Include fixed snprintf for Windows in platform.c
Use _WIN32 to detect it rather that _MSC_VER as it turns out MSYS2 uses the
broken MS version by default too.
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 9fb870a..2445031 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -39,6 +39,10 @@
#error "mbed TLS requires a platform with 8-bit chars"
#endif
+#if defined(_WIN32) && !defined(MBEDTLS_PLATFORM_C)
+#error "MBEDTLS_PLATFORM_C is required on Windows"
+#endif
+
#if defined(MBEDTLS_DEPRECATED_WARNING) && \
!defined(__GNUC__) && !defined(__clang__)
#error "MBEDTLS_DEPRECATED_WARNING only works with GCC and Clang"
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 1fe730c..33b20c0 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -142,10 +142,7 @@
*
* All these define require MBEDTLS_PLATFORM_C to be defined!
*
- * WARNING: MBEDTLS_PLATFORM_SNPRINTF_ALT is not available on Windows
- * for compatibility reasons.
- *
- * WARNING: MBEDTLS_PLATFORM_XXX_ALT cannot be defined at the same time as
+ * \warning MBEDTLS_PLATFORM_XXX_ALT cannot be defined at the same time as
* MBEDTLS_PLATFORM_XXX_MACRO!
*
* Uncomment a macro to enable alternate implementation of specific base
@@ -2004,12 +2001,15 @@
* \def MBEDTLS_PLATFORM_C
*
* Enable the platform abstraction layer that allows you to re-assign
- * functions like calloc(), free(), snprintf(), printf(), fprintf(), exit()
+ * functions like calloc(), free(), snprintf(), printf(), fprintf(), exit().
*
* Enabling MBEDTLS_PLATFORM_C enables to use of MBEDTLS_PLATFORM_XXX_ALT
* or MBEDTLS_PLATFORM_XXX_MACRO directives, allowing the functions mentioned
* above to be specified at runtime or compile time respectively.
*
+ * \note This abstraction layer must be enabled on Windows (including MSYS2)
+ * as other module rely on it for a fixed snprintf implementation.
+ *
* Module: library/platform.c
* Caller: Most other .c files
*
@@ -2379,6 +2379,7 @@
//#define MBEDTLS_PLATFORM_STD_EXIT exit /**< Default exit to use, can be undefined */
//#define MBEDTLS_PLATFORM_STD_FPRINTF fprintf /**< Default fprintf to use, can be undefined */
//#define MBEDTLS_PLATFORM_STD_PRINTF printf /**< Default printf to use, can be undefined */
+/* Note: your snprintf must correclty zero-terminate the buffer! */
//#define MBEDTLS_PLATFORM_STD_SNPRINTF snprintf /**< Default snprintf to use, can be undefined */
/* To Use Function Macros MBEDTLS_PLATFORM_C must be enabled */
@@ -2388,6 +2389,7 @@
//#define MBEDTLS_PLATFORM_EXIT_MACRO exit /**< Default exit macro to use, can be undefined */
//#define MBEDTLS_PLATFORM_FPRINTF_MACRO fprintf /**< Default fprintf macro to use, can be undefined */
//#define MBEDTLS_PLATFORM_PRINTF_MACRO printf /**< Default printf macro to use, can be undefined */
+/* Note: your snprintf must correclty zero-terminate the buffer! */
//#define MBEDTLS_PLATFORM_SNPRINTF_MACRO snprintf /**< Default snprintf macro to use, can be undefined */
/* SSL Cache options */
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index b71a09c..5dab974 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -46,8 +46,12 @@
#include <stdio.h>
#include <stdlib.h>
#if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
+#if defined(_WIN32)
+#define MBEDTLS_PLATFORM_STD_SNPRINTF mbedtls_platform_win32_snprintf /**< Default snprintf to use */
+#else
#define MBEDTLS_PLATFORM_STD_SNPRINTF snprintf /**< Default snprintf to use */
#endif
+#endif
#if !defined(MBEDTLS_PLATFORM_STD_PRINTF)
#define MBEDTLS_PLATFORM_STD_PRINTF printf /**< Default printf to use */
#endif
@@ -150,7 +154,18 @@
/*
* The function pointers for snprintf
+ *
+ * The snprintf implementation should conform to C99:
+ * - it *must* always correctly zero-terminate the buffer
+ * (except when n == 0, then it must leave the buffer untouched)
+ * - however it is acceptable to return -1 instead of the required length when
+ * the destination buffer is too short.
*/
+#if defined(_WIN32)
+/* For Windows (inc. MSYS2), we provide our own fixed implementation */
+int mbedtls_platform_win32_snprintf( char *s, size_t n, const char *fmt, ... );
+#endif
+
#if defined(MBEDTLS_PLATFORM_SNPRINTF_ALT)
extern int (*mbedtls_snprintf)( char * s, size_t n, const char * format, ... );
diff --git a/library/platform.c b/library/platform.c
index 123267a..23dba94 100644
--- a/library/platform.c
+++ b/library/platform.c
@@ -63,6 +63,21 @@
}
#endif /* MBEDTLS_PLATFORM_MEMORY */
+#if defined(_WIN32)
+#include <stdarg.h>
+int mbedtls_platform_win32_snprintf( char *s, size_t n, const char *fmt, ... )
+{
+ int ret;
+ va_list argp;
+
+ va_start( argp, fmt );
+ ret = _vsnprintf_s( s, n, _TRUNCATE, fmt, argp );
+ va_end( argp );
+
+ return( ret );
+}
+#endif
+
#if defined(MBEDTLS_PLATFORM_SNPRINTF_ALT)
#if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
/*