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#ifndef COMPRESSION_H
#define COMPRESSION_H
enum istream_decompress_flags {
/* If stream isn't detected to be compressed, return it as passthrough
istream. */
ISTREAM_DECOMPRESS_FLAG_TRY = BIT(0),
};
/* Compressed input is always detected once at maximum this many bytes have
been read. This value must be smaller than a typical istream max buffer
size. */
#define COMPRESSION_HDR_MAX_SIZE 128
struct compression_handler {
const char *name;
const char *ext;
bool (*is_compressed)(struct istream *input);
struct istream *(*create_istream)(struct istream *input);
struct ostream *(*create_ostream)(struct ostream *output, int level);
/* returns minimum level */
int (*get_min_level)(void);
/* the default can be -1 (e.g. gz), so the return value of this has to
be used as-is. */
int (*get_default_level)(void);
/* returns maximum level */
int (*get_max_level)(void);
};
extern const struct compression_handler compression_handlers[];
/* Returns 1 if compression handler was found and is usable, 0 if support isn't
compiled in, -1 if unknown. */
int compression_lookup_handler(const char *name,
const struct compression_handler **handler_r);
/* Detect handler by looking at the first few bytes of the input stream. */
const struct compression_handler *
compression_detect_handler(struct istream *input);
/* Lookup handler based on filename extension in the path, returns the same
* values as compression_lookup_handler. */
int compression_lookup_handler_from_ext(const char *path,
const struct compression_handler **handler_r);
/* Automatically detect the compression format. Note that using tee-istream as
one of the parent streams is dangerous here: A decompression istream may
have to read a lot of data (e.g. 8 kB isn't enough) before it returns even
the first byte as output. If the other tee children aren't read forward,
this can cause an infinite loop when i_stream_read() is always returning 0.
This is why ISTREAM_DECOMPRESS_FLAG_TRY should be used instead of attempting
to implement similar functionality with tee-istream. */
struct istream *
i_stream_create_decompress(struct istream *input,
enum istream_decompress_flags flags);
#endif
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