C++ 获取 const char* 字符串长度
C++ 获取 const char* 字符串长度
获取字符串长度的方法有哪些。
strlen
strlen.c
源码如下
size_t
strlen(const char *str)
{
const char *s;
for (s = str; *s; ++s)
;
return (s - str);
}
举个例子
1 2 3 4 5 6
a v b d f \0
初始化语句：s = str（只在循环开始时执行一次）
条件判断：*s（如果*s不为\0,为true）
循环体：空语句;
迭代语句：++s（每次循环体执行完后执行，指针后移）
最后计算出字符串长度为5；
模板
#define HA "HA"
HA宏变量的值为字符串常量的引用，为const char(&)[3] .
所以写出如下模板函数
template <size_t N>
size_t getCharLength(const char(&arr)[N]) {
std::cout << "字符串内容: " << arr << ", 字符串长度: " << N << std::endl;
return N;
}
案例
#include "learn001.hpp"
#include <type_traits>
template <size_t N>
size_t getCharLength(const char(&arr)[N]) {
std::cout << "字符串内容: " << arr << ", 字符串长度: " << N << ", p: " << &arr << std::endl;
return N;
}
int main() {
std::cout << getCharLength("Hello") << "\n";
const char (&str1)[6] = "Hello";
const char (&str2)[6] = "Hello";
const char str3[6] = "Hello";
const char* str4 = new char[6]{'H','e','l','l','o','\0'};
std::cout << sizeof(str1) << ", p: " << &str1 << "\n";
std::cout << sizeof(str2) << ", p: " << &str2 << "\n";
std::cout << sizeof(str3) << ", p: " << &str3 << "\n";
std::cout << sizeof(str4) << ", p: " << reinterpret_cast<const void*>(str4) << "\n";
return 0;
}
可变参数
#include "learn001.hpp"
#include <cstdarg>
/**
* 可变参数
*/
void printInts(const int count, ...){
va_list ap;
va_start(ap, count); // 初始化 ap，使其指向第一个可变参数
for(int i = 0; i < count; i ++ ){
std::cout << va_arg(ap, int) << "\n"; // 获取当前 ap 指向的参数，并将 ap 移动到下一个参数
}
va_end(ap); // 回收 ap
}
int main() {
printInts(1, 10);
printInts(2, 10, 20);
return 0;
}
scanf.c
#include <stdio.h>
#include <stdarg.h>
int
scanf(const char *fmt, ...)
{
int ret;
va_list ap;
va_start(ap, fmt);
ret = vfscanf(stdin, fmt, ap);
va_end(ap);
return (ret);
}
vfscanf.c
#include <ctype.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "local.h"
#ifdef FLOATING_POINT
#include "floatio.h"
#endif
#define BUF 513 /* Maximum length of numeric string. */
/*
* Flags used during conversion.
*/
#define LONG 0x00001 /* l: long or double */
#define LONGDBL 0x00002 /* L: long double; unimplemented */
#define SHORT 0x00004 /* h: short */
#define SHORTSHORT 0x00008 /* hh: 8 bit integer */
#define LLONG 0x00010 /* ll: long long (+ deprecated q: quad) */
#define POINTER 0x00020 /* p: void * (as hex) */
#define SIZEINT 0x00040 /* z: (signed) size_t */
#define MAXINT 0x00080 /* j: intmax_t */
#define PTRINT 0x00100 /* t: ptrdiff_t */
#define NOSKIP 0x00200 /* [ or c: do not skip blanks */
#define SUPPRESS 0x00400 /* *: suppress assignment */
#define UNSIGNED 0x00800 /* %[oupxX] conversions */
/*
* The following are used in numeric conversions only:
* SIGNOK, HAVESIGN, NDIGITS, DPTOK, and EXPOK are for floating point;
* SIGNOK, HAVESIGN, NDIGITS, PFXOK, and NZDIGITS are for integral.
*/
#define SIGNOK 0x01000 /* +/- is (still) legal */
#define HAVESIGN 0x02000 /* sign detected */
#define NDIGITS 0x04000 /* no digits detected */
#define DPTOK 0x08000 /* (float) decimal point is still legal */
#define EXPOK 0x10000 /* (float) exponent (e+3, etc) still legal */
#define PFXOK 0x08000 /* 0x prefix is (still) legal */
#define NZDIGITS 0x10000 /* no zero digits detected */
/*
* Conversion types.
*/
#define CT_CHAR 0 /* %c conversion */
#define CT_CCL 1 /* %[...] conversion */
#define CT_STRING 2 /* %s conversion */
#define CT_INT 3 /* integer, i.e., strtoimax or strtoumax */
#define CT_FLOAT 4 /* floating, i.e., strtod */
#define u_char unsigned char
#define u_long unsigned long
static u_char *__sccl(char *, u_char *);
#if !defined(VFSCANF)
#define VFSCANF vfscanf
#endif
/*
* vfscanf
*/
int
VFSCANF(FILE *fp, const char *fmt0, __va_list ap)
{
u_char *fmt = (u_char *)fmt0;
int c; /* character from format, or conversion */
size_t width; /* field width, or 0 */
char *p; /* points into all kinds of strings */
int n; /* handy integer */
int flags; /* flags as defined above */
char *p0; /* saves original value of p when necessary */
int nassigned; /* number of fields assigned */
int nread; /* number of characters consumed from fp */
int base; /* base argument to strtoimax/strtouimax */
char ccltab[256]; /* character class table for %[...] */
char buf[BUF]; /* buffer for numeric conversions */
/* `basefix' is used to avoid `if' tests in the integer scanner */
static short basefix[17] =
{ 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
FLOCKFILE(fp);
_SET_ORIENTATION(fp, -1);
nassigned = 0;
nread = 0;
base = 0; /* XXX just to keep gcc happy */
for (;;) {
c = *fmt++;
if (c == 0) {
FUNLOCKFILE(fp);
return (nassigned);
}
if (isspace(c)) {
while ((fp->_r > 0 || __srefill(fp) == 0) &&
isspace(*fp->_p))
nread++, fp->_r--, fp->_p++;
continue;
}
if (c != '%')
goto literal;
width = 0;
flags = 0;
/*
* switch on the format. continue if done;
* break once format type is derived.
*/
again: c = *fmt++;
switch (c) {
case '%':
literal:
if (fp->_r <= 0 && __srefill(fp))
goto input_failure;
if (*fp->_p != c)
goto match_failure;
fp->_r--, fp->_p++;
nread++;
continue;
case '*':
flags |= SUPPRESS;
goto again;
case 'j':
flags |= MAXINT;
goto again;
case 'L':
flags |=
(*fmt == 'd') ? LLONG :
(*fmt == 'i') ? LLONG :
(*fmt == 'o') ? LLONG :
(*fmt == 'u') ? LLONG :
(*fmt == 'x') ? LLONG :
LONGDBL;
goto again;
case 'h':
if (*fmt == 'h') {
fmt++;
flags |= SHORTSHORT;
} else {
flags |= SHORT;
}
goto again;
case 'l':
if (*fmt == 'l') {
fmt++;
flags |= LLONG;
} else {
flags |= LONG;
}
goto again;
case 'q':
flags |= LLONG; /* deprecated */
goto again;
case 't':
flags |= PTRINT;
goto again;
case 'z':
flags |= SIZEINT;
goto again;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
width = width * 10 + c - '0';
goto again;
/*
* Conversions.
* Those marked `compat' are for 4.[123]BSD compatibility.
*
* (According to ANSI, E and X formats are supposed
* to the same as e and x. Sorry about that.)
*/
case 'D': /* compat */
flags |= LONG;
/* FALLTHROUGH */
case 'd':
c = CT_INT;
base = 10;
break;
case 'i':
c = CT_INT;
base = 0;
break;
case 'O': /* compat */
flags |= LONG;
/* FALLTHROUGH */
case 'o':
c = CT_INT;
flags |= UNSIGNED;
base = 8;
break;
case 'u':
c = CT_INT;
flags |= UNSIGNED;
base = 10;
break;
case 'X':
case 'x':
flags |= PFXOK; /* enable 0x prefixing */
c = CT_INT;
flags |= UNSIGNED;
base = 16;
break;
#ifdef FLOATING_POINT
case 'E':
case 'G':
case 'e':
case 'f':
case 'g':
c = CT_FLOAT;
break;
#endif
case 's':
c = CT_STRING;
break;
case '[':
fmt = __sccl(ccltab, fmt);
flags |= NOSKIP;
c = CT_CCL;
break;
case 'c':
flags |= NOSKIP;
c = CT_CHAR;
break;
case 'p': /* pointer format is like hex */
flags |= POINTER | PFXOK;
c = CT_INT;
flags |= UNSIGNED;
base = 16;
break;
case 'n':
if (flags & SUPPRESS)
continue;
if (flags & SHORTSHORT)
*va_arg(ap, __signed char *) = nread;
else if (flags & SHORT)
*va_arg(ap, short *) = nread;
else if (flags & LONG)
*va_arg(ap, long *) = nread;
else if (flags & SIZEINT)
*va_arg(ap, ssize_t *) = nread;
else if (flags & PTRINT)
*va_arg(ap, ptrdiff_t *) = nread;
else if (flags & LLONG)
*va_arg(ap, long long *) = nread;
else if (flags & MAXINT)
*va_arg(ap, intmax_t *) = nread;
else
*va_arg(ap, int *) = nread;
continue;
/*
* Disgusting backwards compatibility hacks. XXX
*/
case '\0': /* compat */
FUNLOCKFILE(fp);
return (EOF);
default: /* compat */
if (isupper(c))
flags |= LONG;
c = CT_INT;
base = 10;
break;
}
/*
* We have a conversion that requires input.
*/
if (fp->_r <= 0 && __srefill(fp))
goto input_failure;
/*
* Consume leading white space, except for formats
* that suppress this.
*/
if ((flags & NOSKIP) == 0) {
while (isspace(*fp->_p)) {
nread++;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
goto input_failure;
}
/*
* Note that there is at least one character in
* the buffer, so conversions that do not set NOSKIP
* ca no longer result in an input failure.
*/
}
/*
* Do the conversion.
*/
switch (c) {
case CT_CHAR:
/* scan arbitrary characters (sets NOSKIP) */
if (width == 0)
width = 1;
if (flags & SUPPRESS) {
size_t sum = 0;
for (;;) {
if ((n = fp->_r) < (int)width) {
sum += n;
width -= n;
fp->_p += n;
if (__srefill(fp)) {
if (sum == 0)
goto input_failure;
break;
}
} else {
sum += width;
fp->_r -= width;
fp->_p += width;
break;
}
}
nread += sum;
} else {
size_t r = fread((void *)va_arg(ap, char *), 1,
width, fp);
if (r == 0)
goto input_failure;
nread += r;
nassigned++;
}
break;
case CT_CCL:
/* scan a (nonempty) character class (sets NOSKIP) */
if (width == 0)
width = (size_t)~0; /* `infinity' */
/* take only those things in the class */
if (flags & SUPPRESS) {
n = 0;
while (ccltab[*fp->_p]) {
n++, fp->_r--, fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp)) {
if (n == 0)
goto input_failure;
break;
}
}
if (n == 0)
goto match_failure;
} else {
p0 = p = va_arg(ap, char *);
while (ccltab[*fp->_p]) {
fp->_r--;
*p++ = *fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp)) {
if (p == p0)
goto input_failure;
break;
}
}
n = p - p0;
if (n == 0)
goto match_failure;
*p = '\0';
nassigned++;
}
nread += n;
break;
case CT_STRING:
/* like CCL, but zero-length string OK, & no NOSKIP */
if (width == 0)
width = (size_t)~0;
if (flags & SUPPRESS) {
n = 0;
while (!isspace(*fp->_p)) {
n++, fp->_r--, fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp))
break;
}
nread += n;
} else {
p0 = p = va_arg(ap, char *);
while (!isspace(*fp->_p)) {
fp->_r--;
*p++ = *fp->_p++;
if (--width == 0)
break;
if (fp->_r <= 0 && __srefill(fp))
break;
}
*p = '\0';
nread += p - p0;
nassigned++;
}
continue;
case CT_INT:
/* scan an integer as if by strtoimax/strtoumax */
#ifdef hardway
if (width == 0 || width > sizeof(buf) - 1)
width = sizeof(buf) - 1;
#else
/* size_t is unsigned, hence this optimisation */
if (--width > sizeof(buf) - 2)
width = sizeof(buf) - 2;
width++;
#endif
flags |= SIGNOK | NDIGITS | NZDIGITS;
for (p = buf; width; width--) {
c = *fp->_p;
/*
* Switch on the character; `goto ok'
* if we accept it as a part of number.
*/
switch (c) {
/*
* The digit 0 is always legal, but is
* special. For %i conversions, if no
* digits (zero or nonzero) have been
* scanned (only signs), we will have
* base==0. In that case, we should set
* it to 8 and enable 0x prefixing.
* Also, if we have not scanned zero digits
* before this, do not turn off prefixing
* (someone else will turn it off if we
* have scanned any nonzero digits).
*/
case '0':
if (base == 0) {
base = 8;
flags |= PFXOK;
}
if (flags & NZDIGITS)
flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
else
flags &= ~(SIGNOK|PFXOK|NDIGITS);
goto ok;
/* 1 through 7 always legal */
case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
base = basefix[base];
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* digits 8 and 9 ok iff decimal or hex */
case '8': case '9':
base = basefix[base];
if (base <= 8)
break; /* not legal here */
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* letters ok iff hex */
case 'A': case 'B': case 'C':
case 'D': case 'E': case 'F':
case 'a': case 'b': case 'c':
case 'd': case 'e': case 'f':
/* no need to fix base here */
if (base <= 10)
break; /* not legal here */
flags &= ~(SIGNOK | PFXOK | NDIGITS);
goto ok;
/* sign ok only as first character */
case '+': case '-':
if (flags & SIGNOK) {
flags &= ~SIGNOK;
flags |= HAVESIGN;
goto ok;
}
break;
/*
* x ok iff flag still set and 2nd char (or
* 3rd char if we have a sign).
*/
case 'x': case 'X':
if ((flags & PFXOK) && p ==
buf + 1 + !!(flags & HAVESIGN)) {
base = 16; /* if %i */
flags &= ~PFXOK;
goto ok;
}
break;
}
/*
* If we got here, c is not a legal character
* for a number. Stop accumulating digits.
*/
break;
ok:
/*
* c is legal: store it and look at the next.
*/
*p++ = c;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
break; /* EOF */
}
/*
* If we had only a sign, it is no good; push
* back the sign. If the number ends in `x',
* it was [sign] '0' 'x', so push back the x
* and treat it as [sign] '0'.
*/
if (flags & NDIGITS) {
if (p > buf)
(void) ungetc(*(u_char *)--p, fp);
goto match_failure;
}
c = ((u_char *)p)[-1];
if (c == 'x' || c == 'X') {
--p;
(void) ungetc(c, fp);
}
if ((flags & SUPPRESS) == 0) {
uintmax_t res;
*p = '\0';
if (flags & UNSIGNED)
res = strtoumax(buf, NULL, base);
else
res = strtoimax(buf, NULL, base);
if (flags & POINTER)
*va_arg(ap, void **) =
(void *)(uintptr_t)res;
else if (flags & MAXINT)
*va_arg(ap, intmax_t *) = res;
else if (flags & LLONG)
*va_arg(ap, long long *) = res;
else if (flags & SIZEINT)
*va_arg(ap, ssize_t *) = res;
else if (flags & PTRINT)
*va_arg(ap, ptrdiff_t *) = res;
else if (flags & LONG)
*va_arg(ap, long *) = res;
else if (flags & SHORT)
*va_arg(ap, short *) = res;
else if (flags & SHORTSHORT)
*va_arg(ap, __signed char *) = res;
else
*va_arg(ap, int *) = res;
nassigned++;
}
nread += p - buf;
break;
#ifdef FLOATING_POINT
case CT_FLOAT:
/* scan a floating point number as if by strtod */
#ifdef hardway
if (width == 0 || width > sizeof(buf) - 1)
width = sizeof(buf) - 1;
#else
/* size_t is unsigned, hence this optimisation */
if (--width > sizeof(buf) - 2)
width = sizeof(buf) - 2;
width++;
#endif
flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
for (p = buf; width; width--) {
c = *fp->_p;
/*
* This code mimicks the integer conversion
* code, but is much simpler.
*/
switch (c) {
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9':
flags &= ~(SIGNOK | NDIGITS);
goto fok;
case '+': case '-':
if (flags & SIGNOK) {
flags &= ~SIGNOK;
goto fok;
}
break;
case '.':
if (flags & DPTOK) {
flags &= ~(SIGNOK | DPTOK);
goto fok;
}
break;
case 'e': case 'E':
/* no exponent without some digits */
if ((flags&(NDIGITS|EXPOK)) == EXPOK) {
flags =
(flags & ~(EXPOK|DPTOK)) |
SIGNOK | NDIGITS;
goto fok;
}
break;
}
break;
fok:
*p++ = c;
if (--fp->_r > 0)
fp->_p++;
else if (__srefill(fp))
break; /* EOF */
}
/*
* If no digits, might be missing exponent digits
* (just give back the exponent) or might be missing
* regular digits, but had sign and/or decimal point.
*/
if (flags & NDIGITS) {
if (flags & EXPOK) {
/* no digits at all */
while (p > buf)
ungetc(*(u_char *)--p, fp);
goto match_failure;
}
/* just a bad exponent (e and maybe sign) */
c = *(u_char *)--p;
if (c != 'e' && c != 'E') {
(void) ungetc(c, fp);/* sign */
c = *(u_char *)--p;
}
(void) ungetc(c, fp);
}
if ((flags & SUPPRESS) == 0) {
double res;
*p = '\0';
res = strtod(buf, (char **) NULL);
if (flags & LONGDBL)
*va_arg(ap, long double *) = res;
else if (flags & LONG)
*va_arg(ap, double *) = res;
else
*va_arg(ap, float *) = res;
nassigned++;
}
nread += p - buf;
break;
#endif /* FLOATING_POINT */
}
}
input_failure:
if (nassigned == 0)
nassigned = -1;
match_failure:
FUNLOCKFILE(fp);
return (nassigned);
}
/*
* Fill in the given table from the scanset at the given format
* (just after `['). Return a pointer to the character past the
* closing `]'. The table has a 1 wherever characters should be
* considered part of the scanset.
*/
static u_char *
__sccl(char *tab, u_char *fmt)
{
int c, n, v;
/* first `clear' the whole table */
c = *fmt++; /* first char hat => negated scanset */
if (c == '^') {
v = 1; /* default => accept */
c = *fmt++; /* get new first char */
} else
v = 0; /* default => reject */
/* should probably use memset here */
for (n = 0; n < 256; n++)
tab[n] = v;
if (c == 0)
return (fmt - 1);/* format ended before closing ] */
/*
* Now set the entries corresponding to the actual scanset
* to the opposite of the above.
*
* The first character may be ']' (or '-') without being special;
* the last character may be '-'.
*/
v = 1 - v;
for (;;) {
tab[c] = v; /* take character c */
doswitch:
n = *fmt++; /* and examine the next */
switch (n) {
case 0: /* format ended too soon */
return (fmt - 1);
case '-':
/*
* A scanset of the form
* [01+-]
* is defined as `the digit 0, the digit 1,
* the character +, the character -', but
* the effect of a scanset such as
* [a-zA-Z0-9]
* is implementation defined. The V7 Unix
* scanf treats `a-z' as `the letters a through
* z', but treats `a-a' as `the letter a, the
* character -, and the letter a'.
*
* For compatibility, the `-' is not considerd
* to define a range if the character following
* it is either a close bracket (required by ANSI)
* or is not numerically greater than the character
* we just stored in the table (c).
*/
n = *fmt;
if (n == ']' || n < c) {
c = '-';
break; /* resume the for(;;) */
}
fmt++;
do { /* fill in the range */
tab[++c] = v;
} while (c < n);
#if 1 /* XXX another disgusting compatibility hack */
/*
* Alas, the V7 Unix scanf also treats formats
* such as [a-c-e] as `the letters a through e'.
* This too is permitted by the standard....
*/
goto doswitch;
#else
c = *fmt++;
if (c == 0)
return (fmt - 1);
if (c == ']')
return (fmt);
#endif
break;
case ']': /* end of scanset */
return (fmt);
default: /* just another character */
c = n;
break;
}
}
/* NOTREACHED */
}
printf.c
#include <stdio.h>
#include <stdarg.h>
int
printf(const char *fmt, ...)
{
int ret;
va_list ap;
va_start(ap, fmt);
ret = vfprintf(stdout, fmt, ap);
va_end(ap);
return (ret);
}
vfprintf.c
#include <sys/types.h>
#include <sys/mman.h>
#include <errno.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "local.h"
#include "fvwrite.h"
static void __find_arguments(const char *fmt0, va_list ap, va_list **argtable,
size_t *argtablesiz);
static int __grow_type_table(unsigned char **typetable, int *tablesize);
/*
* Flush out all the vectors defined by the given uio,
* then reset it so that it can be reused.
*/
static int
__sprint(FILE *fp, struct __suio *uio)
{
int err;
if (uio->uio_resid == 0) {
uio->uio_iovcnt = 0;
return (0);
}
err = __sfvwrite(fp, uio);
uio->uio_resid = 0;
uio->uio_iovcnt = 0;
return (err);
}
/*
* Helper function for `fprintf to unbuffered unix file': creates a
* temporary buffer. We only work on write-only files; this avoids
* worries about ungetc buffers and so forth.
*/
static int
__sbprintf(FILE *fp, const char *fmt, va_list ap)
{
int ret;
FILE fake;
struct __sfileext fakeext;
unsigned char buf[BUFSIZ];
_FILEEXT_SETUP(&fake, &fakeext);
/* copy the important variables */
fake._flags = fp->_flags & ~__SNBF;
fake._file = fp->_file;
fake._cookie = fp->_cookie;
fake._write = fp->_write;
/* set up the buffer */
fake._bf._base = fake._p = buf;
fake._bf._size = fake._w = sizeof(buf);
fake._lbfsize = 0; /* not actually used, but Just In Case */
/* do the work, then copy any error status */
ret = __vfprintf(&fake, fmt, ap);
if (ret >= 0 && __sflush(&fake))
ret = EOF;
if (fake._flags & __SERR)
fp->_flags |= __SERR;
return (ret);
}
#ifdef FLOATING_POINT
#include <locale.h>
#include <math.h>
#include "floatio.h"
#define BUF (MAXEXP+MAXFRACT+1) /* + decimal point */
#define DEFPREC 6
static char *cvt(double, int, int, char *, int *, int, int *);
static int exponent(char *, int, int);
#else /* no FLOATING_POINT */
#define BUF 40
#endif /* FLOATING_POINT */
#define STATIC_ARG_TBL_SIZE 8 /* Size of static argument table. */
/* BIONIC: do not link libm for only two rather simple functions */
#ifdef FLOATING_POINT
static int _my_isinf(double);
static int _my_isnan(double);
#endif
/*
* Macros for converting digits to letters and vice versa
*/
#define to_digit(c) ((c) - '0')
#define is_digit(c) ((unsigned)to_digit(c) <= 9)
#define to_char(n) ((n) + '0')
/*
* Flags used during conversion.
*/
#define ALT 0x0001 /* alternate form */
#define HEXPREFIX 0x0002 /* add 0x or 0X prefix */
#define LADJUST 0x0004 /* left adjustment */
#define LONGDBL 0x0008 /* long double; unimplemented */
#define LONGINT 0x0010 /* long integer */
#define LLONGINT 0x0020 /* long long integer */
#define SHORTINT 0x0040 /* short integer */
#define ZEROPAD 0x0080 /* zero (as opposed to blank) pad */
#define FPT 0x0100 /* Floating point number */
#define PTRINT 0x0200 /* (unsigned) ptrdiff_t */
#define SIZEINT 0x0400 /* (signed) size_t */
#define CHARINT 0x0800 /* 8 bit integer */
#define MAXINT 0x1000 /* largest integer size (intmax_t) */
int
vfprintf(FILE *fp, const char *fmt0, __va_list ap)
{
int ret;
FLOCKFILE(fp);
ret = __vfprintf(fp, fmt0, ap);
FUNLOCKFILE(fp);
return (ret);
}
int
__vfprintf(FILE *fp, const char *fmt0, __va_list ap)
{
char *fmt; /* format string */
int ch; /* character from fmt */
int n, m, n2; /* handy integers (short term usage) */
char *cp; /* handy char pointer (short term usage) */
char *cp_free = NULL; /* BIONIC: copy of cp to be freed after usage */
struct __siov *iovp;/* for PRINT macro */
int flags; /* flags as above */
int ret; /* return value accumulator */
int width; /* width from format (%8d), or 0 */
int prec; /* precision from format (%.3d), or -1 */
char sign; /* sign prefix (' ', '+', '-', or \0) */
wchar_t wc;
void* ps;
#ifdef FLOATING_POINT
char *decimal_point = ".";
char softsign; /* temporary negative sign for floats */
double _double = 0.; /* double precision arguments %[eEfgG] */
int expt; /* integer value of exponent */
int expsize = 0; /* character count for expstr */
int ndig; /* actual number of digits returned by cvt */
char expstr[7]; /* buffer for exponent string */
#endif
uintmax_t _umax; /* integer arguments %[diouxX] */
enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
int dprec; /* a copy of prec if [diouxX], 0 otherwise */
int realsz; /* field size expanded by dprec */
int size; /* size of converted field or string */
char* xdigs = NULL; /* digits for [xX] conversion */
#define NIOV 8
struct __suio uio; /* output information: summary */
struct __siov iov[NIOV];/* ... and individual io vectors */
char buf[BUF]; /* space for %c, %[diouxX], %[eEfgG] */
char ox[2]; /* space for 0x hex-prefix */
va_list *argtable; /* args, built due to positional arg */
va_list statargtable[STATIC_ARG_TBL_SIZE];
size_t argtablesiz;
int nextarg; /* 1-based argument index */
va_list orgap; /* original argument pointer */
/*
* Choose PADSIZE to trade efficiency vs. size. If larger printf
* fields occur frequently, increase PADSIZE and make the initialisers
* below longer.
*/
#define PADSIZE 16 /* pad chunk size */
static const char blanks[PADSIZE] =
{' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '};
static const char zeroes[PADSIZE] =
{'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'};
/*
* BEWARE, these `goto error' on error, and PAD uses `n'.
*/
#define PRINT(ptr, len) do { \
iovp->iov_base = (ptr); \
iovp->iov_len = (len); \
uio.uio_resid += (len); \
iovp++; \
if (++uio.uio_iovcnt >= NIOV) { \
if (__sprint(fp, &uio)) \
goto error; \
iovp = iov; \
} \
} while (0)
#define PAD(howmany, with) do { \
if ((n = (howmany)) > 0) { \
while (n > PADSIZE) { \
PRINT(with, PADSIZE); \
n -= PADSIZE; \
} \
PRINT(with, n); \
} \
} while (0)
#define FLUSH() do { \
if (uio.uio_resid && __sprint(fp, &uio)) \
goto error; \
uio.uio_iovcnt = 0; \
iovp = iov; \
} while (0)
/*
* To extend shorts properly, we need both signed and unsigned
* argument extraction methods.
*/
#define SARG() \
((intmax_t)(flags&MAXINT ? GETARG(intmax_t) : \
flags&LLONGINT ? GETARG(long long) : \
flags&LONGINT ? GETARG(long) : \
flags&PTRINT ? GETARG(ptrdiff_t) : \
flags&SIZEINT ? GETARG(ssize_t) : \
flags&SHORTINT ? (short)GETARG(int) : \
flags&CHARINT ? (__signed char)GETARG(int) : \
GETARG(int)))
#define UARG() \
((uintmax_t)(flags&MAXINT ? GETARG(uintmax_t) : \
flags&LLONGINT ? GETARG(unsigned long long) : \
flags&LONGINT ? GETARG(unsigned long) : \
flags&PTRINT ? (uintptr_t)GETARG(ptrdiff_t) : /* XXX */ \
flags&SIZEINT ? GETARG(size_t) : \
flags&SHORTINT ? (unsigned short)GETARG(int) : \
flags&CHARINT ? (unsigned char)GETARG(int) : \
GETARG(unsigned int)))
/*
* Get * arguments, including the form *nn$. Preserve the nextarg
* that the argument can be gotten once the type is determined.
*/
#define GETASTER(val) \
n2 = 0; \
cp = fmt; \
while (is_digit(*cp)) { \
n2 = 10 * n2 + to_digit(*cp); \
cp++; \
} \
if (*cp == '$') { \
int hold = nextarg; \
if (argtable == NULL) { \
argtable = statargtable; \
__find_arguments(fmt0, orgap, &argtable, &argtablesiz); \
} \
nextarg = n2; \
val = GETARG(int); \
nextarg = hold; \
fmt = ++cp; \
} else { \
val = GETARG(int); \
}
/*
* Get the argument indexed by nextarg. If the argument table is
* built, use it to get the argument. If its not, get the next
* argument (and arguments must be gotten sequentially).
*/
#define GETARG(type) \
(((argtable != NULL) ? (void)(ap = argtable[nextarg]) : (void)0), \
nextarg++, va_arg(ap, type))
_SET_ORIENTATION(fp, -1);
/* sorry, fprintf(read_only_file, "") returns EOF, not 0 */
if (cantwrite(fp)) {
errno = EBADF;
return (EOF);
}
/* optimise fprintf(stderr) (and other unbuffered Unix files) */
if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) &&
fp->_file >= 0)
return (__sbprintf(fp, fmt0, ap));
fmt = (char *)fmt0;
argtable = NULL;
nextarg = 1;
va_copy(orgap, ap);
uio.uio_iov = iovp = iov;
uio.uio_resid = 0;
uio.uio_iovcnt = 0;
ret = 0;
memset(&ps, 0, sizeof(ps));
/*
* Scan the format for conversions (`%' character).
*/
for (;;) {
cp = fmt;
#if 1 /* BIONIC */
n = -1;
while ( (wc = *fmt) != 0 ) {
if (wc == '%') {
n = 1;
break;
}
fmt++;
}
#else
while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
fmt += n;
if (wc == '%') {
fmt--;
break;
}
}
#endif
if ((m = fmt - cp) != 0) {
PRINT(cp, m);
ret += m;
}
if (n <= 0)
goto done;
fmt++; /* skip over '%' */
flags = 0;
dprec = 0;
width = 0;
prec = -1;
sign = '\0';
rflag: ch = *fmt++;
reswitch: switch (ch) {
case ' ':
/*
* ``If the space and + flags both appear, the space
* flag will be ignored.''
* -- ANSI X3J11
*/
if (!sign)
sign = ' ';
goto rflag;
case '#':
flags |= ALT;
goto rflag;
case '*':
/*
* ``A negative field width argument is taken as a
* - flag followed by a positive field width.''
* -- ANSI X3J11
* They don't exclude field widths read from args.
*/
GETASTER(width);
if (width >= 0)
goto rflag;
width = -width;
/* FALLTHROUGH */
case '-':
flags |= LADJUST;
goto rflag;
case '+':
sign = '+';
goto rflag;
case '.':
if ((ch = *fmt++) == '*') {
GETASTER(n);
prec = n < 0 ? -1 : n;
goto rflag;
}
n = 0;
while (is_digit(ch)) {
n = 10 * n + to_digit(ch);
ch = *fmt++;
}
if (ch == '$') {
nextarg = n;
if (argtable == NULL) {
argtable = statargtable;
__find_arguments(fmt0, orgap,
&argtable, &argtablesiz);
}
goto rflag;
}
prec = n < 0 ? -1 : n;
goto reswitch;
case '0':
/*
* ``Note that 0 is taken as a flag, not as the
* beginning of a field width.''
* -- ANSI X3J11
*/
flags |= ZEROPAD;
goto rflag;
case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
n = 0;
do {
n = 10 * n + to_digit(ch);
ch = *fmt++;
} while (is_digit(ch));
if (ch == '$') {
nextarg = n;
if (argtable == NULL) {
argtable = statargtable;
__find_arguments(fmt0, orgap,
&argtable, &argtablesiz);
}
goto rflag;
}
width = n;
goto reswitch;
#ifdef FLOATING_POINT
case 'L':
flags |= LONGDBL;
goto rflag;
#endif
case 'h':
flags |= SHORTINT;
goto rflag;
case 'j':
flags |= MAXINT;
goto rflag;
case 'l':
if (*fmt == 'l') {
fmt++;
flags |= LLONGINT;
} else {
flags |= LONGINT;
}
goto rflag;
case 'q':
flags |= LLONGINT;
goto rflag;
case 't':
flags |= PTRINT;
goto rflag;
case 'z':
flags |= SIZEINT;
goto rflag;
case 'c':
*(cp = buf) = GETARG(int);
size = 1;
sign = '\0';
break;
case 'D':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'd':
case 'i':
_umax = SARG();
if ((intmax_t)_umax < 0) {
_umax = -_umax;
sign = '-';
}
base = DEC;
goto number;
#ifdef FLOATING_POINT
case 'e':
case 'E':
case 'f':
case 'g':
case 'G':
if (prec == -1) {
prec = DEFPREC;
} else if ((ch == 'g' || ch == 'G') && prec == 0) {
prec = 1;
}
if (flags & LONGDBL) {
_double = (double) GETARG(long double);
} else {
_double = GETARG(double);
}
/* do this before tricky precision changes */
if (_my_isinf(_double)) {
if (_double < 0)
sign = '-';
cp = "Inf";
size = 3;
break;
}
if (_my_isnan(_double)) {
cp = "NaN";
size = 3;
break;
}
flags |= FPT;
cp = cvt(_double, prec, flags, &softsign,
&expt, ch, &ndig);
cp_free = cp;
if (ch == 'g' || ch == 'G') {
if (expt <= -4 || expt > prec)
ch = (ch == 'g') ? 'e' : 'E';
else
ch = 'g';
}
if (ch <= 'e') { /* 'e' or 'E' fmt */
--expt;
expsize = exponent(expstr, expt, ch);
size = expsize + ndig;
if (ndig > 1 || flags & ALT)
++size;
} else if (ch == 'f') { /* f fmt */
if (expt > 0) {
size = expt;
if (prec || flags & ALT)
size += prec + 1;
} else /* "0.X" */
size = prec + 2;
} else if (expt >= ndig) { /* fixed g fmt */
size = expt;
if (flags & ALT)
++size;
} else
size = ndig + (expt > 0 ?
1 : 2 - expt);
if (softsign)
sign = '-';
break;
#endif /* FLOATING_POINT */
/* the Android security team suggests removing support for %n
* since it has no real practical value, and could lead to
* running malicious code (for really bugy programs that
* send to printf() user-generated formatting strings).
*/
#if 0
case 'n':
if (flags & LLONGINT)
*GETARG(long long *) = ret;
else if (flags & LONGINT)
*GETARG(long *) = ret;
else if (flags & SHORTINT)
*GETARG(short *) = ret;
else if (flags & CHARINT)
*GETARG(__signed char *) = ret;
else if (flags & PTRINT)
*GETARG(ptrdiff_t *) = ret;
else if (flags & SIZEINT)
*GETARG(ssize_t *) = ret;
else if (flags & MAXINT)
*GETARG(intmax_t *) = ret;
else
*GETARG(int *) = ret;
continue; /* no output */
#endif
case 'O':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'o':
_umax = UARG();
base = OCT;
goto nosign;
case 'p':
/*
* ``The argument shall be a pointer to void. The
* value of the pointer is converted to a sequence
* of printable characters, in an implementation-
* defined manner.''
* -- ANSI X3J11
*/
/* NOSTRICT */
_umax = (u_long)GETARG(void *);
base = HEX;
xdigs = "0123456789abcdef";
flags |= HEXPREFIX;
ch = 'x';
goto nosign;
case 's':
if ((cp = GETARG(char *)) == NULL)
cp = "(null)";
if (prec >= 0) {
/*
* can't use strlen; can only look for the
* NUL in the first `prec' characters, and
* strlen() will go further.
*/
char *p = memchr(cp, 0, prec);
if (p != NULL) {
size = p - cp;
if (size > prec)
size = prec;
} else
size = prec;
} else
size = strlen(cp);
sign = '\0';
break;
case 'U':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'u':
_umax = UARG();
base = DEC;
goto nosign;
case 'X':
xdigs = "0123456789ABCDEF";
goto hex;
case 'x':
xdigs = "0123456789abcdef";
hex: _umax = UARG();
base = HEX;
/* leading 0x/X only if non-zero */
if (flags & ALT && _umax != 0)
flags |= HEXPREFIX;
/* unsigned conversions */
nosign: sign = '\0';
/*
* ``... diouXx conversions ... if a precision is
* specified, the 0 flag will be ignored.''
* -- ANSI X3J11
*/
number: if ((dprec = prec) >= 0)
flags &= ~ZEROPAD;
/*
* ``The result of converting a zero value with an
* explicit precision of zero is no characters.''
* -- ANSI X3J11
*/
cp = buf + BUF;
if (_umax != 0 || prec != 0) {
/*
* Unsigned mod is hard, and unsigned mod
* by a constant is easier than that by
* a variable; hence this switch.
*/
switch (base) {
case OCT:
do {
*--cp = to_char(_umax & 7);
_umax >>= 3;
} while (_umax);
/* handle octal leading 0 */
if (flags & ALT && *cp != '0')
*--cp = '0';
break;
case DEC:
/* many numbers are 1 digit */
while (_umax >= 10) {
*--cp = to_char(_umax % 10);
_umax /= 10;
}
*--cp = to_char(_umax);
break;
case HEX:
do {
*--cp = xdigs[_umax & 15];
_umax >>= 4;
} while (_umax);
break;
default:
cp = "bug in vfprintf: bad base";
size = strlen(cp);
goto skipsize;
}
}
size = buf + BUF - cp;
skipsize:
break;
default: /* "%?" prints ?, unless ? is NUL */
if (ch == '\0')
goto done;
/* pretend it was %c with argument ch */
cp = buf;
*cp = ch;
size = 1;
sign = '\0';
break;
}
/*
* All reasonable formats wind up here. At this point, `cp'
* points to a string which (if not flags&LADJUST) should be
* padded out to `width' places. If flags&ZEROPAD, it should
* first be prefixed by any sign or other prefix; otherwise,
* it should be blank padded before the prefix is emitted.
* After any left-hand padding and prefixing, emit zeroes
* required by a decimal [diouxX] precision, then print the
* string proper, then emit zeroes required by any leftover
* floating precision; finally, if LADJUST, pad with blanks.
*
* Compute actual size, so we know how much to pad.
* size excludes decimal prec; realsz includes it.
*/
realsz = dprec > size ? dprec : size;
if (sign)
realsz++;
else if (flags & HEXPREFIX)
realsz+= 2;
/* right-adjusting blank padding */
if ((flags & (LADJUST|ZEROPAD)) == 0)
PAD(width - realsz, blanks);
/* prefix */
if (sign) {
PRINT(&sign, 1);
} else if (flags & HEXPREFIX) {
ox[0] = '0';
ox[1] = ch;
PRINT(ox, 2);
}
/* right-adjusting zero padding */
if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
PAD(width - realsz, zeroes);
/* leading zeroes from decimal precision */
PAD(dprec - size, zeroes);
/* the string or number proper */
#ifdef FLOATING_POINT
if ((flags & FPT) == 0) {
PRINT(cp, size);
} else { /* glue together f_p fragments */
if (ch >= 'f') { /* 'f' or 'g' */
if (_double == 0) {
/* kludge for __dtoa irregularity */
PRINT("0", 1);
if (expt < ndig || (flags & ALT) != 0) {
PRINT(decimal_point, 1);
PAD(ndig - 1, zeroes);
}
} else if (expt <= 0) {
PRINT("0", 1);
PRINT(decimal_point, 1);
PAD(-expt, zeroes);
PRINT(cp, ndig);
} else if (expt >= ndig) {
PRINT(cp, ndig);
PAD(expt - ndig, zeroes);
if (flags & ALT)
PRINT(".", 1);
} else {
PRINT(cp, expt);
cp += expt;
PRINT(".", 1);
PRINT(cp, ndig-expt);
}
} else { /* 'e' or 'E' */
if (ndig > 1 || flags & ALT) {
ox[0] = *cp++;
ox[1] = '.';
PRINT(ox, 2);
if (_double) {
PRINT(cp, ndig-1);
} else /* 0.[0..] */
/* __dtoa irregularity */
PAD(ndig - 1, zeroes);
} else /* XeYYY */
PRINT(cp, 1);
PRINT(expstr, expsize);
}
}
#else
PRINT(cp, size);
#endif
/* left-adjusting padding (always blank) */
if (flags & LADJUST)
PAD(width - realsz, blanks);
/* finally, adjust ret */
ret += width > realsz ? width : realsz;
FLUSH(); /* copy out the I/O vectors */
#if 1 /* BIONIC: remove memory leak when printing doubles */
if (cp_free) {
free(cp_free);
cp_free = NULL;
}
#endif
}
done:
FLUSH();
error:
#if 1 /* BIONIC: remove memory leak when printing doubles */
if (cp_free) {
free(cp_free);
cp_free = NULL;
}
#endif
if (argtable != NULL && argtable != statargtable) {
munmap(argtable, argtablesiz);
argtable = NULL;
}
return (__sferror(fp) ? EOF : ret);
/* NOTREACHED */
}
/*
* Type ids for argument type table.
*/
#define T_UNUSED 0
#define T_SHORT 1
#define T_U_SHORT 2
#define TP_SHORT 3
#define T_INT 4
#define T_U_INT 5
#define TP_INT 6
#define T_LONG 7
#define T_U_LONG 8
#define TP_LONG 9
#define T_LLONG 10
#define T_U_LLONG 11
#define TP_LLONG 12
#define T_DOUBLE 13
#define T_LONG_DOUBLE 14
#define TP_CHAR 15
#define TP_VOID 16
#define T_PTRINT 17
#define TP_PTRINT 18
#define T_SIZEINT 19
#define T_SSIZEINT 20
#define TP_SSIZEINT 21
#define T_MAXINT 22
#define T_MAXUINT 23
#define TP_MAXINT 24
/*
* Find all arguments when a positional parameter is encountered. Returns a
* table, indexed by argument number, of pointers to each arguments. The
* initial argument table should be an array of STATIC_ARG_TBL_SIZE entries.
* It will be replaced with a mmap-ed one if it overflows (malloc cannot be
* used since we are attempting to make snprintf thread safe, and alloca is
* problematic since we have nested functions..)
*/
static void
__find_arguments(const char *fmt0, va_list ap, va_list **argtable,
size_t *argtablesiz)
{
char *fmt; /* format string */
int ch; /* character from fmt */
int n, n2; /* handy integer (short term usage) */
char *cp; /* handy char pointer (short term usage) */
int flags; /* flags as above */
unsigned char *typetable; /* table of types */
unsigned char stattypetable[STATIC_ARG_TBL_SIZE];
int tablesize; /* current size of type table */
int tablemax; /* largest used index in table */
int nextarg; /* 1-based argument index */
wchar_t wc;
void* ps;
/*
* Add an argument type to the table, expanding if necessary.
*/
#define ADDTYPE(type) \
((nextarg >= tablesize) ? \
__grow_type_table(&typetable, &tablesize) : 0, \
(nextarg > tablemax) ? tablemax = nextarg : 0, \
typetable[nextarg++] = type)
#define ADDSARG() \
((flags&MAXINT) ? ADDTYPE(T_MAXINT) : \
((flags&PTRINT) ? ADDTYPE(T_PTRINT) : \
((flags&SIZEINT) ? ADDTYPE(T_SSIZEINT) : \
((flags&LLONGINT) ? ADDTYPE(T_LLONG) : \
((flags&LONGINT) ? ADDTYPE(T_LONG) : \
((flags&SHORTINT) ? ADDTYPE(T_SHORT) : ADDTYPE(T_INT)))))))
#define ADDUARG() \
((flags&MAXINT) ? ADDTYPE(T_MAXUINT) : \
((flags&PTRINT) ? ADDTYPE(T_PTRINT) : \
((flags&SIZEINT) ? ADDTYPE(T_SIZEINT) : \
((flags&LLONGINT) ? ADDTYPE(T_U_LLONG) : \
((flags&LONGINT) ? ADDTYPE(T_U_LONG) : \
((flags&SHORTINT) ? ADDTYPE(T_U_SHORT) : ADDTYPE(T_U_INT)))))))
/*
* Add * arguments to the type array.
*/
#define ADDASTER() \
n2 = 0; \
cp = fmt; \
while (is_digit(*cp)) { \
n2 = 10 * n2 + to_digit(*cp); \
cp++; \
} \
if (*cp == '$') { \
int hold = nextarg; \
nextarg = n2; \
ADDTYPE(T_INT); \
nextarg = hold; \
fmt = ++cp; \
} else { \
ADDTYPE(T_INT); \
}
fmt = (char *)fmt0;
typetable = stattypetable;
tablesize = STATIC_ARG_TBL_SIZE;
tablemax = 0;
nextarg = 1;
memset(typetable, T_UNUSED, STATIC_ARG_TBL_SIZE);
memset(&ps, 0, sizeof(ps));
/*
* Scan the format for conversions (`%' character).
*/
for (;;) {
cp = fmt;
#if 1 /* BIONIC */
n = -1;
while ((wc = *fmt) != 0) {
if (wc == '%') {
n = 1;
break;
}
fmt++;
}
#else
while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
fmt += n;
if (wc == '%') {
fmt--;
break;
}
}
#endif
if (n <= 0)
goto done;
fmt++; /* skip over '%' */
flags = 0;
rflag: ch = *fmt++;
reswitch: switch (ch) {
case ' ':
case '#':
goto rflag;
case '*':
ADDASTER();
goto rflag;
case '-':
case '+':
goto rflag;
case '.':
if ((ch = *fmt++) == '*') {
ADDASTER();
goto rflag;
}
while (is_digit(ch)) {
ch = *fmt++;
}
goto reswitch;
case '0':
goto rflag;
case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
n = 0;
do {
n = 10 * n + to_digit(ch);
ch = *fmt++;
} while (is_digit(ch));
if (ch == '$') {
nextarg = n;
goto rflag;
}
goto reswitch;
#ifdef FLOATING_POINT
case 'L':
flags |= LONGDBL;
goto rflag;
#endif
case 'h':
if (*fmt == 'h') {
fmt++;
flags |= CHARINT;
} else {
flags |= SHORTINT;
}
goto rflag;
case 'l':
if (*fmt == 'l') {
fmt++;
flags |= LLONGINT;
} else {
flags |= LONGINT;
}
goto rflag;
case 'q':
flags |= LLONGINT;
goto rflag;
case 't':
flags |= PTRINT;
goto rflag;
case 'z':
flags |= SIZEINT;
goto rflag;
case 'c':
ADDTYPE(T_INT);
break;
case 'D':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'd':
case 'i':
ADDSARG();
break;
#ifdef FLOATING_POINT
case 'e':
case 'E':
case 'f':
case 'g':
case 'G':
if (flags & LONGDBL)
ADDTYPE(T_LONG_DOUBLE);
else
ADDTYPE(T_DOUBLE);
break;
#endif /* FLOATING_POINT */
case 'n':
if (flags & LLONGINT)
ADDTYPE(TP_LLONG);
else if (flags & LONGINT)
ADDTYPE(TP_LONG);
else if (flags & SHORTINT)
ADDTYPE(TP_SHORT);
else if (flags & PTRINT)
ADDTYPE(TP_PTRINT);
else if (flags & SIZEINT)
ADDTYPE(TP_SSIZEINT);
else if (flags & MAXINT)
ADDTYPE(TP_MAXINT);
else
ADDTYPE(TP_INT);
continue; /* no output */
case 'O':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'o':
ADDUARG();
break;
case 'p':
ADDTYPE(TP_VOID);
break;
case 's':
ADDTYPE(TP_CHAR);
break;
case 'U':
flags |= LONGINT;
/*FALLTHROUGH*/
case 'u':
case 'X':
case 'x':
ADDUARG();
break;
default: /* "%?" prints ?, unless ? is NUL */
if (ch == '\0')
goto done;
break;
}
}
done:
/*
* Build the argument table.
*/
if (tablemax >= STATIC_ARG_TBL_SIZE) {
*argtablesiz = sizeof (va_list) * (tablemax + 1);
*argtable = (va_list *)mmap(NULL, *argtablesiz,
PROT_WRITE|PROT_READ, MAP_ANON|MAP_PRIVATE, -1, 0);
}
#if 0
/* XXX is this required? */
(*argtable) [0] = NULL;
#endif
for (n = 1; n <= tablemax; n++) {
va_copy((*argtable)[n], ap);
switch (typetable[n]) {
case T_UNUSED:
(void) va_arg(ap, int);
break;
case T_SHORT:
(void) va_arg(ap, int);
break;
case T_U_SHORT:
(void) va_arg(ap, int);
break;
case TP_SHORT:
(void) va_arg(ap, short *);
break;
case T_INT:
(void) va_arg(ap, int);
break;
case T_U_INT:
(void) va_arg(ap, unsigned int);
break;
case TP_INT:
(void) va_arg(ap, int *);
break;
case T_LONG:
(void) va_arg(ap, long);
break;
case T_U_LONG:
(void) va_arg(ap, unsigned long);
break;
case TP_LONG:
(void) va_arg(ap, long *);
break;
case T_LLONG:
(void) va_arg(ap, long long);
break;
case T_U_LLONG:
(void) va_arg(ap, unsigned long long);
break;
case TP_LLONG:
(void) va_arg(ap, long long *);
break;
case T_DOUBLE:
(void) va_arg(ap, double);
break;
case T_LONG_DOUBLE:
(void) va_arg(ap, long double);
break;
case TP_CHAR:
(void) va_arg(ap, char *);
break;
case TP_VOID:
(void) va_arg(ap, void *);
break;
case T_PTRINT:
(void) va_arg(ap, ptrdiff_t);
break;
case TP_PTRINT:
(void) va_arg(ap, ptrdiff_t *);
break;
case T_SIZEINT:
(void) va_arg(ap, size_t);
break;
case T_SSIZEINT:
(void) va_arg(ap, ssize_t);
break;
case TP_SSIZEINT:
(void) va_arg(ap, ssize_t *);
break;
case TP_MAXINT:
(void) va_arg(ap, intmax_t *);
break;
}
}
if (typetable != NULL && typetable != stattypetable) {
munmap(typetable, *argtablesiz);
typetable = NULL;
}
}
/*
* Increase the size of the type table.
*/
static int
__grow_type_table(unsigned char **typetable, int *tablesize)
{
unsigned char *oldtable = *typetable;
int newsize = *tablesize * 2;
if (*tablesize == STATIC_ARG_TBL_SIZE) {
*typetable = (unsigned char *)mmap(NULL,
sizeof (unsigned char) * newsize, PROT_WRITE|PROT_READ,
MAP_ANON|MAP_PRIVATE, -1, 0);
/* XXX unchecked */
memcpy( *typetable, oldtable, *tablesize);
} else {
unsigned char *new = (unsigned char *)mmap(NULL,
sizeof (unsigned char) * newsize, PROT_WRITE|PROT_READ,
MAP_ANON|MAP_PRIVATE, -1, 0);
memmove(new, *typetable, *tablesize);
munmap(*typetable, *tablesize);
*typetable = new;
/* XXX unchecked */
}
memset(*typetable + *tablesize, T_UNUSED, (newsize - *tablesize));
*tablesize = newsize;
return(0);
}
#ifdef FLOATING_POINT
extern char *__dtoa(double, int, int, int *, int *, char **);
static char *
cvt(double value, int ndigits, int flags, char *sign, int *decpt, int ch,
int *length)
{
int mode, dsgn;
char *digits, *bp, *rve;
if (ch == 'f') {
mode = 3; /* ndigits after the decimal point */
} else {
/* To obtain ndigits after the decimal point for the 'e'
* and 'E' formats, round to ndigits + 1 significant
* figures.
*/
if (ch == 'e' || ch == 'E') {
ndigits++;
}
mode = 2; /* ndigits significant digits */
}
if (value < 0) {
value = -value;
*sign = '-';
} else
*sign = '\000';
digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
if ((ch != 'g' && ch != 'G') || flags & ALT) { /* Print trailing zeros */
bp = digits + ndigits;
if (ch == 'f') {
if (*digits == '0' && value)
*decpt = -ndigits + 1;
bp += *decpt;
}
if (value == 0) /* kludge for __dtoa irregularity */
rve = bp;
while (rve < bp)
*rve++ = '0';
}
*length = rve - digits;
return (digits);
}
static int
exponent(char *p0, int exp, int fmtch)
{
char *p, *t;
char expbuf[MAXEXP];
p = p0;
*p++ = fmtch;
if (exp < 0) {
exp = -exp;
*p++ = '-';
}
else
*p++ = '+';
t = expbuf + MAXEXP;
if (exp > 9) {
do {
*--t = to_char(exp % 10);
} while ((exp /= 10) > 9);
*--t = to_char(exp);
for (; t < expbuf + MAXEXP; *p++ = *t++);
}
else {
*p++ = '0';
*p++ = to_char(exp);
}
return (p - p0);
}
/* BIONIC */
#include <machine/ieee.h>
typedef union {
double d;
struct ieee_double i;
} ieee_u;
static int
_my_isinf (double value)
{
ieee_u u;
u.d = value;
return (u.i.dbl_exp == 2047 && u.i.dbl_frach == 0 && u.i.dbl_fracl == 0);
}
static int
_my_isnan (double value)
{
ieee_u u;
u.d = value;
return (u.i.dbl_exp == 2047 && (u.i.dbl_frach != 0 || u.i.dbl_fracl != 0));
}
#endif /* FLOATING_POINT */
有空慢慢解析一下，多年以来一直困惑的源码。
TODO elf文件格式解析
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