gotosocial/vendor/modernc.org/libc/printf.go

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// Copyright 2020 The Libc Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package libc // import "modernc.org/libc"
import (
"bytes"
"fmt"
"strconv"
"strings"
"unsafe"
)
const (
modNone = iota
modHH
modH
modL
modLL
modQ
modCapitalL
modJ
modZ
modCapitalZ
modT
mod32
mod64
)
// Format of the format string
//
// The format string is a character string, beginning and ending in its initial
// shift state, if any. The format string is composed of zero or more
// directives: ordinary characters (not %), which are copied unchanged to
// the output stream; and conversion specifications, each of which results in
// fetching zero or more subsequent arguments.
func printf(format, args uintptr) []byte {
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format0 := format
args0 := args
buf := bytes.NewBuffer(nil)
for {
switch c := *(*byte)(unsafe.Pointer(format)); c {
case '%':
format = printfConversion(buf, format, &args)
case 0:
if dmesgs {
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dmesg("%v: %q, %#x -> %q", origin(1), GoString(format0), args0, buf.Bytes())
}
return buf.Bytes()
default:
format++
buf.WriteByte(c)
}
}
}
// Each conversion specification is introduced by the character %, and ends
// with a conversion specifier. In between there may be (in this order) zero
// or more flags, an optional minimum field width, an optional precision and
// an optional length modifier.
func printfConversion(buf *bytes.Buffer, format uintptr, args *uintptr) uintptr {
format++ // '%'
spec := "%"
// Flags characters
//
// The character % is followed by zero or more of the following flags:
flags:
for {
switch c := *(*byte)(unsafe.Pointer(format)); c {
case '#':
// The value should be converted to an "alternate form". For o conversions,
// the first character of the output string is made zero (by prefixing a 0 if
// it was not zero already). For x and X conversions, a nonzero result has
// the string "0x" (or "0X" for X conversions) prepended to it. For a, A, e,
// E, f, F, g, and G conversions, the result will always contain a decimal
// point, even if no digits follow it (normally, a decimal point appears in the
// results of those conversions only if a digit follows). For g and G
// conversions, trailing zeros are not removed from the result as they would
// otherwise be. For other conversions, the result is undefined.
format++
spec += "#"
case '0':
// The value should be zero padded. For d, i, o, u, x, X, a, A, e, E, f, F,
// g, and G conversions, the converted value is padded on the left with zeros
// rather than blanks. If the 0 and - flags both appear, the 0 flag is
// ignored. If a precision is given with a numeric conversion (d, i, o, u, x,
// and X), the 0 flag is ignored. For other conversions, the behav ior is
// undefined.
format++
spec += "0"
case '-':
// The converted value is to be left adjusted on the field boundary. (The
// default is right justification.) The converted value is padded on the right
// with blanks, rather than on the left with blanks or zeros. A - overrides a
// 0 if both are given.
format++
spec += "-"
case ' ':
// A blank should be left before a positive number (or empty string) produced
// by a signed conversion.
format++
spec += " "
case '+':
// A sign (+ or -) should always be placed before a number produced by a signed
// conversion. By default, a sign is used only for negative numbers. A +
// overrides a space if both are used.
format++
spec += "+"
default:
break flags
}
}
format, width, hasWidth := parseFieldWidth(format)
if hasWidth {
spec += strconv.Itoa(width)
}
format, prec, hasPrecision := parsePrecision(format, args)
format, mod := parseLengthModifier(format)
var str string
more:
// Conversion specifiers
//
// A character that specifies the type of conversion to be applied. The
// conversion specifiers and their meanings are:
switch c := *(*byte)(unsafe.Pointer(format)); c {
case 'd', 'i':
// The int argument is converted to signed decimal notation. The precision,
// if any, gives the minimum number of digits that must appear; if the
// converted value requires fewer digits, it is padded on the left with zeros.
// The default precision is 1. When 0 is printed with an explicit precision 0,
// the output is empty.
format++
var arg int64
switch mod {
case modNone, modL, modLL, mod64:
arg = VaInt64(args)
case modH:
arg = int64(int16(VaInt32(args)))
case modHH:
arg = int64(int8(VaInt32(args)))
case mod32:
arg = int64(VaInt32(args))
default:
panic(todo("", mod))
}
if arg == 0 && hasPrecision && prec == 0 {
break
}
if hasPrecision {
panic(todo("", prec))
}
f := spec + "d"
str = fmt.Sprintf(f, arg)
case 'u':
// The unsigned int argument is converted to unsigned decimal notation. The
// precision, if any, gives the minimum number of digits that must appear; if
// the converted value requires fewer digits, it is padded on the left with
// zeros. The default precision is 1. When 0 is printed with an explicit
// precision 0, the output is empty.
format++
var arg uint64
switch mod {
case modNone, modL, modLL, mod64:
arg = VaUint64(args)
case modH:
arg = uint64(uint16(VaInt32(args)))
case modHH:
arg = uint64(uint8(VaInt32(args)))
case mod32:
arg = uint64(VaInt32(args))
default:
panic(todo("", mod))
}
if arg == 0 && hasPrecision && prec == 0 {
break
}
if hasPrecision {
panic(todo("", prec))
}
f := spec + "d"
str = fmt.Sprintf(f, arg)
case 'o':
// The unsigned int argument is converted to unsigned octal notation. The
// precision, if any, gives the minimum number of digits that must appear; if
// the converted value requires fewer digits, it is padded on the left with
// zeros. The default precision is 1. When 0 is printed with an explicit
// precision 0, the output is empty.
format++
var arg uint64
switch mod {
case modNone, modL, modLL, mod64:
arg = VaUint64(args)
case modH:
arg = uint64(uint16(VaInt32(args)))
case modHH:
arg = uint64(uint8(VaInt32(args)))
case mod32:
arg = uint64(VaInt32(args))
default:
panic(todo("", mod))
}
if arg == 0 && hasPrecision && prec == 0 {
break
}
if hasPrecision {
panic(todo("", prec))
}
f := spec + "o"
str = fmt.Sprintf(f, arg)
case 'I':
if !isWindows {
panic(todo("%#U", c))
}
format++
switch c = *(*byte)(unsafe.Pointer(format)); c {
case 'x', 'X':
// https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-wsprintfa
//
// Ix, IX
//
// 64-bit unsigned hexadecimal integer in lowercase or uppercase on 64-bit
// platforms, 32-bit unsigned hexadecimal integer in lowercase or uppercase on
// 32-bit platforms.
if unsafe.Sizeof(int(0)) == 4 {
mod = mod32
}
case '3':
// https://en.wikipedia.org/wiki/Printf_format_string#Length_field
//
// I32 For integer types, causes printf to expect a 32-bit (double word) integer argument.
format++
switch c = *(*byte)(unsafe.Pointer(format)); c {
case '2':
format++
mod = mod32
goto more
default:
panic(todo("%#U", c))
}
case '6':
// https://en.wikipedia.org/wiki/Printf_format_string#Length_field
//
// I64 For integer types, causes printf to expect a 64-bit (quad word) integer argument.
format++
switch c = *(*byte)(unsafe.Pointer(format)); c {
case '4':
format++
mod = mod64
goto more
default:
panic(todo("%#U", c))
}
default:
panic(todo("%#U", c))
}
fallthrough
case 'X':
fallthrough
case 'x':
// The unsigned int argument is converted to unsigned hexadecimal notation.
// The letters abcdef are used for x conversions; the letters ABCDEF are used
// for X conversions. The precision, if any, gives the minimum number of
// digits that must appear; if the converted value requires fewer digits, it is
// padded on the left with zeros. The default precision is 1. When 0 is
// printed with an explicit precision 0, the output is empty.
format++
var arg uint64
switch mod {
case modNone, modL, modLL, mod64:
arg = VaUint64(args)
case modH:
arg = uint64(uint16(VaInt32(args)))
case modHH:
arg = uint64(uint8(VaInt32(args)))
case mod32:
arg = uint64(VaInt32(args))
default:
panic(todo("", mod))
}
if arg == 0 && hasPrecision && prec == 0 {
break
}
if strings.Contains(spec, "#") && arg == 0 {
spec = strings.ReplaceAll(spec, "#", "")
}
var f string
switch {
case hasPrecision:
f = fmt.Sprintf("%s.%d%c", spec, prec, c)
default:
f = spec + string(c)
}
str = fmt.Sprintf(f, arg)
case 'e', 'E':
// The double argument is rounded and converted in the style [-]d.ddde±dd where
// there is one digit before the decimal-point character and the number of
// digits after it is equal to the precision; if the precision is missing, it
// is taken as 6; if the precision is zero, no decimal-point character appears.
// An E conversion uses the letter E (rather than e) to intro duce the
// exponent. The exponent always contains at least two digits; if the value is
// zero, the exponent is 00.
format++
arg := VaFloat64(args)
if !hasPrecision {
prec = 6
}
f := fmt.Sprintf("%s.%d%c", spec, prec, c)
str = fmt.Sprintf(f, arg)
case 'f', 'F':
// The double argument is rounded and converted to decimal notation in the
// style [-]ddd.ddd, where the number of digits after the decimal-point
// character is equal to the precision specification. If the precision
// is missing, it is taken as 6; if the precision is explicitly zero, no
// decimal-point character appears. If a decimal point appears, at least one
// digit appears before it.
format++
arg := VaFloat64(args)
if !hasPrecision {
prec = 6
}
f := fmt.Sprintf("%s.%d%c", spec, prec, c)
str = fmt.Sprintf(f, arg)
case 'G':
fallthrough
case 'g':
// The double argument is converted in style f or e (or F or E for G
// conversions). The precision specifies the number of significant digits. If
// the precision is missing, 6 digits are given; if the precision is zero, it
// is treated as 1. Style e is used if the exponent from its conversion is
// less than -4 or greater than or equal to the precision. Trailing zeros are
// removed from the fractional part of the result; a decimal point appears only
// if it is followed by at least one digit.
format++
arg := VaFloat64(args)
if !hasPrecision {
prec = 6
}
if prec == 0 {
prec = 1
}
f := fmt.Sprintf("%s.%d%c", spec, prec, c)
str = fmt.Sprintf(f, arg)
case 's':
// If no l modifier is present: the const char * argument is expected to be a
// pointer to an array of character type (pointer to a string). Characters
// from the array are written up to (but not including) a terminating null byte
// ('\0'); if a precision is specified, no more than the number specified are
// written. If a precision is given, no null byte need be present; if
// the precision is not specified, or is greater than the size of the array,
// the array must contain a terminating null byte.
//
// If an l modifier is present: the const wchar_t * argument is expected
// to be a pointer to an array of wide characters. Wide characters from the
// array are converted to multibyte characters (each by a call to the
// wcrtomb(3) function, with a conversion state starting in the initial state
// before the first wide character), up to and including a terminating null
// wide character. The resulting multibyte characters are written up to
// (but not including) the terminating null byte. If a precision is specified,
// no more bytes than the number specified are written, but no partial
// multibyte characters are written. Note that the precision determines the
// number of bytes written, not the number of wide characters or screen
// positions. The array must contain a terminating null wide character,
// unless a precision is given and it is so small that the number of bytes
// written exceeds it before the end of the array is reached.
format++
arg := VaUintptr(args)
switch mod {
case modNone:
var f string
switch {
case hasPrecision:
f = fmt.Sprintf("%s.%ds", spec, prec)
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str = fmt.Sprintf(f, GoString(arg))
default:
f = spec + "s"
str = fmt.Sprintf(f, GoString(arg))
}
default:
panic(todo(""))
}
case 'p':
// The void * pointer argument is printed in hexadecimal (as if by %#x or
// %#lx).
format++
arg := VaUintptr(args)
buf.WriteString("0x")
buf.WriteString(strconv.FormatInt(int64(arg), 16))
case 'c':
// If no l modifier is present, the int argument is converted to an unsigned
// char, and the resulting character is written. If an l modifier is present,
// the wint_t (wide character) ar gument is converted to a multibyte sequence
// by a call to the wcrtomb(3) function, with a conversion state starting in
// the initial state, and the resulting multibyte string is writ ten.
format++
switch mod {
case modNone:
arg := VaInt32(args)
buf.WriteByte(byte(arg))
default:
panic(todo(""))
}
case '%':
// A '%' is written. No argument is converted. The complete conversion
// specification is '%%'.
format++
buf.WriteByte('%')
default:
panic(todo("%#U", c))
}
buf.WriteString(str)
return format
}
// Field width
//
// An optional decimal digit string (with nonzero first digit) specifying a
// minimum field width. If the converted value has fewer characters than the
// field width, it will be padded with spa ces on the left (or right, if the
// left-adjustment flag has been given). Instead of a decimal digit string one
// may write "*" or "*m$" (for some decimal integer m) to specify that the
// field width is given in the next argument, or in the m-th argument,
// respectively, which must be of type int. A negative field width is taken as
// a '-' flag followed by a positive field width. In no case does a
// nonexistent or small field width cause truncation of a field; if the result
// of a conversion is wider than the field width, the field is expanded to
// contain the conversion result.
func parseFieldWidth(format uintptr) (_ uintptr, n int, ok bool) {
first := true
for {
var digit int
switch c := *(*byte)(unsafe.Pointer(format)); {
case first && c == '0':
return format, n, ok
case first && c == '*':
panic(todo(""))
case c >= '0' && c <= '9':
format++
ok = true
first = false
digit = int(c) - '0'
default:
return format, n, ok
}
n0 := n
n = 10*n + digit
if n < n0 {
panic(todo(""))
}
}
}
// Precision
//
// An optional precision, in the form of a period ('.') followed by an
// optional decimal digit string. Instead of a decimal digit string one may
// write "*" or "*m$" (for some decimal integer m) to specify that the
// precision is given in the next argument, or in the m-th argument,
// respectively, which must be of type int. If the precision is given as just
// '.', the precision is taken to be zero. A negative precision is taken
// as if the precision were omitted. This gives the minimum number of digits
// to appear for d, i, o, u, x, and X conversions, the number of digits to
// appear after the radix character for a, A, e, E, f, and F conversions, the
// maximum number of significant digits for g and G conversions, or the maximum
// number of characters to be printed from a string for s and S conversions.
func parsePrecision(format uintptr, args *uintptr) (_ uintptr, n int, ok bool) {
for {
switch c := *(*byte)(unsafe.Pointer(format)); c {
case '.':
format++
first := true
for {
switch c := *(*byte)(unsafe.Pointer(format)); {
case first && c == '*':
format++
n = int(VaInt32(args))
return format, n, true
case c >= '0' && c <= '9':
format++
first = false
n0 := n
n = 10*n + (int(c) - '0')
if n < n0 {
panic(todo(""))
}
default:
return format, n, true
}
}
default:
return format, 0, false
}
}
}
// Length modifier
//
// Here, "integer conversion" stands for d, i, o, u, x, or X conversion.
//
// hh A following integer conversion corresponds to a signed char or
// unsigned char argument, or a following n conversion corresponds to a pointer
// to a signed char argument.
//
// h A following integer conversion corresponds to a short int or unsigned
// short int argument, or a following n conversion corresponds to a pointer to
// a short int argument.
//
// l (ell) A following integer conversion corresponds to a long int or
// unsigned long int argument, or a following n conversion corresponds to a
// pointer to a long int argument, or a fol lowing c conversion corresponds to
// a wint_t argument, or a following s conversion corresponds to a pointer to
// wchar_t argument.
//
// ll (ell-ell). A following integer conversion corresponds to a long long
// int or unsigned long long int argument, or a following n conversion
// corresponds to a pointer to a long long int argument.
//
// q A synonym for ll. This is a nonstandard extension, derived from BSD;
// avoid its use in new code.
//
// L A following a, A, e, E, f, F, g, or G conversion corresponds to a
// long double argument. (C99 allows %LF, but SUSv2 does not.)
//
// j A following integer conversion corresponds to an intmax_t or
// uintmax_t argument, or a following n conversion corresponds to a pointer to
// an intmax_t argument.
//
// z A following integer conversion corresponds to a size_t or ssize_t
// argument, or a following n conversion corresponds to a pointer to a size_t
// argument.
//
// Z A nonstandard synonym for z that predates the appearance of z. Do
// not use in new code.
//
// t A following integer conversion corresponds to a ptrdiff_t argument,
// or a following n conversion corresponds to a pointer to a ptrdiff_t
// argument.
func parseLengthModifier(format uintptr) (_ uintptr, n int) {
switch c := *(*byte)(unsafe.Pointer(format)); c {
case 'h':
format++
n = modH
switch c := *(*byte)(unsafe.Pointer(format)); c {
case 'h':
format++
n = modHH
}
return format, n
case 'l':
format++
n = modL
switch c := *(*byte)(unsafe.Pointer(format)); c {
case 'l':
format++
n = modLL
}
return format, n
case 'q':
panic(todo(""))
case 'L':
panic(todo(""))
case 'j':
panic(todo(""))
case 'z':
panic(todo(""))
case 'Z':
panic(todo(""))
case 't':
panic(todo(""))
default:
return format, 0
}
}