create stdio.h and stdarg.h for {,v}snprintf

Sometimes coreboot needs to compile external code (e.g.
vboot_reference) using its own set of system header files.
When these headers don't line up with C Standard Library,
it causes problems.

Create stdio.h and stdarg.h header files.  Relocate snprintf
into stdio.h and vsnprintf into stdarg.h from string.h.
Chain include these header files from string.h, since coreboot
doesn't care so much about the legacy POSIX location of these
functions.

Also move va_* definitions from vtxprintf.h into stdarg.h where
they belong (in POSIX).  Just use our own definitions regardless
of GCC or LLVM.

Add string.h header to a few C files which should have had it
in the first place.

BUG=b:124141368
TEST=make clean && make test-abuild
BRANCH=none

Change-Id: I7223cb96e745e11c82d4012c6671a51ced3297c2
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39468
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/include/stdio.h b/src/include/stdio.h
new file mode 100644
index 0000000000..d59b9411ee
--- /dev/null
+++ b/src/include/stdio.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/**
+ * Note: This file is only for POSIX compatibility, and is meant to be
+ * chain-included via string.h.
+ */
+
+#ifndef STDIO_H
+#define STDIO_H
+
+#include <stddef.h>
+
+int snprintf(char *buf, size_t size, const char *fmt, ...);
+
+#endif /* STDIO_H */