libbb: add forgotten file from previous commit :(

1 files changed, 146 insertions, 0 deletions

diff --git a/libbb/read_key.c b/libbb/read_key.c
new file mode 100644
index 000000000..598bd94f5
--- /dev/null
+++ b/libbb/read_key.c
@@ -0,0 +1,146 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 2008 Denys Vlasenko
+ *
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+
+int FAST_FUNC read_key(int fd, smalluint *nbuffered, char *buffer)
+{
+	struct pollfd pfd;
+	const char *seq;
+	int n;
+	int c;
+
+	/* Known escape sequences for cursor and function keys */
+	static const char esccmds[] ALIGN1 = {
+		'O','A'        |0x80,KEYCODE_UP      ,
+		'O','B'        |0x80,KEYCODE_DOWN    ,
+		'O','C'        |0x80,KEYCODE_RIGHT   ,
+		'O','D'        |0x80,KEYCODE_LEFT    ,
+		'O','H'        |0x80,KEYCODE_HOME    ,
+		'O','F'        |0x80,KEYCODE_END     ,
+#if 0
+		'O','P'        |0x80,KEYCODE_FUN1    ,
+		'O','Q'        |0x80,KEYCODE_FUN2    ,
+		'O','R'        |0x80,KEYCODE_FUN3    ,
+		'O','S'        |0x80,KEYCODE_FUN4    ,
+#endif
+		'[','A'        |0x80,KEYCODE_UP      ,
+		'[','B'        |0x80,KEYCODE_DOWN    ,
+		'[','C'        |0x80,KEYCODE_RIGHT   ,
+		'[','D'        |0x80,KEYCODE_LEFT    ,
+		'[','H'        |0x80,KEYCODE_HOME    ,
+		'[','F'        |0x80,KEYCODE_END     ,
+		'[','1','~'    |0x80,KEYCODE_HOME    ,
+		'[','2','~'    |0x80,KEYCODE_INSERT  ,
+		'[','3','~'    |0x80,KEYCODE_DELETE  ,
+		'[','4','~'    |0x80,KEYCODE_END     ,
+		'[','5','~'    |0x80,KEYCODE_PAGEUP  ,
+		'[','6','~'    |0x80,KEYCODE_PAGEDOWN,
+#if 0
+		'[','1','1','~'|0x80,KEYCODE_FUN1    ,
+		'[','1','2','~'|0x80,KEYCODE_FUN2    ,
+		'[','1','3','~'|0x80,KEYCODE_FUN3    ,
+		'[','1','4','~'|0x80,KEYCODE_FUN4    ,
+		'[','1','5','~'|0x80,KEYCODE_FUN5    ,
+		'[','1','7','~'|0x80,KEYCODE_FUN6    ,
+		'[','1','8','~'|0x80,KEYCODE_FUN7    ,
+		'[','1','9','~'|0x80,KEYCODE_FUN8    ,
+		'[','2','0','~'|0x80,KEYCODE_FUN9    ,
+		'[','2','1','~'|0x80,KEYCODE_FUN10   ,
+		'[','2','3','~'|0x80,KEYCODE_FUN11   ,
+		'[','2','4','~'|0x80,KEYCODE_FUN12   ,
+#endif
+		0
+	};
+
+	n = *nbuffered;
+	if (n == 0) {
+		/* If no data, block waiting for input. If we read more
+		 * than the minimal ESC sequence size, the "n=0" below
+		 * would instead have to figure out how much to keep,
+		 * resulting in larger code. */
+		n = safe_read(fd, buffer, 3);
+		if (n <= 0)
+			return -1;
+	}
+
+	/* Grab character to return from buffer */
+	c = (unsigned char)buffer[0];
+	n--;
+	if (n)
+		memmove(buffer, buffer + 1, n);
+
+	/* Only ESC starts ESC sequences */
+	if (c != 27)
+		goto ret;
+
+	/* Loop through known ESC sequences */
+	pfd.fd = fd;
+	pfd.events = POLLIN;
+	seq = esccmds;
+	while (*seq != '\0') {
+		/* n - position in sequence we did not read yet */
+		int i = 0; /* position in sequence to compare */
+
+		/* Loop through chars in this sequence */
+		while (1) {
+			/* So far escape sequence matched up to [i-1] */
+			if (n <= i) {
+				/* Need more chars, read another one if it wouldn't block.
+				 * Note that escape sequences come in as a unit,
+				 * so if we block for long it's not really an escape sequence.
+				 * Timeout is needed to reconnect escape sequences
+				 * split up by transmission over a serial console. */
+				if (safe_poll(&pfd, 1, 50) == 0) {
+					/* No more data!
+					 * Array is sorted from shortest to longest,
+					 * we can't match anything later in array,
+					 * break out of both loops. */
+					goto ret;
+				}
+				errno = 0;
+				if (safe_read(fd, buffer + n, 1) <= 0) {
+					/* If EAGAIN, then fd is O_NONBLOCK and poll lied:
+					 * in fact, there is no data. */
+					if (errno != EAGAIN)
+						c = -1; /* otherwise it's EOF/error */
+					goto ret;
+				}
+				n++;
+			}
+			if (buffer[i] != (seq[i] & 0x7f)) {
+				/* This seq doesn't match, go to next */
+				seq += i;
+				/* Forward to last char */
+				while (!(*seq & 0x80))
+					seq++;
+				/* Skip it and the keycode which follows */
+				seq += 2;
+				break;
+			}
+			if (seq[i] & 0x80) {
+				/* Entire seq matched */
+				c = (signed char)seq[i+1];
+				n = 0;
+				/* n -= i; memmove(...);
+				 * would be more correct,
+				 * but we never read ahead that much,
+				 * and n == i here. */
+				goto ret;
+			}
+			i++;
+		}
+	}
+	/* We did not find matching sequence, it was a bare ESC.
+	 * We possibly read and stored more input in buffer[]
+	 * by now. */
+
+ ret:
+	*nbuffered = n;
+	return c;
+}