/**************************************************************************//**
 * Utility functions for RMagick.
 *
 * Copyright © 2002 - 2009 by Timothy P. Hunter
 *
 * Changes since Nov. 2009 copyright © by Benjamin Thomas and Omer Bar-or
 *
 * @file     rmutil.cpp
 * @version  $Id: rmutil.cpp,v 1.182 2009/12/21 10:34:58 baror Exp $
 * @author   Tim Hunter
 ******************************************************************************/

#include "rmagick.h"
#include <errno.h>
#if defined(_WIN32)
#include <Windows.h>
#else
#include <pthread.h>
#endif

static VALUE rescue_not_str(VALUE, VALUE ATTRIBUTE_UNUSED) ATTRIBUTE_NORETURN;
static void handle_exception(ExceptionInfo *, Image *, ErrorRetention);


DEFINE_GVL_STUB5(CloneImage, const Image *, const size_t, const size_t, const MagickBooleanType, ExceptionInfo *);


/**
 * ImageMagick safe version of malloc.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Use when managing memory that ImageMagick may have allocated or may free.
 *   - If malloc fails, it raises an exception.
 *   - magick_safe_malloc and magick_safe_realloc prevent exceptions caused by
 *     integer overflow. Added in 6.3.5-9 but backwards compatible with prior
 *     releases.
 *
 * @param count the number of quantum elements to allocate
 * @param quantum the number of bytes in each quantum
 * @return a pointer to a block of memory that is at least count*quantum
 */
void *
magick_safe_malloc(const size_t count, const size_t quantum)
{
    void *ptr;

    ptr = AcquireQuantumMemory(count, quantum);
    if (!ptr)
    {
        rb_raise(rb_eNoMemError, "not enough memory to continue");
    }
    return ptr;
}


/**
 * ImageMagick version of malloc.
 *
 * No Ruby usage (internal function)
 *
 * @param size the size of memory to allocate
 * @return pointer to a block of memory
 */
void *
magick_malloc(const size_t size)
{
    void *ptr;
    ptr = AcquireMagickMemory(size);
    if (!ptr)
    {
        rb_raise(rb_eNoMemError, "not enough memory to continue");
    }

    return ptr;
}


/**
 * ImageMagick version of free.
 *
 * No Ruby usage (internal function)
 *
 * @param ptr pointer to the existing block of memory
 */
void
magick_free(void *ptr)
{
    RelinquishMagickMemory(ptr);
}


/**
 * ImageMagick safe version of realloc.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Use when managing memory that ImageMagick may have allocated or may free.
 *   - If malloc fails, it raises an exception.
 *   - magick_safe_malloc and magick_safe_realloc prevent exceptions caused by
 *     integer overflow. Added in 6.3.5-9 but backwards compatible with prior
 *     releases.
 *
 * @param memory the existing block of memory
 * @param count the number of quantum elements to allocate
 * @param quantum the number of bytes in each quantum
 * @return a pointer to a block of memory that is at least count*quantum in size
 */
void *
magick_safe_realloc(void *memory, const size_t count, const size_t quantum)
{
    void *v;
    v = ResizeQuantumMemory(memory, count, quantum);
    if (!v)
    {
        rb_raise(rb_eNoMemError, "not enough memory to continue");
    }
    return v;
}


/**
 * Make a copy of a string in malloc'd memory.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Any existing string pointed to by *new_str is freed.
 *   - CloneString asserts if no memory. No need to check its return value.
 *
 * @param new_str pointer to the new string
 * @param str the string to copy
 */
void
 magick_clone_string(char **new_str, const char *str)
{
    CloneString(new_str, str);
}


/**
 * Compare s1 and s2 ignoring case.
 *
 * No Ruby usage (internal function)
 *
 * @param s1 the first string
 * @param s2 the second string
 * @return same as strcmp(3)
 */
int
rm_strcasecmp(const char *s1, const char *s2)
{
    while (*s1 && *s2)
    {
        if (toupper(*s1) != toupper(*s2))
        {
            break;
        }
        s1 += 1;
        s2 += 1;
    }
    return (int)(*s1 - *s2);
}


/**
 * Compare s1 and s2 ignoring case.
 *
 * No Ruby usage (internal function)
 *
 * @param s1 the first string
 * @param s2 the second string
 * @param n number of characters to compare
 * @return same as strcmp(3)
 */
int
rm_strncasecmp(const char *s1, const char *s2, size_t n)
{
    if (n == 0)
    {
        return 0;
    }
    while (toupper(*s1) == toupper(*s2))
    {
        if (--n == 0 || *s1 == '\0')
        {
            return 0;
        }
        s1 += 1;
        s2 += 1;
    }
    return (int)(*s1 - *s2);
}


/**
 * Get string length.
 *
 * No Ruby usage (internal function)
 *
 * @param str the string
 * @param strsz the maximum number of characters
 * @return same as strnlen_s()
 */
size_t
rm_strnlen_s(const char *str, size_t strsz)
{
    size_t length = 0;
    while(*str && length < strsz)
    {
        str++;
        length++;
    }
    return length;
}


/**
 * Raise exception if array too short.
 *
 * No Ruby usage (internal function)
 *
 * @param ary the array
 * @param len the minimum length
 * @throw IndexError
 */
void
rm_check_ary_len(VALUE ary, long len)
{
    if (RARRAY_LEN(ary) < len)
    {
        rb_raise(rb_eIndexError, "not enough elements in array - expecting %ld, got %ld",
                        len, (long)RARRAY_LEN(ary));
    }
}


/**
 * Raise exception if ary argument was invalid type
 *
 * No Ruby usage (internal function)
 *
 * @param ary the array
 * @return the array that is converted type of argument object if needed
 * @throw TypeError
 */
VALUE
rm_check_ary_type(VALUE ary)
{
    VALUE checked = rb_check_array_type(ary);
    if (NIL_P(checked))
    {
        rb_raise(rb_eTypeError, "wrong argument type %" RMIsVALUE " was given. (must respond to :to_ary)", rb_obj_class(ary));
    }
    return checked;
}


/**
 * Raise an error if the image has been destroyed.
 *
 * No Ruby usage (internal function)
 *
 * @param obj the image
 * @return the C image structure for the image
 * @throw DestroyedImageError
 */
Image *
rm_check_destroyed(VALUE obj)
{
    Image *image;

    TypedData_Get_Struct(obj, Image, &rm_image_data_type, image);
    if (!image)
    {
        rb_raise(Class_DestroyedImageError, "destroyed image");
    }

    return image;
}


/**
 * Raise an error if the image has been destroyed or is frozen.
 *
 * No Ruby usage (internal function)
 *
 * @param obj the image
 * @return the C image structure for the image
 */
Image *
rm_check_frozen(VALUE obj)
{
    Image *image = rm_check_destroyed(obj);
    rb_check_frozen(obj);
    return image;
}


/**
 * Overrides freeze in classes that can't be frozen.
 *
 * No Ruby usage (internal function)
 *
 * @raise [TypeError]
 */
VALUE
rm_no_freeze(VALUE obj)
{
    rb_raise(rb_eTypeError, "can't freeze %s", rb_class2name(CLASS_OF(obj)));
}


/**
 * Supply our own version of the "obsolete" rb_str2cstr.
 *
 * No Ruby usage (internal function)
 *
 * @param str the Ruby string
 * @param len pointer to a size_t in which to store the number of characters
 * @return a C string version of str
 */
char *
rm_str2cstr(VALUE str, size_t *len)
{
    StringValue(str);
    if (len)
    {
        *len = (size_t)RSTRING_LEN(str);
    }
    return RSTRING_PTR(str);
}


/**
 * Called when `rb_str_to_str' raises an exception.
 *
 * No Ruby usage (internal function)
 *
 * @param arg the argument
 * @return 0
 * @throw TypeError
 */
static VALUE
rescue_not_str(VALUE arg, VALUE raised_exc ATTRIBUTE_UNUSED)
{
    rb_raise(rb_eTypeError, "argument must be a number or a string in the form 'NN%%' (%s given)",
            rb_class2name(CLASS_OF(arg)));
}


/**
 * Return a double between 0.0 and max (the second argument), inclusive. If the
 * argument is a number convert to a Float object, otherwise it's supposed to be
 * a string in the form * "NN%". Convert to a number and then to a Float.
 *
 * No Ruby usage (internal function)
 *
 * @param arg the argument
 * @param max the maximum allowed value
 * @return a double
 */
double
rm_percentage(VALUE arg, double max)
{
    double pct;
    char *end;

    if (!rm_check_num2dbl(arg))
    {
        char *pct_str;
        long pct_long;

        arg = rb_rescue(RESCUE_FUNC(rb_str_to_str), arg, RESCUE_EXCEPTION_HANDLER_FUNC(rescue_not_str), arg);
        pct_str = StringValueCStr(arg);
        errno = 0;
        pct_long = strtol(pct_str, &end, 10);
        if (errno == ERANGE)
        {
            rb_raise(rb_eRangeError, "`%s' out of range", pct_str);
        }
        if (*end != '\0' && *end != '%')
        {
            rb_raise(rb_eArgError, "expected percentage, got `%s'", pct_str);
        }

        if (*end == '%' && pct_long != 0)
        {
            pct = (((double)pct_long) / 100.0) * max;
        }
        else
        {
            pct = (double) pct_long;
        }
        if (pct < 0.0)
        {
            rb_raise(rb_eArgError, "percentages may not be negative (got `%s')", pct_str);
        }
    }
    else
    {
        pct = NUM2DBL(arg);
        if (pct < 0.0)
        {
            rb_raise(rb_eArgError, "percentages may not be negative (got `%g')", pct);
        }
    }

    return pct;
}


/**
 * Return 0 if rb_num2dbl doesn't raise an exception.
 *
 * No Ruby usage (internal function)
 *
 * @param obj the object to convert to a double
 * @return 0
 */
static VALUE
check_num2dbl(VALUE obj)
{
    rb_num2dbl(obj);
    return INT2FIX(1);
}


/**
 * Called if rb_num2dbl raises an exception.
 *
 * No Ruby usage (internal function)
 *
 * @param ignored a Ruby object (unused)
 * @return 0
 */
static VALUE
rescue_not_dbl(VALUE ignored ATTRIBUTE_UNUSED, VALUE raised_exc ATTRIBUTE_UNUSED)
{
    return INT2FIX(0);
}


/**
 * Return 1 if the object can be converted to a double, 0 otherwise.
 *
 * No Ruby usage (internal function)
 *
 * @param obj the object
 * @return 1 or 0
 */
int
rm_check_num2dbl(VALUE obj)
{
    return FIX2INT(rb_rescue(RESCUE_FUNC(check_num2dbl), obj, RESCUE_EXCEPTION_HANDLER_FUNC(rescue_not_dbl), (VALUE)0));
}


/**
 * Given a string in the form NN% return the corresponding double.
 *
 * No Ruby usage (internal function)
 *
 * @param str the string
 * @return a double
 */
double
rm_str_to_pct(VALUE str)
{
    long pct;
    char *pct_str, *end;

    str = rb_rescue(RESCUE_FUNC(rb_str_to_str), str, RESCUE_EXCEPTION_HANDLER_FUNC(rescue_not_str), str);
    pct_str = StringValueCStr(str);
    errno = 0;
    pct = strtol(pct_str, &end, 10);

    if (errno == ERANGE)
    {
        rb_raise(rb_eRangeError, "`%s' out of range", pct_str);
    }
    if (*end != '%')
    {
        rb_raise(rb_eArgError, "expected percentage, got `%s'", pct_str);
    }
    if (pct < 0L)
    {
        rb_raise(rb_eArgError, "percentages may not be negative (got `%s')", pct_str);
    }

    return pct / 100.0;
}


/**
 * If the argument is a number, convert it to a double. Otherwise it's supposed
 * to be a string in the form 'NN%'.  Return a percentage of QuantumRange.
 *
 * No Ruby usage (internal function)
 *
 * @param fuzz_arg the fuzz argument
 * @return a double
 * @see Image_fuzz
 * @see Image_fuzz_eq
 */
double
rm_fuzz_to_dbl(VALUE fuzz_arg)
{
    double fuzz;
    char *end;

    if (!rm_check_num2dbl(fuzz_arg))
    {
        char *fuzz_str;

        // Convert to string, issue error message if failure.
        fuzz_arg = rb_rescue(RESCUE_FUNC(rb_str_to_str), fuzz_arg, RESCUE_EXCEPTION_HANDLER_FUNC(rescue_not_str), fuzz_arg);
        fuzz_str = StringValueCStr(fuzz_arg);
        errno = 0;
        fuzz = strtod(fuzz_str, &end);
        if (errno == ERANGE)
        {
            rb_raise(rb_eRangeError, "`%s' out of range", fuzz_str);
        }
        if(*end == '%')
        {
            if (fuzz < 0.0)
            {
                rb_raise(rb_eArgError, "percentages may not be negative (got `%s')", fuzz_str);
            }
            fuzz = (fuzz * QuantumRange) / 100.0;
        }
        else if(*end != '\0')
        {
            rb_raise(rb_eArgError, "expected percentage, got `%s'", fuzz_str);
        }
    }
    else
    {
        fuzz = NUM2DBL(fuzz_arg);
        if (fuzz < 0.0)
        {
            rb_raise(rb_eArgError, "fuzz may not be negative (got `%g')", fuzz);
        }
    }

    return fuzz;
}


/**
 * Convert a application-supplied number to a Quantum. If the object is a Float,
 * truncate it before converting.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Ruby says that 2147483647.5 doesn't fit into an unsigned long. If you
 *     truncate it, it works.
 *   - Should use this only when the input value is possibly subject to this
 *     problem.
 *
 * @param obj the application-supplied number
 * @return a Quantum
 */
Quantum
rm_app2quantum(VALUE obj)
{
    VALUE v = obj;

    if (TYPE(obj) == T_FLOAT)
    {
        v = rb_Integer(obj);
    }

    return NUM2QUANTUM(v);
}


/**
 * Returns a pointer to an image structure initialized to default values
 *
 * No Ruby usage (internal function)
 *
 * @param info the info
 * @return the created image
 */
Image *
rm_acquire_image(ImageInfo *info)
{
#if defined(IMAGEMAGICK_7)
    Image *new_image;
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();
    new_image = AcquireImage(info, exception);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);
    return new_image;
#else
    return AcquireImage(info);
#endif
}


/**
 * Send the "cur_image" method to the object. If 'img' is an ImageList, then
 * cur_image is self[\@scene]. If 'img' is an image, then cur_image is simply
 * 'self'.
 *
 * No Ruby usage (internal function)
 *
 * @param img the object
 * @return the return value from "cur_image"
 */
VALUE
rm_cur_image(VALUE img)
{
    return rb_funcall(img, rm_ID_cur_image, 0);
}


/**
 * Map the color intensity to a named color.
 *
 * No Ruby usage (internal function)
 *
 * @param image the image
 * @param color the color intensity as a PixelColor
 * @return the named color as a String
 * @see rm_pixelcolor_to_color_name_info
 */
VALUE
rm_pixelcolor_to_color_name(Image *image, PixelColor *color)
{
    PixelColor pp;
    char name[MaxTextExtent];
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();

    pp = *color;
#if defined(IMAGEMAGICK_7)
    pp.depth = MAGICKCORE_QUANTUM_DEPTH;
    pp.colorspace = image->colorspace;
#endif

    QueryColorname(image, &pp, X11Compliance, name, exception);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);

    return rb_str_new2(name);
}


/**
 * Map the color intensity to a named color.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Simply create an Image from the Info, call QueryColorname, and then
 *     destroy the Image.
 *   - The default depth is always used, and the matte value is set to False,
 *     which means "don't use the alpha channel".
 *
 * @param info the info
 * @param color the color intensity as a PixelColor
 * @return the named color as a String
 * @see rm_pixelcolor_to_color_name
 */
VALUE
rm_pixelcolor_to_color_name_info(Info *info, PixelColor *color)
{
    Image *image;
    VALUE color_name;

    image = rm_acquire_image(info);
    if (!image)
    {
        rb_raise(rb_eNoMemError, "not enough memory to continue.");
    }

#if defined(IMAGEMAGICK_7)
    image->alpha_trait = UndefinedPixelTrait;
#else
    image->matte = MagickFalse;
#endif

    color_name = rm_pixelcolor_to_color_name(image, color);
    DestroyImage(image);

    return color_name;
}

/**
 * Initializes the MagickPixel structure.
 *
 * No Ruby usage (internal function)
 *
 * @param image the image
 * @param pp the MagickPixel
 */
void
rm_init_magickpixel(const Image *image, MagickPixel *pp)
{
#if defined(IMAGEMAGICK_7)
    GetPixelInfo(image, pp);
#else
    GetMagickPixelPacket(image, pp);
#endif
}

/**
 * Initializes the MagickPixel structure to the specified color.
 *
 * No Ruby usage (internal function)
 *
 * @param pp the MagickPixel
 * @param color the color
 */
void
rm_set_magickpixel(MagickPixel *pp, const char *color)
{
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();

#if defined(IMAGEMAGICK_7)
    QueryColorCompliance(color, AllCompliance, pp, exception);
#else
    QueryMagickColor(color, pp, exception);
#endif
    // This exception is ignored because the color comes from places where we control
    // the value and it is very unlikely that an exception will be thrown.
    DestroyExceptionInfo(exception);
}

/**
 * Write a temporary copy of the image to the IM registry.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - The `temp_name' argument must point to an char array of size
 *     MaxTextExtent.
 *
 * @param image the image
 * @param temp_name the temporary name to use
 * @param temp_name_l the length of temp_name
 * @return the "filename" of the registered image
 */
void
rm_write_temp_image(Image *image, char *temp_name, size_t temp_name_l)
{

#define TMPNAM_CLASS_VAR "@@_tmpnam_"

    MagickBooleanType okay;
    ExceptionInfo *exception;
    VALUE id_value;
    int id;

    exception = AcquireExceptionInfo();


    // 'id' is always the value of its previous use
    if (rb_cvar_defined(Module_Magick, rb_intern(TMPNAM_CLASS_VAR)) == Qtrue)
    {
        id_value = rb_cv_get(Module_Magick, TMPNAM_CLASS_VAR);
        id = FIX2INT(id_value);
    }
    else
    {
        id = 0;
        rb_cv_set(Module_Magick, TMPNAM_CLASS_VAR, INT2FIX(id));
    }

    id += 1;
    rb_cv_set(Module_Magick, TMPNAM_CLASS_VAR, INT2FIX(id));
    snprintf(temp_name, temp_name_l, "mpri:%d", id);

    // Omit "mpri:" from filename to form the key
    okay = (MagickBooleanType)SetImageRegistry(ImageRegistryType, temp_name+5, image, exception);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);
    if (!okay)
    {
        rb_raise(rb_eRuntimeError, "SetImageRegistry failed.");
    }

    RB_GC_GUARD(id_value);
}


/**
 * Delete the temporary image from the registry.
 *
 * No Ruby usage (internal function)
 *
 * @param temp_name the name of temporary image in the registry.
 */
void
rm_delete_temp_image(char *temp_name)
{
    MagickBooleanType okay = DeleteImageRegistry(temp_name+5);

    if (!okay)
    {
        rb_warn("DeleteImageRegistry failed for `%s'", temp_name);
    }
}


/**
 * Raise NotImplementedError.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Called when a xMagick API is not available.
 *   - Replaces Ruby's rb_notimplement function.
 *
 * @throw NotImpError
 */
void
rm_not_implemented(void)
{

    rb_raise(rb_eNotImpError, "the `%s' method is not supported by ImageMagick "
            MagickLibVersionText, rb_id2name(rb_frame_this_func()));
}


/**
 * Create a new ImageMagickError object and raise an exception.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - This funky technique allows me to safely add additional information to
 *     the ImageMagickError object in both 1.6.8 and 1.8.0.
 *
 * @param msg the error mesage
 * @throw ImageMagickError
 * @see www.ruby_talk.org/36408.
 */
void
rm_magick_error(const char *msg)
{
    VALUE exc, mesg;

    mesg = rb_str_new2(msg);

    exc = rb_funcall(Class_ImageMagickError, rm_ID_new, 2, mesg, Qnil);
    rb_funcall(rb_cObject, rb_intern("raise"), 1, exc);

    RB_GC_GUARD(exc);
    RB_GC_GUARD(mesg);
}

#if defined(IMAGEMAGICK_7)
/**
 * Sets the alpha channel of a pixel color
 *
 * No Ruby usage (internal function)
 *
 * @param pixel the Pixel
 * @param value the value
 */
void
rm_set_pixelinfo_alpha(PixelInfo *pixel, const MagickRealType value)
{
    pixel->alpha = value;
    if (value != (MagickRealType) OpaqueAlpha)
    {
        pixel->alpha_trait = BlendPixelTrait;
    }
}
#endif

/**
 * Initialize a new ImageMagickError object - store the "loc" string in the
 * magick_location instance variable.
 *
 * @overload initialize(msg, loc = nil)
 *   @param msg [String] the exception message
 *   @param loc [String] the location stored in the magick_location instance variable
 *   @return [Magick::ImageMagickError] self
 */
VALUE
ImageMagickError_initialize(int argc, VALUE *argv, VALUE self)
{
    VALUE super_argv[1] = {(VALUE)0};
    int super_argc = 0;
    VALUE extra = Qnil;

    switch(argc)
    {
        case 2:
            extra = argv[1];
        case 1:
            super_argv[0] = argv[0];
            super_argc = 1;
        case 0:
            break;
        default:
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 0 to 2)", argc);
    }

    rb_call_super(super_argc, (const VALUE *)super_argv);
    rb_iv_set(self, "@" MAGICK_LOC, extra);

    RB_GC_GUARD(extra);

    return self;
}


/**
 * Backport GetImageProperty for pre-6.3.1 versions of ImageMagick.
 *
 * No Ruby usage (internal function)
 *
 * @param img the image
 * @param property the property name
 * @return the property value
 */
const char *
rm_get_property(const Image *img, const char *property)
{
#if defined(IMAGEMAGICK_7)
    const char *result;
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();
    result = GetImageProperty(img, property, exception);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);
    return result;
#else
    return GetImageProperty(img, property);
#endif
}


/**
 * Backport SetImageProperty for pre-6.3.1 versions of ImageMagick.
 *
 * No Ruby usage (internal function)
 *
 * @param image the image
 * @param property the property name
 * @param value the property value
 * @return true if successful, otherwise false
 */
MagickBooleanType
rm_set_property(Image *image, const char *property, const char *value)
{
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
    MagickBooleanType okay;

    exception = AcquireExceptionInfo();
    okay = SetImageProperty(image, property, value, exception);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);
    return okay;
#else
    return SetImageProperty(image, property, value);
#endif
}


/**
 * If a "user" option is present in the Info, assign its value to a "user"
 * artifact in each image.
 *
 * No Ruby usage (internal function)
 *
 * @param images a list of images
 * @param info the info
 */
void rm_set_user_artifact(Image *images, Info *info)
{
    const char *value;

    value = GetImageOption(info, "user");
    if (value)
    {
        Image *image;

        image = GetFirstImageInList(images);
        while (image)
        {
            SetImageArtifact(image, "user", value);
            image = GetNextImageInList(image);
        }
    }
}


/**
 * Collect optional method arguments via Magick::OptionalMethodArguments.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Creates an instance of Magick::OptionalMethodArguments, then yields to a
 *     block in the context of the instance.
 *
 * @param img the image
 */
void
rm_get_optional_arguments(VALUE img)
{
    VALUE optional_method_arguments;
    VALUE opt_args;
    VALUE argv[1];

    // opt_args = Magick::OptionalMethodArguments.new(img)
    // opt_args.instance_eval { block }
    if (rb_block_given_p())
    {
        optional_method_arguments = rb_const_get_from(Module_Magick, rb_intern("OptionalMethodArguments"));
        argv[0] = img;
        opt_args = rb_class_new_instance(1, argv, optional_method_arguments);

        rb_yield(opt_args);
    }

    RB_GC_GUARD(optional_method_arguments);
    RB_GC_GUARD(opt_args);

    return;
}


/**
 * Copy image options from the Info structure to the Image structure.
 *
 * No Ruby usage (internal function)
 *
 * @param image the Image structure to modify
 * @param info the Info structure
 */
static void copy_options(Image *image, Info *info)
{
    char property[MaxTextExtent];
    const char *option;

    ResetImageOptionIterator(info);
    for (option = GetNextImageOption(info); option; option = GetNextImageOption(info))
    {
        const char *value;

        value = GetImageOption(info, option);
        if (value)
        {
            strlcpy(property, value, sizeof(property));
            SetImageArtifact(image, property, value);
        }
    }
}


/**
 * Propagate ImageInfo values to the Image
 *
 * No Ruby usage (internal function)
 *
 * @param image the Image structure to modify
 * @param info the Info structure
 * @see SyncImageSettings in mogrify.c in ImageMagick
 */
void rm_sync_image_options(Image *image, Info *info)
{
    MagickStatusType flags;
    GeometryInfo geometry_info;
    const char *option;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
#endif

    // The option strings will be set only when their attribute values were
    // set in the optional argument block.
    option = GetImageOption(info, "background");
    if (option)
    {
        image->background_color = info->background_color;
    }

    option = GetImageOption(info, "bordercolor");
    if (option)
    {
        image->border_color = info->border_color;
    }

    if (info->colorspace != UndefinedColorspace)
    {
#if defined(IMAGEMAGICK_7)
        exception = AcquireExceptionInfo();
        SetImageColorspace(image, info->colorspace, exception);
        // We should not throw an exception in this method because we will
        // leak memory in the place where this method is called. And that is
        // why the exception is being ignored here.
        DestroyExceptionInfo(exception);
#else
        SetImageColorspace(image, info->colorspace);
#endif
    }

    if (info->compression != UndefinedCompression)
    {
        image->compression = info->compression;
    }

    option = GetImageOption(info, "delay");
    if (option)
    {
        image->delay = strtoul(option, NULL, 0);
    }

    if (info->density)
    {
        flags = ParseGeometry(info->density, &geometry_info);
#if defined(IMAGEMAGICK_7)
        image->resolution.x = geometry_info.rho;
        image->resolution.y = geometry_info.sigma;
#else
        image->x_resolution = geometry_info.rho;
        image->y_resolution = geometry_info.sigma;
#endif
        if ((flags & SigmaValue) == 0)
        {
#if defined(IMAGEMAGICK_7)
            image->resolution.y = image->resolution.x;
#else
            image->y_resolution = image->x_resolution;
#endif
        }
    }

    if (info->depth != 0)
    {
        image->depth = info->depth;
    }

    option = GetImageOption(info, "dispose");
    if (option)
    {
        image->dispose = rm_dispose_to_enum(option);
    }

    if (info->extract)
    {
        ParseAbsoluteGeometry(info->extract, &image->extract_info);
    }

    if (info->fuzz != 0.0)
    {
        image->fuzz = info->fuzz;
    }

    option = GetImageOption(info, "gravity");
    if (option)
    {
        image->gravity = rm_gravity_to_enum(option);
    }

    if (info->interlace != NoInterlace)
    {
        image->interlace = info->interlace;
    }

    option = GetImageOption(info, "mattecolor");
    if (option)
    {
        image->matte_color = info->matte_color;
    }

    if (info->orientation != UndefinedOrientation)
    {
        image->orientation = info->orientation;
    }

    if (info->page)
    {
        ParseAbsoluteGeometry(info->page, &image->page);
    }

    if (info->quality != 0UL)
    {
        image->quality = info->quality;
    }

    option = GetImageOption(info, "scene");
    if (option)
    {
        image->scene = info->scene;
    }

    option = GetImageOption(info, "tile-offset");
    if (option)
    {
        ParseAbsoluteGeometry(option, &image->tile_offset);
    }

    option = GetImageOption(info, "transparent");
    if (option)
    {
        image->transparent_color = info->transparent_color;
    }

    if (info->type != UndefinedType)
    {
        image->type = info->type;
    }

    if (info->units != UndefinedResolution)
    {
        if (image->units != info->units)
        {
            switch (image->units)
            {
              case PixelsPerInchResolution:
              {
                if (info->units == PixelsPerCentimeterResolution)
                {
#if defined(IMAGEMAGICK_7)
                    image->resolution.x /= 2.54;
                    image->resolution.y /= 2.54;
#else
                    image->x_resolution /= 2.54;
                    image->y_resolution /= 2.54;
#endif
                }
                break;
              }
              case PixelsPerCentimeterResolution:
              {
                if (info->units == PixelsPerInchResolution)
                {
#if defined(IMAGEMAGICK_7)
                    image->resolution.x *= 2.54;
                    image->resolution.y *= 2.54;
#else
                    image->x_resolution *= 2.54;
                    image->y_resolution *= 2.54;
#endif
                }
                break;
              }
              default:
                break;
            }
        }

        image->units = info->units;
    }

    copy_options(image, info);
}


/**
 * Replicate old (ImageMagick < 6.3.2) EXIF:* functionality using
 * GetImageProperty by returning the exif entries as a single string, separated
 * by \n's.  Do this so that RMagick works no matter which version of
 * ImageMagick is in use.
 *
 * No Ruby usage (internal function)
 *
 * @param image the image
 * @return string representation of exif properties
 * @see magick/identify.c in ImageMagick
 */
VALUE
rm_exif_by_entry(Image *image)
{
    const char *property, *value;
    char *str;
    size_t len = 0, property_l, value_l;
    VALUE v;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();
    GetImageProperty(image, "exif:*", exception);
    CHECK_EXCEPTION();
#else
    GetImageProperty(image, "exif:*");
#endif

    ResetImagePropertyIterator(image);
    property = GetNextImageProperty(image);

    // Measure the exif properties and values
    while (property)
    {
        // ignore properties that don't start with "exif:"
        property_l = rm_strnlen_s(property, MaxTextExtent);
        if (property_l > 5 && rm_strncasecmp(property, "exif:", 5) == 0)
        {
            if (len > 0)
            {
                len += 1;   // there will be a \n between property=value entries
            }
            len += property_l - 5;
#if defined(IMAGEMAGICK_7)
            value = GetImageProperty(image, property, exception);
            CHECK_EXCEPTION();
#else
            value = GetImageProperty(image, property);
#endif
            if (value)
            {
                // add 1 for the = between property and value
                len += 1 + rm_strnlen_s(value, MaxTextExtent);
            }
        }
        property = GetNextImageProperty(image);
    }

    if (len == 0)
    {
#if defined(IMAGEMAGICK_7)
        DestroyExceptionInfo(exception);
#endif
        return Qnil;
    }

    str = (char *)xmalloc(len);
    len = 0;

    // Copy the exif properties and values into the string.
    ResetImagePropertyIterator(image);
    property = GetNextImageProperty(image);

    while (property)
    {
        property_l = rm_strnlen_s(property, MaxTextExtent);
        if (property_l > 5 && rm_strncasecmp(property, "exif:", 5) == 0)
        {
            if (len > 0)
            {
                str[len++] = '\n';
            }
            memcpy(str+len, property+5, property_l-5);
            len += property_l - 5;
#if defined(IMAGEMAGICK_7)
            value = GetImageProperty(image, property, exception);
            if (rm_should_raise_exception(exception, RetainExceptionRetention))
            {
                xfree(str);
                rm_raise_exception(exception);
            }
#else
            value = GetImageProperty(image, property);
#endif
            if (value)
            {
                value_l = rm_strnlen_s(value, MaxTextExtent);
                str[len++] = '=';
                memcpy(str+len, value, value_l);
                len += value_l;
            }
        }
        property = GetNextImageProperty(image);
    }

#if defined(IMAGEMAGICK_7)
    DestroyExceptionInfo(exception);
#endif

    v = rb_str_new(str, len);
    xfree(str);

    RB_GC_GUARD(v);

    return v;
}


/**
 * Replicate old (ImageMagick < 6.3.2) EXIF:! functionality using
 * GetImageProperty by returning the exif entries as a single string, separated
 * by \n's. Do this so that RMagick works no matter which version of
 * ImageMagick is in use.
 *
 * No Ruby usage (internal function)
 *
 * @param image the image
 * @return string representation of exif properties
 * @see magick/identify.c in ImageMagick
 */
VALUE
rm_exif_by_number(Image *image)
{
    const char *property, *value;
    char *str;
    size_t len = 0, property_l, value_l;
    VALUE v;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();
    GetImageProperty(image, "exif:!", exception);
    CHECK_EXCEPTION();
#else
    GetImageProperty(image, "exif:!");
#endif
    ResetImagePropertyIterator(image);
    property = GetNextImageProperty(image);

    // Measure the exif properties and values
    while (property)
    {
        // ignore properties that don't start with "#"
        property_l = rm_strnlen_s(property, MaxTextExtent);
        if (property_l > 1 && property[0] == '#')
        {
            if (len > 0)
            {
                len += 1;   // there will be a \n between property=value entries
            }
            len += property_l;
#if defined(IMAGEMAGICK_7)
            value = GetImageProperty(image, property, exception);
            CHECK_EXCEPTION();
#else
            value = GetImageProperty(image, property);
#endif
            if (value)
            {
                // add 1 for the = between property and value
                len += 1 + rm_strnlen_s(value, MaxTextExtent);
            }
        }
        property = GetNextImageProperty(image);
    }

    if (len == 0)
    {
#if defined(IMAGEMAGICK_7)
        DestroyExceptionInfo(exception);
#endif
        return Qnil;
    }

    str = (char *)xmalloc(len);
    len = 0;

    // Copy the exif properties and values into the string.
    ResetImagePropertyIterator(image);
    property = GetNextImageProperty(image);

    while (property)
    {
        property_l = rm_strnlen_s(property, MaxTextExtent);
        if (property_l > 1 && property[0] == '#')
        {
            if (len > 0)
            {
                str[len++] = '\n';
            }
            memcpy(str+len, property, property_l);
            len += property_l;
#if defined(IMAGEMAGICK_7)
            value = GetImageProperty(image, property, exception);
            if (rm_should_raise_exception(exception, RetainExceptionRetention))
            {
                xfree(str);
                rm_raise_exception(exception);
            }
#else
            value = GetImageProperty(image, property);
#endif
            if (value)
            {
                value_l = rm_strnlen_s(value, MaxTextExtent);
                str[len++] = '=';
                memcpy(str+len, value, value_l);
                len += value_l;
            }
        }
        property = GetNextImageProperty(image);
    }

#if defined(IMAGEMAGICK_7)
    DestroyExceptionInfo(exception);
#endif

    v = rb_str_new(str, len);
    xfree(str);

    RB_GC_GUARD(v);

    return v;
}


/**
 * Clone an image, handle errors.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - Don't trace creation - the clone may not be used as an Image object. Let
 *     the caller do the trace if desired.
 *
 * @param image the image to clone
 * @return the cloned image
 */
Image *
rm_clone_image(Image *image)
{
    Image *clone;
    ExceptionInfo *exception;

    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(CloneImage) args = { image, 0, 0, MagickTrue, exception };
    clone = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(CloneImage), &args);
    if (!clone)
    {
        rb_raise(rb_eNoMemError, "not enough memory to continue");
    }
    rm_check_exception(exception, clone, DestroyOnError);
    DestroyExceptionInfo(exception);

    return clone;
}


/**
 * Remove the ImageMagick links between images in an scene sequence.
 *
 * No Ruby usage (internal function)
 *
 * Notes:
 *   - The images remain grouped via the ImageList
 *
 * @param image the image
 */
void
rm_split(Image *image)
{

    if (!image)
    {
        rb_bug("RMagick FATAL: split called with NULL argument.");
    }
    while (image)
    {
        RemoveFirstImageFromList(&image);
    }
}


#if defined(IMAGEMAGICK_6)
/**
 * If an ExceptionInfo struct in a list of images indicates a warning, issue a
 * warning message. If an ExceptionInfo struct indicates an error, raise an
 * exception and optionally destroy the images.
 *
 * No Ruby usage (internal function)
 *
 * @param imglist the list of images
 * @param retention retention strategy in case of an error (either RetainOnError
 * or DestroyOnError)
 */
void
rm_check_image_exception(Image *imglist, ErrorRetention retention)
{
    ExceptionInfo *exception;
    Image *badboy = NULL;
    Image *image;

    if (imglist == NULL)
    {
        return;
    }

    exception = AcquireExceptionInfo();

    // Find the image with the highest severity
    image = GetFirstImageInList(imglist);
    while (image)
    {
        if (image->exception.severity != UndefinedException)
        {
            if (!badboy || image->exception.severity > badboy->exception.severity)
            {
                badboy = image;
                InheritException(exception, &badboy->exception);
            }

            ClearMagickException(&image->exception);
        }
        image = GetNextImageInList(image);
    }

    if (badboy)
    {
        rm_check_exception(exception, imglist, retention);
    }

    DestroyExceptionInfo(exception);
}
#endif


#define ERROR_MSG_SIZE 1024
/**
 * Formats the exception into the message buffer
 *
 * No Ruby usage (internal function)
 *
 * @param severity information about the severity of the error
 * @param reason the reason for the error
 * @param description description of the error
 * @param msg the buffer where the exception message should be formated in
 */
static void
format_exception(const ExceptionType severity, const char *reason, const char *description, char *msg)
{
    int len;
    memset(msg, 0, ERROR_MSG_SIZE);

    len = snprintf(msg, ERROR_MSG_SIZE, "%s%s%s",
        GetLocaleExceptionMessage(severity, reason),
        description ? ": " : "",
        description ? GetLocaleExceptionMessage(severity, description) : "");

    msg[len] = '\0';
}


/**
 * Call handle_exception if there is an exception to handle.
 *
 * No Ruby usage (internal function)
 *
 * @param exception information about the exception
 * @param imglist the images that caused the exception
 * @param retention retention strategy in case of an error (either RetainOnError
 * or DestroyOnError)
 */
void
rm_check_exception(ExceptionInfo *exception, Image *imglist, ErrorRetention retention)
{
    if (exception->severity == UndefinedException)
    {
        return;
    }

    handle_exception(exception, imglist, retention);
}



/**
 * Called from ImageMagick for a warning.
 *
 * No Ruby usage (internal function)
 *
 * @param severity information about the severity of the warning (ignored)
 * @param reason the reason for the warning
 * @param description description of the warning
 */
void
rm_warning_handler(const ExceptionType severity, const char *reason, const char *description)
{
    rb_warning("RMagick: %s%s%s",
        GetLocaleExceptionMessage(severity, reason),
        description ? ": " : "",
        description ? GetLocaleExceptionMessage(severity, description) : "");
}


/**
 * Called from ImageMagick for a error.
 *
 * No Ruby usage (internal function)
 *
 * @param severity information about the severity of the error
 * @param reason the reason for the error
 * @param description description of the error
 */
void
rm_error_handler(const ExceptionType severity, const char *reason, const char *description)
{
    char msg[ERROR_MSG_SIZE];

    format_exception(severity, reason, description, msg);

    rm_magick_error(msg);
}


/**
 * Called from ImageMagick for a fatal error.
 *
 * No Ruby usage (internal function)
 *
 * @param severity information about the severity of the error
 * @param reason the reason for the error
 * @param description description of the error
 * @throw FatalImageMagickError
 */
void
rm_fatal_error_handler(const ExceptionType severity, const char *reason, const char *description)
{
    rb_raise(Class_FatalImageMagickError, "%s%s%s",
        GetLocaleExceptionMessage(severity, reason),
        description ? ": " : "",
        description ? GetLocaleExceptionMessage(severity, description) : "");
}


/**
 * Called when rm_check_exception determines that we need to either issue a
 * warning message or raise an exception. This function allocates a bunch of
 * stack so we don't call it unless we have to.
 *
 * No Ruby usage (internal function)
 *
 * @param exception information about the exception
 * @param imglist the images that caused the exception
 * @param retention retention strategy in case of an error (either RetainOnError
 * or DestroyOnError)
 */
static void
handle_exception(ExceptionInfo *exception, Image *imglist, ErrorRetention retention)
{
    char msg[ERROR_MSG_SIZE];

    // Handle simple warning
    if (exception->severity < ErrorException)
    {
        rm_warning_handler(exception->severity, exception->reason, exception->description);

        // Caller deletes ExceptionInfo...

        return;
    }

    // Raise an exception. We're not coming back...


    // Newly-created images should be destroyed, images that are part
    // of image objects should be retained but split.
    if (imglist)
    {
        if (retention == DestroyOnError)
        {
            DestroyImageList(imglist);
            imglist = NULL;
        }
        else
        {
            rm_split(imglist);
        }
    }

    format_exception(exception->severity, exception->reason, exception->description, msg);

    DestroyExceptionInfo(exception);

    rm_magick_error(msg);
}


/**
 * RMagick expected a result. If it got NULL instead raise an exception.
 *
 * No Ruby usage (internal function)
 *
 * @param image the expected result
 * @throw RuntimeError
 */
void
rm_ensure_result(Image *image)
{
    if (!image)
    {
        rb_raise(rb_eRuntimeError, MagickPackageName " library function failed to return a result.");
    }
}


/**
 * Checks if an error should be raised for the exception.
 *
 * No Ruby usage (internal function)
 *
 * @param exception information about the exception
 * @param retention retention strategy for the exception in case there was no error
 */
MagickBooleanType
rm_should_raise_exception(ExceptionInfo *exception, const ExceptionRetention retention)
{
    if (exception->severity < ErrorException)
    {
        if (exception->severity != UndefinedException)
        {
            rm_warning_handler(exception->severity, exception->reason, exception->description);
        }

        if (retention == DestroyExceptionRetention)
        {
            DestroyExceptionInfo(exception);
        }

        return MagickFalse;
    }

    return MagickTrue;
}


/**
 * Raises an exception.
 *
 * No Ruby usage (internal function)
 *
 * @param exception information about the exception
 */
void
rm_raise_exception(ExceptionInfo *exception)
{
    char msg[ERROR_MSG_SIZE];

    format_exception(exception->severity, exception->reason, exception->description, msg);

    DestroyExceptionInfo(exception);

    rm_magick_error(msg);
}

/**
 * Get IO path.
 *
 * No Ruby usage (internal function)
 *
 * @param io An IO object
 * @return string of the path
 */
VALUE
rm_io_path(VALUE io)
{
#ifdef HAVE_RB_IO_PATH
    return rb_io_path(io);
#else
    rb_io_t *fptr;
    GetOpenFile(io, fptr);
    return fptr->pathv;
#endif
}