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implementation of secure CRT string functions

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This was SVN commit r1953.
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janwas 2005-02-28 15:27:04 +00:00
parent f8f2245846
commit 8e16010d3e
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356
source/lib/string_s.cpp Normal file
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// implementation of proposed CRT safe string functions
//
// Copyright (c) 2005 Jan Wassenberg
//
// 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 of the
// License, 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.
//
// Contact info:
// Jan.Wassenberg@stud.uni-karlsruhe.de
// http://www.stud.uni-karlsruhe.de/~urkt/
#include "precompiled.h"
#include "lib.h"
#include "posix.h" // SIZE_MAX
#include "timer.h"
#include <string.h>
// these are already shipped with VC2005
#if _MSC_VER < 1400
// written against http://std.dkuug.dk/jtc1/sc22/wg14/www/docs/n1031.pdf .
// optimized for size - e.g. strcpy calls strncpy with n = SIZE_MAX.
// since char and wide versions of these functions are basically the same,
// this source file implements generic versions and bridges the differences
// with these macros. wstring_s.cpp #defines WSTRING_S and includes this file.
#ifdef WSTRING_S
# define tchar wchar_t
# define T(string_literal) L ## string_literal
# define tlen_s wcslen_s
# define tncpy_s wcsncpy_s
# define tcpy_s wcscpy_s
# define tncat_s wcsncat_s
# define tcat_s wcscat_s
# define tcmp wcscmp
# define tcpy wcscpy
#else
# define tchar char
# define T(string_literal) string_literal
# define tlen_s strlen_s
# define tncpy_s strncpy_s
# define tcpy_s strcpy_s
# define tncat_s strncat_s
# define tcat_s strcat_s
# define tcmp strcmp
# define tcpy strcpy
#endif
// return <retval> and raise an assertion if <condition> doesn't hold.
// usable as a statement.
#define ENFORCE(condition, retval) STMT(\
if(!(condition)) \
{ \
/*assert2(condition);*/ \
return retval; \
} \
)
// return length [in characters] of a string, not including the trailing
// null character. to protect against access violations, only the
// first <max_len> characters are examined; if the null character is
// not encountered by then, <max_len> is returned.
size_t tlen_s(const tchar* str, size_t max_len)
{
// note: we can't bail - what would the return value be?
assert(str != 0);
size_t len;
for(len = 0; len < max_len; len++)
if(*str++ == '\0')
break;
return len;
}
// copy at most <max_src_chars> (not including trailing null) from
// <src> into <dst>, which must not overlap.
// if thereby <max_dst_chars> (including null) would be exceeded,
// <dst> is set to the empty string and ERANGE returned; otherwise,
// 0 is returned to indicate success and that <dst> is null-terminated.
//
// note: padding with zeroes is not called for by NG1031.
int tncpy_s(tchar* dst, size_t max_dst_chars, const tchar* src, size_t max_src_chars)
{
// the MS implementation returns EINVAL and allows dst = 0 if
// max_dst_chars = max_src_chars = 0. no mention of this in
// NG1031 3.6.2.1.1, so don't emulate that behavior.
ENFORCE(dst != 0, EINVAL);
ENFORCE(max_dst_chars != 0, ERANGE);
*dst = '\0';
ENFORCE(src != 0, EINVAL);
// copy string until null character encountered or limit reached.
// optimized for size (less comparisons than MS impl) and
// speed (due to well-predicted jumps; we don't bother unrolling).
tchar* p = dst;
size_t chars_left = MIN(max_dst_chars, max_src_chars);
copy_loop:
if(chars_left == 0)
goto hit_limit;
if((*p++ = *src++) == '\0')
return 0;
chars_left--;
goto copy_loop;
hit_limit:
// which limit was responsible?
// .. dest, and last character wasn't null: overflow.
if(max_dst_chars <= max_src_chars)
{
*dst = '\0';
ENFORCE(0 && "Buffer too small", ERANGE);
}
// .. source: success, but still need to null-terminate the destination.
*p = '\0';
return 0;
}
// copy <src> (including trailing null) into <dst>, which must not overlap.
// if thereby <max_dst_chars> (including null) would be exceeded,
// <dst> is set to the empty string and ERANGE returned; otherwise,
// 0 is returned to indicate success and that <dst> is null-terminated.
int tcpy_s(tchar* dst, size_t max_dst_chars, const tchar* src)
{
return tncpy_s(dst, max_dst_chars, src, SIZE_MAX);
}
// append <src> to <dst>, which must not overlap.
// if thereby <max_dst_chars> (including null) would be exceeded,
// <dst> is set to the empty string and ERANGE returned; otherwise,
// 0 is returned to indicate success and that <dst> is null-terminated.
int tncat_s(tchar* dst, size_t max_dst_chars, const tchar* src, size_t max_src_chars)
{
ENFORCE(dst != 0, EINVAL);
ENFORCE(max_dst_chars != 0, ERANGE);
// src is checked in tncpy_s
const size_t dst_len = tlen_s(dst, max_dst_chars);
if(dst_len == max_dst_chars)
{
*dst = '\0';
ENFORCE(0 && "Destination string not null-terminated", ERANGE);
}
tchar* const end = dst+dst_len;
const size_t chars_left = max_dst_chars-dst_len;
int ret = tncpy_s(end, chars_left, src, max_src_chars);
// if tncpy_s overflowed, we need to clear the start of our string
// (not just the appended part). can't do that by default, because
// the beginning of dst is not changed in normal operation.
if(ret != 0)
*dst = '\0';
return ret;
}
int tcat_s(tchar* dst, size_t max_chars, const tchar* src)
{
return tncat_s(dst, max_chars, src, SIZE_MAX);
}
#endif
//////////////////////////////////////////////////////////////////////////////
//
// built-in self test
//
//////////////////////////////////////////////////////////////////////////////
#ifndef NDEBUG
static int test()
{
debug_out("%s\n", __FILE__);
TIMER(stringtest);
const tchar* s0 = T("");
const tchar* s1 = T("a");
const tchar* s5 = T("abcde");
const tchar* s10 = T("abcdefghij");
tchar d1[1];
tchar d2[2];
tchar d3[3];
tchar d5[5];
tchar d6[6];
tchar d10[10];
tchar d11[11];
tchar no_null[] = { 'n','o','_','n','u','l','l'};
//
// len
//
#define TEST_LEN(string, limit, expected)\
STMT(\
assert2(tlen_s((string), (limit)) == (expected));\
)
TEST_LEN(s0, 0 , 0 );
TEST_LEN(s0, 1 , 0 );
TEST_LEN(s0, 50, 0 );
TEST_LEN(s1, 0 , 0 );
TEST_LEN(s1, 1 , 1 );
TEST_LEN(s1, 50, 1 );
TEST_LEN(s5, 0 , 0 );
TEST_LEN(s5, 1 , 1 );
TEST_LEN(s5, 50, 5 );
TEST_LEN(s10,9 , 9 );
TEST_LEN(s10,10, 10);
TEST_LEN(s10,11, 10);
//
// cpy
//
#define TEST_CPY(dst, dst_max, src, expected_ret, expected_dst) \
STMT( \
int ret = tcpy_s((dst), dst_max, (src)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, T(expected_dst))); \
)
#define TEST_CPY2(dst, src, expected_ret, expected_dst) \
STMT( \
int ret = tcpy_s((dst), ARRAY_SIZE(dst), (src)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, T(expected_dst))); \
)
#define TEST_NCPY(dst, src, max_src_chars, expected_ret, expected_dst) \
STMT( \
int ret = tncpy_s((dst), ARRAY_SIZE(dst), (src), (max_src_chars)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, T(expected_dst))); \
)
TEST_CPY(0 ,0,0 , EINVAL,""); // all invalid
TEST_CPY(0 ,0,s1, EINVAL,""); // dst = 0, max = 0
TEST_CPY(0 ,1,s1, EINVAL,""); // dst = 0, max > 0
TEST_CPY(d1,1,0 , EINVAL,""); // src = 0
TEST_CPY(d1,0,s1, ERANGE,""); // max_dst_chars = 0
TEST_CPY2(d1 ,s1, ERANGE,"");
TEST_CPY2(d1 ,s5, ERANGE,"");
TEST_CPY2(d5 ,s5, ERANGE,"");
TEST_CPY2(d2 ,s1, 0,"a");
TEST_CPY2(d6 ,s5, 0,"abcde");
TEST_CPY2(d11,s5, 0,"abcde");
TEST_NCPY(d1 ,s1,1, ERANGE,"");
TEST_NCPY(d1 ,s5,1, ERANGE,"");
TEST_NCPY(d5 ,s5,5, ERANGE,"");
TEST_NCPY(d2 ,s1,1, 0,"a");
TEST_NCPY(d6 ,s5,5, 0,"abcde");
TEST_NCPY(d11,s5,5, 0,"abcde");
tcpy(d5, T("----"));
TEST_NCPY(d5,s5,0 , 0,""); // specified behavior! see 3.6.2.1.1 #4
TEST_NCPY(d5,s5,1 , 0,"a");
TEST_NCPY(d5,s5,4 , 0,"abcd");
TEST_NCPY(d6,s5,5 , 0,"abcde");
TEST_NCPY(d6,s5,10, 0,"abcde");
//
// cat
//
#define TEST_CAT(dst, dst_max, src, expected_ret, expected_dst) \
STMT( \
int ret = tcat_s((dst), dst_max, (src)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, expected_dst)); \
)
#define TEST_CAT2(dst, dst_val, src, expected_ret, expected_dst) \
STMT( \
tcpy(dst, T(dst_val)); \
int ret = tcat_s((dst), ARRAY_SIZE(dst), (src)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, T(expected_dst))); \
)
#define TEST_NCAT(dst, dst_val, src, max_src_chars, expected_ret, expected_dst)\
STMT( \
tcpy(dst, T(dst_val)); \
int ret = tncat_s((dst), ARRAY_SIZE(dst), (src), (max_src_chars)); \
assert2(ret == expected_ret); \
if(dst != 0) \
assert2(!tcmp(dst, T(expected_dst))); \
)
TEST_CAT(0 ,0,0 , EINVAL,""); // all invalid
TEST_CAT(0 ,0,s1, EINVAL,""); // dst = 0, max = 0
TEST_CAT(0 ,1,s1, EINVAL,""); // dst = 0, max > 0
TEST_CAT(d1,1,0 , EINVAL,""); // src = 0
TEST_CAT(d1,0,s1, ERANGE,""); // max_dst_chars = 0
TEST_CAT(no_null,5,s1, ERANGE,T("")); // dst not terminated
TEST_CAT2(d1 ,"" ,s1, ERANGE,"");
TEST_CAT2(d1 ,"" ,s5, ERANGE,"");
TEST_CAT2(d3 ,"1",s1, 0,"1a");
TEST_CAT2(d5 ,"1",s1, 0,"1a");
TEST_CAT2(d6 ,"" ,s5, 0,"abcde");
TEST_CAT2(d10,"" ,s5, 0,"abcde");
TEST_CAT2(d10,"" ,s10, ERANGE,""); // empty, total overflow
TEST_CAT2(d10,"12345",s5 , ERANGE,""); // not empty, overflow
TEST_CAT2(d10,"12345",s10, ERANGE,""); // not empty, total overflow
TEST_CAT2(d10,"1234" ,s5 , 0,"1234abcde");
TEST_NCAT(d1 ,"" ,s1,1, ERANGE,"");
TEST_NCAT(d1 ,"" ,s5,5, ERANGE,"");
TEST_NCAT(d3 ,"1",s1,1, 0,"1a");
TEST_NCAT(d5 ,"1",s1,1, 0,"1a");
TEST_NCAT(d6 ,"" ,s5,5, 0,"abcde");
TEST_NCAT(d10,"" ,s5,5, 0,"abcde");
TEST_NCAT(d10,"" ,s10,10, ERANGE,""); // empty, total overflow
TEST_NCAT(d10,"12345",s5 ,5 , ERANGE,""); // not empty, overflow
TEST_NCAT(d10,"12345",s10,10, ERANGE,""); // not empty, total overflow
TEST_NCAT(d10,"1234" ,s5 ,5 , 0,"1234abcde");
TEST_NCAT(d5,"----",s5,0 , 0,"----");
TEST_NCAT(d5,"",s5,1 , 0,"a");
TEST_NCAT(d5,"",s5,4 , 0,"abcd");
TEST_NCAT(d5,"12",s5,2 , 0,"12ab");
TEST_NCAT(d6,"",s5,10, 0,"abcde");
return 0;
}
static int dummy = test();
#endif // #ifndef NDEBUG

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source/lib/wstring_s.cpp Normal file
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#include "precompiled.h"
#define WSTRING_S
#include "string_s.cpp"