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// Copyright (c) 2020 Johannes Stoelp
#pragma once
#include "fmt.h"
#include "syscall.h"
#include <asm/unistd.h>
// `pfmt` uses fixed-size buffer on the stack for formating the message
// (for simplicity and since we don't impl buffered I/O).
//
// Size can be re-configured by defining `MAX_PRINTF_LEN` before including
// `io.h`.
//
// NOTE: This allows to specify a large buffer on the stack, but for
// the purpose of this study that's fine, we are cautious.
#if !defined(MAX_PRINTF_LEN)
# define MAX_PRINTF_LEN 128
#elif MAX_PRINTF_LEN > 512
# error MAX_PRINTF_LEN is limited by 512!
#endif
#define FD_STDOUT 1
#define FD_STDERR 2
static 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;
}
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