/
scanf.c
184 lines (171 loc) · 3 KB
/
scanf.c
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#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
static int ic(FILE *fp)
{
int nr;
if (fp->back != EOF) {
int i = fp->back;
fp->back = EOF;
return i;
}
while (fp->fd >= 0 && fp->icur == fp->ilen) {
int nr = read(fp->fd, fp->ibuf, fp->isize);
if (nr <= 0)
break;
fp->ilen = nr;
fp->icur = 0;
}
return fp->icur < fp->ilen ? (unsigned char) fp->ibuf[fp->icur++] : EOF;
}
void setbuf(FILE *fp, char *buf)
{
}
int fgetc(FILE *fp)
{
return ic(fp);
}
int getchar(void)
{
return ic(stdin);
}
int ungetc(int c, FILE *fp)
{
if (fp->back == EOF)
fp->back = c;
return fp->back;
}
/* t is 1 for char, 2 for short, 4 for int, and 8 for long */
static int iint(FILE *fp, void *dst, int t, int wid)
{
long n = 0;
int c;
int neg = 0;
c = ic(fp);
if (c == '-')
neg = 1;
if ((c == '-' || c == '+') && wid-- > 0)
c = ic(fp);
if (!isdigit(c) || wid <= 0) {
ungetc(c, fp);
return 1;
}
do {
n = n * 10 + c - '0';
} while (isdigit(c = ic(fp)) && --wid > 0);
ungetc(c, fp);
if (t == 8)
*(long *) dst = neg ? -n : n;
else if (t == 4)
*(int *) dst = neg ? -n : n;
else if (t == 2)
*(short *) dst = neg ? -n : n;
else
*(char *) dst = neg ? -n : n;
return 0;
}
static int istr(FILE *fp, char *dst, int wid)
{
char *d = dst;
int c;
while ((c = ic(fp)) != EOF && wid-- > 0 && !isspace(c))
*d++ = c;
*d = '\0';
ungetc(c, fp);
return d == dst;
}
int vfscanf(FILE *fp, char *fmt, va_list ap)
{
int ret = 0;
int t, c;
int wid = 1 << 20;
while (*fmt) {
while (isspace((unsigned char) *fmt))
fmt++;
while (isspace(c = ic(fp)))
;
ungetc(c, fp);
while (*fmt && *fmt != '%' && !isspace((unsigned char) *fmt))
if (*fmt++ != ic(fp))
return ret;
if (*fmt != '%')
continue;
fmt++;
if (isdigit((unsigned char) *fmt)) {
wid = 0;
while (isdigit((unsigned char) *fmt))
wid = wid * 10 + *fmt++ - '0';
}
t = sizeof(int);
while (*fmt == 'l') {
t = sizeof(long);
fmt++;
}
while (*fmt == 'h') {
t = t < sizeof(int) ? sizeof(char) : sizeof(short);
fmt++;
}
switch (*fmt++) {
case 'u':
case 'd':
if (iint(fp, va_arg(ap, long *), t, wid))
return ret;
ret++;
break;
case 's':
if (istr(fp, va_arg(ap, char *), wid))
return ret;
ret++;
break;
}
}
return ret;
}
int fscanf(FILE *fp, char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = vfscanf(fp, fmt, ap);
va_end(ap);
return ret;
}
int scanf(char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = vfscanf(stdin, fmt, ap);
va_end(ap);
return ret;
}
int vsscanf(char *s, char *fmt, va_list ap)
{
FILE f = {-1, EOF};
f.ibuf = s;
f.ilen = strlen(s);
return vfscanf(&f, fmt, ap);
}
int sscanf(char *s, char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = vsscanf(s, fmt, ap);
va_end(ap);
return ret;
}
char *fgets(char *s, int sz, FILE *fp)
{
int i = 0;
int c;
while (i + 1 < sz && (c = ic(fp)) != EOF) {
s[i++] = c;
if (c == '\n')
break;
}
s[i] = '\0';
return i ? s : NULL;
}