unposted: move poll_read

1 files changed, 99 insertions, 0 deletions

diff --git a/Src/utils.c b/Src/utils.c
index f423795ab..f5242bbaa 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -1298,6 +1298,105 @@ setblock_stdin(void)
     return setblock_fd(1, 0, &mode);
 }
 
+/*
+ * Check for pending input on fd.  If polltty is set, we may need to
+ * use termio to look for input.  As a final resort, go to non-blocking
+ * input and try to read a character, which in this case will be
+ * returned in *readchar.
+ *
+ * Note that apart from setting (and restoring) non-blocking input,
+ * this function does not change the input mode.  The calling function
+ * should have set cbreak mode if necessary.
+ */
+
+/**/
+int
+read_poll(int fd, int *readchar, int polltty)
+{
+    int ret = 0;
+    long mode = -1;
+    char c;
+#ifdef FIONREAD
+    int val;
+#endif
+#ifdef HAVE_SELECT
+    fd_set foofd;
+    struct timeval expire_tv;
+#endif
+#ifdef HAS_TIO
+    struct ttyinfo ti;
+#endif
+
+
+#if defined(HAS_TIO) && !defined(__CYGWIN__)
+    /*
+     * Under Solaris, at least, reading from the terminal in non-canonical
+     * mode requires that we use the VMIN mechanism to poll.  Any attempt
+     * to check any other way, or to set the terminal to non-blocking mode
+     * and poll that way, fails; it will just for canonical mode input.
+     * We should probably use this mechanism if the user has set non-canonical
+     * mode, in which case testing here for isatty() and ~ICANON would be
+     * better than testing whether bin_read() set it, but for now we've got
+     * enough problems.
+     *
+     * Under Cygwin, you won't be surprised to here, this mechanism,
+     * although present, doesn't work, and we *have* to use ordinary
+     * non-blocking reads to find out if there is a character present
+     * in non-canonical mode.
+     *
+     * I am assuming Solaris is nearer the UNIX norm.  This is not necessarily
+     * as plausible as it sounds, but it seems the right way to guess.
+     *		pws 2000/06/26
+     */
+    if (polltty) {
+	gettyinfo(&ti);
+	ti.tio.c_cc[VMIN] = 0;
+	settyinfo(&ti);
+    }
+#else
+    polltty = 0;
+#endif
+#ifdef HAVE_SELECT
+    if (!ret) {
+	expire_tv.tv_sec = expire_tv.tv_usec = 0;
+	FD_ZERO(&foofd);
+	FD_SET(fd, &foofd);
+	if (select(fd+1, (SELECT_ARG_2_T) &foofd, NULL, NULL, &expire_tv)
+	    > 1)
+	    ret = 1;
+    }
+#else
+#ifdef FIONREAD
+    if (!ret) {
+	ioctl(fd, FIONREAD, (char *)&val);
+	if (val)
+	    ret = 1;
+    }
+#endif
+#endif
+
+    if (!ret) {
+	/*
+	 * Final attempt: set non-blocking read and try to read a character.
+	 * Praise Bill, this works under Cygwin (nothing else seems to).
+	 */
+	if ((polltty || setblock_fd(0, fd, &mode))
+	    && read(fd, &c, 1) > 0) {
+	    *readchar = STOUC(c);
+	    ret = 1;
+	}
+	if (mode != -1)
+	    fcntl(fd, F_SETFL, mode);
+    }
+#ifdef HAS_TIO
+    if (polltty) {
+	ti.tio.c_cc[VMIN] = 1;
+	settyinfo(&ti);
+    }
+#endif
+    return ret;
+}
+
 /**/
 int
 checkrmall(char *s)