mirror of
https://https.git.savannah.gnu.org/git/diffutils.git
synced 2026-01-26 15:03:22 +00:00
123 lines
3.5 KiB
C
123 lines
3.5 KiB
C
/* Buffer primitives for comparison operations.
|
|
|
|
Copyright (C) 1993, 1995, 1998, 2001-2002, 2006, 2009-2013, 2015-2026 Free
|
|
Software Foundation, Inc.
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#include <config.h>
|
|
|
|
#include "cmpbuf.h"
|
|
|
|
#include <errno.h>
|
|
#include <limits.h>
|
|
#include <signal.h>
|
|
#include <stdckdint.h>
|
|
#include <unistd.h>
|
|
#include <stdint.h>
|
|
#include <inttypes.h>
|
|
#include <sys/types.h>
|
|
|
|
#include "intprops.h"
|
|
#include "minmax.h"
|
|
|
|
/* Read NBYTES bytes from descriptor FD into BUF.
|
|
Return the number of characters successfully read.
|
|
On error, return -1, setting errno.
|
|
The number returned is always NBYTES unless end-of-file or error. */
|
|
|
|
ptrdiff_t
|
|
block_read (int fd, char *buf, idx_t nbytes)
|
|
{
|
|
char *bp = buf;
|
|
char const *buflim = buf + nbytes;
|
|
idx_t readlim = MIN (IDX_MAX, MIN (SSIZE_MAX, SIZE_MAX));
|
|
|
|
do
|
|
{
|
|
idx_t bytes_remaining = buflim - bp;
|
|
idx_t bytes_to_read = MIN (bytes_remaining, readlim);
|
|
ssize_t nread = read (fd, bp, bytes_to_read);
|
|
if (nread <= 0)
|
|
{
|
|
if (nread == 0)
|
|
break;
|
|
|
|
/* Accommodate FreeBSD 13, which can't read more than INT_MAX bytes
|
|
when debug.iosize_max_clamp is nonzero. Prefer a power
|
|
of two for the read limit in this case.
|
|
|
|
Also, work around a bug in Linux kernel 6.3.8 tmpfs,
|
|
which fails if the current offset + bytes_to_read exceeds
|
|
TYPE_MAXIMUM (off_t), even if EOF occurs before then. */
|
|
if (errno == EINVAL)
|
|
{
|
|
if (bytes_to_read <= 1)
|
|
{
|
|
if (lseek (fd, 0, SEEK_CUR) == TYPE_MAXIMUM (off_t))
|
|
{
|
|
nread = 0;
|
|
break;
|
|
}
|
|
errno = EINVAL;
|
|
}
|
|
else
|
|
{
|
|
readlim = MIN (bytes_to_read >> 1, INT_MAX / 2 + 1);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* This is needed for programs that have signal handlers on
|
|
older hosts without SA_RESTART. It also accommodates
|
|
ancient AIX hosts that set errno to EINTR after uncaught
|
|
SIGCONT. See <news:1r77ojINN85n@ftp.UU.NET>
|
|
(1993-04-22). */
|
|
if (! SA_RESTART && errno == EINTR)
|
|
continue;
|
|
|
|
return -1;
|
|
}
|
|
bp += nread;
|
|
}
|
|
while (bp < buflim);
|
|
|
|
return bp - buf;
|
|
}
|
|
|
|
/* Least common multiple of two buffer sizes A and B. However, if
|
|
either A or B is zero, or if the multiple is greater than LCM_MAX,
|
|
return a reasonable buffer size. */
|
|
|
|
idx_t
|
|
buffer_lcm (idx_t a, idx_t b, idx_t lcm_max)
|
|
{
|
|
/* Yield reasonable values if buffer sizes are zero. Although A and
|
|
B must be nonnegative, GCC generates better code from (A <= 0)
|
|
than from (A != 0). */
|
|
if (a <= 0)
|
|
return b <= 0 ? 8 * 1024 : b;
|
|
if (b <= 0)
|
|
return a;
|
|
|
|
/* n = gcd (a, b) */
|
|
idx_t m, n, r;
|
|
for (m = a, n = b; (r = m % n) != 0; m = n, n = r)
|
|
continue;
|
|
|
|
/* Yield a if there is an overflow. */
|
|
idx_t q = a / n, lcm;
|
|
return !ckd_mul (&lcm, b, q) && lcm <= lcm_max ? lcm : a;
|
|
}
|