zircon/system/core/devmgr/devcoordinator/boot-args.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 <lib/zx/vmar.h>

#include "boot-args.h"

namespace devmgr {

zx_status_t BootArgs::Create(zx::vmo vmo, size_t size, BootArgs* out) {
    // If we have no valid data in the VMO, return early success.
    if (size == 0) {
        return ZX_OK;
    }

    uintptr_t addr;
    zx_status_t status = zx::vmar::root_self()->map(0, vmo, 0, size, ZX_VM_PERM_READ, &addr);
    if (status != ZX_OK) {
        return status;
    }

    // Build boot arguments map for fast lookup.
    std::string_view view(reinterpret_cast<char*>(addr), size);
    ArgsMap args;
    for (size_t begin = 0, end; (end = view.find_first_of('\0', begin)) != std::string_view::npos;
         begin = end + 1) {
        size_t sep = view.find_first_of('=', begin);
        std::string_view key;
        const char* value;
        if (sep < end) {
            // Handle arguments of the form "key=value".
            key = std::string_view(&view[begin], sep - begin);
            value = &view[sep + 1];
        } else {
            // Handle arguments of the form "key".
            key = std::string_view(&view[begin], end - begin);
            value = &view[end];
        }
        args.insert_or_assign(key, value);
    }

    out->addr_ = addr;
    out->size_ = size;
    out->args_ = std::move(args);
    return ZX_OK;
}

BootArgs::~BootArgs() {
    if (addr_ != 0) {
        zx::vmar::root_self()->unmap(addr_, size_);
    }
}

const char* BootArgs::Get(std::string_view name) const {
    auto it = args_.find(name);
    if (it == args_.end()) {
        return nullptr;
    }
    return it->second;
}

bool BootArgs::GetBool(std::string_view name, bool default_value) const {
    const char* value = Get(name);
    if (value == nullptr) {
        return default_value;
    } else if (strcmp(value, "0") == 0 || strcmp(value, "false") == 0 ||
               strcmp(value, "off") == 0) {
        return false;
    } else {
        return true;
    }
}

void BootArgs::Collect(std::string_view prefix, fbl::Vector<const char*>* out) const {
    std::string_view view(reinterpret_cast<char*>(addr_), size_);
    for (size_t pos = 0; (pos = view.find(prefix, pos)) != std::string_view::npos;
         pos = view.find_first_of('\0', pos)) {
        out->push_back(&view[pos]);
    }
}

} // namespace devmgr