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#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
extern int errno;
extern int get_value(char c, long base);
long ftnum(FILE *stream, int base, int *error) {
char c;
long ret_value = 0;
*error = 0;
// Ignore inital white-space sequence
for (;;) {
if (EOF == (c = fgetc(stream))) {
*error = 1;
return 0;
}
if (!isspace(c)) {
ungetc(c, stream);
break;
}
}
if (c == '\0') {
*error = 1;
return 0;
}
if (!isdigit(c)) {
*error = 1;
return 0;
}
if (!(2 <= base && 36 >= base)) {
*error = 1;
return 0;
}
for (;;) {
if (EOF == (c = fgetc(stream)))
break;
if (c == '\0') {
ungetc(c, stream);
break;
}
int val = get_value(c, base);
if (-1 == val) {
ungetc(c, stream);
break;
}
if (ret_value * base > LONG_MAX - val) {
ungetc(c, stream);
errno = ERANGE;
*error = 1;
return 0;
}
ret_value *= base;
ret_value += val;
}
return ret_value;
}
int vfscanf(FILE *stream, const char *format, va_list ap) {
int rc = 0; // Upon successful completion, these functions shall return the
// number of successfully matched and assigned input items
int cont = 0;
int suppress = 0;
for (; *format; format++) {
if (*format != '%' && !cont) {
char c;
if (isspace(*format))
continue;
if (EOF == (c = fgetc(stream))) {
break;
}
if (*format == c) // TODO: Make sure this is the correct behaviour
continue;
// TODO: Make sure this is the correct behaviour
errno = EINVAL;
assert(0);
break;
}
if (*format == '%' && !cont) {
cont = 1;
continue;
}
int is_long = 0;
switch (*format) {
case 'l':
is_long++;
assert(is_long < 3);
cont = 1;
break;
case 'i': // Matches an optionally signed integer, whose format is the same
// as expected for the subject sequence of strtol() with 0 for the
// base argument.
case 'd': {
// Matches an optionally signed decimal integer, whose format is the
// same as expected for the subject sequence of strtol() with the value
// 10 for the base argument. In the absence of a size modifier, the
// application shall ensure that the corresponding argument is a pointer
// to int.
int err = 0;
int result = ftnum(stream, 10, &err);
if (err) {
cont = 0;
break;
}
if (!suppress) {
if (2 == is_long) {
*((long long *)va_arg(ap, long long *)) = result;
} else if (1 == is_long) {
*((long *)va_arg(ap, long *)) = result;
} else {
*((int *)va_arg(ap, int *)) = result;
}
rc++;
}
assert(0 == err);
cont = 0;
break;
}
case 'c': {
char result = fgetc(stream);
if (!suppress) {
*((char *)va_arg(ap, char *)) = result;
rc++;
}
cont = 0;
break;
}
case '*': // Assignment suppression
suppress = 1;
cont = 1;
break;
default:
printf("vfscanf: Got %c but not supported.\n", *format);
assert(0);
break;
}
if (!cont) {
suppress = 0;
}
}
return rc;
}
struct sscanf_cookie {
const char *s;
unsigned long offset;
};
size_t sscanf_read(FILE *f, unsigned char *s, size_t l) {
struct sscanf_cookie *c = f->cookie;
if (!*(c->s + c->offset)) {
return 0;
}
size_t r = 0;
for (; l && *(c->s); l--, c->offset += 1) {
*s = *(c->s + c->offset);
s++;
r++;
}
if (!(*(c->s + c->offset)))
f->is_eof = 1;
/*
memcpy(s, c->s, l);
c->s += l;*/
return r;
}
int sscanf_seek(FILE *stream, long offset, int whence) {
struct sscanf_cookie *c = stream->cookie;
off_t ret_offset = c->offset;
switch (whence) {
case SEEK_SET:
// TODO: Avoid running past the pointer
// Should that even be checked?
ret_offset = offset;
break;
case SEEK_CUR:
ret_offset += offset;
break;
case SEEK_END:
for (; *(c->s + ret_offset); ret_offset++)
;
break;
default:
return -EINVAL;
break;
}
c->offset = ret_offset;
return ret_offset;
}
int vsscanf(const char *s, const char *restrict format, va_list ap) {
struct sscanf_cookie c = {.s = s, .offset = 0};
FILE f = {
.read = sscanf_read,
.seek = sscanf_seek,
.cookie = &c,
.has_buffered_char = 0,
.is_eof = 0,
.has_error = 0,
.offset_in_file = 0,
};
return vfscanf(&f, format, ap);
}
int sscanf(const char *s, const char *restrict format, ...) {
va_list ap;
va_start(ap, format);
int rc = vsscanf(s, format, ap);
va_end(ap);
return rc;
}
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