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linux_vsprintf.c

/*
 *  linux/lib/vsprintf.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

/* 
 * Fri Jul 13 2001 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 * - changed to provide snprintf and vsnprintf functions
 */

#include "linux_vsprintf.h"

static int skip_atoi(const char **s)
{
      int i=0;

      while (isdigit(**s))
            i = i*10 + *((*s)++) - '0';
      return i;
}

static char *number(char * buf, char * end, long long num, int base, int size, int precision, int type)
{
      char c,sign,tmp[66];
      const char *digits;
      const char small_digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
      const char large_digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
      int i;

      digits = (type & LARGE) ? large_digits : small_digits;
      if (type & LEFT)
            type &= ~ZEROPAD;
      if (base < 2 || base > 36)
            return 0;
      c = (type & ZEROPAD) ? '0' : ' ';
      sign = 0;
      if (type & SIGN) {
            if (num < 0) {
                  sign = '-';
                  num = -num;
                  size--;
            } else if (type & PLUS) {
                  sign = '+';
                  size--;
            } else if (type & SPACE) {
                  sign = ' ';
                  size--;
            }
      }
      if (type & SPECIAL) {
            if (base == 16)
                  size -= 2;
            else if (base == 8)
                  size--;
      }
      i = 0;
      if (num == 0)
            tmp[i++]='0';
      else while (num != 0)
            tmp[i++] = digits[do_div(num,base)];
      if (i > precision)
            precision = i;
      size -= precision;
      if (!(type&(ZEROPAD+LEFT))) {
            while(size-->0) {
                  if (buf <= end)
                        *buf = ' ';
                  ++buf;
            }
      }
      if (sign) {
            if (buf <= end)
                  *buf = sign;
            ++buf;
      }
      if (type & SPECIAL) {
            if (base==8) {
                  if (buf <= end)
                        *buf = '0';
                  ++buf;
            } else if (base==16) {
                  if (buf <= end)
                        *buf = '0';
                  ++buf;
                  if (buf <= end)
                        *buf = digits[33];
                  ++buf;
            }
      }
      if (!(type & LEFT)) {
            while (size-- > 0) {
                  if (buf <= end)
                        *buf = c;
                  ++buf;
            }
      }
      while (i < precision--) {
            if (buf <= end)
                  *buf = '0';
            ++buf;
      }
      while (i-- > 0) {
            if (buf <= end)
                  *buf = tmp[i];
            ++buf;
      }
      while (size-- > 0) {
            if (buf <= end)
                  *buf = ' ';
            ++buf;
      }
      return buf;
}

/**
* vsnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
* @size: The size of the buffer, including the trailing null space
* @fmt: The format string to use
* @args: Arguments for the format string
*
* Call this function if you are already dealing with a va_list.
* You probably want snprintf instead.
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
      int len;
      unsigned long long num;
      int i, base;
      char *str, *end, c;
      const char *s;

      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', 'l', or 'L' for integer fields */
                        /* 'z' support added 23/7/1999 S.H.    */
                        /* 'z' changed to 'Z' --davidm 1/25/99 */

      str = buf;
      end = buf + size - 1;

      if (end < buf - 1) {
            end = ((void *) -1);
            size = end - buf + 1;
      }

      for (; *fmt ; ++fmt) {
            if (*fmt != '%') {
                  if (str <= end)
                        *str = *fmt;
                  ++str;
                  continue;
            }

            /* process flags */
            flags = 0;
            repeat:
                  ++fmt;            /* this also skips first '%' */
                  switch (*fmt) {
                        case '-': flags |= LEFT; goto repeat;
                        case '+': flags |= PLUS; goto repeat;
                        case ' ': flags |= SPACE; goto repeat;
                        case '#': flags |= SPECIAL; goto repeat;
                        case '0': flags |= ZEROPAD; goto repeat;
                  }

            /* get field width */
            field_width = -1;
            if (isdigit(*fmt))
                  field_width = skip_atoi(&fmt);
            else if (*fmt == '*') {
                  ++fmt;
                  /* it's the next argument */
                  field_width = va_arg(args, int);
                  if (field_width < 0) {
                        field_width = -field_width;
                        flags |= LEFT;
                  }
            }

            /* get the precision */
            precision = -1;
            if (*fmt == '.') {
                  ++fmt;      
                  if (isdigit(*fmt))
                        precision = skip_atoi(&fmt);
                  else if (*fmt == '*') {
                        ++fmt;
                        /* it's the next argument */
                        precision = va_arg(args, int);
                  }
                  if (precision < 0)
                        precision = 0;
            }

            /* get the conversion qualifier */
            qualifier = -1;
            if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' || *fmt =='Z') {
                  qualifier = *fmt;
                  ++fmt;
                  if (qualifier == 'l' && *fmt == 'l') {
                        qualifier = 'L';
                        ++fmt;
                  }
            }

            /* default base */
            base = 10;

            switch (*fmt) {
                  case 'c':
                        if (!(flags & LEFT)) {
                              while (--field_width > 0) {
                                    if (str <= end)
                                          *str = ' ';
                                    ++str;
                              }
                        }
                        c = (unsigned char) va_arg(args, int);
                        if (str <= end)
                              *str = c;
                        ++str;
                        while (--field_width > 0) {
                              if (str <= end)
                                    *str = ' ';
                              ++str;
                        }
                        continue;

                  case 's':
                        s = va_arg(args, char *);
                        if (!s)
                              s = "(empty)";

                        len = strnlen(s, precision);

                        if (!(flags & LEFT)) {
                              while (len < field_width--) {
                                    if (str <= end)
                                          *str = ' ';
                                    ++str;
                              }
                        }
                        for (i = 0; i < len; ++i) {
                              if (str <= end)
                                    *str = *s;
                              ++str; ++s;
                        }
                        while (len < field_width--) {
                              if (str <= end)
                                    *str = ' ';
                              ++str;
                        }
                        continue;

                  case 'p':
                        if (field_width == -1) {
                              field_width = 2*sizeof(void *);
                              flags |= ZEROPAD;
                        }
                        str = number(str, end,
                                    (unsigned long) va_arg(args, void *),
                                    16, field_width, precision, flags);
                        continue;


                  case 'n':
                        /* FIXME:
                        * What does C99 say about the overflow case here? */
                        if (qualifier == 'l') {
                              long * ip = va_arg(args, long *);
                              *ip = (str - buf);
                        } else if (qualifier == 'Z') {
                              size_t * ip = va_arg(args, size_t *);
                              *ip = (str - buf);
                        } else {
                              int * ip = va_arg(args, int *);
                              *ip = (str - buf);
                        }
                        continue;

                  case '%':
                        if (str <= end)
                              *str = '%';
                        ++str;
                        continue;

                        /* integer number formats - set up the flags and "break" */
                  case 'o':
                        base = 8;
                        break;

                  case 'X':
                        flags |= LARGE;
                  case 'x':
                        base = 16;
                        break;

                  case 'd':
                  case 'i':
                        flags |= SIGN;
                  case 'u':
                        break;

                  default:
                        if (str <= end)
                              *str = '%';
                        ++str;
                        if (*fmt) {
                              if (str <= end)
                                    *str = *fmt;
                              ++str;
                        } else {
                              --fmt;
                        }
                        continue;
            }
            if (qualifier == 'L')
                  num = va_arg(args, long long);
            else if (qualifier == 'l') {
                  num = va_arg(args, unsigned long);
                  if (flags & SIGN)
                        num = (signed long) num;
            } else if (qualifier == 'Z') {
                  num = va_arg(args, size_t);
            } else if (qualifier == 'h') {
                  num = (unsigned short) va_arg(args, int);
                  if (flags & SIGN)
                        num = (signed short) num;
            } else {
                  num = va_arg(args, unsigned int);
                  if (flags & SIGN)
                        num = (signed int) num;
            }
            str = number(str, end, num, base,
                        field_width, precision, flags);
      }
      if (str <= end)
            *str = '\0';
      else if (size > 0)
            /* don't write out a null byte if the buf size is zero */
            *end = '\0';
      /* the trailing null byte doesn't count towards the total
      * ++str;
      */
      return str-buf;
}

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 */
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;
}

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want sprintf instead.
 */
int vsprintf(char *buf, const char *fmt, va_list args)
{
      return vsnprintf(buf, 0xFFFFFFFFUL, fmt, args);
}


/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 */
int sprintf(char * buf, const char *fmt, ...)
{
      va_list args;
      int i;

      va_start(args, fmt);
      i=vsprintf(buf,fmt,args);
      va_end(args);
      return i;
}

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