i386/MIT/course/src/src.lab/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 JOS_KERNEL
  13         if (prompt != NULL)
  14                 cprintf("%s", prompt);
  15 #else
  16         if (prompt != NULL)
  17                 fprintf(1, "%s", prompt);
  18 #endif
  19
  20         i = 0;
  21         echoing = iscons(0);
  22         while (1) {
  23                 c = getchar();
  24                 if (c < 0) {
  25                         if (c != -E_EOF)
  26                                 cprintf("read error: %e\n", c);
  27                         return NULL;
  28                 } else if ((c == '\b' || c == '\x7f') && i > 0) {
  29                         if (echoing)
  30                                 cputchar('\b');
  31                         i--;
  32                 } else if (c >= ' ' && i < BUFLEN-1) {
  33                         if (echoing)
  34                                 cputchar(c);
  35                         buf[i++] = c;
  36                 } else if (c == '\n' || c == '\r') {
  37                         if (echoing)
  38                                 cputchar('\n');
  39                         buf[i] = 0;
  40                         return buf;
  41                 }
  42         }
  43 }
  44