1 files changed, 64 insertions, 0 deletions
diff --git a/compat/snprintf.c b/compat/snprintf.c
new file mode 100644
index 0000000000..e1e0e7543d
--- /dev/null
+++ b/compat/snprintf.c
@@ -0,0 +1,64 @@
+#include "../git-compat-util.h"
+
+/*
+ * The size parameter specifies the available space, i.e. includes
+ * the trailing NUL byte; but Windows's vsnprintf uses the entire
+ * buffer and avoids the trailing NUL, should the buffer be exactly
+ * big enough for the result. Defining SNPRINTF_SIZE_CORR to 1 will
+ * therefore remove 1 byte from the reported buffer size, so we
+ * always have room for a trailing NUL byte.
+ */
+#ifndef SNPRINTF_SIZE_CORR
+#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4)
+#define SNPRINTF_SIZE_CORR 1
+#else
+#define SNPRINTF_SIZE_CORR 0
+#endif
+#endif
+
+#undef vsnprintf
+int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
+{
+	char *s;
+	int ret = -1;
+
+	if (maxsize > 0) {
+		ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
+		if (ret == maxsize-1)
+			ret = -1;
+		/* Windows does not NUL-terminate if result fills buffer */
+		str[maxsize-1] = 0;
+	}
+	if (ret != -1)
+		return ret;
+
+	s = NULL;
+	if (maxsize < 128)
+		maxsize = 128;
+
+	while (ret == -1) {
+		maxsize *= 4;
+		str = realloc(s, maxsize);
+		if (! str)
+			break;
+		s = str;
+		ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
+		if (ret == maxsize-1)
+			ret = -1;
+	}
+	free(s);
+	return ret;
+}
+
+int git_snprintf(char *str, size_t maxsize, const char *format, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, format);
+	ret = git_vsnprintf(str, maxsize, format, ap);
+	va_end(ap);
+
+	return ret;
+}
+