com32/lib/sys/line_input.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * line_input.c
  30  *
  31  * Line-oriented input discupline
  32  */
  33
  34 #include "file.h"
  35 #include <errno.h>
  36 #include <syslinux/idle.h>
  37
  38 ssize_t __line_input(struct file_info * fp, char *buf, size_t bufsize,
  39                      ssize_t(*get_char) (struct file_info *, void *, size_t))
  40 {
  41     size_t n = 0;
  42     char ch;
  43     int rv;
  44     ssize_t(*const Write) (struct file_info *, const void *, size_t) =
  45         fp->oop->write;
  46
  47     for (;;) {
  48         rv = get_char(fp, &ch, 1);
  49
  50         if (rv != 1) {
  51             syslinux_idle();
  52             continue;
  53         }
  54
  55         switch (ch) {
  56         case '\n':              /* Ignore incoming linefeed */
  57             break;
  58
  59         case '\r':
  60             *buf = '\n';
  61             Write(fp, "\n", 1);
  62             return n + 1;
  63
  64         case '\b':
  65             if (n > 0) {
  66                 n--;
  67                 buf--;
  68                 Write(fp, "\b \b", 3);
  69             }
  70             break;
  71
  72         case '\x15':            /* Ctrl-U */
  73             while (n) {
  74                 n--;
  75                 buf--;
  76                 Write(fp, "\b \b", 3);
  77             }
  78             break;
  79
  80         default:
  81             if (n < bufsize - 1) {
  82                 *buf = ch;
  83                 Write(fp, buf, 1);
  84                 n++;
  85                 buf++;
  86             }
  87             break;
  88         }
  89     }
  90 }