/* * Copyright (c) 2001 * The President and Fellows of Harvard College. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <types.h> #include <lib.h> /* * Do a backspace in typed input. * We overwrite the current character with a space in case we're on * a terminal where backspace is nondestructive. */ static void backsp(void) { putch('\b'); putch(' '); putch('\b'); } /* * Read a string off the console. Support a few of the more useful * common control characters. Do not include the terminating newline * in the buffer passed back. */ void kgets(char *buf, size_t maxlen) { size_t pos = 0; int ch; while (1) { ch = getch(); if (ch=='\n' || ch=='\r') { putch('\n'); break; } /* Only allow the normal 7-bit ascii */ if (ch>=32 && ch<127 && pos < maxlen-1) { putch(ch); buf[pos++] = ch; } else if ((ch=='\b' || ch==127) && pos>0) { /* backspace */ backsp(); pos--; } else if (ch==3) { /* ^C - return empty string */ putch('^'); putch('C'); putch('\n'); pos = 0; break; } else if (ch==18) { /* ^R - reprint input */ buf[pos] = 0; kprintf("^R\n%s", buf); } else if (ch==21) { /* ^U - erase line */ while (pos > 0) { backsp(); pos--; } } else if (ch==23) { /* ^W - erase word */ while (pos > 0 && buf[pos-1]==' ') { backsp(); pos--; } while (pos > 0 && buf[pos-1]!=' ') { backsp(); pos--; } } else { beep(); } } buf[pos] = 0; }