1 files changed, 81 insertions, 0 deletions
diff --git a/lib/compat/vsnprintf.c b/lib/compat/vsnprintf.c
new file mode 100644
index 0000000..5f709d9
--- /dev/null
+++ b/lib/compat/vsnprintf.c
@@ -0,0 +1,81 @@
+/*
+ * libcompat - system compatibility library
+ *
+ * Copyright © 1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
+ * Copyright © 2008-2012 Guillem Jover <guillem@debian.org>
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+
+#include <unistd.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "compat.h"
+
+int
+vsnprintf(char *buf, size_t maxsize, const char *fmt, va_list args)
+{
+	static FILE *file = NULL;
+	static pid_t file_pid;
+
+	size_t want, nr;
+	int total;
+
+	if (maxsize != 0 && buf == NULL)
+		return -1;
+
+	/* Avoid race conditions from children after a fork(2). */
+	if (file_pid > 0 && file_pid != getpid()) {
+		fclose(file);
+		file = NULL;
+	}
+
+	if (!file) {
+		file = tmpfile();
+		if (!file)
+			return -1;
+		file_pid = getpid();
+	} else {
+		if (fseek(file, 0, 0))
+			return -1;
+		if (ftruncate(fileno(file), 0))
+			return -1;
+	}
+
+	total = vfprintf(file, fmt, args);
+	if (total < 0)
+		return -1;
+	if (maxsize == 0)
+		return total;
+	if (total >= (int)maxsize)
+		want = maxsize - 1;
+	else
+		want = total;
+	if (fflush(file))
+		return -1;
+	if (fseek(file, 0, SEEK_SET))
+		return -1;
+
+	nr = fread(buf, 1, want, file);
+	if (nr != want)
+		return -1;
+	buf[want] = '\0';
+
+	return total;
+}