scanf.c

   1 #include <stdarg.h>
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <string.h>
   5
   6 static int ic(FILE *fp)
   7 {
   8         int nr;
   9         if (fp->back != EOF) {
  10                 int i = fp->back;
  11                 fp->back = EOF;
  12                 return i;
  13         }
  14         while (fp->fd >= 0 && fp->icur == fp->ilen) {
  15                 int nr = read(fp->fd, fp->ibuf, fp->isize);
  16                 if (nr <= 0)
  17                         break;
  18                 fp->ilen = nr;
  19                 fp->icur = 0;
  20         }
  21         return fp->icur < fp->ilen ? (unsigned char) fp->ibuf[fp->icur++] : EOF;
  22 }
  23
  24 void setbuf(FILE *fp, char *buf)
  25 {
  26 }
  27
  28 int fgetc(FILE *fp)
  29 {
  30         return ic(fp);
  31 }
  32
  33 int getchar(void)
  34 {
  35         return ic(stdin);
  36 }
  37
  38 int ungetc(int c, FILE *fp)
  39 {
  40         if (fp->back == EOF)
  41                 fp->back = c;
  42         return fp->back;
  43 }
  44
  45 static int iint(FILE *fp, void *dst, int l)
  46 {
  47         long n = 0;
  48         int c;
  49         int neg = 0;
  50         c = ic(fp);
  51         if (c == '-') {
  52                 neg = 1;
  53                 c = ic(fp);
  54         }
  55         if (!isdigit(c)) {
  56                 ungetc(c, fp);
  57                 return 1;
  58         }
  59         do {
  60                 n = n * 10 + c - '0';
  61         } while (isdigit(c = ic(fp)));
  62         ungetc(c, fp);
  63         if (l)
  64                 *(long *) dst = neg ? -n : n;
  65         else
  66                 *(int *) dst = neg ? -n : n;
  67         return 0;
  68 }
  69
  70 static int istr(FILE *fp, char *dst)
  71 {
  72         char *d = dst;
  73         int c;
  74         while ((c = ic(fp)) != EOF && !isspace(c))
  75                 *d++ = c;
  76         *d = '\0';
  77         ungetc(c, fp);
  78         return d == dst;
  79 }
  80
  81 int vfscanf(FILE *fp, char *fmt, va_list ap)
  82 {
  83         int ret = 0;
  84         int l = 0;
  85         int c;
  86         char *s;
  87         while (*fmt) {
  88                 while (isspace(*fmt))
  89                         fmt++;
  90                 while (isspace(c = ic(fp)))
  91                         ;
  92                 ungetc(c, fp);
  93                 while (*fmt && *fmt != '%' && !isspace(*fmt))
  94                         if (*fmt++ != ic(fp))
  95                                 return ret;
  96                 if (*fmt != '%')
  97                         continue;
  98                 fmt++;
  99                 if (*fmt == 'l') {
 100                         l = 1;
 101                         fmt++;
 102                 }
 103                 switch (*fmt++) {
 104                 case 'u':
 105                 case 'd':
 106                         if (iint(fp, va_arg(ap, long *), l))
 107                                 return ret;
 108                         ret++;
 109                         break;
 110                 case 's':
 111                         if (istr(fp, va_arg(ap, char *)))
 112                                 return ret;
 113                         ret++;
 114                         break;
 115                 }
 116         }
 117         return ret;
 118 }
 119
 120 int fscanf(FILE *fp, char *fmt, ...)
 121 {
 122         va_list ap;
 123         int ret;
 124         va_start(ap, fmt);
 125         ret = vfscanf(fp, fmt, ap);
 126         va_end(ap);
 127         return ret;
 128 }
 129
 130 int scanf(char *fmt, ...)
 131 {
 132         va_list ap;
 133         int ret;
 134         va_start(ap, fmt);
 135         ret = vfscanf(stdin, fmt, ap);
 136         va_end(ap);
 137         return ret;
 138 }
 139
 140 int vsscanf(char *s, char *fmt, va_list ap)
 141 {
 142         FILE f = {-1, EOF};
 143         f.ibuf = s;
 144         f.ilen = strlen(s);
 145         return vfscanf(&f, fmt, ap);
 146 }
 147
 148 int sscanf(char *s, char *fmt, ...)
 149 {
 150         va_list ap;
 151         int ret;
 152         va_start(ap, fmt);
 153         ret = vsscanf(s, fmt, ap);
 154         va_end(ap);
 155         return ret;
 156 }
 157
 158 char *fgets(char *s, int sz, FILE *fp)
 159 {
 160         int i = 0;
 161         int c;
 162         while (i + 1 < sz && (c = ic(fp)) != EOF) {
 163                 s[i++] = c;
 164                 if (c == '\n')
 165                         break;
 166         }
 167         s[i] = '\0';
 168         return i ? s : NULL;
 169 }