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-rw-r--r--lib/sh/input_avail.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/lib/sh/input_avail.c b/lib/sh/input_avail.c
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+/* input_avail.c -- check whether or not data is available for reading on a
+ specified file descriptor. */
+
+/* Copyright (C) 2008,2009-2019 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/>.
+*/
+
+#if defined (__TANDEM)
+# include <floss.h>
+#endif
+
+#if defined (HAVE_CONFIG_H)
+# include <config.h>
+#endif
+
+#include <sys/types.h>
+#include <fcntl.h>
+#if defined (HAVE_SYS_FILE_H)
+# include <sys/file.h>
+#endif /* HAVE_SYS_FILE_H */
+
+#if defined (HAVE_PSELECT)
+# include <signal.h>
+#endif
+
+#if defined (HAVE_UNISTD_H)
+# include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+
+#include "bashansi.h"
+
+#include "posixselect.h"
+
+#if defined (FIONREAD_IN_SYS_IOCTL)
+# include <sys/ioctl.h>
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+
+#if !defined (errno)
+extern int errno;
+#endif /* !errno */
+
+#if !defined (O_NDELAY) && defined (O_NONBLOCK)
+# define O_NDELAY O_NONBLOCK /* Posix style */
+#endif
+
+/* Return >= 1 if select/FIONREAD indicates data available for reading on
+ file descriptor FD; 0 if no data available. Return -1 on error. */
+int
+input_avail (fd)
+ int fd;
+{
+ int result, chars_avail;
+#if defined(HAVE_SELECT)
+ fd_set readfds, exceptfds;
+ struct timeval timeout;
+#endif
+
+ if (fd < 0)
+ return -1;
+
+ chars_avail = 0;
+
+#if defined (HAVE_SELECT)
+ FD_ZERO (&readfds);
+ FD_ZERO (&exceptfds);
+ FD_SET (fd, &readfds);
+ FD_SET (fd, &exceptfds);
+ timeout.tv_sec = 0;
+ timeout.tv_usec = 0;
+ result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, &timeout);
+ return ((result <= 0) ? 0 : 1);
+#endif
+
+#if defined (FIONREAD)
+ errno = 0;
+ result = ioctl (fd, FIONREAD, &chars_avail);
+ if (result == -1 && errno == EIO)
+ return -1;
+ return (chars_avail);
+#endif
+
+ return 0;
+}
+
+/* Wait until NCHARS are available for reading on file descriptor FD.
+ This can wait indefinitely. Return -1 on error. */
+int
+nchars_avail (fd, nchars)
+ int fd;
+ int nchars;
+{
+ int result, chars_avail;
+#if defined(HAVE_SELECT)
+ fd_set readfds, exceptfds;
+#endif
+#if defined (HAVE_PSELECT)
+ sigset_t set, oset;
+#endif
+
+ if (fd < 0 || nchars < 0)
+ return -1;
+ if (nchars == 0)
+ return (input_avail (fd));
+
+ chars_avail = 0;
+
+#if defined (HAVE_SELECT)
+ FD_ZERO (&readfds);
+ FD_ZERO (&exceptfds);
+ FD_SET (fd, &readfds);
+ FD_SET (fd, &exceptfds);
+#endif
+#if defined (HAVE_SELECT) || defined (HAVE_PSELECT)
+ sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &set);
+# ifdef SIGCHLD
+ sigaddset (&set, SIGCHLD);
+# endif
+ sigemptyset (&oset);
+#endif
+
+ while (1)
+ {
+ result = 0;
+#if defined (HAVE_PSELECT)
+ /* XXX - use pselect(2) to block SIGCHLD atomically */
+ result = pselect (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, (struct timespec *)NULL, &set);
+#elif defined (HAVE_SELECT)
+ sigprocmask (SIG_BLOCK, &set, &oset);
+ result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, (struct timeval *)NULL);
+ sigprocmask (SIG_BLOCK, &oset, (sigset_t *)NULL);
+#endif
+ if (result < 0)
+ return -1;
+
+#if defined (FIONREAD)
+ errno = 0;
+ result = ioctl (fd, FIONREAD, &chars_avail);
+ if (result == -1 && errno == EIO)
+ return -1;
+ if (chars_avail >= nchars)
+ break;
+#else
+ break;
+#endif
+ }
+
+ return 0;
+}