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/* zread - read data from file descriptor into buffer with retries */
/* Copyright (C) 1999-2020 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash 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.
Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <sys/types.h>
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include <signal.h>
#include <errno.h>
#if !defined (errno)
extern int errno;
#endif
#ifndef SEEK_CUR
# define SEEK_CUR 1
#endif
#ifndef ZBUFSIZ
# define ZBUFSIZ 4096
#endif
extern int executing_builtin;
extern void check_signals_and_traps (void);
extern void check_signals (void);
extern int signal_is_trapped (int);
extern int read_builtin_timeout (int);
/* Read LEN bytes from FD into BUF. Retry the read on EINTR. Any other
error causes the loop to break. */
ssize_t
zread (fd, buf, len)
int fd;
char *buf;
size_t len;
{
ssize_t r;
check_signals (); /* check for signals before a blocking read */
/* should generalize into a mechanism where different parts of the shell can
`register' timeouts and have them checked here. */
while (((r = read_builtin_timeout (fd)) < 0 || (r = read (fd, buf, len)) < 0) &&
errno == EINTR)
{
int t;
t = errno;
/* XXX - bash-5.0 */
/* We check executing_builtin and run traps here for backwards compatibility */
if (executing_builtin)
check_signals_and_traps (); /* XXX - should it be check_signals()? */
else
check_signals ();
errno = t;
}
return r;
}
/* Read LEN bytes from FD into BUF. Retry the read on EINTR, up to three
interrupts. Any other error causes the loop to break. */
#ifdef NUM_INTR
# undef NUM_INTR
#endif
#define NUM_INTR 3
ssize_t
zreadretry (fd, buf, len)
int fd;
char *buf;
size_t len;
{
ssize_t r;
int nintr;
for (nintr = 0; ; )
{
r = read (fd, buf, len);
if (r >= 0)
return r;
if (r == -1 && errno == EINTR)
{
if (++nintr >= NUM_INTR)
return -1;
continue;
}
return r;
}
}
/* Call read(2) and allow it to be interrupted. Just a stub for now. */
ssize_t
zreadintr (fd, buf, len)
int fd;
char *buf;
size_t len;
{
check_signals ();
return (read (fd, buf, len));
}
/* Read one character from FD and return it in CP. Return values are as
in read(2). This does some local buffering to avoid many one-character
calls to read(2), like those the `read' builtin performs. */
static char lbuf[ZBUFSIZ];
static size_t lind, lused;
ssize_t
zreadc (fd, cp)
int fd;
char *cp;
{
ssize_t nr;
if (lind == lused || lused == 0)
{
nr = zread (fd, lbuf, sizeof (lbuf));
lind = 0;
if (nr <= 0)
{
lused = 0;
return nr;
}
lused = nr;
}
if (cp)
*cp = lbuf[lind++];
return 1;
}
/* Don't mix calls to zreadc and zreadcintr in the same function, since they
use the same local buffer. */
ssize_t
zreadcintr (fd, cp)
int fd;
char *cp;
{
ssize_t nr;
if (lind == lused || lused == 0)
{
nr = zreadintr (fd, lbuf, sizeof (lbuf));
lind = 0;
if (nr <= 0)
{
lused = 0;
return nr;
}
lused = nr;
}
if (cp)
*cp = lbuf[lind++];
return 1;
}
/* Like zreadc, but read a specified number of characters at a time. Used
for `read -N'. */
ssize_t
zreadn (fd, cp, len)
int fd;
char *cp;
size_t len;
{
ssize_t nr;
if (lind == lused || lused == 0)
{
if (len > sizeof (lbuf))
len = sizeof (lbuf);
nr = zread (fd, lbuf, len);
lind = 0;
if (nr <= 0)
{
lused = 0;
return nr;
}
lused = nr;
}
if (cp)
*cp = lbuf[lind++];
return 1;
}
void
zreset ()
{
lind = lused = 0;
}
/* Sync the seek pointer for FD so that the kernel's idea of the last char
read is the last char returned by zreadc. */
void
zsyncfd (fd)
int fd;
{
off_t off, r;
off = lused - lind;
r = 0;
if (off > 0)
r = lseek (fd, -off, SEEK_CUR);
if (r != -1)
lused = lind = 0;
}
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