Wmem: Use the native v*printf routines on Windows.

GLib's v*printf routines are close to unreasonably slow on
Windows. Use the native CRT routines in wmem_strdup_vprintf and
wmem_strbuf_append_vprintf on that platform.

Change-Id: I5e94aa6fe47434e5a18f3a4d5b6b24ebe71499c1
Reviewed-on: https://code.wireshark.org/review/14868
Reviewed-by: Evan Huus <eapache@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

2 files changed, 68 insertions, 0 deletions

diff --git a/epan/wmem/wmem_strbuf.c b/epan/wmem/wmem_strbuf.c
index bd074e7584..0a0f1a5f56 100644
--- a/epan/wmem/wmem_strbuf.c
+++ b/epan/wmem/wmem_strbuf.c
@@ -29,6 +29,10 @@
 #include "wmem_core.h"
 #include "wmem_strbuf.h"
 
+#ifdef _WIN32
+#include <stdio.h>
+#endif
+
 #define DEFAULT_MINIMUM_LEN 16
 
 /* Holds a wmem-allocated string-buffer.
@@ -154,6 +158,7 @@ wmem_strbuf_append(wmem_strbuf_t *strbuf, const gchar *str)
     strbuf->len = MIN(strbuf->len + append_len, strbuf->alloc_len - 1);
 }
 
+#ifndef _WIN32
 static void
 wmem_strbuf_append_vprintf(wmem_strbuf_t *strbuf, const gchar *fmt, va_list ap)
 {
@@ -176,6 +181,37 @@ wmem_strbuf_append_vprintf(wmem_strbuf_t *strbuf, const gchar *fmt, va_list ap)
 
     strbuf->len = MIN(strbuf->len + append_len, strbuf->alloc_len - 1);
 }
+#else /* _WIN32 */
+/*
+ * GLib's v*printf routines are surprisingly slow on Windows, at least with
+ * GLib 2.40.0. This appears to be due to GLib using the gnulib version of
+ * vasnprintf when compiled under MinGW. If GLib ever ends up using the
+ * native Windows v*printf routines this can be removed.
+ */
+static void
+wmem_strbuf_append_vprintf(wmem_strbuf_t *strbuf, const gchar *fmt, va_list ap)
+{
+    va_list ap2;
+    gsize append_len;
+    gsize printed_len;
+
+    G_VA_COPY(ap2, ap);
+
+    append_len = _vscprintf(fmt, ap);
+
+    wmem_strbuf_grow(strbuf, append_len);
+
+    printed_len = vsnprintf_s(&strbuf->str[strbuf->len],
+            (gulong) WMEM_STRBUF_RAW_ROOM(strbuf),
+            _TRUNCATE,
+            fmt, ap2);
+    if (printed_len > -1) append_len = printed_len;
+
+    va_end(ap2);
+
+    strbuf->len = MIN(strbuf->len + append_len, strbuf->alloc_len - 1);
+}
+#endif /* _WIN32 */
 
 void
 wmem_strbuf_append_printf(wmem_strbuf_t *strbuf, const gchar *format, ...)
diff --git a/epan/wmem/wmem_strutl.c b/epan/wmem/wmem_strutl.c
index c35f2e68f0..009abf1d80 100644
--- a/epan/wmem/wmem_strutl.c
+++ b/epan/wmem/wmem_strutl.c
@@ -26,6 +26,10 @@
 #include <string.h>
 #include <stdarg.h>
 
+#ifdef _WIN32
+#include <stdio.h>
+#endif
+
 #include <glib.h>
 
 #include "wmem_core.h"
@@ -86,6 +90,7 @@ wmem_strdup_printf(wmem_allocator_t *allocator, const gchar *fmt, ...)
  * in my test file all strings was less than 72 characters long and quite a few
  * over 68 characters long. Chose 80 as the default.
  */
+#ifndef _WIN32
 #define WMEM_STRDUP_VPRINTF_DEFAULT_BUFFER 80
 gchar *
 wmem_strdup_vprintf(wmem_allocator_t *allocator, const gchar *fmt, va_list ap)
@@ -115,6 +120,33 @@ wmem_strdup_vprintf(wmem_allocator_t *allocator, const gchar *fmt, va_list ap)
 
     return dst;
 }
+#else /* _WIN32 */
+/*
+ * GLib's v*printf routines are surprisingly slow on Windows, at least with
+ * GLib 2.40.0. This appears to be due to GLib using the gnulib version of
+ * vasnprintf when compiled under MinGW. If GLib ever ends up using the
+ * native Windows v*printf routines this can be removed.
+ */
+gchar *
+wmem_strdup_vprintf(wmem_allocator_t *allocator, const gchar *fmt, va_list ap)
+{
+    va_list ap2;
+    gchar *dst;
+    int needed_len;
+
+    G_VA_COPY(ap2, ap);
+
+    needed_len = _vscprintf(fmt, ap2) + 1;
+
+    dst = (gchar *)wmem_alloc(allocator, needed_len);
+
+    vsprintf(dst, fmt, ap2);
+
+    va_end(ap2);
+
+    return dst;
+}
+#endif /* _WIN32 */
 
 gchar *
 wmem_strconcat(wmem_allocator_t *allocator, const gchar *first, ...)