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DEFINITIONS
This source file includes following definitions.
- io_init
- io_no_sparse
- io_unlink
- io_copy_attrs
- io_open_src_real
- io_open_src
- io_close_src
- io_open_dest_real
- io_open_dest
- io_close_dest
- io_close
- io_read
- io_pread
- is_sparse
- io_write_buf
- io_write
///////////////////////////////////////////////////////////////////////////////
//
/// \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 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 if the reason
// for failing was that the file was a symbolic link.
//
// Note that at least Linux, OpenBSD, Solaris, and Darwin
// use ELOOP to indicate that 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,
// and this stupidity went into POSIX-1.2008 too.
//
// 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__)
// As of 2010-09-05, NetBSD doesn't document what errno is
// used with O_NOFOLLOW. It is EFTYPE though, and I
// understood that is very unlikely to change even though
// it is undocumented.
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 && !S_ISREG(pair->src_st.st_mode)) {
message_warning(_("%s: Not a regular file, skipping"),
pair->src_name);
goto error;
}
#ifndef TUKLIB_DOSLIKE
if (reg_files_only && !opt_force) {
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);
}