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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2022, Google Inc.
*
* yaml_parser.cpp - libcamera YAML parsing helper
*/
#include "libcamera/internal/yaml_parser.h"
#include <cstdlib>
#include <errno.h>
#include <functional>
#include <limits>
#include <libcamera/base/file.h>
#include <libcamera/base/log.h>
#include <yaml.h>
/**
* \file libcamera/internal/yaml_parser.h
* \brief A YAML parser helper
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(YamlParser)
namespace {
/* Empty static YamlObject as a safe result for invalid operations */
static const YamlObject empty;
} /* namespace */
/**
* \class YamlObject
* \brief A class representing the tree structure of the YAML content
*
* The YamlObject class represents the tree structure of YAML content. A
* YamlObject can be a dictionary or list of YamlObjects or a value if a tree
* leaf.
*/
YamlObject::YamlObject()
: type_(Type::Value)
{
}
YamlObject::~YamlObject() = default;
/**
* \fn YamlObject::isValue()
* \brief Return whether the YamlObject is a value
*
* \return True if the YamlObject is a value, false otherwise
*/
/**
* \fn YamlObject::isList()
* \brief Return whether the YamlObject is a list
*
* \return True if the YamlObject is a list, false otherwise
*/
/**
* \fn YamlObject::isDictionary()
* \brief Return whether the YamlObject is a dictionary
*
* \return True if the YamlObject is a dictionary, false otherwise
*/
/**
* \fn YamlObject::size()
* \brief Retrieve the number of elements in a dictionary or list YamlObject
*
* This function retrieves the size of the YamlObject, defined as the number of
* child elements it contains. Only YamlObject instances of Dictionary or List
* types have a size, calling this function on other types of instances is
* invalid and results in undefined behaviour.
*
* \return The size of the YamlObject
*/
std::size_t YamlObject::size() const
{
switch (type_) {
case Type::Dictionary:
case Type::List:
return list_.size();
default:
return 0;
}
}
/**
* \fn template<typename T> YamlObject::get<T>() const
* \brief Parse the YamlObject as a \a T value
*
* This function parses the value of the YamlObject as a \a T object, and
* returns the value. If parsing fails (usually because the YamlObject doesn't
* store a \a T value), std::nullopt is returned.
*
* \return The YamlObject value, or std::nullopt if parsing failed
*/
/**
* \fn template<typename T> YamlObject::get<T>(const T &defaultValue) const
* \brief Parse the YamlObject as a \a T value
* \param[in] defaultValue The default value when failing to parse
*
* This function parses the value of the YamlObject as a \a T object, and
* returns the value. If parsing fails (usually because the YamlObject doesn't
* store a \a T value), the \a defaultValue is returned.
*
* \return The YamlObject value, or \a defaultValue if parsing failed
*/
#ifndef __DOXYGEN__
template<>
std::optional<bool> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "true")
return true;
else if (value_ == "false")
return false;
return std::nullopt;
}
template<>
std::optional<int16_t> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "")
return std::nullopt;
char *end;
errno = 0;
int16_t value = std::strtol(value_.c_str(), &end, 10);
if ('\0' != *end || errno == ERANGE ||
value < std::numeric_limits<int16_t>::min() ||
value > std::numeric_limits<int16_t>::max())
return std::nullopt;
return value;
}
template<>
std::optional<uint16_t> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "")
return std::nullopt;
/*
* libyaml parses all scalar values as strings. When a string has
* leading spaces before a minus sign, for example " -10", strtoul
* skips leading spaces, accepts the leading minus sign, and the
* calculated digits are negated as if by unary minus. Rule it out in
* case the user gets a large number when the value is negative.
*/
std::size_t found = value_.find_first_not_of(" \t");
if (found != std::string::npos && value_[found] == '-')
return std::nullopt;
char *end;
errno = 0;
uint16_t value = std::strtoul(value_.c_str(), &end, 10);
if ('\0' != *end || errno == ERANGE ||
value < std::numeric_limits<uint16_t>::min() ||
value > std::numeric_limits<uint16_t>::max())
return std::nullopt;
return value;
}
template<>
std::optional<int32_t> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "")
return std::nullopt;
char *end;
errno = 0;
long value = std::strtol(value_.c_str(), &end, 10);
if ('\0' != *end || errno == ERANGE ||
value < std::numeric_limits<int32_t>::min() ||
value > std::numeric_limits<int32_t>::max())
return std::nullopt;
return value;
}
template<>
std::optional<uint32_t> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "")
return std::nullopt;
/*
* libyaml parses all scalar values as strings. When a string has
* leading spaces before a minus sign, for example " -10", strtoul
* skips leading spaces, accepts the leading minus sign, and the
* calculated digits are negated as if by unary minus. Rule it out in
* case the user gets a large number when the value is negative.
*/
std::size_t found = value_.find_first_not_of(" \t");
if (found != std::string::npos && value_[found] == '-')
return std::nullopt;
char *end;
errno = 0;
unsigned long value = std::strtoul(value_.c_str(), &end, 10);
if ('\0' != *end || errno == ERANGE ||
value < std::numeric_limits<uint32_t>::min() ||
value > std::numeric_limits<uint32_t>::max())
return std::nullopt;
return value;
}
template<>
std::optional<double> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
if (value_ == "")
return std::nullopt;
char *end;
errno = 0;
double value = std::strtod(value_.c_str(), &end);
if ('\0' != *end || errno == ERANGE)
return std::nullopt;
return value;
}
template<>
std::optional<std::string> YamlObject::get() const
{
if (type_ != Type::Value)
return std::nullopt;
return value_;
}
template<>
std::optional<Size> YamlObject::get() const
{
if (type_ != Type::List)
return std::nullopt;
if (list_.size() != 2)
return std::nullopt;
auto width = list_[0].value->get<uint32_t>();
if (!width)
return std::nullopt;
auto height = list_[1].value->get<uint32_t>();
if (!height)
return std::nullopt;
return Size(*width, *height);
}
#endif /* __DOXYGEN__ */
/**
* \fn template<typename T> YamlObject::getList<T>() const
* \brief Parse the YamlObject as a list of \a T
*
* This function parses the value of the YamlObject as a list of \a T objects,
* and returns the value as a \a std::vector<T>. If parsing fails, std::nullopt
* is returned.
*
* \return The YamlObject value as a std::vector<T>, or std::nullopt if parsing
* failed
*/
#ifndef __DOXYGEN__
template<typename T,
std::enable_if_t<
std::is_same_v<bool, T> ||
std::is_same_v<double, T> ||
std::is_same_v<int16_t, T> ||
std::is_same_v<uint16_t, T> ||
std::is_same_v<int32_t, T> ||
std::is_same_v<uint32_t, T> ||
std::is_same_v<std::string, T> ||
std::is_same_v<Size, T>> *>
std::optional<std::vector<T>> YamlObject::getList() const
{
if (type_ != Type::List)
return std::nullopt;
std::vector<T> values;
values.reserve(list_.size());
for (const YamlObject &entry : asList()) {
const auto value = entry.get<T>();
if (!value)
return std::nullopt;
values.emplace_back(*value);
}
return values;
}
template std::optional<std::vector<bool>> YamlObject::getList<bool>() const;
template std::optional<std::vector<double>> YamlObject::getList<double>() const;
template std::optional<std::vector<int16_t>> YamlObject::getList<int16_t>() const;
template std::optional<std::vector<uint16_t>> YamlObject::getList<uint16_t>() const;
template std::optional<std::vector<int32_t>> YamlObject::getList<int32_t>() const;
template std::optional<std::vector<uint32_t>> YamlObject::getList<uint32_t>() const;
template std::optional<std::vector<std::string>> YamlObject::getList<std::string>() const;
template std::optional<std::vector<Size>> YamlObject::getList<Size>() const;
#endif /* __DOXYGEN__ */
/**
* \fn YamlObject::asDict() const
* \brief Wrap a dictionary YamlObject in an adapter that exposes iterators
*
* The YamlObject class doesn't directly implement iterators, as the iterator
* type depends on whether the object is a Dictionary or List. This function
* wraps a YamlObject of Dictionary type into an adapter that exposes
* iterators, as well as begin() and end() functions, allowing usage of
* range-based for loops with YamlObject. As YAML mappings are not ordered, the
* iteration order is not specified.
*
* The iterator's value_type is a
* <em>std::pair<const std::string &, const \ref YamlObject &></em>.
*
* If the YamlObject is not of Dictionary type, the returned adapter operates
* as an empty container.
*
* \return An adapter of unspecified type compatible with range-based for loops
*/
/**
* \fn YamlObject::asList() const
* \brief Wrap a list YamlObject in an adapter that exposes iterators
*
* The YamlObject class doesn't directly implement iterators, as the iterator
* type depends on whether the object is a Dictionary or List. This function
* wraps a YamlObject of List type into an adapter that exposes iterators, as
* well as begin() and end() functions, allowing usage of range-based for loops
* with YamlObject. As YAML lists are ordered, the iteration order is identical
* to the list order in the YAML data.
*
* The iterator's value_type is a <em>const YamlObject &</em>.
*
* If the YamlObject is not of List type, the returned adapter operates as an
* empty container.
*
* \return An adapter of unspecified type compatible with range-based for loops
*/
/**
* \fn YamlObject::operator[](std::size_t index) const
* \brief Retrieve the element from list YamlObject by index
*
* This function retrieves an element of the YamlObject. Only YamlObject
* instances of List type associate elements with index, calling this function
* on other types of instances is invalid and results in undefined behaviour.
*
* \return The YamlObject as an element of the list
*/
const YamlObject &YamlObject::operator[](std::size_t index) const
{
if (type_ != Type::List || index >= size())
return empty;
return *list_[index].value;
}
/**
* \fn YamlObject::contains()
* \brief Check if an element of a dictionary exists
*
* This function check if the YamlObject contains an element. Only YamlObject
* instances of Dictionary type associate elements with names, calling this
* function on other types of instances is invalid and results in undefined
* behaviour.
*
* \return True if an element exists, false otherwise
*/
bool YamlObject::contains(const std::string &key) const
{
if (dictionary_.find(std::ref(key)) == dictionary_.end())
return false;
return true;
}
/**
* \fn YamlObject::operator[](const std::string &key) const
* \brief Retrieve a member by name from the dictionary
*
* This function retrieve a member of a YamlObject by name. Only YamlObject
* instances of Dictionary type associate elements with names, calling this
* function on other types of instances is invalid and results in undefined
* behaviour.
*
* \return The YamlObject corresponding to the \a key member
*/
const YamlObject &YamlObject::operator[](const std::string &key) const
{
if (type_ != Type::Dictionary || !contains(key))
return empty;
auto iter = dictionary_.find(key);
return *iter->second;
}
#ifndef __DOXYGEN__
class YamlParserContext
{
public:
YamlParserContext();
~YamlParserContext();
int init(File &file);
int parseContent(YamlObject &yamlObject);
private:
struct EventDeleter {
void operator()(yaml_event_t *event) const
{
yaml_event_delete(event);
delete event;
}
};
using EventPtr = std::unique_ptr<yaml_event_t, EventDeleter>;
static int yamlRead(void *data, unsigned char *buffer, size_t size,
size_t *sizeRead);
EventPtr nextEvent();
void readValue(std::string &value, EventPtr event);
int parseDictionaryOrList(YamlObject::Type type,
const std::function<int(EventPtr event)> &parseItem);
int parseNextYamlObject(YamlObject &yamlObject, EventPtr event);
bool parserValid_;
yaml_parser_t parser_;
};
/**
* \class YamlParserContext
* \brief Class for YamlParser parsing and context data
*
* The YamlParserContext class stores the internal yaml_parser_t and provides
* helper functions to do event-based parsing for YAML files.
*/
YamlParserContext::YamlParserContext()
: parserValid_(false)
{
}
/**
* \class YamlParserContext
* \brief Destructor of YamlParserContext
*/
YamlParserContext::~YamlParserContext()
{
if (parserValid_) {
yaml_parser_delete(&parser_);
parserValid_ = false;
}
}
/**
* \fn YamlParserContext::init()
* \brief Initialize a parser with an opened file for parsing
* \param[in] fh The YAML file to parse
*
* Prior to parsing the YAML content, the YamlParserContext must be initialized
* with a file to create an internal parser. The file needs to stay valid until
* parsing completes.
*
* \return 0 on success or a negative error code otherwise
* \retval -EINVAL The parser has failed to initialize
*/
int YamlParserContext::init(File &file)
{
/* yaml_parser_initialize returns 1 when it succeededs */
if (!yaml_parser_initialize(&parser_)) {
LOG(YamlParser, Error) << "Failed to initialize YAML parser";
return -EINVAL;
}
parserValid_ = true;
yaml_parser_set_input(&parser_, &YamlParserContext::yamlRead, &file);
return 0;
}
int YamlParserContext::yamlRead(void *data, unsigned char *buffer, size_t size,
size_t *sizeRead)
{
File *file = static_cast<File *>(data);
Span<unsigned char> buf{ buffer, size };
ssize_t ret = file->read(buf);
if (ret < 0)
return 0;
*sizeRead = ret;
return 1;
}
/**
* \fn YamlParserContext::nextEvent()
|