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-rw-r--r--libbb/read_key.c146
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;
+}