/*
  * Unreal Internet Relay Chat Daemon, src/ircsprintf.c
  *
  * (C) Copyright 2013
  *
  * Author: Falcon Darkstar Momot based upon earlier code by Carlo Wood in 1997:
  * 1024/624ACAD5 1997/01/26 Carlo Wood, Run on IRC <carlo@runaway.xs4all.nl>
  * Key fingerprint = 32 EC A7 B6 AC DB 65 A6  F6 F6 55 DD 1C DC FF 61
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
  * 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  * $Id$
  */
 #include "ircsprintf.h"
 #include <stdio.h>
 
 /** Optimized version of vsnprintf() for us.
  * ircvsnprintf is optimized for the formats: %s, %c, %d, %i, %u, %lu and %lld.
  * If you only use these format string types then this function is significantly
  * faster than regular vsnprintf().
  * When it encounters any other format type or things like padding, precision,
  * etc. then it will resort to calling vsnprintf(), so no problem.
  */
 char *ircvsnprintf(char *str, size_t size, const char *format, va_list vl)
 {
 	char *str_begin = str;
 	char c;
 	const char *end = str+size-1; /* for comparison, not dereferencing.  It is the last position a null can go. */
 	char scratch_buffer[32]; /* large enough for 64 bit integer as a string */
 
 	if (!size) return str;
 
 	while (str!=end && (c = *format++))
 	{
 		if (c == '%')
 		{
 			c = *format++;
 			if (c == 's')
 			{
 				/* %s - string */
 				const char *p1 = va_arg(vl, const char *);
 				while (str!=end && *p1) *str++ = *p1++;
 				continue;
 			}
 			else if (c == 'c')
 			{
 				/* %c - single character */
 				*str++ = (char)va_arg(vl, int);
 				continue;
 			}
 			else if (c == 'd' || c == 'i')
 			{
 				/* %d and %i - integer */
 				char *t;
 				int v = va_arg(vl, int);
 				int i = 0;
 				size_t len;
 				if (v==0)
 				{
 					*str++ = '0';
 					continue;
 				}
 				t = scratch_buffer + sizeof(scratch_buffer);
 				if (v<0)
 				{
 					*str++ = '-';
 					if (str==end) break;
 					while (v)
 					{
 						*--t = '0' - (v%10);
 						v/=10;
 					}
 				} else {
 					while (v)
 					{
 						*--t = (v%10) + '0';
 						v/=10;
 					}
 				}
 
 				len = sizeof(scratch_buffer)-(t-scratch_buffer);
 				if ((str+len)>end) break;
 				for (i = 0; i < len; i++)
 					*str++=t[i];
 				continue;
 			}
 			else if (c == 'l')
 			{
 				if (format[0] == 'l' && format[1] == 'd')
 				{
 					/* %lld - long long */
 					char *t;
 					long long v = va_arg(vl, long long);
 					int i = 0;
 					size_t len;
 
 					format += 2;
 
 					if (v==0)
 					{
 						*str++ = '0';
 						continue;
 					}
 					t = scratch_buffer + sizeof(scratch_buffer);
 					if (v<0)
 					{
 						*str++ = '-';
 						if (str==end) break;
 						while (v)
 						{
 							*--t = '0' - (v%10);
 							v/=10;
 						}
 					} else {
 						while (v)
 						{
 							*--t = (v%10) + '0';
 							v/=10;
 						}
 					}
 
 					len = sizeof(scratch_buffer)-(t-scratch_buffer);
 					if ((str+len)>end) break;
 					for (i = 0; i < len; i++)
 						*str++=t[i];
 					continue;
 				}
 				if (*format == 'u')
 				{
 					/* %lu - unsigned long */
 					char *t;
 					unsigned long v = va_arg(vl, unsigned long);
 					int i = 0;
 					size_t len;
 
 					format++;
 					if (v==0)
 					{
 						*str++ = '0';
 						continue;
 					}
 
 					t = scratch_buffer + sizeof(scratch_buffer);
 					while (v)
 					{
 						*--t = (v%10) + '0';
 						v/=10;
 					}
 
 					len = sizeof(scratch_buffer)-(t-scratch_buffer);
 					if ((str+len)>end) break;
 					for (i = 0; i < len; i++)
 						*str++=t[i];
 					continue;
 				}
 			}
 			else if (c == 'u')
 			{
 				/* %u - unsigned integer */
 				char *t;
 				unsigned int v = va_arg(vl, unsigned int);
 				int i = 0;
 				size_t len;
 				if (v==0)
 				{
 					*str++ = '0';
 					continue;
 				}
 
 				t = scratch_buffer + sizeof(scratch_buffer);
 				while (v)
 				{
 					*--t = (v%10) + '0';
 					v/=10;
 				}
 
 				len = sizeof(scratch_buffer)-(t-scratch_buffer);
 				if ((str+len)>end) break;
 				for (i = 0; i < len; i++)
 					*str++=t[i];
 				continue;
 			}
 			else if (c == '%')
 			{
 				/* %% - literal percent character */
 				*str++ = '%';
 				continue;
 			}
 			else if (!c)
 				break; /* A % at the end of the format string (illegal, skipped) */
 			
 			/* The default case, when we cannot handle the % format:
 			 * Stop what we are doing and pass control to the real vsnprintf()
 			 */
 			format -= 2;
 			vsnprintf(str, (size_t)(end-str+1), format, vl);
 			return str_begin;
 		}
 		*str++ = c;
 	}
 	*str = 0;
 	return str_begin;
 }
 
 char *ircsnprintf(char *str, size_t size, const char *format, ...) {
 	va_list vl;
 	char *ret;
 	va_start(vl, format);
 	ret = ircvsnprintf(str, size, format, vl);
 	va_end(vl);
 	return ret;
 }

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