/* Write NBYTES of BUF to FD at given position OFFSET without changing
the file position. Return the number written, or -1. */
ssize_t
__libc_pwrite (int fd, const void *buf, size_t nbytes, off_t offset)
{
return __libc_pwrite64 (fd, buf, nbytes, (off64_t) offset);
}
int
__posix_fallocate64_l64 (int fd, __off64_t offset, __off64_t len)
{
struct stat64 st;
if (offset < 0 || len < 0)
return EINVAL;
/* Perform overflow check. The outer cast relies on a GCC
extension. */
if ((__off64_t) ((uint64_t) offset + (uint64_t) len) < 0)
return EFBIG;
/* pwrite64 below will not do the right thing in O_APPEND mode. */
{
int flags = __fcntl (fd, F_GETFL, 0);
if (flags < 0 || (flags & O_APPEND) != 0)
return EBADF;
}
/* We have to make sure that this is really a regular file. */
if (__fxstat64 (_STAT_VER, fd, &st) != 0)
return EBADF;
if (S_ISFIFO (st.st_mode))
return ESPIPE;
if (! S_ISREG (st.st_mode))
return ENODEV;
if (len == 0)
{
/* This is racy, but there is no good way to satisfy a
zero-length allocation request. */
if (st.st_size < offset)
{
int ret = __ftruncate64 (fd, offset);
if (ret != 0)
ret = errno;
return ret;
}
return 0;
}
/* Minimize data transfer for network file systems, by issuing
single-byte write requests spaced by the file system block size.
(Most local file systems have fallocate support, so this fallback
code is not used there.) */
unsigned increment;
{
struct statfs64 f;
if (__fstatfs64 (fd, &f) != 0)
return errno;
if (f.f_bsize == 0)
increment = 512;
else if (f.f_bsize < 4096)
increment = f.f_bsize;
else
/* NFS clients do not propagate the block size of the underlying
storage and may report a much larger value which would still
leave holes after the loop below, so we cap the increment at
4096. */
increment = 4096;
}
/* Write a null byte to every block. This is racy; we currently
lack a better option. Compare-and-swap against a file mapping
might address local races, but requires interposition of a signal
handler to catch SIGBUS. */
for (offset += (len - 1) % increment; len > 0; offset += increment)
{
len -= increment;
if (offset < st.st_size)
{
unsigned char c;
ssize_t rsize = __libc_pread64 (fd, &c, 1, offset);
if (rsize < 0)
return errno;
/* If there is a non-zero byte, the block must have been
allocated already. */
else if (rsize == 1 && c != 0)
continue;
}
if (__libc_pwrite64 (fd, "", 1, offset) != 1)
return errno;
}
return 0;
}
COPY_FILE_RANGE_DECL
ssize_t
COPY_FILE_RANGE (int infd, __off64_t *pinoff,
int outfd, __off64_t *poutoff,
size_t length, unsigned int flags)
{
if (flags != 0)
{
__set_errno (EINVAL);
return -1;
}
{
struct stat64 instat;
struct stat64 outstat;
if (fstat64 (infd, &instat) != 0 || fstat64 (outfd, &outstat) != 0)
return -1;
if (S_ISDIR (instat.st_mode) || S_ISDIR (outstat.st_mode))
{
__set_errno (EISDIR);
return -1;
}
if (!S_ISREG (instat.st_mode) || !S_ISREG (outstat.st_mode))
{
/* We need a regular input file so that the we can seek
backwards in case of a write failure. */
__set_errno (EINVAL);
return -1;
}
if (instat.st_dev != outstat.st_dev)
{
/* Cross-device copies are not supported. */
__set_errno (EXDEV);
return -1;
}
}
/* The output descriptor must not have O_APPEND set. */
{
int flags = __fcntl (outfd, F_GETFL);
if (flags & O_APPEND)
{
__set_errno (EBADF);
return -1;
}
}
/* Avoid an overflow in the result. */
if (length > SSIZE_MAX)
length = SSIZE_MAX;
/* Main copying loop. The buffer size is arbitrary and is a
trade-off between stack size consumption, cache usage, and
amortization of system call overhead. */
size_t copied = 0;
char buf[8192];
while (length > 0)
{
size_t to_read = length;
if (to_read > sizeof (buf))
to_read = sizeof (buf);
/* Fill the buffer. */
ssize_t read_count;
if (pinoff == NULL)
read_count = read (infd, buf, to_read);
else
read_count = __libc_pread64 (infd, buf, to_read, *pinoff);
if (read_count == 0)
/* End of file reached prematurely. */
return copied;
if (read_count < 0)
{
if (copied > 0)
/* Report the number of bytes copied so far. */
return copied;
return -1;
}
if (pinoff != NULL)
*pinoff += read_count;
/* Write the buffer part which was read to the destination. */
char *end = buf + read_count;
for (char *p = buf; p < end; )
{
ssize_t write_count;
if (poutoff == NULL)
write_count = write (outfd, p, end - p);
else
write_count = __libc_pwrite64 (outfd, p, end - p, *poutoff);
if (write_count < 0)
{
/* Adjust the input read position to match what we have
written, so that the caller can pick up after the
error. */
size_t written = p - buf;
/* NB: This needs to be signed so that we can form the
negative value below. */
ssize_t overread = read_count - written;
if (pinoff == NULL)
{
if (overread > 0)
{
/* We are on an error recovery path, so we
cannot deal with failure here. */
int save_errno = errno;
(void) __libc_lseek64 (infd, -overread, SEEK_CUR);
__set_errno (save_errno);
}
}
else /* pinoff != NULL */
*pinoff -= overread;
if (copied + written > 0)
/* Report the number of bytes copied so far. */
return copied + written;
return -1;
}
p += write_count;
if (poutoff != NULL)
*poutoff += write_count;
} /* Write loop. */
copied += read_count;
length -= read_count;
}
return copied;
}
