i386/ucla/src/lab2/lib/readline.c

   1 #include <inc/stdio.h>
   2 #include <inc/error.h>
   3
   4 #define BUFLEN 1024
   5 static char buf[BUFLEN];
   6
   7 char *
   8 readline(const char *prompt)
   9 {
  10         int i, c, echoing;
  11
  12         if (prompt != NULL)
  13                 cprintf("%s", prompt);
  14
  15         i = 0;
  16         echoing = iscons(0) > 0;
  17         while (1) {
  18                 c = getchar();
  19                 if (c < 0) {
  20                         cprintf("read error: %e\n", c);
  21                         return NULL;
  22                 } else if ((c == '\b' || c == '\x7f') && i > 0) {
  23                         if (echoing)
  24                                 cputchar('\b');
  25                         i--;
  26                 } else if (c >= ' ' && i < BUFLEN-1) {
  27                         if (echoing)
  28                                 cputchar(c);
  29                         buf[i++] = c;
  30                 } else if (c == '\n' || c == '\r') {
  31                         if (echoing)
  32                                 cputchar('\n');
  33                         buf[i] = 0;
  34                         return buf;
  35                 }
  36         }
  37 }
  38