com32/lib/sys/line_input.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004 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.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--; buf--;
  67         Write(fp, "\b \b", 3);
  68       }
  69       break;
  70
  71     case '\x15':                /* Ctrl-U */
  72       while ( n ) {
  73         n--; buf--;
  74         Write(fp, "\b \b", 3);
  75       }
  76       break;
  77
  78     default:
  79       if ( n < bufsize-1 ) {
  80         *buf = ch;
  81         Write(fp, buf, 1);
  82         n++;
  83         buf++;
  84       }
  85       break;
  86     }
  87   }
  88 }