stdio.c

   1 #include <errno.h>
   2 #include <stdarg.h>
   3 #include <stdio.h>
   4 #include <unistd.h>
   5
   6 static char *putstr(char *d, char *s)
   7 {
   8         while (*s)
   9                 *d++ = *s++;
  10         return d;
  11 }
  12
  13 static int digits(unsigned long n, int base)
  14 {
  15         int i;
  16         for (i = 0; n; i++)
  17                 n /= base;
  18         return i ? i : 1;
  19 }
  20
  21 static char *digs = "0123456789abcdef";
  22
  23 static char *putint(char *s, unsigned long n, int base, int sign)
  24 {
  25         int d;
  26         int i;
  27         if (sign && n & 0x80000000) {
  28                 *s++ = '-';
  29                 n = -n;
  30         }
  31         d = digits(n, base);
  32         for (i = 0; i < d; i++) {
  33                 s[d - i - 1] = digs[n % base];
  34                 n /= base;
  35         }
  36         return s + d;
  37 }
  38
  39 int vsprintf(char *dst, char *fmt, va_list ap)
  40 {
  41         char *d = dst;
  42         char *s = fmt;
  43         while (*s) {
  44                 int c = *s++;
  45                 if (c != '%') {
  46                         *d++ = c;
  47                         continue;
  48                 }
  49                 if (*s == 'l')
  50                         s++;
  51                 switch ((c = *s++)) {
  52                 case 'd':
  53                         d = putint(d, va_arg(ap, long), 10, 1);
  54                         break;
  55                 case 'u':
  56                         d = putint(d, va_arg(ap, long), 10, 0);
  57                         break;
  58                 case 'x':
  59                 case 'p':
  60                         d = putint(d, va_arg(ap, long), 16, 0);
  61                         break;
  62                 case 'c':
  63                         *d++ = va_arg(ap, int);
  64                         break;
  65                 case 's':
  66                         d = putstr(d, va_arg(ap, char *));
  67                         break;
  68                 case '\0':
  69                         s--;
  70                         break;
  71                 default:
  72                         *d++ = c;
  73                 }
  74         }
  75         *d = '\0';
  76         return d - dst;
  77 }
  78
  79 static char buf[1 << 12];
  80
  81 static FILE _stdout = {1};
  82 static FILE _stderr = {2};
  83 FILE *stdout = &_stdout;
  84 FILE *stderr = &_stderr;
  85
  86 int printf(char *fmt, ...)
  87 {
  88         va_list ap;
  89         int ret;
  90         va_start(ap, fmt);
  91         ret = vsprintf(buf, fmt, ap);
  92         va_end(ap);
  93         return write(1, buf, ret);
  94 }
  95
  96 int fprintf(FILE *filp, char *fmt, ...)
  97 {
  98         va_list ap;
  99         int ret;
 100         va_start(ap, fmt);
 101         ret = vsprintf(buf, fmt, ap);
 102         va_end(ap);
 103         return write(filp->fd, buf, ret);
 104 }
 105
 106 int sprintf(char *dst, char *fmt, ...)
 107 {
 108         va_list ap;
 109         int ret;
 110         va_start(ap, fmt);
 111         ret = vsprintf(dst, fmt, ap);
 112         va_end(ap);
 113         return ret;
 114 }
 115
 116 void perror(char *s)
 117 {
 118         int idx = errno;
 119         if (idx >= sys_nerr)
 120                 idx = 0;
 121         fprintf(stderr, "%s: %s\n", s, sys_errlist[idx]);
 122 }