Ruby: ext/zlib/zlib-1.2.13/examples/zran.h Source File

Ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c52d4d35cc6a173c89eda98ceffa2dcf)

zran.h
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1/* zran.h -- example of zlib/gzip stream indexing and random access
2 * Copyright (C) 2005, 2012, 2018 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 * Version 1.2 14 Oct 2018 Mark Adler */
5
6#include <stdio.h>
7#include "zlib.h"
8
9/* Access point list. */
10 struct deflate_index {
11 int have; /* number of list entries */
12 int gzip; /* 1 if the index is of a gzip file, 0 if it is of a
13 zlib stream */
14 off_t length; /* total length of uncompressed data */
15 void *list; /* allocated list of entries */
16};
17
18/* Make one entire pass through a zlib or gzip compressed stream and build an
19 index, with access points about every span bytes of uncompressed output.
20 gzip files with multiple members are indexed in their entirety. span should
21 be chosen to balance the speed of random access against the memory
22 requirements of the list, about 32K bytes per access point. The return value
23 is the number of access points on success (>= 1), Z_MEM_ERROR for out of
24 memory, Z_DATA_ERROR for an error in the input file, or Z_ERRNO for a file
25 read error. On success, *built points to the resulting index. */
26int deflate_index_build(FILE *in, off_t span, struct deflate_index **built);
27
28/* Deallocate an index built by deflate_index_build() */
29void deflate_index_free(struct deflate_index *index);
30
31/* Use the index to read len bytes from offset into buf. Return bytes read or
32 negative for error (Z_DATA_ERROR or Z_MEM_ERROR). If data is requested past
33 the end of the uncompressed data, then deflate_index_extract() will return a
34 value less than len, indicating how much was actually read into buf. This
35 function should not return a data error unless the file was modified since
36 the index was generated, since deflate_index_build() validated all of the
37 input. deflate_index_extract() will return Z_ERRNO if there is an error on
38 reading or seeking the input file. */
39int deflate_index_extract(FILE *in, struct deflate_index *index, off_t offset,
40 unsigned char *buf, int len);
len
uint8_t len
Definition: escape.c:17
in
unsigned in(void *in_desc, z_const unsigned char **buf)
Definition: gun.c:89
offset
voidpf uLong offset
Definition: ioapi.h:144
buf
voidpf void * buf
Definition: ioapi.h:138
__sFILE
Definition: vsnprintf.c:169
deflate_index
Definition: zran.h:10
deflate_index::gzip
int gzip
Definition: zran.h:12
deflate_index::have
int have
Definition: zran.h:11
deflate_index::list
void * list
Definition: zran.h:15
deflate_index::length
off_t length
Definition: zran.h:14
off_t
#define off_t
Definition: win32.h:194
zlib.h
deflate_index_free
void deflate_index_free(struct deflate_index *index)
Definition: zran.c:76
deflate_index_extract
int deflate_index_extract(FILE *in, struct deflate_index *index, off_t offset, unsigned char *buf, int len)
Definition: zran.c:248
deflate_index_build
int deflate_index_build(FILE *in, off_t span, struct deflate_index **built)
Definition: zran.c:135