platform compatibility work (by Dan Fandrich)

Signed-off-by: Dan Fandrich <dan@coneharvesters.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/platform.c b/libbb/platform.c
new file mode 100644
index 0000000..470185a
--- /dev/null
+++ b/libbb/platform.c
@@ -0,0 +1,57 @@
+/*
+ * Replacements for common but usually nonstandard functions that aren't
+ * supplied by all platforms.
+ *
+ * Copyright (C) 2009 by Dan Fandrich <dan@coneharvesters.com>, et. al.
+ *
+ * Licensed under the GPL version 2, see the file LICENSE in this tarball.
+ */
+
+#include "libbb.h"
+
+#ifndef HAVE_STRCHRNUL
+char * FAST_FUNC strchrnul(const char *s, int c)
+{
+	while (*s && *s != c) ++s;
+	return (char*)s;
+}
+#endif
+
+#ifndef HAVE_VASPRINTF
+int FAST_FUNC vasprintf(char **string_ptr, const char *format, va_list p)
+{
+	int r;
+	va_list p2;
+
+	va_copy(p2, p);
+	r = vsnprintf(NULL, 0, format, p);
+	va_end(p);
+	*string_ptr = xmalloc(r+1);
+	if (!*string_ptr)
+		r = -1;
+	else
+		r = vsnprintf(*string_ptr, r+1, format, p2);
+	va_end(p2);
+
+	return r;
+}
+#endif
+
+#ifndef HAVE_FDPRINTF
+int fdprintf(int fd, const char *format, ...)
+{
+	va_list p;
+	int r;
+	char *string_ptr;
+
+	va_start(p, format);
+	r = vasprintf(&string_ptr, format, p);
+	va_end(p);
+	if (r >= 0) {
+		r = full_write(fd, string_ptr, r);
+		free(string_ptr);
+	}
+	return r;
+}
+#endif
+