MinGW snprintf/vsnprintf work properly

3 files changed, 13 insertions, 28 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 89268d62b..b281a4b49 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -1,5 +1,17 @@
 #include <sys/utime.h>
 
+/*
+ * MS Windows has broken versions of snprintf/vsnprintf that return -1 if
+ * the string is too large for the buffer and don't null terminate the
+ * string if it fills the buffer.  However, if we're using a sufficiently
+ * modern version of MinGW and have an appropriate source code qualifier
+ * (such as _GNU_SOURCE) MinGW will use its own standards-compliant
+ * implementation.  Check for this.
+ */
+#if !defined(__USE_MINGW_ANSI_STDIO)
+#error "Must use MinGW stdio for snprintf/vsnprintf"
+#endif
+
 #define NOIMPL(name,...) static inline int name(__VA_ARGS__) { errno = ENOSYS; return -1; }
 #define IMPL(name,ret,retval,...) static inline ret name(__VA_ARGS__) { return retval; }
 
diff --git a/libbb/platform.c b/libbb/platform.c
index 3cb41347f..2bf34f5bc 100644
--- a/libbb/platform.c
+++ b/libbb/platform.c
@@ -51,21 +51,8 @@ int dprintf(int fd, const char *format, ...)
         char *string_ptr;
 
         va_start(p, format);
-        if (ENABLE_PLATFORM_MINGW32) {
-                string_ptr = xmalloc(1024);
-                r = vsnprintf(string_ptr, 1024, format, p);
-        }
-        else
-                r = vasprintf(&string_ptr, format, p);
+        r = vasprintf(&string_ptr, format, p);
         va_end(p);
-        if (ENABLE_PLATFORM_MINGW32 && r > 0) {
-                free(string_ptr);
-                r += 2;
-                string_ptr = xmalloc(r);
-                va_start(p, format);
-                r = vsnprintf(string_ptr, r, format, p);
-                va_end(p);
-        }
         if (r >= 0) {
                 r = full_write(fd, string_ptr, r);
                 free(string_ptr);
diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index 70d3fc96c..d8a42ba0b 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -295,22 +295,8 @@ char* FAST_FUNC xasprintf(const char *format, ...)
         char *string_ptr;
 
         va_start(p, format);
-#if ENABLE_PLATFORM_MINGW32
-        string_ptr = xmalloc(1024);
-        r = vsnprintf(string_ptr, 1024, format, p);
-        va_end(p);
-        if (r > 0) {
-                free(string_ptr);
-                r += 2;
-                string_ptr = xmalloc(r);
-                va_start(p, format);
-                r = vsnprintf(string_ptr, r, format, p);
-                va_end(p);
-        }
-#else
         r = vasprintf(&string_ptr, format, p);
         va_end(p);
-#endif
 
         if (r < 0)
                 bb_error_msg_and_die(bb_msg_memory_exhausted);