1 /* 2 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers. 3 * All rights reserved. 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * By using this file, you agree to the terms and conditions set 11 * forth in the LICENSE file which can be found at the top level of 12 * the sendmail distribution. 13 */ 14 15 #include <sm/gen.h> 16 SM_RCSID("@(#)$Id: snprintf.c,v 1.24 2006/10/12 21:50:10 ca Exp $") 17 #include <limits.h> 18 #include <sm/varargs.h> 19 #include <sm/io.h> 20 #include <sm/string.h> 21 #include "local.h" 22 23 /* 24 ** SM_SNPRINTF -- format a string to a memory location of restricted size 25 ** 26 ** Parameters: 27 ** str -- memory location to place formatted string 28 ** n -- size of buffer pointed to by str, capped to 29 ** a maximum of INT_MAX 30 ** fmt -- the formatting directives 31 ** ... -- the data to satisfy the formatting 32 ** 33 ** Returns: 34 ** Failure: -1 35 ** Success: number of bytes that would have been written 36 ** to str, not including the trailing '\0', 37 ** up to a maximum of INT_MAX, as if there was 38 ** no buffer size limitation. If the result >= n 39 ** then the output was truncated. 40 ** 41 ** Side Effects: 42 ** If n > 0, then between 0 and n-1 bytes of formatted output 43 ** are written into 'str', followed by a '\0'. 44 */ 45 46 int 47 #if SM_VA_STD 48 sm_snprintf(char *str, size_t n, char const *fmt, ...) 49 #else /* SM_VA_STD */ 50 sm_snprintf(str, n, fmt, va_alist) 51 char *str; 52 size_t n; 53 char *fmt; 54 va_dcl 55 #endif /* SM_VA_STD */ 56 { 57 int ret; 58 SM_VA_LOCAL_DECL 59 SM_FILE_T fake; 60 61 /* While snprintf(3) specifies size_t stdio uses an int internally */ 62 if (n > INT_MAX) 63 n = INT_MAX; 64 SM_VA_START(ap, fmt); 65 66 /* XXX put this into a static? */ 67 fake.sm_magic = SmFileMagic; 68 fake.f_file = -1; 69 fake.f_flags = SMWR | SMSTR; 70 fake.f_cookie = &fake; 71 fake.f_bf.smb_base = fake.f_p = (unsigned char *)str; 72 fake.f_bf.smb_size = fake.f_w = n ? n - 1 : 0; 73 fake.f_timeout = SM_TIME_FOREVER; 74 fake.f_timeoutstate = SM_TIME_BLOCK; 75 fake.f_close = NULL; 76 fake.f_open = NULL; 77 fake.f_read = NULL; 78 fake.f_write = NULL; 79 fake.f_seek = NULL; 80 fake.f_setinfo = fake.f_getinfo = NULL; 81 fake.f_type = "sm_snprintf:fake"; 82 ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap); 83 if (n > 0) 84 *fake.f_p = '\0'; 85 SM_VA_END(ap); 86 return ret; 87 } 88