blob: 1088e288c04d73d6b349b229e2963b5e0e0d83ff [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* ----------------------------------------------------------------------- */
/*
* Oh, it's a waste of space, but oh-so-yummy for debugging.
*/
#include <stdarg.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/string.h>
#include <linux/types.h>
static
int skip_atoi(const char **s)
{
int i = 0;
while (isdigit(**s))
i = i * 10 + *((*s)++) - '0';
return i;
}
/*
* put_dec_full4 handles numbers in the range 0 <= r < 10000.
* The multiplier 0xccd is round(2^15/10), and the approximation
* r/10 == (r * 0xccd) >> 15 is exact for all r < 16389.
*/
static
void put_dec_full4(char *end, unsigned int r)
{
int i;
for (i = 0; i < 3; i++) {
unsigned int q = (r * 0xccd) >> 15;
*--end = '0' + (r - q * 10);
r = q;
}
*--end = '0' + r;
}
/* put_dec is copied from lib/vsprintf.c with small modifications */
/*
* Call put_dec_full4 on x % 10000, return x / 10000.
* The approximation x/10000 == (x * 0x346DC5D7) >> 43
* holds for all x < 1,128,869,999. The largest value this
* helper will ever be asked to convert is 1,125,520,955.
* (second call in the put_dec code, assuming n is all-ones).
*/
static
unsigned int put_dec_helper4(char *end, unsigned int x)
{
unsigned int q = (x * 0x346DC5D7ULL) >> 43;
put_dec_full4(end, x - q * 10000);
return q;
}
/* Based on code by Douglas W. Jones found at
* <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
* (with permission from the author).
* Performs no 64-bit division and hence should be fast on 32-bit machines.
*/
static
char *put_dec(char *end, unsigned long long n)
{
unsigned int d3, d2, d1, q, h;
char *p = end;
d1 = ((unsigned int)n >> 16); /* implicit "& 0xffff" */
h = (n >> 32);
d2 = (h ) & 0xffff;
d3 = (h >> 16); /* implicit "& 0xffff" */
/* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
= 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((unsigned int)n & 0xffff);
q = put_dec_helper4(p, q);
p -= 4;
q += 7671 * d3 + 9496 * d2 + 6 * d1;
q = put_dec_helper4(p, q);
p -= 4;
q += 4749 * d3 + 42 * d2;
q = put_dec_helper4(p, q);
p -= 4;
q += 281 * d3;
q = put_dec_helper4(p, q);
p -= 4;
put_dec_full4(p, q);
p -= 4;
/* strip off the extra 0's we printed */
while (p < end && *p == '0')
++p;
return p;
}
static
char *number(char *end, unsigned long long num, int base, char locase)
{
/*
* locase = 0 or 0x20. ORing digits or letters with 'locase'
* produces same digits or (maybe lowercased) letters
*/
/* we are called with base 8, 10 or 16, only, thus don't need "G..." */
static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */
switch (base) {
case 10:
if (num != 0)
end = put_dec(end, num);
break;
case 8:
for (; num != 0; num >>= 3)
*--end = '0' + (num & 07);
break;
case 16:
for (; num != 0; num >>= 4)
*--end = digits[num & 0xf] | locase;
break;
default:
unreachable();
}
return end;
}
#define ZEROPAD 1 /* pad with zero */
#define SIGN 2 /* unsigned/signed long */
#define PLUS 4 /* show plus */
#define SPACE 8 /* space if plus */
#define LEFT 16 /* left justified */
#define SMALL 32 /* Must be 32 == 0x20 */
#define SPECIAL 64 /* 0x */
#define WIDE 128 /* UTF-16 string */
static
int get_flags(const char **fmt)
{
int flags = 0;
do {
switch (**fmt) {
case '-':
flags |= LEFT;
break;
case '+':
flags |= PLUS;
break;
case ' ':
flags |= SPACE;
break;
case '#':
flags |= SPECIAL;
break;
case '0':
flags |= ZEROPAD;
break;
default:
return flags;
}
++(*fmt);
} while (1);
}
static
int get_int(const char **fmt, va_list *ap)
{
if (isdigit(**fmt))
return skip_atoi(fmt);
if (**fmt == '*') {
++(*fmt);
/* it's the next argument */
return va_arg(*ap, int);
}
return 0;
}
static
unsigned long long get_number(int sign, int qualifier, va_list *ap)
{
if (sign) {
switch (qualifier) {
case 'L':
return va_arg(*ap, long long);
case 'l':
return va_arg(*ap, long);
case 'h':
return (short)va_arg(*ap, int);
case 'H':
return (signed char)va_arg(*ap, int);
default:
return va_arg(*ap, int);
};
} else {
switch (qualifier) {
case 'L':
return va_arg(*ap, unsigned long long);
case 'l':
return va_arg(*ap, unsigned long);
case 'h':
return (unsigned short)va_arg(*ap, int);
case 'H':
return (unsigned char)va_arg(*ap, int);
default:
return va_arg(*ap, unsigned int);
}
}
}
static
char get_sign(long long *num, int flags)
{
if (!(flags & SIGN))
return 0;
if (*num < 0) {
*num = -(*num);
return '-';
}
if (flags & PLUS)
return '+';
if (flags & SPACE)
return ' ';
return 0;
}
static
size_t utf16s_utf8nlen(const u16 *s16, size_t maxlen)
{
size_t len, clen;
for (len = 0; len < maxlen && *s16; len += clen) {
u16 c0 = *s16++;
/* First, get the length for a BMP character */
clen = 1 + (c0 >= 0x80) + (c0 >= 0x800);
if (len + clen > maxlen)
break;
/*
* If this is a high surrogate, and we're already at maxlen, we
* can't include the character if it's a valid surrogate pair.
* Avoid accessing one extra word just to check if it's valid
* or not.
*/
if ((c0 & 0xfc00) == 0xd800) {
if (len + clen == maxlen)
break;
if ((*s16 & 0xfc00) == 0xdc00) {
++s16;
++clen;
}
}
}
return len;
}
static
u32 utf16_to_utf32(const u16 **s16)
{
u16 c0, c1;
c0 = *(*s16)++;
/* not a surrogate */
if ((c0 & 0xf800) != 0xd800)
return c0;
/* invalid: low surrogate instead of high */
if (c0 & 0x0400)
return 0xfffd;
c1 = **s16;
/* invalid: missing low surrogate */
if ((c1 & 0xfc00) != 0xdc00)
return 0xfffd;
/* valid surrogate pair */
++(*s16);
return (0x10000 - (0xd800 << 10) - 0xdc00) + (c0 << 10) + c1;
}
#define PUTC(c) \
do { \
if (pos < size) \
buf[pos] = (c); \
++pos; \
} while (0);
int vsnprintf(char *buf, size_t size, const char *fmt, va_list ap)
{
/* The maximum space required is to print a 64-bit number in octal */
char tmp[(sizeof(unsigned long long) * 8 + 2) / 3];
char *tmp_end = &tmp[ARRAY_SIZE(tmp)];
long long num;
int base;
const char *s;
size_t len, pos;
char sign;
int flags; /* flags to number() */
int field_width; /* width of output field */
int precision; /* min. # of digits for integers; max
number of chars for from string */
int qualifier; /* 'h', 'hh', 'l' or 'll' for integer fields */
va_list args;
/*
* We want to pass our input va_list to helper functions by reference,
* but there's an annoying edge case. If va_list was originally passed
* to us by value, we could just pass &ap down to the helpers. This is
* the case on, for example, X86_32.
* However, on X86_64 (and possibly others), va_list is actually a
* size-1 array containing a structure. Our function parameter ap has
* decayed from T[1] to T*, and &ap has type T** rather than T(*)[1],
* which is what will be expected by a function taking a va_list *
* parameter.
* One standard way to solve this mess is by creating a copy in a local
* variable of type va_list and then passing a pointer to that local
* copy instead, which is what we do here.
*/
va_copy(args, ap);
for (pos = 0; *fmt; ++fmt) {
if (*fmt != '%' || *++fmt == '%') {
PUTC(*fmt);
continue;
}
/* process flags */
flags = get_flags(&fmt);
/* get field width */
field_width = get_int(&fmt, &args);
if (field_width < 0) {
field_width = -field_width;
flags |= LEFT;
}
if (flags & LEFT)
flags &= ~ZEROPAD;
/* get the precision */
precision = -1;
if (*fmt == '.') {
++fmt;
precision = get_int(&fmt, &args);
if (precision >= 0)
flags &= ~ZEROPAD;
}
/* get the conversion qualifier */
qualifier = -1;
if (*fmt == 'h' || *fmt == 'l') {
qualifier = *fmt;
++fmt;
if (qualifier == *fmt) {
qualifier -= 'a'-'A';
++fmt;
}
}
sign = 0;
switch (*fmt) {
case 'c':
flags &= LEFT;
s = tmp;
if (qualifier == 'l') {
((u16 *)tmp)[0] = (u16)va_arg(args, unsigned int);
((u16 *)tmp)[1] = L'\0';
precision = INT_MAX;
goto wstring;
} else {
tmp[0] = (unsigned char)va_arg(args, int);
precision = len = 1;
}
goto output;
case 's':
flags &= LEFT;
if (precision < 0)
precision = INT_MAX;
s = va_arg(args, void *);
if (!s)
s = precision < 6 ? "" : "(null)";
else if (qualifier == 'l') {
wstring:
flags |= WIDE;
precision = len = utf16s_utf8nlen((const u16 *)s, precision);
goto output;
}
precision = len = strnlen(s, precision);
goto output;
/* integer number formats - set up the flags and "break" */
case 'o':
base = 8;
break;
case 'p':
if (precision < 0)
precision = 2 * sizeof(void *);
fallthrough;
case 'x':
flags |= SMALL;
fallthrough;
case 'X':
base = 16;
break;
case 'd':
case 'i':
flags |= SIGN;
fallthrough;
case 'u':
flags &= ~SPECIAL;
base = 10;
break;
default:
/*
* Bail out if the conversion specifier is invalid.
* There's probably a typo in the format string and the
* remaining specifiers are unlikely to match up with
* the arguments.
*/
goto fail;
}
if (*fmt == 'p') {
num = (unsigned long)va_arg(args, void *);
} else {
num = get_number(flags & SIGN, qualifier, &args);
}
sign = get_sign(&num, flags);
if (sign)
--field_width;
s = number(tmp_end, num, base, flags & SMALL);
len = tmp_end - s;
/* default precision is 1 */
if (precision < 0)
precision = 1;
/* precision is minimum number of digits to print */
if (precision < len)
precision = len;
if (flags & SPECIAL) {
/*
* For octal, a leading 0 is printed only if necessary,
* i.e. if it's not already there because of the
* precision.
*/
if (base == 8 && precision == len)
++precision;
/*
* For hexadecimal, the leading 0x is skipped if the
* output is empty, i.e. both the number and the
* precision are 0.
*/
if (base == 16 && precision > 0)
field_width -= 2;
else
flags &= ~SPECIAL;
}
/*
* For zero padding, increase the precision to fill the field
* width.
*/
if ((flags & ZEROPAD) && field_width > precision)
precision = field_width;
output:
/* Calculate the padding necessary */
field_width -= precision;
/* Leading padding with ' ' */
if (!(flags & LEFT))
while (field_width-- > 0)
PUTC(' ');
/* sign */
if (sign)
PUTC(sign);
/* 0x/0X for hexadecimal */
if (flags & SPECIAL) {
PUTC('0');
PUTC( 'X' | (flags & SMALL));
}
/* Zero padding and excess precision */
while (precision-- > len)
PUTC('0');
/* Actual output */
if (flags & WIDE) {
const u16 *ws = (const u16 *)s;
while (len-- > 0) {
u32 c32 = utf16_to_utf32(&ws);
u8 *s8;
size_t clen;
if (c32 < 0x80) {
PUTC(c32);
continue;
}
/* Number of trailing octets */
clen = 1 + (c32 >= 0x800) + (c32 >= 0x10000);
len -= clen;
s8 = (u8 *)&buf[pos];
/* Avoid writing partial character */
PUTC('\0');
pos += clen;
if (pos >= size)
continue;
/* Set high bits of leading octet */
*s8 = (0xf00 >> 1) >> clen;
/* Write trailing octets in reverse order */
for (s8 += clen; clen; --clen, c32 >>= 6)
*s8-- = 0x80 | (c32 & 0x3f);
/* Set low bits of leading octet */
*s8 |= c32;
}
} else {
while (len-- > 0)
PUTC(*s++);
}
/* Trailing padding with ' ' */
while (field_width-- > 0)
PUTC(' ');
}
fail:
va_end(args);
if (size)
buf[min(pos, size-1)] = '\0';
return pos;
}
int snprintf(char *buf, size_t size, const char *fmt, ...)
{
va_list args;
int i;
va_start(args, fmt);
i = vsnprintf(buf, size, fmt, args);
va_end(args);
return i;
}