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-rw-r--r--lib/sh/zread.c228
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diff --git a/lib/sh/zread.c b/lib/sh/zread.c
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--- /dev/null
+++ b/lib/sh/zread.c
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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;
+}