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#ifndef AWS_IO_STREAM_H
#define AWS_IO_STREAM_H
/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/common/ref_count.h>
#include <aws/io/io.h>
AWS_PUSH_SANE_WARNING_LEVEL
struct aws_input_stream;
struct aws_byte_buf;
/*
* For seek calls, where in the stream to seek from.
* CUR support can come later
* Intentionally mirror libc constants
*/
enum aws_stream_seek_basis { AWS_SSB_BEGIN = 0, AWS_SSB_END = 2 };
struct aws_stream_status {
bool is_end_of_stream;
bool is_valid;
};
struct aws_input_stream_vtable {
int (*seek)(struct aws_input_stream *stream, int64_t offset, enum aws_stream_seek_basis basis);
/**
* Stream as much data as will fit into the destination buffer and update its length.
* The destination buffer's capacity MUST NOT be changed.
*
* Return AWS_OP_SUCCESS if the read is successful.
* If AWS_OP_ERR is returned, the stream is assumed to be invalid and any data written to the buffer is ignored.
*
* If no more data is currently available, or the end of the stream has been reached, simply return AWS_OP_SUCCESS
* without touching the destination buffer.
*/
int (*read)(struct aws_input_stream *stream, struct aws_byte_buf *dest);
int (*get_status)(struct aws_input_stream *stream, struct aws_stream_status *status);
int (*get_length)(struct aws_input_stream *stream, int64_t *out_length);
/**
* Optional.
* If not set, the default aws_ref_count_acquire/release will be used.
* Set for high level language binding that has its own refcounting implementation and needs to be kept alive from
* C.
* If set, ref_count member will not be used.
*/
void (*acquire)(struct aws_input_stream *stream);
void (*release)(struct aws_input_stream *stream);
};
/**
* Base class for input streams.
* Note: when you implement one input stream, the ref_count needs to be initialized to clean up the resource when
* reaches to zero.
*/
struct aws_input_stream {
/* point to the impl only set if needed. */
void *impl;
const struct aws_input_stream_vtable *vtable;
struct aws_ref_count ref_count;
};
AWS_EXTERN_C_BEGIN
/**
* Increments the reference count on the input stream, allowing the caller to take a reference to it.
*
* Returns the same input stream passed in.
*/
AWS_IO_API struct aws_input_stream *aws_input_stream_acquire(struct aws_input_stream *stream);
/**
* Decrements a input stream's ref count. When the ref count drops to zero, the input stream will be destroyed.
*
* Returns NULL always.
*/
AWS_IO_API struct aws_input_stream *aws_input_stream_release(struct aws_input_stream *stream);
/*
* Seek to a position within a stream; analagous to fseek() and its relatives
*/
AWS_IO_API int aws_input_stream_seek(struct aws_input_stream *stream, int64_t offset, enum aws_stream_seek_basis basis);
/*
* Read data from a stream. If data is available, will read up to the (capacity - len) open bytes
* in the destination buffer. If AWS_OP_ERR is returned, the destination buffer will be unchanged.
*/
AWS_IO_API int aws_input_stream_read(struct aws_input_stream *stream, struct aws_byte_buf *dest);
/*
* Queries miscellaneous properties of the stream
*/
AWS_IO_API int aws_input_stream_get_status(struct aws_input_stream *stream, struct aws_stream_status *status);
/*
* Returns the total stream length, if able, regardless of current stream position. Under certain conditions,
* a valid stream may return an error instead when there is not a good answer (socket stream, for example).
*
*/
AWS_IO_API int aws_input_stream_get_length(struct aws_input_stream *stream, int64_t *out_length);
/* DEPRECATED
* Tears down the stream. Equivalent to aws_input_stream_release()
*/
AWS_IO_API void aws_input_stream_destroy(struct aws_input_stream *stream);
/*
* Creates a stream that operates on a range of bytes
*/
AWS_IO_API struct aws_input_stream *aws_input_stream_new_from_cursor(
struct aws_allocator *allocator,
const struct aws_byte_cursor *cursor);
/*
* Creates a stream that operates on a (not-yet-opened) file.
* Destruction closes the file.
*/
AWS_IO_API struct aws_input_stream *aws_input_stream_new_from_file(
struct aws_allocator *allocator,
const char *file_name);
/*
* Creates an input stream that reads from an already opened file.
* Destruction does not close the file.
*/
AWS_IO_API struct aws_input_stream *aws_input_stream_new_from_open_file(struct aws_allocator *allocator, FILE *file);
AWS_EXTERN_C_END
AWS_POP_SANE_WARNING_LEVEL
#endif /* AWS_IO_STREAM_H */
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