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Correctly handle zero-length buffers.

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This commit is contained in:
Michael Brown 2006-05-14 11:18:42 +00:00
parent 25f5d114a0
commit efd6281a35
1 changed files with 9 additions and 10 deletions
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19
src/core/vsprintf.c
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@ -171,7 +171,7 @@ static char * format_decimal ( char *end, signed long num, int width ) {
* @v args Arguments corresponding to the format string
* @ret len Length of formatted string
*/
int vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
int flags;
int width;
uint8_t *length;
@ -296,14 +296,8 @@ static void printf_sputc ( struct printf_context *ctx, unsigned int c ) {
*/
int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args ) {
struct printf_context ctx;
int len;
/* Ensure last byte is NUL if a size is specified. This
* catches the case of the buffer being too small, in which
* case a trailing NUL would not otherwise be added.
*/
if ( size != PRINTF_NO_LENGTH )
buf[size-1] = '\0';
size_t len;
size_t end;
/* Hand off to vcprintf */
ctx.handler = printf_sputc;
@ -312,7 +306,12 @@ int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args ) {
len = vcprintf ( &ctx, fmt, args );
/* Add trailing NUL */
printf_sputc ( &ctx, '\0' );
if ( size ) {
end = size - 1;
if ( len < end )
end = len;
buf[end] = '\0';
}
return len;
}