MirageContext: libMirage Reference Manual

## MirageContext MirageContext — Context object. |

## Functions

gchar * | (*MiragePasswordFunction) ()
void | mirage_context_clear_options ()
MirageStream * | mirage_context_create_input_stream ()
MirageStream * | mirage_context_create_output_stream ()
const gchar * | mirage_context_get_debug_domain ()
gint | mirage_context_get_debug_mask ()
const gchar * | mirage_context_get_debug_name ()
GVariant * | mirage_context_get_option ()
MirageDisc * | mirage_context_load_image ()
gchar * | mirage_context_obtain_password ()
void | mirage_context_set_debug_domain ()
void | mirage_context_set_debug_mask ()
void | mirage_context_set_debug_name ()
void | mirage_context_set_option ()
void | mirage_context_set_password_function ()

## Types and Values

struct | MirageContext
struct | MirageContextClass

## Object Hierarchy

        GObject
        ╰── MirageContext

## Includes

    #include <mirage-context.h>

## Description

MirageContext provides a context, which is attached to libMirage's objects. This way, it allows sharing and propagation of settings, such as debug verbosity, parser options, password function, etc. It also provides I/O stream caching, which is used by image parsers and writers.

Due to all the properties it holds, MirageContext is designed as the core object of libMirage and provides the library's main functionality, the loading of image files. Therefore, loading an image usually looks as follows:

- initialize the library using `mirage_initialize()`

- create a MirageContext object, i.e. using `g_object_new()` and `MIRAGE_TYPE_CONTEXT`

- (optionally) set debug name, domain and mask

- load the image using `mirage_context_load_image()`

## Functions

### MiragePasswordFunction ()

    gchar *
    (*MiragePasswordFunction) (gpointer user_data);

Password function type used to obtain password for encrypted images. A password function needs to be set to MirageContext via `mirage_context_set_password_function()`, along with `user_data` that the password function should be called with.

#### Parameters

user_data | user data passed to password function. | [in][closure]

#### Returns

password string on success, otherwise `NULL`. Password string should be a copy, allocated via function such as `g_strdup()`, and will be freed after it is used.

### mirage_context_clear_options ()

    void
    mirage_context_clear_options (MirageContext *self);

Clears all the options from the context.

#### Parameters

self | a MirageContext |

### mirage_context_create_input_stream ()

    MirageStream *
    mirage_context_create_input_stream (MirageContext *self,
                                        const gchar *filename,
                                        GError **error);

Opens a file pointed to by `filename` and creates a chain of filter streams on top of it.

#### Parameters

self | a MirageContext |
filename | filename to create input stream on. | [in]
error | location to store error, or `NULL`. | [out][allow-none]

#### Returns

on success, an object implementing MirageStream interface is returned, which can be used to access data stored in file. On failure, `NULL` is returned. The reference to the object should be released using `g_object_unref()` when no longer needed.

[transfer full]

### mirage_context_create_output_stream ()

    MirageStream *
    mirage_context_create_output_stream (MirageContext *self,
                                         const gchar *filename,
                                         const gchar **filter_chain,
                                         GError **error);

Opens a file pointed to by `filename` and optionally creates a chain of filter streams on top of it.

The chain of filters is described by `filter` -chain, which is a NULL-terminated array of strings corresponding to type names of filters, with the last filter being the one on the top. Filters are passed by their name types because their actual type values are determined when the plugins are loaded. If invalid filter is specified in the chain, this function will fail. It is the caller's responsibility to construct a valid filter chain.

#### Parameters

self | a MirageContext |
filename | filename to create output stream on. | [in]
filter_chain | NULL-terminated array of strings describing types of filters to include in the filter chain, or `NULL`. | [in][allow-none][array zero-terminated=1]
error | location to store error, or `NULL`. | [out][allow-none]

#### Returns

on success, an object implementing MirageStream interface is returned, which can be used to write data to file. On failure, `NULL` is returned. The reference to the object should be released using `g_object_unref()` when no longer needed.

[transfer full]

### mirage_context_get_debug_domain ()

    const gchar *
    mirage_context_get_debug_domain (MirageContext *self);

Retrieves debug context's domain name.

#### Parameters

self | a MirageContext |

#### Returns

pointer to buffer containing the domain name, or `NULL`. The buffer belongs to the object and should not be modified.

[transfer none]

### mirage_context_get_debug_mask ()

    gint
    mirage_context_get_debug_mask (MirageContext *self);

Retrieves debug context's debug mask.

#### Parameters

self | a MirageContext |

#### Returns

debug context's debug mask

### mirage_context_get_debug_name ()

    const gchar *
    mirage_context_get_debug_name (MirageContext *self);

Retrieves debug context's name.

#### Parameters

self | a MirageContext |

#### Returns

pointer to buffer containing the name, or `NULL`. The buffer belongs to the object and should not be modified.

[transfer none]

### mirage_context_get_option ()

    GVariant *
    mirage_context_get_option (MirageContext *self,
                               const gchar *name);

Retrieves option named `name` from the context.

#### Parameters

self | a MirageContext |
name | option name. | [in]

#### Returns

pointer to a GVariant containing the option value on success, `NULL` on failure.

[transfer full]

### mirage_context_load_image ()

    MirageDisc *
    mirage_context_load_image (MirageContext *self,
                               gchar **filenames,
                               GError **error);

Creates a MirageDisc object representing image stored in `filenames` . `filenames` is a NULL-terminated list of filenames containing image data. The function tries to find a parser that can handle give filename(s) and uses it to load the data into disc object.

If multiple filenames are provided and parser supports only single-file images, only the first filename is used.

#### Parameters

self | a MirageContext |
filenames | filename(s). | [in][array zero-terminated=1]
error | location to store error, or `NULL`. | [out][allow-none]

#### Returns

a MirageDisc object on success, `NULL` on failure. The reference to the object should be released using `g_object_unref()` when no longer needed.

[transfer full]

### mirage_context_obtain_password ()

    gchar *
    mirage_context_obtain_password (MirageContext *self,
                                    GError **error);

Obtains password string, using the MiragePasswordFunction callback that was provided via `mirage_context_set_password_function()`.

#### Parameters

self | a MirageContext |
error | location to store error, or `NULL`. | [out][allow-none]

#### Returns

password string on success, `NULL` on failure. The string should be freed with `g_free()` when no longer needed.

### mirage_context_set_debug_domain ()

    void
    mirage_context_set_debug_domain (MirageContext *self,
                                     const gchar *domain);

Sets debug context's domain name to `domain` .

#### Parameters

self | a MirageContext |
domain | domain name. | [in]

### mirage_context_set_debug_mask ()

    void
    mirage_context_set_debug_mask (MirageContext *self,
                                   gint debug_mask);

Sets debug context's debug mask.

#### Parameters

self | a MirageContext |
debug_mask | debug mask. | [in]

### mirage_context_set_debug_name ()

    void
    mirage_context_set_debug_name (MirageContext *self,
                                   const gchar *name);

Sets debug context's name to `name` .

#### Parameters

self | a MirageContext |
name | name. | [in]

### mirage_context_set_option ()

    void
    mirage_context_set_option (MirageContext *self,
                               const gchar *name,
                               GVariant *value);

Sets an option to the context. If option with the specified name already exists, it is replaced.

#### Parameters

self | a MirageContext |
name | option name. | [in]
value | option value. | [in][transfer full]

### mirage_context_set_password_function ()

    void
    mirage_context_set_password_function (MirageContext *self,
                                          MiragePasswordFunction func,
                                          gpointer user_data,
                                          GDestroyNotify destroy);

Sets the password function to context. The function is used by parsers that support encrypted images to obtain password for unlocking such images.

Both `func` and `user_data` can be `NULL`; in that case the appropriate setting will be reset.

#### Parameters

self | a MirageContext |
func | a password function pointer. | [in][allow-none][scope notified]
user_data | pointer to user data to be passed to the password function. | [in][closure]
destroy | destroy notify for `user_data` , or `NULL`. | [in][allow-none]

## Types and Values

### struct MirageContext

    struct MirageContext;

All the fields in the MirageContext structure are private to the MirageContext implementation and should never be accessed directly.

### struct MirageContextClass

    struct MirageContextClass {
        GObjectClass parent_class;
    };

The class structure for the MirageContext type.

#### Members

## See Also

MirageContextual, MirageObject