my_vsnprintf.c

/* Copyright (c) 2000, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
   http://oss.oracle.com/licenses/universal-foss-exception.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include <my_global.h>
#include <m_string.h>
#include <stdarg.h>
#include <m_ctype.h>


#define MAX_ARGS 32                           /* max positional args count*/
#define MAX_PRINT_INFO 32                     /* max print position count */

#define LENGTH_ARG     1
#define WIDTH_ARG      2
#define PREZERO_ARG    4
#define ESCAPED_ARG    8 

typedef struct pos_arg_info ARGS_INFO;
typedef struct print_info PRINT_INFO;

struct pos_arg_info
{
  char arg_type;                              /* argument type */
  uint have_longlong;                         /* used from integer values */
  char *str_arg;                              /* string value of the arg */
  longlong longlong_arg;                      /* integer value of the arg */
  double double_arg;                          /* double value of the arg */
};


struct print_info
{
  char arg_type;                              /* argument type */
  size_t arg_idx;                             /* index of the positional arg */
  size_t length;                              /* print width or arg index */
  size_t width;                               /* print width or arg index */
  uint flags;
  const char *begin;                          /**/
  const char *end;                            /**/
};


/**
  Calculates print length or index of positional argument

  @param fmt         processed string
  @param length      print length or index of positional argument
  @param pre_zero    returns flags with PREZERO_ARG set if necessary

  @retval
    string position right after length digits
*/

static const char *get_length(const char *fmt, size_t *length, uint *pre_zero)
{
  for (; my_isdigit(&my_charset_latin1, *fmt); fmt++)
  {
    *length= *length * 10 + (uint)(*fmt - '0');
    if (!*length)
      *pre_zero|= PREZERO_ARG;                  /* first digit was 0 */
  }
  return fmt;
}


/**
  Calculates print width or index of positional argument

  @param fmt         processed string
  @param width       print width or index of positional argument

  @retval
    string position right after width digits
*/

static const char *get_width(const char *fmt, size_t *width)
{
  for (; my_isdigit(&my_charset_latin1, *fmt); fmt++)
  {
    *width= *width * 10 + (uint)(*fmt - '0');
  }
  return fmt;
}

/**
  Calculates print width or index of positional argument

  @param fmt            processed string
  @param have_longlong  TRUE if longlong is required

  @retval
    string position right after modifier symbol
*/

static const char *check_longlong(const char *fmt, uint *have_longlong)
{
  *have_longlong= 0;
  if (*fmt == 'l')
  {
    fmt++;
    if (*fmt != 'l')
      *have_longlong= (sizeof(long) == sizeof(longlong));
    else
    {
      fmt++;
      *have_longlong= 1;
    }
  }
  else if (*fmt == 'z')
  {
    fmt++;
    *have_longlong= (sizeof(size_t) == sizeof(longlong));
  }
  return fmt;
}


/**
  Returns escaped string

  @param cs         string charset
  @param to         buffer where escaped string will be placed
  @param end        end of buffer
  @param par        string to escape
  @param par_len    string length
  @param quote_char character for quoting

  @retval
    position in buffer which points on the end of escaped string
*/

static char *backtick_string(const CHARSET_INFO *cs, char *to, char *end,
                             char *par, size_t par_len, char quote_char)
{
  uint char_len;
  char *start= to;
  char *par_end= par + par_len;
  size_t buff_length= (size_t) (end - to);

  if (buff_length <= par_len)
    goto err;
  *start++= quote_char;

  for ( ; par < par_end; par+= char_len)
  {
    if (!(char_len= my_mbcharlen_ptr(cs, par, par_end)))
      goto err;
    if (char_len == 1 && *par == quote_char)
    {
      if (start + 1 >= end)
        goto err;
      *start++= quote_char;
    }
    if (start + char_len >= end)
      goto err;
    start= my_stpnmov(start, par, char_len);
  }

  if (start + 1 >= end)
    goto err;
  *start++= quote_char;
  return start;

err:
    *to='\0';
  return to;
}


/**
  Prints string argument
*/

static char *process_str_arg(const CHARSET_INFO *cs, char *to, char *end,
                             size_t width, char *par, uint print_type)
{
  int well_formed_error;
  size_t plen, left_len= (size_t) (end - to) + 1;
  if (!par)
    par = (char*) "(null)";

  plen= strnlen(par, width);
  if (left_len <= plen)
    plen = left_len - 1;
  plen= cs->cset->well_formed_len(cs, par, par + plen,
                                  width, &well_formed_error);
  if (print_type & ESCAPED_ARG)
    to= backtick_string(cs, to, end, par, plen, '`');
  else
    to= my_stpnmov(to,par,plen);
  return to;
}


/**
  Prints binary argument
*/

static char *process_bin_arg(char *to, char *end, size_t width, char *par)
{
  assert(to <= end);
  if (to + width + 1 > end)
    width= end - to - 1;  /* sign doesn't matter */
  memmove(to, par, width);
  to+= width;
  return to;
}


/**
  Prints double or float argument
*/

static char *process_dbl_arg(char *to, char *end, size_t width,
                             double par, char arg_type)
{
  if (width == SIZE_T_MAX)
    width= FLT_DIG; /* width not set, use default */
  else if (width >= NOT_FIXED_DEC)
    width= NOT_FIXED_DEC - 1; /* max.precision for my_fcvt() */
  width= MY_MIN(width, (size_t)(end-to) - 1);
  
  if (arg_type == 'f')
    to+= my_fcvt(par, (int)width , to, NULL);
  else
    to+= my_gcvt(par, MY_GCVT_ARG_DOUBLE, (int) width , to, NULL);
  return to;
}


/**
  Prints integer argument
*/

static char *process_int_arg(char *to, char *end, size_t length,
                             longlong par, char arg_type, uint print_type)
{
  size_t res_length, to_length;
  char *store_start= to, *store_end;
  char buff[32];

  if ((to_length= (size_t) (end-to)) < 16 || length)
    store_start= buff;

  if (arg_type == 'd' || arg_type == 'i')
    store_end= longlong10_to_str(par, store_start, -10);
  else if (arg_type == 'u')
    store_end= longlong10_to_str(par, store_start, 10);
  else if (arg_type == 'p')
  {
    store_start[0]= '0';
    store_start[1]= 'x';
    store_end= ll2str(par, store_start + 2, 16, 0);
  }
  else if (arg_type == 'o')
  {
    store_end= ll2str(par, store_start, 8, 0);
  }
  else
  {
    assert(arg_type == 'X' || arg_type =='x');
    store_end= ll2str(par, store_start, 16, (arg_type == 'X'));
  }

  if ((res_length= (size_t) (store_end - store_start)) > to_length)
    return to;                           /* num doesn't fit in output */
  /* If %#d syntax was used, we have to pre-zero/pre-space the string */
  if (store_start == buff)
  {
    length= MY_MIN(length, to_length);
    if (res_length < length)
    {
      size_t diff= (length- res_length);
      memset(to, (print_type & PREZERO_ARG) ? '0' : ' ', diff);
      if (arg_type == 'p' && print_type & PREZERO_ARG)
      {
        if (diff > 1)
          to[1]= 'x';
        else
          store_start[0]= 'x';
        store_start[1]= '0';
      }
      to+= diff;
    }
    memmove(to, store_start, res_length);
  }
  to+= res_length;
  return to;
}


/**
  Procesed positional arguments.

  @param cs         string charset
  @param to         buffer where processed string will be place
  @param end        end of buffer
  @param par        format string
  @param arg_index  arg index of the first occurrence of positional arg
  @param ap         list of parameters

  @retval
    end of buffer where processed string is placed
*/

static char *process_args(const CHARSET_INFO *cs, char *to, char *end,
                          const char* fmt, size_t arg_index, va_list ap)
{
  ARGS_INFO args_arr[MAX_ARGS];
  PRINT_INFO print_arr[MAX_PRINT_INFO];
  uint idx= 0;
  size_t arg_count= arg_index;

start:
  /* Here we are at the beginning of positional argument, right after $ */
  arg_index--;
  print_arr[idx].flags= 0;
  if (*fmt == '`')
  {
    print_arr[idx].flags|= ESCAPED_ARG;
    fmt++;
  }
  if (*fmt == '-')
    fmt++;
  print_arr[idx].length= print_arr[idx].width= 0;
  /* Get print length */
  if (*fmt == '*')
  {          
    fmt++;
    fmt= get_length(fmt, &print_arr[idx].length, &print_arr[idx].flags);
    print_arr[idx].length--;    
    assert(*fmt == '$' && print_arr[idx].length < MAX_ARGS);
    args_arr[print_arr[idx].length].arg_type= 'd';
    args_arr[print_arr[idx].length].have_longlong= 0;
    print_arr[idx].flags|= LENGTH_ARG;
    arg_count= MY_MAX(arg_count, print_arr[idx].length + 1);
    fmt++;
  }
  else
    fmt= get_length(fmt, &print_arr[idx].length, &print_arr[idx].flags);
  
  if (*fmt == '.')
  {
    fmt++;
    /* Get print width */
    if (*fmt == '*')
    {
      fmt++;
      fmt= get_width(fmt, &print_arr[idx].width);
      print_arr[idx].width--;
      assert(*fmt == '$' && print_arr[idx].width < MAX_ARGS);
      args_arr[print_arr[idx].width].arg_type= 'd';
      args_arr[print_arr[idx].width].have_longlong= 0;
      print_arr[idx].flags|= WIDTH_ARG;
      arg_count= MY_MAX(arg_count, print_arr[idx].width + 1);
      fmt++;
    }
    else
      fmt= get_width(fmt, &print_arr[idx].width);
  }
  else
    print_arr[idx].width= SIZE_T_MAX;

  fmt= check_longlong(fmt, &args_arr[arg_index].have_longlong);
  if (*fmt == 'p')
    args_arr[arg_index].have_longlong= (sizeof(void *) == sizeof(longlong));
  args_arr[arg_index].arg_type= print_arr[idx].arg_type= *fmt;
  
  print_arr[idx].arg_idx= arg_index;
  print_arr[idx].begin= ++fmt;

  while (*fmt && *fmt != '%')
    fmt++;

  if (!*fmt)                                  /* End of format string */
  {
    uint i;
    print_arr[idx].end= fmt;
    /* Obtain parameters from the list */
    for (i= 0 ; i < arg_count; i++)
    {
      switch (args_arr[i].arg_type) {
      case 's':
      case 'b':
        args_arr[i].str_arg= va_arg(ap, char *);
        break;
      case 'f':
      case 'g':
        args_arr[i].double_arg= va_arg(ap, double);
        break;
      case 'd':
      case 'i':
      case 'u':
      case 'x':
      case 'X':
      case 'o':
      case 'p':
        if (args_arr[i].have_longlong)
          args_arr[i].longlong_arg= va_arg(ap,longlong);
        else if (args_arr[i].arg_type == 'd' || args_arr[i].arg_type == 'i')
          args_arr[i].longlong_arg= va_arg(ap, int);
        else
          args_arr[i].longlong_arg= va_arg(ap, uint);
        break;
      case 'c':
        args_arr[i].longlong_arg= va_arg(ap, int);
        break;
      default:
        assert(0);
      }
    }
    /* Print result string */
    for (i= 0; i <= idx; i++)
    {
      size_t width= 0, length= 0;
      switch (print_arr[i].arg_type) {
      case 's':
      {
        char *par= args_arr[print_arr[i].arg_idx].str_arg;
        width= (print_arr[i].flags & WIDTH_ARG)
          ? (size_t)args_arr[print_arr[i].width].longlong_arg
          : print_arr[i].width;
        to= process_str_arg(cs, to, end, width, par, print_arr[i].flags);
        break;
      }
      case 'b':
      {
        char *par = args_arr[print_arr[i].arg_idx].str_arg;
        width= (print_arr[i].flags & WIDTH_ARG)
          ? (size_t)args_arr[print_arr[i].width].longlong_arg
          : print_arr[i].width;
        to= process_bin_arg(to, end, width, par);
        break;
      }
      case 'c':
      {
        if (to == end)
          break;
        *to++= (char) args_arr[print_arr[i].arg_idx].longlong_arg;
        break;
      }
      case 'f':
      case 'g':
      {
        double d= args_arr[print_arr[i].arg_idx].double_arg;
        width= (print_arr[i].flags & WIDTH_ARG) ?
          (uint)args_arr[print_arr[i].width].longlong_arg : print_arr[i].width;
        to= process_dbl_arg(to, end, width, d, print_arr[i].arg_type);
        break;
      }
      case 'd':
      case 'i':
      case 'u':
      case 'x':
      case 'X':
      case 'o':
      case 'p':
      {
        /* Integer parameter */
        longlong larg;
        length= (print_arr[i].flags & LENGTH_ARG)
          ? (size_t)args_arr[print_arr[i].length].longlong_arg
          : print_arr[i].length;

        if (args_arr[print_arr[i].arg_idx].have_longlong)
          larg = args_arr[print_arr[i].arg_idx].longlong_arg;
        else if (print_arr[i].arg_type == 'd' || print_arr[i].arg_type == 'i' )
          larg = (int) args_arr[print_arr[i].arg_idx].longlong_arg;
        else
          larg= (uint) args_arr[print_arr[i].arg_idx].longlong_arg;

        to= process_int_arg(to, end, length, larg, print_arr[i].arg_type,
                            print_arr[i].flags);
        break;
      }
      default:
        break;
      }

      if (to == end)
        break;

      length= MY_MIN(end - to , print_arr[i].end - print_arr[i].begin);
      if (to + length < end)
        length++;
      to= my_stpnmov(to, print_arr[i].begin, length);
    }
    assert(to <= end);
    *to='\0';				/* End of errmessage */
    return to;
  }
  else
  {
    /* Process next positional argument*/
    assert(*fmt == '%');
    print_arr[idx].end= fmt - 1;
    idx++;
    fmt++;
    arg_index= 0;
    fmt= get_width(fmt, &arg_index);
    assert(*fmt == '$');
    fmt++;
    arg_count= MY_MAX(arg_count, arg_index);
    goto start;
  }

  return 0;
}



/**
  Produces output string according to a format string

  See the detailed documentation around my_snprintf_service_st

  @param cs         string charset
  @param to         buffer where processed string will be place
  @param n          size of buffer
  @param par        format string
  @param ap         list of parameters

  @retval
    length of result string
*/

size_t my_vsnprintf_ex(const CHARSET_INFO *cs, char *to, size_t n,
                       const char* fmt, va_list ap)
{
  char *start=to, *end=to+n-1;
  size_t length, width;
  uint print_type, have_longlong;

  for (; *fmt ; fmt++)
  {
    if (*fmt != '%')
    {
      if (to == end)                            /* End of buffer */
	break;
      *to++= *fmt;                            /* Copy ordinary char */
      continue;
    }
    fmt++;					/* skip '%' */

    length= width= 0;
    print_type= 0;

    /* Read max fill size (only used with %d and %u) */
    if (my_isdigit(&my_charset_latin1, *fmt))
    {
      fmt= get_length(fmt, &length, &print_type);
      if (*fmt == '$')
      {
        to= process_args(cs, to, end, (fmt+1), length, ap);
        return (size_t) (to - start);
      }
    }
    else
    {
      if (*fmt == '`')
      {
        print_type|= ESCAPED_ARG;
        fmt++;
      }
      if (*fmt == '-')
        fmt++;
      if (*fmt == '*')
      {
        fmt++;
        length= va_arg(ap, int);
      }
      else
        fmt= get_length(fmt, &length, &print_type);
    }

    if (*fmt == '.')
    {
      fmt++;
      if (*fmt == '*')
      {
        fmt++;
        width= va_arg(ap, int);
      }
      else
        fmt= get_width(fmt, &width);
    }
    else
      width= SIZE_T_MAX;   

    fmt= check_longlong(fmt, &have_longlong);

    if (*fmt == 's')				/* String parameter */
    {
      char *par= va_arg(ap, char *);
      to= process_str_arg(cs, to, end, width, par, print_type);
      continue;
    }
    else if (*fmt == 'b')				/* Buffer parameter */
    {
      char *par = va_arg(ap, char *);
      to= process_bin_arg(to, end, width, par);
      continue;
    }
    else if (*fmt == 'f' || *fmt == 'g')
    {
      double d= va_arg(ap, double);
      to= process_dbl_arg(to, end, width, d, *fmt);
      continue;
    }
    else if (*fmt == 'd' || *fmt == 'i' || *fmt == 'u' || *fmt == 'x' || 
             *fmt == 'X' || *fmt == 'p' || *fmt == 'o')
    {
      /* Integer parameter */
      longlong larg;
      if (*fmt == 'p')
        have_longlong= (sizeof(void *) == sizeof(longlong));

      if (have_longlong)
        larg = va_arg(ap,longlong);
      else if (*fmt == 'd' || *fmt == 'i')
        larg = va_arg(ap, int);
      else
        larg= va_arg(ap, uint);

      to= process_int_arg(to, end, length, larg, *fmt, print_type);
      continue;
    }
    else if (*fmt == 'c')                       /* Character parameter */
    {
      int larg;
      if (to == end)
        break;
      larg = va_arg(ap, int);
      *to++= (char) larg;
      continue;
    }

    /* We come here on '%%', unknown code or too long parameter */
    if (to == end)
      break;
    *to++='%';				/* % used as % or unknown code */
  }
  assert(to <= end);
  *to='\0';				/* End of errmessage */
  return (size_t) (to - start);
}


/*
  Limited snprintf() implementations

  exported to plugins as a service, see the detailed documentation
  around my_snprintf_service_st
*/

size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap)
{
  return my_vsnprintf_ex(&my_charset_latin1, to, n, fmt, ap);
}


size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
{
  size_t result;
  va_list args;
  va_start(args,fmt);
  result= my_vsnprintf(to, n, fmt, args);
  va_end(args);
  return result;
}