AlsaSubsystemObject.cpp

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#include "AlsaSubsystemObject.hpp"
#include "MappingContext.h"
#include "AlsaMappingKeys.hpp"
#include <convert.hpp>

#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <string>

using std::string;

#define base CFormattedSubsystemObject

const char AlsaSubsystemObject::_soundCardPath[] = "/proc/asound/";

AlsaSubsystemObject::AlsaSubsystemObject(const string &mappingValue,
                                         CInstanceConfigurableElement *instanceConfigurableElement,
                                         const CMappingContext &context, core::log::Logger &logger)
    : base(instanceConfigurableElement, logger, mappingValue), _cardName(context.getItem(AlsaCard)),
      _cardIndex(getCardNumberByName(context.getItem(AlsaCard)))
{
}

AlsaSubsystemObject::AlsaSubsystemObject(const string &mappingValue,
                                         CInstanceConfigurableElement *instanceConfigurableElement,
                                         core::log::Logger &logger, uint32_t firstAmendKey,
                                         uint32_t nbAmendKeys, const CMappingContext &context)
    : base(instanceConfigurableElement, logger, mappingValue, firstAmendKey, nbAmendKeys, context),
      _cardName(context.getItem(AlsaCard)),
      _cardIndex(getCardNumberByName(context.getItem(AlsaCard)))
{
}
int32_t AlsaSubsystemObject::getCardNumberByName(const string &cardName)
{
    string idFilePath;
    char numberFilepath[PATH_MAX] = "";
    ssize_t writtenSize;

    // Compute card path (Example: /proc/asound/cloverviewaudio)
    idFilePath = string(_soundCardPath) + cardName;

    // Read corresponding link (Example: card5)
    writtenSize = readlink(idFilePath.c_str(), numberFilepath, sizeof(numberFilepath));

    if (writtenSize < 0) {

        // Sound card does not exist
        return -errno;
    }

    if (static_cast<size_t>(writtenSize) >= sizeof(numberFilepath)) {

        // buffer too small
        return -ENAMETOOLONG;
    }

    // Extract card number from link (Example: 5 from card5)
    int32_t cardNumber = 0;
    if (convertTo(numberFilepath + strlen("card"), cardNumber)) {
        return cardNumber;
    }

    return -1; // A negative value indicates a failure
}