backend/genesys/error.cpp

/* sane - Scanner Access Now Easy.

   Copyright (C) 2019 Povilas Kanapickas <povilas@radix.lt>

   This file is part of the SANE package.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

#define DEBUG_DECLARE_ONLY

#include "error.h"
#include <cstdarg>
#include <cstdlib>

namespace genesys {

extern "C" void sanei_debug_msg(int level, int max_level, const char *be, const char *fmt,
                                std::va_list ap);

#if (defined(__GNUC__) || defined(__CLANG__)) && (defined(__linux__) || defined(__APPLE__))
extern "C" char* __cxa_get_globals();
#endif

static unsigned num_uncaught_exceptions()
{
#if __cplusplus >= 201703L
    int count = std::uncaught_exceptions();
    return count >= 0 ? count : 0;
#elif (defined(__GNUC__) || defined(__CLANG__)) && (defined(__linux__) || defined(__APPLE__))
    // the format of the __cxa_eh_globals struct is enshrined into the Itanium C++ ABI and it's
    // very unlikely we'll get issues referencing it directly
    char* cxa_eh_globals_ptr = __cxa_get_globals();
    return *reinterpret_cast<unsigned*>(cxa_eh_globals_ptr + sizeof(void*));
#else
    return std::uncaught_exception() ? 1 : 0;
#endif
}

SaneException::SaneException(SANE_Status status) : status_(status)
{
    set_msg();
}

SaneException::SaneException(SANE_Status status, const char* format, ...) : status_(status)
{
    std::va_list args;
    va_start(args, format);
    set_msg(format, args);
    va_end(args);
}

SaneException::SaneException(const char* format, ...) : status_(SANE_STATUS_INVAL)
{
    std::va_list args;
    va_start(args, format);
    set_msg(format, args);
    va_end(args);
}

SANE_Status SaneException::status() const
{
    return status_;
}

const char* SaneException::what() const noexcept
{
    return msg_.c_str();
}

void SaneException::set_msg()
{
    const char* status_msg = sane_strstatus(status_);
    std::size_t status_msg_len = std::strlen(status_msg);
    msg_.reserve(status_msg_len);
    msg_ = status_msg;
}

void SaneException::set_msg(const char* format, std::va_list vlist)
{
    const char* status_msg = sane_strstatus(status_);
    std::size_t status_msg_len = std::strlen(status_msg);

    std::va_list vlist2;
    va_copy(vlist2, vlist);
    int msg_len = std::vsnprintf(nullptr, 0, format, vlist2);
    va_end(vlist2);

    if (msg_len < 0) {
        const char* formatting_error_msg = "(error formatting arguments)";
        msg_.reserve(std::strlen(formatting_error_msg) + 3 + status_msg_len);
        msg_ = formatting_error_msg;
        msg_ += " : ";
        msg_ += status_msg;
        return;
    }

    msg_.reserve(msg_len + status_msg_len + 3);
    msg_.resize(msg_len + 1, ' ');
    std::vsnprintf(&msg_[0], msg_len + 1, format, vlist);
    msg_.resize(msg_len, ' ');

    msg_ += " : ";
    msg_ += status_msg;
}

DebugMessageHelper::DebugMessageHelper(const char* func)
{
    func_ = func;
    num_exceptions_on_enter_ = num_uncaught_exceptions();
    msg_[0] = '\0';
    DBG(DBG_proc, "%s: start\n", func_);
}

DebugMessageHelper::DebugMessageHelper(const char* func, const char* format, ...)
{
    func_ = func;
    num_exceptions_on_enter_ = num_uncaught_exceptions();
    msg_[0] = '\0';
    DBG(DBG_proc, "%s: start\n", func_);
    DBG(DBG_proc, "%s: ", func_);

    std::va_list args;
    va_start(args, format);
    sanei_debug_msg(DBG_proc, DBG_LEVEL, STRINGIFY(BACKEND_NAME), format, args);
    va_end(args);
    DBG(DBG_proc, "\n");
}


DebugMessageHelper::~DebugMessageHelper()
{
    if (num_exceptions_on_enter_ < num_uncaught_exceptions()) {
        if (msg_[0] != '\0') {
            DBG(DBG_error, "%s: failed during %s\n", func_, msg_);
        } else {
            DBG(DBG_error, "%s: failed\n", func_);
        }
    } else {
        DBG(DBG_proc, "%s: completed\n", func_);
    }
}

void DebugMessageHelper::vstatus(const char* format, ...)
{
    std::va_list args;
    va_start(args, format);
    std::vsnprintf(msg_, MAX_BUF_SIZE, format, args);
    va_end(args);
}

void DebugMessageHelper::log(unsigned level, const char* msg)
{
    DBG(level, "%s: %s\n", func_, msg);
}

void DebugMessageHelper::vlog(unsigned level, const char* format, ...)
{
    std::string msg;

    std::va_list args;

    va_start(args, format);
    int msg_len = std::vsnprintf(nullptr, 0, format, args);
    va_end(args);

    if (msg_len < 0) {
        DBG(level, "%s: error formatting error message: %s\n", func_, format);
        return;
    }
    msg.resize(msg_len + 1, ' ');

    va_start(args, format);
    std::vsnprintf(&msg.front(), msg.size(), format, args);
    va_end(args);

    msg.resize(msg_len, ' '); // strip the null character

    DBG(level, "%s: %s\n", func_, msg.c_str());
}

enum class LogImageDataStatus
{
    NOT_SET,
    ENABLED,
    DISABLED
};

static LogImageDataStatus s_log_image_data_setting = LogImageDataStatus::NOT_SET;

LogImageDataStatus dbg_read_log_image_data_setting()
{
    auto* setting = std::getenv("SANE_DEBUG_GENESYS_IMAGE");
    if (!setting)
        return LogImageDataStatus::DISABLED;
    auto setting_int = std::strtol(setting, nullptr, 10);
    if (setting_int == 0)
        return LogImageDataStatus::DISABLED;
    return LogImageDataStatus::ENABLED;
}

bool dbg_log_image_data()
{
    if (s_log_image_data_setting == LogImageDataStatus::NOT_SET) {
        s_log_image_data_setting = dbg_read_log_image_data_setting();
    }
    return s_log_image_data_setting == LogImageDataStatus::ENABLED;
}

} // namespace genesys