 2008-11-20, NetBSD doesn't document what
+		// errno is used with O_NOFOLLOW. It seems to be EFTYPE,
+		// but since it isn't documented, it may be wrong to rely
+		// on it here.
+		if (errno == EFTYPE)
+			was_symlink = true;
+
+#	else
+		if (errno == ELOOP && !follow_symlinks) {
+			const int saved_errno = errno;
+			struct stat st;
+			if (lstat(pair->src_name, &st) == 0
+					&& S_ISLNK(st.st_mode))
+				was_symlink = true;
+
+			errno = saved_errno;
+		}
+#	endif
+
+		if (was_symlink)
+			message_warning(_("%s: Is a symbolic link, "
+					"skipping"), pair->src_name);
+		else
+#endif
+			// Something else than O_NOFOLLOW failing
+			// (assuming that the race conditions didn't
+			// confuse us).
+			message_error("%s: %s", pair->src_name,
+					strerror(errno));
+
+		return true;
+	}
+
+#ifndef TUKLIB_DOSLIKE
+	// Drop O_NONBLOCK, which is used only when we are accepting only
+	// regular files. After the open() call, we want things to block
+	// instead of giving EAGAIN.
+	if (reg_files_only) {
+		flags = fcntl(pair->src_fd, F_GETFL);
+		if (flags == -1)
+			goto error_msg;
+
+		flags &= ~O_NONBLOCK;
+
+		if (fcntl(pair->src_fd, F_SETFL, flags))
+			goto error_msg;
+	}
+#endif
+
+	// Stat the source file. We need the result also when we copy
+	// the permissions, and when unlinking.
+	if (fstat(pair->src_fd, &pair->src_st))
+		goto error_msg;
+
+	if (S_ISDIR(pair->src_st.st_mode)) {
+		message_warning(_("%s: Is a directory, skipping"),
+				pair->src_name);
+		goto error;
+	}
+
+	if (reg_files_only) {
+		if (!S_ISREG(pair->src_st.st_mode)) {
+			message_warning(_("%s: Not a regular file, "
+					"skipping"), pair->src_name);
+			goto error;
+		}
+
+		// These are meaningless on Windows.
+#ifndef TUKLIB_DOSLIKE
+		if (pair->src_st.st_mode & (S_ISUID | S_ISGID)) {
+			// gzip rejects setuid and setgid files even
+			// when --force was used. bzip2 doesn't check
+			// for them, but calls fchown() after fchmod(),
+			// and many systems automatically drop setuid
+			// and setgid bits there.
+			//
+			// We accept setuid and setgid files if
+			// --force was used. We drop these bits
+			// explicitly in io_copy_attr().
+			message_warning(_("%s: File has setuid or "
+					"setgid bit set, skipping"),
+					pair->src_name);
+			goto error;
+		}
+
+		if (pair->src_st.st_mode & S_ISVTX) {
+			message_warning(_("%s: File has sticky bit "
+					"set, skipping"),
+					pair->src_name);
+			goto error;
+		}
+
+		if (pair->src_st.st_nlink > 1) {
+			message_warning(_("%s: Input file has more "
+					"than one hard link, "
+					"skipping"), pair->src_name);
+			goto error;
+		}
+#endif
+	}
+
+	return false;
+
+error_msg:
+	message_error("%s: %s", pair->src_name, strerror(errno));
+error:
+	(void)close(pair->src_fd);
+	return true;
+}
+
+
+extern file_pair *
+io_open_src(const char *src_name)
+{
+	if (is_empty_filename(src_name))
+		return NULL;
+
+	// Since we have only one file open at a time, we can use
+	// a statically allocated structure.
+	static file_pair pair;
+
+	pair = (file_pair){
+		.src_name = src_name,
+		.dest_name = NULL,
+		.src_fd = -1,
+		.dest_fd = -1,
+		.src_eof = false,
+		.dest_try_sparse = false,
+		.dest_pending_sparse = 0,
+	};
+
+	// Block the signals, for which we have a custom signal handler, so
+	// that we don't need to worry about EINTR.
+	signals_block();
+	const bool error = io_open_src_real(&pair);
+	signals_unblock();
+
+	return error ? NULL : &pair;
+}
+
+
+/// \brief      Closes source file of the file_pair structure
+///
+/// \param      pair    File whose src_fd should be closed
+/// \param      success If true, the file will be removed from the disk if
+///                     closing succeeds and --keep hasn't been used.
+static void
+io_close_src(file_pair *pair, bool success)
+{
+	if (pair->src_fd != STDIN_FILENO && pair->src_fd != -1) {
+#ifdef TUKLIB_DOSLIKE
+		(void)close(pair->src_fd);
+#endif
+
+		// If we are going to unlink(), do it before closing the file.
+		// This way there's no risk that someone replaces the file and
+		// happens to get same inode number, which would make us
+		// unlink() wrong file.
+		//
+		// NOTE: DOS-like systems are an exception to this, because
+		// they don't allow unlinking files that are open. *sigh*
+		if (success && !opt_keep_original)
+			io_unlink(pair->src_name, &pair->src_st);
+
+#ifndef TUKLIB_DOSLIKE
+		(void)close(pair->src_fd);
+#endif
+	}
+
+	return;
+}
+
+
+static bool
+io_open_dest_real(file_pair *pair)
+{
+	if (opt_stdout || pair->src_fd == STDIN_FILENO) {
+		// We don't modify or free() this.
+		pair->dest_name = (char *)"(stdout)";
+		pair->dest_fd = STDOUT_FILENO;
+#ifdef TUKLIB_DOSLIKE
+		setmode(STDOUT_FILENO, O_BINARY);
+#endif
+	} else {
+		pair->dest_name = suffix_get_dest_name(pair->src_name);
+		if (pair->dest_name == NULL)
+			return true;
+
+		// If --force was used, unlink the target file first.
+		if (opt_force && unlink(pair->dest_name) && errno != ENOENT) {
+			message_error(_("%s: Cannot remove: %s"),
+					pair->dest_name, strerror(errno));
+			free(pair->dest_name);
+			return true;
+		}
+
+		// Open the file.
+		const int flags = O_WRONLY | O_BINARY | O_NOCTTY
+				| O_CREAT | O_EXCL;
+		const mode_t mode = S_IRUSR | S_IWUSR;
+		pair->dest_fd = open(pair->dest_name, flags, mode);
+
+		if (pair->dest_fd == -1) {
+			message_error("%s: %s", pair->dest_name,
+					strerror(errno));
+			free(pair->dest_name);
+			return true;
+		}
+	}
+
+	// If this really fails... well, we have a safe fallback.
+	if (fstat(pair->dest_fd, &pair->dest_st)) {
+#if defined(__VMS)
+		pair->dest_st.st_ino[0] = 0;
+		pair->dest_st.st_ino[1] = 0;
+		pair->dest_st.st_ino[2] = 0;
+#elif !defined(TUKLIB_DOSLIKE)
+		pair->dest_st.st_dev = 0;
+		pair->dest_st.st_ino = 0;
+#endif
+#ifndef TUKLIB_DOSLIKE
+	} else if (try_sparse && opt_mode == MODE_DECOMPRESS) {
+		// When writing to standard output, we need to be extra
+		// careful:
+		//  - It may be connected to something else than
+		//    a regular file.
+		//  - We aren't necessarily writing to a new empty file
+		//    or to the end of an existing file.
+		//  - O_APPEND may be active.
+		//
+		// TODO: I'm keeping this disabled for DOS-like systems
+		// for now. FAT doesn't support sparse files, but NTFS
+		// does, so maybe this should be enabled on Windows after
+		// some testing.
+		if (pair->dest_fd == STDOUT_FILENO) {
+			if (!S_ISREG(pair->dest_st.st_mode))
+				return false;
+
+			const int flags = fcntl(STDOUT_FILENO, F_GETFL);
+			if (flags == -1)
+				return false;
+
+			if (flags & O_APPEND) {
+				// Creating a sparse file is not possible
+				// when O_APPEND is active (it's used by
+				// shell's >> redirection). As I understand
+				// it, it is safe to temporarily disable
+				// O_APPEND in xz, because if someone
+				// happened to write to the same file at the
+				// same time, results would be bad anyway
+				// (users shouldn't assume that xz uses any
+				// specific block size when writing data).
+				//
+				// The write position may be something else
+				// than the end of the file, so we must fix
+				// it to start writing at the end of the file
+				// to imitate O_APPEND.
+				if (lseek(STDOUT_FILENO, 0, SEEK_END) == -1)
+					return false;
+
+				if (fcntl(STDOUT_FILENO, F_SETFL,
+						stdout_flags & ~O_APPEND))
+					return false;
+
+				// Remember the flags so that io_close_dest()
+				// can restore them.
+				stdout_flags = flags;
+
+			} else if (lseek(STDOUT_FILENO, 0, SEEK_CUR)
+					!= pair->dest_st.st_size) {
+				// Writing won't start exactly at the end
+				// of the file. We cannot use sparse output,
+				// because it would probably corrupt the file.
+				return false;
+			}
+		}
+
+		pair->dest_try_sparse = true;
+#endif
+	}
+
+	return false;
+}
+
+
+extern bool
+io_open_dest(file_pair *pair)
+{
+	signals_block();
+	const bool ret = io_open_dest_real(pair);
+	signals_unblock();
+	return ret;
+}
+
+
+/// \brief      Closes destination file of the file_pair structure
+///
+/// \param      pair    File whose dest_fd should be closed
+/// \param      success If false, the file will be removed from the disk.
+///
+/// \return     Zero if closing succeeds. On error, -1 is returned and
+///             error message printed.
+static bool
+io_close_dest(file_pair *pair, bool success)
+{
+#ifndef TUKLIB_DOSLIKE
+	// If io_open_dest() has disabled O_APPEND, restore it here.
+	if (stdout_flags != 0) {
+		assert(pair->dest_fd == STDOUT_FILENO);
+
+		const int fail = fcntl(STDOUT_FILENO, F_SETFL, stdout_flags);
+		stdout_flags = 0;
+
+		if (fail) {
+			message_error(_("Error restoring the O_APPEND flag "
+					"to standard output: %s"),
+					strerror(errno));
+			return true;
+		}
+	}
+#endif
+
+	if (pair->dest_fd == -1 || pair->dest_fd == STDOUT_FILENO)
+		return false;
+
+	if (close(pair->dest_fd)) {
+		message_error(_("%s: Closing the file failed: %s"),
+				pair->dest_name, strerror(errno));
+
+		// Closing destination file failed, so we cannot trust its
+		// contents. Get rid of junk:
+		io_unlink(pair->dest_name, &pair->dest_st);
+		free(pair->dest_name);
+		return true;
+	}
+
+	// If the operation using this file wasn't successful, we git rid
+	// of the junk file.
+	if (!success)
+		io_unlink(pair->dest_name, &pair->dest_st);
+
+	free(pair->dest_name);
+
+	return false;
+}
+
+
+extern void
+io_close(file_pair *pair, bool success)
+{
+	// Take care of sparseness at the end of the output file.
+	if (success && pair->dest_try_sparse
+			&& pair->dest_pending_sparse > 0) {
+		// Seek forward one byte less than the size of the pending
+		// hole, then write one zero-byte. This way the file grows
+		// to its correct size. An alternative would be to use
+		// ftruncate() but that isn't portable enough (e.g. it
+		// doesn't work with FAT on Linux; FAT isn't that important
+		// since it doesn't support sparse files anyway, but we don't
+		// want to create corrupt files on it).
+		if (lseek(pair->dest_fd, pair->dest_pending_sparse - 1,
+				SEEK_CUR) == -1) {
+			message_error(_("%s: Seeking failed when trying "
+					"to create a sparse file: %s"),
+					pair->dest_name, strerror(errno));
+			success = false;
+		} else {
+			const uint8_t zero[1] = { '\0' };
+			if (io_write_buf(pair, zero, 1))
+				success = false;
+		}
+	}
+
+	signals_block();
+
+	// Copy the file attributes. We need to skip this if destination
+	// file isn't open or it is standard output.
+	if (success && pair->dest_fd != -1 && pair->dest_fd != STDOUT_FILENO)
+		io_copy_attrs(pair);
+
+	// Close the destination first. If it fails, we must not remove
+	// the source file!
+	if (io_close_dest(pair, success))
+		success = false;
+
+	// Close the source file, and unlink it if the operation using this
+	// file pair was successful and we haven't requested to keep the
+	// source file.
+	io_close_src(pair, success);
+
+	signals_unblock();
+
+	return;
+}
+
+
+extern size_t
+io_read(file_pair *pair, io_buf *buf_union, size_t size)
+{
+	// We use small buffers here.
+	assert(size < SSIZE_MAX);
+
+	uint8_t *buf = buf_union->u8;
+	size_t left = size;
+
+	while (left > 0) {
+		const ssize_t amount = read(pair->src_fd, buf, left);
+
+		if (amount == 0) {
+			pair->src_eof = true;
+			break;
+		}
+
+		if (amount == -1) {
+			if (errno == EINTR) {
+				if (user_abort)
+					return SIZE_MAX;
+
+				continue;
+			}
+
+			message_error(_("%s: Read error: %s"),
+					pair->src_name, strerror(errno));
+
+			// FIXME Is this needed?
+			pair->src_eof = true;
+
+			return SIZE_MAX;
+		}
+
+		buf += (size_t)(amount);
+		left -= (size_t)(amount);
+	}
+
+	return size - left;
+}
+
+
+extern bool
+io_pread(file_pair *pair, io_buf *buf, size_t size, off_t pos)
+{
+	// Using lseek() and read() is more portable than pread() and
+	// for us it is as good as real pread().
+	if (lseek(pair->src_fd, pos, SEEK_SET) != pos) {
+		message_error(_("%s: Error seeking the file: %s"),
+				pair->src_name, strerror(errno));
+		return true;
+	}
+
+	const size_t amount = io_read(pair, buf, size);
+	if (amount == SIZE_MAX)
+		return true;
+
+	if (amount != size) {
+		message_error(_("%s: Unexpected end of file"),
+				pair->src_name);
+		return true;
+	}
+
+	return false;
+}
+
+
+static bool
+is_sparse(const io_buf *buf)
+{
+	assert(IO_BUFFER_SIZE % sizeof(uint64_t) == 0);
+
+	for (size_t i = 0; i < ARRAY_SIZE(buf->u64); ++i)
+		if (buf->u64[i] != 0)
+			return false;
+
+	return true;
+}
+
+
+static bool
+io_write_buf(file_pair *pair, const uint8_t *buf, size_t size)
+{
+	assert(size < SSIZE_MAX);
+
+	while (size > 0) {
+		const ssize_t amount = write(pair->dest_fd, buf, size);
+		if (amount == -1) {
+			if (errno == EINTR) {
+				if (user_abort)
+					return -1;
+
+				continue;
+			}
+
+			// Handle broken pipe specially. gzip and bzip2
+			// don't print anything on SIGPIPE. In addition,
+			// gzip --quiet uses exit status 2 (warning) on
+			// broken pipe instead of whatever raise(SIGPIPE)
+			// would make it return. It is there to hide "Broken
+			// pipe" message on some old shells (probably old
+			// GNU bash).
+			//
+			// We don't do anything special with --quiet, which
+			// is what bzip2 does too. If we get SIGPIPE, we
+			// will handle it like other signals by setting
+			// user_abort, and get EPIPE here.
+			if (errno != EPIPE)
+				message_error(_("%s: Write error: %s"),
+					pair->dest_name, strerror(errno));
+
+			return true;
+		}
+
+		buf += (size_t)(amount);
+		size -= (size_t)(amount);
+	}
+
+	return false;
+}
+
+
+extern bool
+io_write(file_pair *pair, const io_buf *buf, size_t size)
+{
+	assert(size <= IO_BUFFER_SIZE);
+
+	if (pair->dest_try_sparse) {
+		// Check if the block is sparse (contains only zeros). If it
+		// sparse, we just store the amount and return. We will take
+		// care of actually skipping over the hole when we hit the
+		// next data block or close the file.
+		//
+		// Since io_close() requires that dest_pending_sparse > 0
+		// if the file ends with sparse block, we must also return
+		// if size == 0 to avoid doing the lseek().
+		if (size == IO_BUFFER_SIZE) {
+			if (is_sparse(buf)) {
+				pair->dest_pending_sparse += size;
+				return false;
+			}
+		} else if (size == 0) {
+			return false;
+		}
+
+		// This is not a sparse block. If we have a pending hole,
+		// skip it now.
+		if (pair->dest_pending_sparse > 0) {
+			if (lseek(pair->dest_fd, pair->dest_pending_sparse,
+					SEEK_CUR) == -1) {
+				message_error(_("%s: Seeking failed when "
+						"trying to create a sparse "
+						"file: %s"), pair->dest_name,
+						strerror(errno));
+				return true;
+			}
+
+			pair->dest_pending_sparse = 0;
+		}
+	}
+
+	return io_write_buf(pair, buf->u8, size);
+}
Property changes on: xz/src/xz/file_io.c
___________________________________________________________________
Added: svn:eol-style
   + LF