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Correctly handle zero-length buffers.

tags/v0.9.3
Michael Brown 18 gadus atpakaļ
vecāks
revīzija
efd6281a35
1 mainītis faili ar 9 papildinājumiem un 10 dzēšanām
  1. 9
    10
      src/core/vsprintf.c

+ 9
- 10
src/core/vsprintf.c Parādīt failu

@@ -171,7 +171,7 @@ static char * format_decimal ( char *end, signed long num, int width ) {
171 171
  * @v args		Arguments corresponding to the format string
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  * @ret len		Length of formatted string
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  */
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-int vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
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+size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
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 	int flags;
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 	int width;
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 	uint8_t *length;
@@ -296,14 +296,8 @@ static void printf_sputc ( struct printf_context *ctx, unsigned int c ) {
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  */
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 int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args ) {
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 	struct printf_context ctx;
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-	int len;
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-
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-	/* Ensure last byte is NUL if a size is specified.  This
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-	 * catches the case of the buffer being too small, in which
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-	 * case a trailing NUL would not otherwise be added.
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-	 */
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-	if ( size != PRINTF_NO_LENGTH )
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-		buf[size-1] = '\0';
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+	size_t len;
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+	size_t end;
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 	/* Hand off to vcprintf */
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 	ctx.handler = printf_sputc;
@@ -312,7 +306,12 @@ int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args ) {
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 	len = vcprintf ( &ctx, fmt, args );
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 	/* Add trailing NUL */
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-	printf_sputc ( &ctx, '\0' );
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+	if ( size ) {
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+		end = size - 1;
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+		if ( len < end )
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+			end = len;
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+		buf[end] = '\0';
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+	}
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 	return len;
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 }

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