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Fix snprintf(NULL, 0, ...) undefined behavior.

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Jonas 'Sortie' Termansen 2015-12-01 21:10:25 +01:00
parent 15fd58b6a0
commit 23810c1a48
4 changed files with 21 additions and 23 deletions
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2
libc/stdio/snprintf.cpp
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@ -18,7 +18,7 @@
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>. along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/snprintf.cpp stdio/snprintf.cpp
Prints a formatted string to a limited string. Prints a formatted string to the supplied buffer.
*******************************************************************************/ *******************************************************************************/

2
libc/stdio/sprintf.cpp
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@ -18,7 +18,7 @@
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>. along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/sprintf.cpp stdio/sprintf.cpp
Prints a formatted string to a string. Prints a formatted string to the supplied buffer.
*******************************************************************************/ *******************************************************************************/

38
libc/stdio/vsnprintf.cpp
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@ -1,6 +1,6 @@
/******************************************************************************* /*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014. Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014, 2015.
This file is part of the Sortix C Library. This file is part of the Sortix C Library.
@ -18,7 +18,7 @@
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>. along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/vsnprintf.cpp stdio/vsnprintf.cpp
Prints a formatted string to a limited string. Prints a formatted string to the supplied buffer.
*******************************************************************************/ *******************************************************************************/
@ -26,40 +26,38 @@
#include <stdio.h> #include <stdio.h>
#include <string.h> #include <string.h>
typedef struct vsnprintf_struct struct vsnprintf
{ {
char* str; char* str;
size_t size; size_t size;
size_t produced;
size_t written; size_t written;
} vsnprintf_t; };
static size_t StringPrintCallback(void* user, const char* string, static size_t vsnprintf_callback(void* ctx, const char* string, size_t length)
size_t stringlen)
{ {
vsnprintf_t* info = (vsnprintf_t*) user; struct vsnprintf* info = (struct vsnprintf*) ctx;
if ( info->produced < info->size ) if ( 1 <= info->size && info->written < info->size )
{ {
size_t available = info->size - info->produced; size_t available = info->size - info->written;
size_t possible = (stringlen < available) ? stringlen : available; size_t possible = length < available ? length : available;
memcpy(info->str + info->produced, string, possible); memcpy(info->str + info->written, string, possible);
info->written += possible; info->written += possible;
} }
info->produced += stringlen; return length;
return stringlen;
} }
extern "C" extern "C"
int vsnprintf(char* restrict str, size_t size, const char* restrict format, int vsnprintf(char* restrict str,
size_t size,
const char* restrict format,
va_list list) va_list list)
{ {
vsnprintf_t info; struct vsnprintf info;
info.str = str; info.str = str;
info.size = size ? size-1 : 0; info.size = size ? size - 1 : 0;
info.produced = 0;
info.written = 0; info.written = 0;
int result = vcbprintf(&info, StringPrintCallback, format, list); int result = vcbprintf(&info, vsnprintf_callback, format, list);
if ( size ) if ( 1 <= size )
info.str[info.written] = '\0'; info.str[info.written] = '\0';
return result; return result;
} }

2
libc/stdio/vsprintf.cpp
View file

@ -18,7 +18,7 @@
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>. along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/vsprintf.cpp stdio/vsprintf.cpp
Prints a formatted string to a string. Prints a formatted string to the supplied buffer.
*******************************************************************************/ *******************************************************************************/