kern/src/readline.c

   1 #include <error.h>
   2 #include <stdio.h>
   3 #include <assert.h>
   4 #include <atomic.h>
   5
   6 int readline(char *buf, size_t buf_l, const char *prompt, ...)
   7 {
   8         static spinlock_t readline_lock = SPINLOCK_INITIALIZER_IRQSAVE;
   9         int i, c, echoing, retval;
  10         va_list ap;
  11
  12         spin_lock_irqsave(&readline_lock);
  13         va_start(ap, prompt);
  14         if (prompt != NULL)
  15                 vcprintf(prompt, ap);
  16         va_end(ap);
  17
  18         i = 0;
  19         echoing = iscons(0);
  20         while (1) {
  21                 c = getchar();
  22                 if (c < 0) {
  23                         printk("read error: %d\n", c);
  24                         retval = i;
  25                         break;
  26                 } else if (c == '\b' || c == 0x7f) {
  27                         if (i > 0) {
  28                                 if (echoing)
  29                                         cputchar(c);
  30                                 i--;
  31                         }
  32                         continue;
  33                 } else if (c == '\n' || c == '\r') {
  34                         /* sending a \n regardless, since the serial port gives
  35                          * us a \r for carriage returns. (probably won't get a
  36                          * \r anymore) */
  37                         if (echoing)
  38                                 cputchar('\n');
  39                         assert(i <= buf_l - 1);
  40                         /* never write to buf_l - 1 til the end */
  41                         buf[i++] = c;
  42                         retval =  i;
  43                         break;
  44                 } else if (c >= ' ' && i < buf_l - 1) {
  45                         if (echoing)
  46                                 cputchar(c);
  47                         buf[i++] = c;
  48                 }
  49         }
  50         spin_unlock_irqsave(&readline_lock);
  51         return retval;
  52 }
  53