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
sm_snprintf(char * str,size_t n,char const * fmt,...)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