system/dev/sysmem/sysmem/logging.cpp

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "logging.h"

#include <ddk/debug.h>
#include <zircon/assert.h>

#include <memory>
#include <stdio.h>

void vLog(bool is_error, const char* prefix1, const char* prefix2,
          const char* format, va_list args) {
    // Let's not have a buffer on the stack, not because it couldn't be done
    // safely, but because we'd potentially run into stack size vs. message
    // length tradeoffs, stack expansion granularity fun, or whatever else.

    va_list args2;
    va_copy(args2, args);

    size_t buffer_bytes = vsnprintf(nullptr, 0, format, args) + 1;

    std::unique_ptr<char[]> buffer(new char[buffer_bytes]);

    size_t buffer_bytes_2 =
        vsnprintf(buffer.get(), buffer_bytes, format, args2) + 1;
    (void)buffer_bytes_2;
    // sanity check; should match so go ahead and assert that it does.
    ZX_DEBUG_ASSERT(buffer_bytes == buffer_bytes_2);
    va_end(args2);

    if (is_error) {
        zxlogf(ERROR, "[%s %s] %s\n", prefix1, prefix2, buffer.get());
    } else {
        zxlogf(INFO, "[%s %s] %s\n", prefix1, prefix2, buffer.get());
    }
}