system/include/emscripten/fetch.h - external/github.com/kripken/emscripten - Git at Google

 /*
  * Copyright 2016 The Emscripten Authors.  All rights reserved.
  * Emscripten is available under two separate licenses, the MIT license and the
  * University of Illinois/NCSA Open Source License.  Both these licenses can be
  * found in the LICENSE file.
  */

 #pragma once

 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <emscripten/html5.h>

 #ifdef __cplusplus
 extern "C" {
 #endif

 // Emscripten fetch attributes:
 // If passed, the body of the request will be present in full in the onsuccess() handler.
 #define EMSCRIPTEN_FETCH_LOAD_TO_MEMORY  1

 // If passed, the intermediate streamed bytes will be passed in to the onprogress() handler. If not specified, the
 // onprogress() handler will still be called, but without data bytes.
 // Note: Firefox only as it depends on 'moz-chunked-arraybuffer'.
 #define EMSCRIPTEN_FETCH_STREAM_DATA 2

 // If passed, the final download will be stored in IndexedDB. If not specified, the file will only reside in browser memory.
 #define EMSCRIPTEN_FETCH_PERSIST_FILE 4

 // Looks up if the file already exists in IndexedDB, and if so, it is returned without redownload. If a partial transfer
 // exists in IndexedDB, the download will resume from where it left off and run to completion.
 // EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
 // If none of these three flags is specified, the fetch operation is implicitly treated as if EMSCRIPTEN_FETCH_APPEND
 // had been passed.
 #define EMSCRIPTEN_FETCH_APPEND 8

 // If the file already exists in IndexedDB, the old file will be deleted and a new download is started.
 // EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
 // If you would like to perform an XHR that neither reads or writes to IndexedDB, pass this flag EMSCRIPTEN_FETCH_REPLACE,
 // and do not pass the flag EMSCRIPTEN_FETCH_PERSIST_FILE.
 #define EMSCRIPTEN_FETCH_REPLACE 16

 // If specified, the file will only be looked up in IndexedDB, but if it does not exist, it is not attempted to be downloaded
 // over the network but an error is raised.
 // EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
 #define EMSCRIPTEN_FETCH_NO_DOWNLOAD 32

 // If specified, emscripten_fetch() will synchronously run to completion before returning.
 // The callback handlers will be called from within emscripten_fetch() while the operation is in progress.
 #define EMSCRIPTEN_FETCH_SYNCHRONOUS 64

 // If specified, it will be possible to call emscripten_fetch_wait() on the fetch
 // to test or wair for its completion.
 #define EMSCRIPTEN_FETCH_WAITABLE 128

 struct emscripten_fetch_t;

 // Specifies the parameters for a newly initiated fetch operation.
 typedef struct emscripten_fetch_attr_t
 {
 	// 'POST', 'GET', etc.
 	char requestMethod[32];

 	// Custom data that can be tagged along the process.
 	void *userData;

 	void (*onsuccess)(struct emscripten_fetch_t *fetch);
 	void (*onerror)(struct emscripten_fetch_t *fetch);
 	void (*onprogress)(struct emscripten_fetch_t *fetch);
 	void (*onreadystatechange)(struct emscripten_fetch_t *fetch);

 	// EMSCRIPTEN_FETCH_* attributes
 	uint32_t attributes;

 	// Specifies the amount of time the request can take before failing due to a timeout.
 	unsigned long timeoutMSecs;

 	// Indicates whether cross-site access control requests should be made using credentials.
 	EM_BOOL withCredentials;

 	// Specifies the destination path in IndexedDB where to store the downloaded content body. If this is empty, the transfer
 	// is not stored to IndexedDB at all.
 	// Note that this struct does not contain space to hold this string, it only carries a pointer.
 	// Calling emscripten_fetch() will make an internal copy of this string.
 	const char *destinationPath;

 	// Specifies the authentication username to use for the request, if necessary.
 	// Note that this struct does not contain space to hold this string, it only carries a pointer.
 	// Calling emscripten_fetch() will make an internal copy of this string.
 	const char *userName;

 	// Specifies the authentication username to use for the request, if necessary.
 	// Note that this struct does not contain space to hold this string, it only carries a pointer.
 	// Calling emscripten_fetch() will make an internal copy of this string.
 	const char *password;

 	// Points to an array of strings to pass custom headers to the request. This array takes the form
 	// {"key1", "value1", "key2", "value2", "key3", "value3", ..., 0 }; Note especially that the array
 	// needs to be terminated with a null pointer.
 	const char * const *requestHeaders;

 	// Pass a custom MIME type here to force the browser to treat the received data with the given type.
 	const char *overriddenMimeType;

 	// If non-zero, specifies a pointer to the data that is to be passed as the body (payload) of the request
 	// that is being performed. Leave as zero if no request body needs to be sent.
 	// The memory pointed to by this field is provided by the user, and needs to be valid throughout the
 	// duration of the fetch operation. If passing a non-zero pointer into this field, make sure to implement
 	// *both* the onsuccess and onerror handlers to be notified when the fetch finishes to know when this memory
 	// block can be freed. Do not pass a pointer to memory on the stack or other temporary area here.
 	const char *requestData;

 	// Specifies the length of the buffer pointed by 'requestData'. Leave as 0 if no request body needs to be sent.
 	size_t requestDataSize;
 } emscripten_fetch_attr_t;

 typedef struct emscripten_fetch_t
 {
 	// Unique identifier for this fetch in progress.
 	unsigned int id;

 	// Custom data that can be tagged along the process.
 	void *userData;

 	// The remote URL that is being downloaded.
 	const char *url;

 	// In onsuccess() handler:
 	//   - If the EMSCRIPTEN_FETCH_LOAD_TO_MEMORY attribute was specified for the transfer, this points to the
 	//     body of the downloaded data. Otherwise this will be null.
 	// In onprogress() handler:
 	//   - If the EMSCRIPTEN_FETCH_STREAM_DATA attribute was specified for the transfer, this points to a partial
 	//     chunk of bytes related to the transfer. Otherwise this will be null.
 	// The data buffer provided here has identical lifetime with the emscripten_fetch_t object itself, and is freed by
 	// calling emscripten_fetch_close() on the emscripten_fetch_t pointer.
 	const char *data;

 	// Specifies the length of the above data block in bytes. When the download finishes, this field will be valid even if
 	// EMSCRIPTEN_FETCH_LOAD_TO_MEMORY was not specified.
 	uint64_t numBytes;

 	// If EMSCRIPTEN_FETCH_STREAM_DATA is being performed, this indicates the byte offset from the start of the stream
 	// that the data block specifies. (for onprogress() streaming XHR transfer, the number of bytes downloaded so far before this chunk)
 	uint64_t dataOffset;

 	// Specifies the total number of bytes that the response body will be.
 	// Note: This field may be zero, if the server does not report the Content-Length field.
 	uint64_t totalBytes;

 	// Specifies the readyState of the XHR request:
 	// 0: UNSENT: request not sent yet
 	// 1: OPENED: emscripten_fetch has been called.
 	// 2: HEADERS_RECEIVED: emscripten_fetch has been called, and headers and status are available.
 	// 3: LOADING: download in progress.
 	// 4: DONE: download finished.
 	// See https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/readyState
 	unsigned short readyState;

 	// Specifies the status code of the response.
 	unsigned short status;

 	// Specifies a human-readable form of the status code.
 	char statusText[64];

 	uint32_t __proxyState;

 	// For internal use only.
 	emscripten_fetch_attr_t __attributes;
 } emscripten_fetch_t;

 // Clears the fields of an emscripten_fetch_attr_t structure to their default values in a future-compatible manner.
 void emscripten_fetch_attr_init(emscripten_fetch_attr_t *fetch_attr);

 // Initiates a new Emscripten fetch operation, which downloads data from the given URL or from IndexedDB database.
 emscripten_fetch_t *emscripten_fetch(emscripten_fetch_attr_t *fetch_attr, const char *url);

 // Synchronously blocks to wait for the given fetch operation to complete. This operation is not allowed in the main browser
 // thread, in which case it will return EMSCRIPTEN_RESULT_NOT_SUPPORTED. Pass timeoutMSecs=infinite to wait indefinitely. If
 // the wait times out, the return value will be EMSCRIPTEN_RESULT_TIMEOUT.
 // The onsuccess()/onerror()/onprogress() handlers will be called in the calling thread from within this function before
 // this function returns.
 EMSCRIPTEN_RESULT emscripten_fetch_wait(emscripten_fetch_t *fetch, double timeoutMSecs);

 // Closes a finished or an executing fetch operation and frees up all memory. If the fetch operation was still executing, the
 // onerror() handler will be called in the calling thread before this function returns.
 EMSCRIPTEN_RESULT emscripten_fetch_close(emscripten_fetch_t *fetch);

 // Gets the size (in bytes) of the response headers as plain text.
 // This must be called on the same thread as the fetch originated on.
 // Note that this will return 0 if readyState < HEADERS_RECEIVED.
 size_t emscripten_fetch_get_response_headers_length(emscripten_fetch_t *fetch);

 // Gets the response headers as plain text. dstSizeBytes should be headers_length + 1 (for the null terminator).
 // This must be called on the same thread as the fetch originated on.
 size_t emscripten_fetch_get_response_headers(emscripten_fetch_t *fetch, char *dst, size_t dstSizeBytes);

 // Converts the plain text headers into an array of strings. This array takes the form
 // {"key1", "value1", "key2", "value2", "key3", "value3", ..., 0 }; Note especially that the array
 // is terminated with a null pointer.
 char **emscripten_fetch_unpack_response_headers(const char *headersString);

 // This frees the memory used by the array of headers. Call this when finished with the data returned
 // by emscripten_fetch_unpack_response_headers.
 void emscripten_fetch_free_unpacked_response_headers(char **unpackedHeaders);

 #define emscripten_asmfs_open_t int

 // The following flags specify how opening files for reading works (from strictest behavior to most flexible)

 // When a file is opened for reading, the file data must already fully reside in memory. (most similar to MEMFS behavior)
 #define EMSCRIPTEN_ASMFS_OPEN_MEMORY    0

 // The file data does not need to be already in memory, but can reside in IndexedDB.
 #define EMSCRIPTEN_ASMFS_OPEN_INDEXEDDB 1

 // The file will be downloaded from remote server, as long as it has an index entry in local filesystem.
 #define EMSCRIPTEN_ASMFS_OPEN_REMOTE    2

 // A file entry does not need to exist on the local filesystem, but discovery will be attempted from remote server via an XHR first.
 #define EMSCRIPTEN_ASMFS_OPEN_REMOTE_DISCOVER 3

 // Specifies how calls to non-truncating open(), fopen(), std::ifstream etc. behave on the calling thread.
 void emscripten_asmfs_set_file_open_behavior(emscripten_asmfs_open_t behavior);

 // Returns the current file open behavior modein the calling thread.
 emscripten_asmfs_open_t emscripten_asmfs_get_file_open_behavior();

 // Records the URL from where the given file on the ASMFS filesystem can be obtained from.
 void emscripten_asmfs_set_remote_url(const char *filename, const char *remoteUrl);

 // Given a filename, outputs the remote URL address that file can be located in.
 void emscripten_asmfs_remote_url(const char *filename, char *outRemoteUrl, int maxBytesToWrite);

 // Unloads the given file from the ASMFS filesystem. Call this function to save memory from files that have been already loaded
 // in to memory and will no longer be needed.
 void emscripten_asmfs_unload_data(const char *pathname);

 // Starts an asynchronous preload of a file from the given URL to the local filesystem to destination path 'pathname' for synchronous
 // access on the main thread. Specify a onsuccess callback in options structure to be notified of when the transfer finishes.
 // The resulting download will always be performed with the flag EMSCRIPTEN_FETCH_LOAD_TO_MEMORY and without the flags
 // EMSCRIPTEN_FETCH_SYNCHRONOUS | EMSCRIPTEN_FETCH_WAITABLE | EMSCRIPTEN_FETCH_STREAM_DATA. The remaining flags
 // EMSCRIPTEN_FETCH_NO_DOWNLOAD, EMSCRIPTEN_FETCH_PERSIST_FILE, EMSCRIPTEN_FETCH_APPEND/REPLACE are
 // customizable in the options field. In particular, if EMSCRIPTEN_FETCH_NO_DOWNLOAD is passed, then the file is loaded to memory for
 // synchronous access by looking at IndexedDB only.
 EMSCRIPTEN_RESULT emscripten_asmfs_preload_file(const char *url, const char *pathname, int mode, emscripten_fetch_attr_t *options);

 // Computes the total amount of bytes in memory utilized by the filesystem at the moment.
 // Note: This function can be slow since it walks through the whole filesystem.
 uint64_t emscripten_asmfs_compute_memory_usage();

 #ifdef __cplusplus
 }
 #endif
	/*
	* Copyright 2016 The Emscripten Authors. All rights reserved.
	* Emscripten is available under two separate licenses, the MIT license and the
	* University of Illinois/NCSA Open Source License. Both these licenses can be
	* found in the LICENSE file.
	*/

	#pragma once

	#include <limits.h>
	#include <stddef.h>
	#include <stdint.h>
	#include <emscripten/html5.h>

	#ifdef __cplusplus
	extern "C" {
	#endif

	// Emscripten fetch attributes:
	// If passed, the body of the request will be present in full in the onsuccess() handler.
	#define EMSCRIPTEN_FETCH_LOAD_TO_MEMORY 1

	// If passed, the intermediate streamed bytes will be passed in to the onprogress() handler. If not specified, the
	// onprogress() handler will still be called, but without data bytes.
	// Note: Firefox only as it depends on 'moz-chunked-arraybuffer'.
	#define EMSCRIPTEN_FETCH_STREAM_DATA 2

	// If passed, the final download will be stored in IndexedDB. If not specified, the file will only reside in browser memory.
	#define EMSCRIPTEN_FETCH_PERSIST_FILE 4

	// Looks up if the file already exists in IndexedDB, and if so, it is returned without redownload. If a partial transfer
	// exists in IndexedDB, the download will resume from where it left off and run to completion.
	// EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
	// If none of these three flags is specified, the fetch operation is implicitly treated as if EMSCRIPTEN_FETCH_APPEND
	// had been passed.
	#define EMSCRIPTEN_FETCH_APPEND 8

	// If the file already exists in IndexedDB, the old file will be deleted and a new download is started.
	// EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
	// If you would like to perform an XHR that neither reads or writes to IndexedDB, pass this flag EMSCRIPTEN_FETCH_REPLACE,
	// and do not pass the flag EMSCRIPTEN_FETCH_PERSIST_FILE.
	#define EMSCRIPTEN_FETCH_REPLACE 16

	// If specified, the file will only be looked up in IndexedDB, but if it does not exist, it is not attempted to be downloaded
	// over the network but an error is raised.
	// EMSCRIPTEN_FETCH_APPEND, EMSCRIPTEN_FETCH_REPLACE and EMSCRIPTEN_FETCH_NO_DOWNLOAD are mutually exclusive.
	#define EMSCRIPTEN_FETCH_NO_DOWNLOAD 32

	// If specified, emscripten_fetch() will synchronously run to completion before returning.
	// The callback handlers will be called from within emscripten_fetch() while the operation is in progress.
	#define EMSCRIPTEN_FETCH_SYNCHRONOUS 64

	// If specified, it will be possible to call emscripten_fetch_wait() on the fetch
	// to test or wair for its completion.
	#define EMSCRIPTEN_FETCH_WAITABLE 128

	struct emscripten_fetch_t;

	// Specifies the parameters for a newly initiated fetch operation.
	typedef struct emscripten_fetch_attr_t
	{
	// 'POST', 'GET', etc.
	char requestMethod[32];

	// Custom data that can be tagged along the process.
	void *userData;

	void (onsuccess)(struct emscripten_fetch_t fetch);
	void (onerror)(struct emscripten_fetch_t fetch);
	void (onprogress)(struct emscripten_fetch_t fetch);
	void (onreadystatechange)(struct emscripten_fetch_t fetch);

	// EMSCRIPTEN_FETCH_* attributes
	uint32_t attributes;

	// Specifies the amount of time the request can take before failing due to a timeout.
	unsigned long timeoutMSecs;

	// Indicates whether cross-site access control requests should be made using credentials.
	EM_BOOL withCredentials;

	// Specifies the destination path in IndexedDB where to store the downloaded content body. If this is empty, the transfer
	// is not stored to IndexedDB at all.
	// Note that this struct does not contain space to hold this string, it only carries a pointer.
	// Calling emscripten_fetch() will make an internal copy of this string.
	const char *destinationPath;

	// Specifies the authentication username to use for the request, if necessary.
	// Note that this struct does not contain space to hold this string, it only carries a pointer.
	// Calling emscripten_fetch() will make an internal copy of this string.
	const char *userName;

	// Specifies the authentication username to use for the request, if necessary.
	// Note that this struct does not contain space to hold this string, it only carries a pointer.
	// Calling emscripten_fetch() will make an internal copy of this string.
	const char *password;

	// Points to an array of strings to pass custom headers to the request. This array takes the form
	// {"key1", "value1", "key2", "value2", "key3", "value3", ..., 0 }; Note especially that the array
	// needs to be terminated with a null pointer.
	const char * const *requestHeaders;

	// Pass a custom MIME type here to force the browser to treat the received data with the given type.
	const char *overriddenMimeType;

	// If non-zero, specifies a pointer to the data that is to be passed as the body (payload) of the request
	// that is being performed. Leave as zero if no request body needs to be sent.
	// The memory pointed to by this field is provided by the user, and needs to be valid throughout the
	// duration of the fetch operation. If passing a non-zero pointer into this field, make sure to implement
	// both the onsuccess and onerror handlers to be notified when the fetch finishes to know when this memory
	// block can be freed. Do not pass a pointer to memory on the stack or other temporary area here.
	const char *requestData;

	// Specifies the length of the buffer pointed by 'requestData'. Leave as 0 if no request body needs to be sent.
	size_t requestDataSize;
	} emscripten_fetch_attr_t;

	typedef struct emscripten_fetch_t
	{
	// Unique identifier for this fetch in progress.
	unsigned int id;

	// Custom data that can be tagged along the process.
	void *userData;

	// The remote URL that is being downloaded.
	const char *url;

	// In onsuccess() handler:
	// - If the EMSCRIPTEN_FETCH_LOAD_TO_MEMORY attribute was specified for the transfer, this points to the
	// body of the downloaded data. Otherwise this will be null.
	// In onprogress() handler:
	// - If the EMSCRIPTEN_FETCH_STREAM_DATA attribute was specified for the transfer, this points to a partial
	// chunk of bytes related to the transfer. Otherwise this will be null.
	// The data buffer provided here has identical lifetime with the emscripten_fetch_t object itself, and is freed by
	// calling emscripten_fetch_close() on the emscripten_fetch_t pointer.
	const char *data;

	// Specifies the length of the above data block in bytes. When the download finishes, this field will be valid even if
	// EMSCRIPTEN_FETCH_LOAD_TO_MEMORY was not specified.
	uint64_t numBytes;

	// If EMSCRIPTEN_FETCH_STREAM_DATA is being performed, this indicates the byte offset from the start of the stream
	// that the data block specifies. (for onprogress() streaming XHR transfer, the number of bytes downloaded so far before this chunk)
	uint64_t dataOffset;

	// Specifies the total number of bytes that the response body will be.
	// Note: This field may be zero, if the server does not report the Content-Length field.
	uint64_t totalBytes;

	// Specifies the readyState of the XHR request:
	// 0: UNSENT: request not sent yet
	// 1: OPENED: emscripten_fetch has been called.
	// 2: HEADERS_RECEIVED: emscripten_fetch has been called, and headers and status are available.
	// 3: LOADING: download in progress.
	// 4: DONE: download finished.
	// See https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/readyState
	unsigned short readyState;

	// Specifies the status code of the response.
	unsigned short status;

	// Specifies a human-readable form of the status code.
	char statusText[64];

	uint32_t __proxyState;

	// For internal use only.
	emscripten_fetch_attr_t __attributes;
	} emscripten_fetch_t;

	// Clears the fields of an emscripten_fetch_attr_t structure to their default values in a future-compatible manner.
	void emscripten_fetch_attr_init(emscripten_fetch_attr_t *fetch_attr);

	// Initiates a new Emscripten fetch operation, which downloads data from the given URL or from IndexedDB database.
	emscripten_fetch_t emscripten_fetch(emscripten_fetch_attr_t fetch_attr, const char *url);

	// Synchronously blocks to wait for the given fetch operation to complete. This operation is not allowed in the main browser
	// thread, in which case it will return EMSCRIPTEN_RESULT_NOT_SUPPORTED. Pass timeoutMSecs=infinite to wait indefinitely. If
	// the wait times out, the return value will be EMSCRIPTEN_RESULT_TIMEOUT.
	// The onsuccess()/onerror()/onprogress() handlers will be called in the calling thread from within this function before
	// this function returns.
	EMSCRIPTEN_RESULT emscripten_fetch_wait(emscripten_fetch_t *fetch, double timeoutMSecs);

	// Closes a finished or an executing fetch operation and frees up all memory. If the fetch operation was still executing, the
	// onerror() handler will be called in the calling thread before this function returns.
	EMSCRIPTEN_RESULT emscripten_fetch_close(emscripten_fetch_t *fetch);

	// Gets the size (in bytes) of the response headers as plain text.
	// This must be called on the same thread as the fetch originated on.
	// Note that this will return 0 if readyState < HEADERS_RECEIVED.
	size_t emscripten_fetch_get_response_headers_length(emscripten_fetch_t *fetch);

	// Gets the response headers as plain text. dstSizeBytes should be headers_length + 1 (for the null terminator).
	// This must be called on the same thread as the fetch originated on.
	size_t emscripten_fetch_get_response_headers(emscripten_fetch_t fetch, char dst, size_t dstSizeBytes);

	// Converts the plain text headers into an array of strings. This array takes the form
	// {"key1", "value1", "key2", "value2", "key3", "value3", ..., 0 }; Note especially that the array
	// is terminated with a null pointer.
	char *emscripten_fetch_unpack_response_headers(const char headersString);

	// This frees the memory used by the array of headers. Call this when finished with the data returned
	// by emscripten_fetch_unpack_response_headers.
	void emscripten_fetch_free_unpacked_response_headers(char **unpackedHeaders);

	#define emscripten_asmfs_open_t int

	// The following flags specify how opening files for reading works (from strictest behavior to most flexible)

	// When a file is opened for reading, the file data must already fully reside in memory. (most similar to MEMFS behavior)
	#define EMSCRIPTEN_ASMFS_OPEN_MEMORY 0

	// The file data does not need to be already in memory, but can reside in IndexedDB.
	#define EMSCRIPTEN_ASMFS_OPEN_INDEXEDDB 1

	// The file will be downloaded from remote server, as long as it has an index entry in local filesystem.
	#define EMSCRIPTEN_ASMFS_OPEN_REMOTE 2

	// A file entry does not need to exist on the local filesystem, but discovery will be attempted from remote server via an XHR first.
	#define EMSCRIPTEN_ASMFS_OPEN_REMOTE_DISCOVER 3

	// Specifies how calls to non-truncating open(), fopen(), std::ifstream etc. behave on the calling thread.
	void emscripten_asmfs_set_file_open_behavior(emscripten_asmfs_open_t behavior);

	// Returns the current file open behavior modein the calling thread.
	emscripten_asmfs_open_t emscripten_asmfs_get_file_open_behavior();

	// Records the URL from where the given file on the ASMFS filesystem can be obtained from.
	void emscripten_asmfs_set_remote_url(const char filename, const char remoteUrl);

	// Given a filename, outputs the remote URL address that file can be located in.
	void emscripten_asmfs_remote_url(const char filename, char outRemoteUrl, int maxBytesToWrite);

	// Unloads the given file from the ASMFS filesystem. Call this function to save memory from files that have been already loaded
	// in to memory and will no longer be needed.
	void emscripten_asmfs_unload_data(const char *pathname);

	// Starts an asynchronous preload of a file from the given URL to the local filesystem to destination path 'pathname' for synchronous
	// access on the main thread. Specify a onsuccess callback in options structure to be notified of when the transfer finishes.
	// The resulting download will always be performed with the flag EMSCRIPTEN_FETCH_LOAD_TO_MEMORY and without the flags
	// EMSCRIPTEN_FETCH_SYNCHRONOUS \| EMSCRIPTEN_FETCH_WAITABLE \| EMSCRIPTEN_FETCH_STREAM_DATA. The remaining flags
	// EMSCRIPTEN_FETCH_NO_DOWNLOAD, EMSCRIPTEN_FETCH_PERSIST_FILE, EMSCRIPTEN_FETCH_APPEND/REPLACE are
	// customizable in the options field. In particular, if EMSCRIPTEN_FETCH_NO_DOWNLOAD is passed, then the file is loaded to memory for
	// synchronous access by looking at IndexedDB only.
	EMSCRIPTEN_RESULT emscripten_asmfs_preload_file(const char url, const char pathname, int mode, emscripten_fetch_attr_t *options);

	// Computes the total amount of bytes in memory utilized by the filesystem at the moment.
	// Note: This function can be slow since it walks through the whole filesystem.
	uint64_t emscripten_asmfs_compute_memory_usage();

	#ifdef __cplusplus
	}
	#endif