313 lines
7.4 KiB
C
313 lines
7.4 KiB
C
/*
|
|
* Minimal vsnprintf(), snprintf(), sprintf(), and sscanf() for Duktape.
|
|
* The supported conversion formats narrowly match what Duktape needs.
|
|
*/
|
|
|
|
#include <stdarg.h> /* va_list etc */
|
|
#include <stddef.h> /* size_t */
|
|
#include <stdint.h> /* SIZE_MAX */
|
|
|
|
/* Write character with bound checking. Offset 'off' is updated regardless
|
|
* of whether an actual write is made. This is necessary to satisfy snprintf()
|
|
* return value semantics.
|
|
*/
|
|
#define DUK__WRITE_CHAR(c) do { \
|
|
if (off < size) { \
|
|
str[off] = (char) c; \
|
|
} \
|
|
off++; \
|
|
} while (0)
|
|
|
|
/* Digits up to radix 16. */
|
|
static const char duk__format_digits[16] = {
|
|
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
|
|
};
|
|
|
|
/* Format an unsigned long with various options. An unsigned long is large
|
|
* enough for formatting all supported types.
|
|
*/
|
|
static size_t duk__format_long(char *str,
|
|
size_t size,
|
|
size_t off,
|
|
int fixed_length,
|
|
char pad,
|
|
int radix,
|
|
int neg_sign,
|
|
unsigned long v) {
|
|
char buf[24]; /* 2^64 = 18446744073709552000, length 20 */
|
|
char *required;
|
|
char *p;
|
|
int i;
|
|
|
|
/* Format in reverse order first. Ensure at least one digit is output
|
|
* to handle '0' correctly. Note that space padding and zero padding
|
|
* handle negative sign differently:
|
|
*
|
|
* %9d and -321 => ' -321'
|
|
* %09d and -321 => '-00000321'
|
|
*/
|
|
|
|
for (i = 0; i < (int) sizeof(buf); i++) {
|
|
buf[i] = pad; /* compiles into memset() equivalent, avoid memset() dependency */
|
|
}
|
|
|
|
p = buf;
|
|
do {
|
|
*p++ = duk__format_digits[v % radix];
|
|
v /= radix;
|
|
} while (v != 0);
|
|
|
|
required = buf + fixed_length;
|
|
if (p < required && pad == (char) '0') {
|
|
/* Zero padding and we didn't reach maximum length: place
|
|
* negative sign at the last position. We can't get here
|
|
* with fixed_length == 0 so that required[-1] is safe.
|
|
*
|
|
* Technically we should only do this for 'neg_sign == 1',
|
|
* but it's OK to advance the pointer even when that's not
|
|
* the case.
|
|
*/
|
|
p = required - 1;
|
|
}
|
|
if (neg_sign) {
|
|
*p++ = (char) '-';
|
|
}
|
|
if (p < required) {
|
|
p = required;
|
|
}
|
|
|
|
/* Now [buf,p[ contains the result in reverse; copy into place. */
|
|
|
|
while (p > buf) {
|
|
p--;
|
|
DUK__WRITE_CHAR(*p);
|
|
}
|
|
|
|
return off;
|
|
}
|
|
|
|
/* Parse a pointer. Must parse whatever is produced by '%p' in sprintf(). */
|
|
static int duk__parse_pointer(const char *str, void **out) {
|
|
const unsigned char *p;
|
|
unsigned char ch;
|
|
int count;
|
|
int limit;
|
|
long val; /* assume void * fits into long */
|
|
|
|
/* We only need to parse what our minimal printf() produces, so that
|
|
* we can check for a '0x' prefix, and assume all hex digits are
|
|
* lowercase.
|
|
*/
|
|
|
|
p = (const unsigned char *) str;
|
|
if (p[0] != (unsigned char) '0' || p[1] != (unsigned char) 'x') {
|
|
return 0;
|
|
}
|
|
p += 2;
|
|
|
|
for (val = 0, count = 0, limit = sizeof(void *) * 2; count < limit; count++) {
|
|
ch = *p++;
|
|
|
|
val <<= 4;
|
|
if (ch >= (unsigned char) '0' && ch <= (unsigned char) '9') {
|
|
val += ch - (unsigned char) '0';
|
|
} else if (ch >= (unsigned char) 'a' && ch <= (unsigned char) 'f') {
|
|
val += ch - (unsigned char) 'a' + 0x0a;
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* The input may end at a NUL or garbage may follow. As long as we
|
|
* parse the '%p' correctly, garbage is allowed to follow, and the
|
|
* JX pointer parsing also relies on that.
|
|
*/
|
|
|
|
*out = (void *) val;
|
|
return 1;
|
|
}
|
|
|
|
/* Minimal vsnprintf() entry point. */
|
|
int duk_minimal_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
|
|
size_t off = 0;
|
|
const char *p;
|
|
#if 0
|
|
const char *p_tmp;
|
|
const char *p_fmt_start;
|
|
#endif
|
|
char c;
|
|
char pad;
|
|
int fixed_length;
|
|
int is_long;
|
|
|
|
/* Assume str != NULL unless size == 0.
|
|
* Assume format != NULL.
|
|
*/
|
|
|
|
p = format;
|
|
for (;;) {
|
|
c = *p++;
|
|
if (c == (char) 0) {
|
|
break;
|
|
}
|
|
if (c != (char) '%') {
|
|
DUK__WRITE_CHAR(c);
|
|
continue;
|
|
}
|
|
|
|
/* Start format sequence. Scan flags and format specifier. */
|
|
|
|
#if 0
|
|
p_fmt_start = p - 1;
|
|
#endif
|
|
is_long = 0;
|
|
pad = ' ';
|
|
fixed_length = 0;
|
|
for (;;) {
|
|
c = *p++;
|
|
if (c == (char) 'l') {
|
|
is_long = 1;
|
|
} else if (c == (char) '0') {
|
|
/* Only support pad character '0'. */
|
|
pad = '0';
|
|
} else if (c >= (char) '1' && c <= (char) '9') {
|
|
/* Only support fixed lengths 1-9. */
|
|
fixed_length = (int) (c - (char) '0');
|
|
} else if (c == (char) 'd') {
|
|
long v;
|
|
int neg_sign = 0;
|
|
if (is_long) {
|
|
v = va_arg(ap, long);
|
|
} else {
|
|
v = (long) va_arg(ap, int);
|
|
}
|
|
if (v < 0) {
|
|
neg_sign = 1;
|
|
v = -v;
|
|
}
|
|
off = duk__format_long(str, size, off, fixed_length, pad, 10, neg_sign, (unsigned long) v);
|
|
break;
|
|
} else if (c == (char) 'u') {
|
|
unsigned long v;
|
|
if (is_long) {
|
|
v = va_arg(ap, unsigned long);
|
|
} else {
|
|
v = (unsigned long) va_arg(ap, unsigned int);
|
|
}
|
|
off = duk__format_long(str, size, off, fixed_length, pad, 10, 0, v);
|
|
break;
|
|
} else if (c == (char) 'x') {
|
|
unsigned long v;
|
|
if (is_long) {
|
|
v = va_arg(ap, unsigned long);
|
|
} else {
|
|
v = (unsigned long) va_arg(ap, unsigned int);
|
|
}
|
|
off = duk__format_long(str, size, off, fixed_length, pad, 16, 0, v);
|
|
break;
|
|
} else if (c == (char) 'c') {
|
|
char v;
|
|
v = (char) va_arg(ap, int); /* intentionally not 'char' */
|
|
DUK__WRITE_CHAR(v);
|
|
break;
|
|
} else if (c == (char) 's') {
|
|
const char *v;
|
|
char c_tmp;
|
|
v = va_arg(ap, const char *);
|
|
if (v) {
|
|
for (;;) {
|
|
c_tmp = *v++;
|
|
if (c_tmp) {
|
|
DUK__WRITE_CHAR(c_tmp);
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
} else if (c == (char) 'p') {
|
|
/* Assume a void * can be represented by 'long'. This is not
|
|
* always the case. NULL pointer is printed out as 0x0000...
|
|
*/
|
|
void *v;
|
|
v = va_arg(ap, void *);
|
|
DUK__WRITE_CHAR('0');
|
|
DUK__WRITE_CHAR('x');
|
|
off = duk__format_long(str, size, off, sizeof(void *) * 2, '0', 16, 0, (unsigned long) v);
|
|
break;
|
|
} else {
|
|
/* Unrecognized, bail out early. We could also emit the format
|
|
* specifier verbatim, but it'd be a waste of footprint because
|
|
* this case should never happen in practice.
|
|
*/
|
|
#if 0
|
|
DUK__WRITE_CHAR('!');
|
|
#endif
|
|
#if 0
|
|
for (p_tmp = p_fmt_start; p_tmp != p; p_tmp++) {
|
|
DUK__WRITE_CHAR(*p_tmp);
|
|
}
|
|
break;
|
|
#endif
|
|
goto finish;
|
|
}
|
|
}
|
|
}
|
|
|
|
finish:
|
|
if (off < size) {
|
|
str[off] = (char) 0; /* No increment for 'off', not counted in return value. */
|
|
} else if (size > 0) {
|
|
/* Forced termination. */
|
|
str[size - 1] = 0;
|
|
}
|
|
|
|
return (int) off;
|
|
}
|
|
|
|
/* Minimal snprintf() entry point. */
|
|
int duk_minimal_snprintf(char *str, size_t size, const char *format, ...) {
|
|
va_list ap;
|
|
int ret;
|
|
|
|
va_start(ap, format);
|
|
ret = duk_minimal_vsnprintf(str, size, format, ap);
|
|
va_end(ap);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* Minimal sprintf() entry point. */
|
|
int duk_minimal_sprintf(char *str, const char *format, ...) {
|
|
va_list ap;
|
|
int ret;
|
|
|
|
va_start(ap, format);
|
|
ret = duk_minimal_vsnprintf(str, SIZE_MAX, format, ap);
|
|
va_end(ap);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* Minimal sscanf() entry point. */
|
|
int duk_minimal_sscanf(const char *str, const char *format, ...) {
|
|
va_list ap;
|
|
int ret;
|
|
void **out;
|
|
|
|
/* Only the exact "%p" format is supported. */
|
|
if (format[0] != (char) '%' ||
|
|
format[1] != (char) 'p' ||
|
|
format[2] != (char) 0) {
|
|
}
|
|
|
|
va_start(ap, format);
|
|
out = va_arg(ap, void **);
|
|
ret = duk__parse_pointer(str, out);
|
|
va_end(ap);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#undef DUK__WRITE_CHAR
|