From ef6a411ce8ff615d65e2be105834c2fdbe557de1 Mon Sep 17 00:00:00 2001 From: johannst Date: Sat, 20 Mar 2021 02:34:01 +0100 Subject: Split common headers in header/src files. --- lib/src/io.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 lib/src/io.c (limited to 'lib/src/io.c') diff --git a/lib/src/io.c b/lib/src/io.c new file mode 100644 index 0000000..efe938b --- /dev/null +++ b/lib/src/io.c @@ -0,0 +1,37 @@ +// Copyright (c) 2020 Johannes Stoelp + +#include +#include +#include + +#include + +// `pfmt` uses fixed-size buffer on the stack for formating the message +// (for simplicity and since we don't impl buffered I/O). +// +// NOTE: This allows to specify a large buffer on the stack, but for +// the purpose of this study that's fine, we are cautious. +#define MAX_PRINTF_LEN 128 + +#define FD_STDOUT 1 +#define FD_STDERR 2 + +int pfmt(const char* fmt, ...) { + char buf[MAX_PRINTF_LEN]; + + va_list ap; + va_start(ap, fmt); + int ret = vfmt(buf, sizeof(buf), fmt, ap); + va_end(ap); + + if (ret > MAX_PRINTF_LEN - 1) { + syscall3(__NR_write, FD_STDERR, buf, MAX_PRINTF_LEN - 1); + + static const char warn[] = "\npfmt: Message truncated, max length can be configured by defining MAX_PRINTF_LEN\n"; + syscall3(__NR_write, FD_STDOUT, warn, sizeof(warn)); + return MAX_PRINTF_LEN - 1; + } + + syscall3(__NR_write, FD_STDOUT, buf, ret); + return ret; +} -- cgit v1.2.3