snprintf.c

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     /* Digital Unix and Linux does not. */
#if !defined(SOLARIS_COMPATIBLE) && !defined(HPUX_COMPATIBLE)
        zero_padding = 0;    /* turn zero padding off for string conversions */
#endif
        str_arg_l = 1;
        switch (fmt_spec) {
        case '%':
          str_arg = p; break;
        case 'c': {
          int j = va_arg(ap, int);
          uchar_arg = (unsigned char) j;   /* standard demands unsigned char */
          str_arg = (const char *) &uchar_arg;
          break;
        }
        case 's':
          str_arg = va_arg(ap, const char *);
          if (!str_arg) str_arg_l = 0;
       /* make sure not to address string beyond the specified precision !!! */
          else if (!precision_specified) str_arg_l = strlen(str_arg);
       /* truncate string if necessary as requested by precision */
          else if (precision == 0) str_arg_l = 0;
          else {
       /* memchr on HP does not like n > 2^31  !!! */
            const char *q = (char*)memchr(str_arg, '\0',
                             precision <= 0x7fffffff ? precision : 0x7fffffff);
            str_arg_l = !q ? precision : (q-str_arg);
          }
          break;
        default: break;
        }
        break;
      case 'd': case 'u': case 'o': case 'x': case 'X': case 'p': {
        /* NOTE: the u, o, x, X and p conversion specifiers imply
                 the value is unsigned;  d implies a signed value */

        int arg_sign = 0;
          /* 0 if numeric argument is zero (or if pointer is NULL for 'p'),
            +1 if greater than zero (or nonzero for unsigned arguments),
            -1 if negative (unsigned argument is never negative) */

        int int_arg = 0;  unsigned int uint_arg = 0;
          /* only defined for length modifier h, or for no length modifiers */

        long int long_arg = 0;  unsigned long int ulong_arg = 0;
          /* only defined for length modifier l */

        void *ptr_arg = NULL;
          /* pointer argument value -only defined for p conversion */

#ifdef SNPRINTF_LONGLONG_SUPPORT
        long long int long_long_arg = 0;
        unsigned long long int ulong_long_arg = 0;
          /* only defined for length modifier ll */
#endif
        if (fmt_spec == 'p') {
        /* HPUX 10: An l, h, ll or L before any other conversion character
         *   (other than d, i, u, o, x, or X) is ignored.
         * Digital Unix:
         *   not specified, but seems to behave as HPUX does.
         * Solaris: If an h, l, or L appears before any other conversion
         *   specifier (other than d, i, u, o, x, or X), the behavior
         *   is undefined. (Actually %hp converts only 16-bits of address
         *   and %llp treats address as 64-bit data which is incompatible
         *   with (void *) argument on a 32-bit system).
         */
#ifdef SOLARIS_COMPATIBLE
#  ifdef SOLARIS_BUG_COMPATIBLE
          /* keep length modifiers even if it represents 'll' */
#  else
          if (length_modifier == '2') length_modifier = '\0';
#  endif
#else
          length_modifier = '\0';
#endif
          ptr_arg = va_arg(ap, void *);
          if (ptr_arg != NULL) arg_sign = 1;
        } else if (fmt_spec == 'd') {  /* signed */
          switch (length_modifier) {
          case '\0':
          case 'h':
         /* It is non-portable to specify a second argument of char or short
          * to va_arg, because arguments seen by the called function
          * are not char or short.  C converts char and short arguments
          * to int before passing them to a function.
          */
            int_arg = va_arg(ap, int);
            if      (int_arg > 0) arg_sign =  1;
            else if (int_arg < 0) arg_sign = -1;
            break;
          case 'l':
            long_arg = va_arg(ap, long int);
            if      (long_arg > 0) arg_sign =  1;
            else if (long_arg < 0) arg_sign = -1;
            break;
#ifdef SNPRINTF_LONGLONG_SUPPORT
          case '2':
            long_long_arg = va_arg(ap, long long int);
            if      (long_long_arg > 0) arg_sign =  1;
            else if (long_long_arg < 0) arg_sign = -1;
            break;
#endif
          }
        } else {  /* unsigned */
          switch (length_modifier) {
          case '\0':
          case 'h':
            uint_arg = va_arg(ap, unsigned int);
            if (uint_arg) arg_sign = 1;
            break;
          case 'l':
            ulong_arg = va_arg(ap, unsigned long int);
            if (ulong_arg) arg_sign = 1;
            break;
#ifdef SNPRINTF_LONGLONG_SUPPORT
          case '2':
            ulong_long_arg = va_arg(ap, unsigned long long int);
            if (ulong_long_arg) arg_sign = 1;
            break;
#endif
          }
        }
        str_arg = tmp; str_arg_l = 0;
     /* NOTE:
      *   For d, i, u, o, x, and X conversions, if precision is specified,
      *   the '0' flag should be ignored. This is so with Solaris 2.6,
      *   Digital UNIX 4.0, HPUX 10, Linux, FreeBSD, NetBSD; but not with Perl.
      */
#ifndef PERL_COMPATIBLE
        if (precision_specified) zero_padding = 0;
#endif
        if (fmt_spec == 'd') {
          if (force_sign && arg_sign >= 0)
            tmp[str_arg_l++] = space_for_positive ? ' ' : '+';
         /* leave negative numbers for sprintf to handle,
            to avoid handling tricky cases like (short int)(-32768) */
#ifdef LINUX_COMPATIBLE
        } else if (fmt_spec == 'p' && force_sign && arg_sign > 0) {
          tmp[str_arg_l++] = space_for_positive ? ' ' : '+';
#endif
        } else if (alternate_form) {
          if (arg_sign != 0 && (fmt_spec == 'x' || fmt_spec == 'X') )
            { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = fmt_spec; }
         /* alternate form should have no effect for p conversion, but ... */
#ifdef HPUX_COMPATIBLE
          else if (fmt_spec == 'p'
         /* HPUX 10: for an alternate form of p conversion,
          *          a nonzero result is prefixed by 0x. */
#ifndef HPUX_BUG_COMPATIBLE
         /* Actually it uses 0x prefix even for a zero value. */
                   && arg_sign != 0
#endif
                  ) { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = 'x'; }
#endif
        }
        zero_padding_insertion_ind = str_arg_l;
        if (!precision_specified) precision = 1;   /* default precision is 1 */
        if (precision == 0 && arg_sign == 0
#if defined(HPUX_BUG_COMPATIBLE) || defined(LINUX_COMPATIBLE)
            && fmt_spec != 'p'
         /* HPUX 10 man page claims: With conversion character p the result of
          * converting a zero value with a precision of zero is a null string.
          * Actually HP returns all zeroes, and Linux returns "(nil)". */
#endif
        ) {
         /* converted to null string */
         /* When zero value is formatted with an explicit precision 0,
            the resulting formatted string is empty (d, i, u, o, x, X, p).   */
        } else {
          char f[5]; int f_l = 0;
          f[f_l++] = '%';    /* construct a simple format string for sprintf */
          if (!length_modifier) { }
          else if (length_modifier=='2') { f[f_l++] = 'l'; f[f_l++] = 'l'; }
          else f[f_l++] = length_modifier;
          f[f_l++] = fmt_spec; f[f_l++] = '\0';
          if (fmt_spec == 'p') str_arg_l += sprintf(tmp+str_arg_l, f, ptr_arg);
          else if (fmt_spec == 'd') {  /* signed */
            switch (length_modifier) {
            case '\0':
            case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, int_arg);  break;
            case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, long_arg); break;
#ifdef SNPRINTF_LONGLONG_SUPPORT
            case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,long_long_arg); break;
#endif
            }
          } else {  /* unsigned */
            switch (length_modifier) {
            case '\0':
            case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, uint_arg);  break;
            case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, ulong_arg); break;
#ifdef SNPRINTF_LONGLONG_SUPPORT
            case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,ulong_long_arg);break;
#endif
            }
          }
         /* include the optional minus sign and possible "0x"
            in the region before the zero padding insertion point */
          if (zero_padding_insertion_ind < str_arg_l &&
              tmp[zero_padding_insertion_ind] == '-') {
            zero_padding_insertion_ind++;
          }
          if (zero_padding_insertion_ind+1 < str_arg_l &&
              tmp[zero_padding_insertion_ind]   == '0' &&
             (tmp[zero_padding_insertion_ind+1] == 'x' ||
              tmp[zero_padding_insertion_ind+1] == 'X') ) {
            zero_padding_insertion_ind += 2;
          }
        }
        { size_t num_of_digits = str_arg_l - zero_padding_insertion_ind;
          if (alternate_form && fmt_spec == 'o'
#ifdef HPUX_COMPATIBLE                                  /* ("%#.o",0) -> ""  */
              && (str_arg_l > 0)
#endif
#ifdef DIGITAL_UNIX_BUG_COMPATIBLE                      /* ("%#o",0) -> "00" */
#else
              /* unless zero is already the first character */
              && !(zero_padding_insertion_ind < str_arg_l
                   && tmp[zero_padding_insertion_ind] == '0')
#endif
          ) {        /* assure leading zero for alternate-form octal numbers */
            if (!precision_specified || precision < num_of_digits+1) {
             /* precision is increased to force the first character to be zero,
                except if a zero value is formatted with an explicit precision
                of zero */
              precision = num_of_digits+1; precision_specified = 1;
            }
          }
       /* zero padding to specified precision? */
          if (num_of_digits < precision) 
            number_of_zeros_to_pad = precision - num_of_digits;
        }
     /* zero padding to specified minimal field width? */
        if (!justify_left && zero_padding) {
          int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
          if (n > 0) number_of_zeros_to_pad += n;
        }
        break;
      }
      default: /* unrecognized conversion specifier, keep format string as-is*/
        zero_padding = 0;  /* turn zero padding off for non-numeric convers. */
#ifndef DIGITAL_UNIX_COMPATIBLE
        justify_left = 1; min_field_width = 0;                /* reset flags */
#endif
#if defined(PERL_COMPATIBLE) || defined(LINUX_COMPATIBLE)
     /* keep the entire format string unchanged */
        str_arg = starting_p; str_arg_l = p - starting_p;
     /* well, not exactly so for Linux, which does something inbetween,
      * and I don't feel an urge to imitate it: "%+++++hy" -> "%+y"  */
#else
     /* discard the unrecognized conversion, just keep *
      * the unrecognized conversion character          */
        str_arg = p; str_arg_l = 0;
#endif
        if (*p) str_arg_l++;  /* include invalid conversion specifier unchanged
                                 if not at end-of-string */
        break;
      }
      if (*p) p++;      /* step over the just processed conversion specifier */
   /* insert padding to the left as requested by min_field_width;
      this does not include the zero padding in case of numerical conversions*/
      if (!justify_left) {                /* left padding with blank or zero */
        int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
        if (n > 0) {
          if (str_l < str_m) {
            size_t avail = str_m-str_l;
            fast_memset(str+str_l, (zero_padding?'0':' '), (n>avail?avail:n));
          }
          str_l += n;
        }
      }
   /* zero padding as requested by the precision or by the minimal field width
    * for numeric conversions required? */
      if (number_of_zeros_to_pad <= 0) {
     /* will not copy first part of numeric right now, *
      * force it to be copied later in its entirety    */
        zero_padding_insertion_ind = 0;
      } else {
     /* insert first part of numerics (sign or '0x') before zero padding */
        int n = zero_padding_insertion_ind;
        if (n > 0) {
          if (str_l < str_m) {
            size_t avail = str_m-str_l;
            fast_memcpy(str+str_l, str_arg, (n>avail?avail:n));
          }
          str_l += n;
        }
     /* insert zero padding as requested by the precision or min field width */
        n = number_of_zeros_to_pad;
        if (n > 0) {
          if (str_l < str_m) {
            size_t avail = str_m-str_l;
            fast_memset(str+str_l, '0', (n>avail?avail:n));
          }
          str_l += n;
        }
      }
   /* insert formatted string
    * (or as-is conversion specifier for unknown conversions) */
      { int n = str_arg_l - zero_padding_insertion_ind;
        if (n > 0) {
          if (str_l < str_m) {
            size_t avail = str_m-str_l;
            fast_memcpy(str+str_l, str_arg+zero_padding_insertion_ind,
                        (n>avail?avail:n));
          }
          str_l += n;
        }
      }
   /* insert right padding */
      if (justify_left) {          /* right blank padding to the field width */
        int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
        if (n > 0) {
          if (str_l < str_m) {
            size_t avail = str_m-str_l;
            fast_memset(str+str_l, ' ', (n>avail?avail:n));
          }
          str_l += n;
        }
      }
    }
  }
#if defined(NEED_SNPRINTF_ONLY)
  va_end(ap);
#endif
  if (str_m > 0) { /* make sure the string is null-terminated
                      even at the expense of overwriting the last character
                      (shouldn't happen, but just in case) */
    str[str_l <= str_m-1 ? str_l : str_m-1] = '\0';
  }
  /* Return the number of characters formatted (excluding trailing null
   * character), that is, the number of characters that would have been
   * written to the buffer if it were large enough.
   *
   * The value of str_l should be returned, but str_l is of unsigned type
   * size_t, and snprintf is int, possibly leading to an undetected
   * integer overflow, resulting in a negative return value, which is illegal.
   * Both XSH5 and ISO C99 (at least the draft) are silent on this issue.
   * Should errno be set to EOVERFLOW and EOF returned in this case???
   */
  return (int) str_l;
}
#endif