Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * bbstreamer.h
4 : *
5 : * Each tar archive returned by the server is passed to one or more
6 : * bbstreamer objects for further processing. The bbstreamer may do
7 : * something simple, like write the archive to a file, perhaps after
8 : * compressing it, but it can also do more complicated things, like
9 : * annotating the byte stream to indicate which parts of the data
10 : * correspond to tar headers or trailing padding, vs. which parts are
11 : * payload data. A subsequent bbstreamer may use this information to
12 : * make further decisions about how to process the data; for example,
13 : * it might choose to modify the archive contents.
14 : *
15 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
16 : *
17 : * IDENTIFICATION
18 : * src/bin/pg_basebackup/bbstreamer.h
19 : *-------------------------------------------------------------------------
20 : */
21 :
22 : #ifndef BBSTREAMER_H
23 : #define BBSTREAMER_H
24 :
25 : #include "common/compression.h"
26 : #include "lib/stringinfo.h"
27 : #include "pqexpbuffer.h"
28 :
29 : struct bbstreamer;
30 : struct bbstreamer_ops;
31 : typedef struct bbstreamer bbstreamer;
32 : typedef struct bbstreamer_ops bbstreamer_ops;
33 :
34 : /*
35 : * Each chunk of archive data passed to a bbstreamer is classified into one
36 : * of these categories. When data is first received from the remote server,
37 : * each chunk will be categorized as BBSTREAMER_UNKNOWN, and the chunks will
38 : * be of whatever size the remote server chose to send.
39 : *
40 : * If the archive is parsed (e.g. see bbstreamer_tar_parser_new()), then all
41 : * chunks should be labelled as one of the other types listed here. In
42 : * addition, there should be exactly one BBSTREAMER_MEMBER_HEADER chunk and
43 : * exactly one BBSTREAMER_MEMBER_TRAILER chunk per archive member, even if
44 : * that means a zero-length call. There can be any number of
45 : * BBSTREAMER_MEMBER_CONTENTS chunks in between those calls. There
46 : * should exactly BBSTREAMER_ARCHIVE_TRAILER chunk, and it should follow the
47 : * last BBSTREAMER_MEMBER_TRAILER chunk.
48 : *
49 : * In theory, we could need other classifications here, such as a way of
50 : * indicating an archive header, but the "tar" format doesn't need anything
51 : * else, so for the time being there's no point.
52 : */
53 : typedef enum
54 : {
55 : BBSTREAMER_UNKNOWN,
56 : BBSTREAMER_MEMBER_HEADER,
57 : BBSTREAMER_MEMBER_CONTENTS,
58 : BBSTREAMER_MEMBER_TRAILER,
59 : BBSTREAMER_ARCHIVE_TRAILER,
60 : } bbstreamer_archive_context;
61 :
62 : /*
63 : * Each chunk of data that is classified as BBSTREAMER_MEMBER_HEADER,
64 : * BBSTREAMER_MEMBER_CONTENTS, or BBSTREAMER_MEMBER_TRAILER should also
65 : * pass a pointer to an instance of this struct. The details are expected
66 : * to be present in the archive header and used to fill the struct, after
67 : * which all subsequent calls for the same archive member are expected to
68 : * pass the same details.
69 : */
70 : typedef struct
71 : {
72 : char pathname[MAXPGPATH];
73 : pgoff_t size;
74 : mode_t mode;
75 : uid_t uid;
76 : gid_t gid;
77 : bool is_directory;
78 : bool is_link;
79 : char linktarget[MAXPGPATH];
80 : } bbstreamer_member;
81 :
82 : /*
83 : * Generally, each type of bbstreamer will define its own struct, but the
84 : * first element should be 'bbstreamer base'. A bbstreamer that does not
85 : * require any additional private data could use this structure directly.
86 : *
87 : * bbs_ops is a pointer to the bbstreamer_ops object which contains the
88 : * function pointers appropriate to this type of bbstreamer.
89 : *
90 : * bbs_next is a pointer to the successor bbstreamer, for those types of
91 : * bbstreamer which forward data to a successor. It need not be used and
92 : * should be set to NULL when not relevant.
93 : *
94 : * bbs_buffer is a buffer for accumulating data for temporary storage. Each
95 : * type of bbstreamer makes its own decisions about whether and how to use
96 : * this buffer.
97 : */
98 : struct bbstreamer
99 : {
100 : const bbstreamer_ops *bbs_ops;
101 : bbstreamer *bbs_next;
102 : StringInfoData bbs_buffer;
103 : };
104 :
105 : /*
106 : * There are three callbacks for a bbstreamer. The 'content' callback is
107 : * called repeatedly, as described in the bbstreamer_archive_context comments.
108 : * Then, the 'finalize' callback is called once at the end, to give the
109 : * bbstreamer a chance to perform cleanup such as closing files. Finally,
110 : * because this code is running in a frontend environment where, as of this
111 : * writing, there are no memory contexts, the 'free' callback is called to
112 : * release memory. These callbacks should always be invoked using the static
113 : * inline functions defined below.
114 : */
115 : struct bbstreamer_ops
116 : {
117 : void (*content) (bbstreamer *streamer, bbstreamer_member *member,
118 : const char *data, int len,
119 : bbstreamer_archive_context context);
120 : void (*finalize) (bbstreamer *streamer);
121 : void (*free) (bbstreamer *streamer);
122 : };
123 :
124 : /* Send some content to a bbstreamer. */
125 : static inline void
126 1686208 : bbstreamer_content(bbstreamer *streamer, bbstreamer_member *member,
127 : const char *data, int len,
128 : bbstreamer_archive_context context)
129 : {
130 : Assert(streamer != NULL);
131 1686208 : streamer->bbs_ops->content(streamer, member, data, len, context);
132 1686208 : }
133 :
134 : /* Finalize a bbstreamer. */
135 : static inline void
136 622 : bbstreamer_finalize(bbstreamer *streamer)
137 : {
138 : Assert(streamer != NULL);
139 622 : streamer->bbs_ops->finalize(streamer);
140 622 : }
141 :
142 : /* Free a bbstreamer. */
143 : static inline void
144 622 : bbstreamer_free(bbstreamer *streamer)
145 : {
146 : Assert(streamer != NULL);
147 622 : streamer->bbs_ops->free(streamer);
148 622 : }
149 :
150 : /*
151 : * This is a convenience method for use when implementing a bbstreamer; it is
152 : * not for use by outside callers. It adds the amount of data specified by
153 : * 'nbytes' to the bbstreamer's buffer and adjusts '*len' and '*data'
154 : * accordingly.
155 : */
156 : static inline void
157 258626 : bbstreamer_buffer_bytes(bbstreamer *streamer, const char **data, int *len,
158 : int nbytes)
159 : {
160 : Assert(nbytes <= *len);
161 :
162 258626 : appendBinaryStringInfo(&streamer->bbs_buffer, *data, nbytes);
163 258626 : *len -= nbytes;
164 258626 : *data += nbytes;
165 258626 : }
166 :
167 : /*
168 : * This is a convenience method for use when implementing a bbstreamer; it is
169 : * not for use by outsider callers. It attempts to add enough data to the
170 : * bbstreamer's buffer to reach a length of target_bytes and adjusts '*len'
171 : * and '*data' accordingly. It returns true if the target length has been
172 : * reached and false otherwise.
173 : */
174 : static inline bool
175 258330 : bbstreamer_buffer_until(bbstreamer *streamer, const char **data, int *len,
176 : int target_bytes)
177 : {
178 258330 : int buflen = streamer->bbs_buffer.len;
179 :
180 258330 : if (buflen >= target_bytes)
181 : {
182 : /* Target length already reached; nothing to do. */
183 0 : return true;
184 : }
185 :
186 258330 : if (buflen + *len < target_bytes)
187 : {
188 : /* Not enough data to reach target length; buffer all of it. */
189 0 : bbstreamer_buffer_bytes(streamer, data, len, *len);
190 0 : return false;
191 : }
192 :
193 : /* Buffer just enough to reach the target length. */
194 258330 : bbstreamer_buffer_bytes(streamer, data, len, target_bytes - buflen);
195 258330 : return true;
196 : }
197 :
198 : /*
199 : * Functions for creating bbstreamer objects of various types. See the header
200 : * comments for each of these functions for details.
201 : */
202 : extern bbstreamer *bbstreamer_plain_writer_new(char *pathname, FILE *file);
203 : extern bbstreamer *bbstreamer_gzip_writer_new(char *pathname, FILE *file,
204 : pg_compress_specification *compress);
205 : extern bbstreamer *bbstreamer_extractor_new(const char *basepath,
206 : const char *(*link_map) (const char *),
207 : void (*report_output_file) (const char *));
208 :
209 : extern bbstreamer *bbstreamer_gzip_decompressor_new(bbstreamer *next);
210 : extern bbstreamer *bbstreamer_lz4_compressor_new(bbstreamer *next,
211 : pg_compress_specification *compress);
212 : extern bbstreamer *bbstreamer_lz4_decompressor_new(bbstreamer *next);
213 : extern bbstreamer *bbstreamer_zstd_compressor_new(bbstreamer *next,
214 : pg_compress_specification *compress);
215 : extern bbstreamer *bbstreamer_zstd_decompressor_new(bbstreamer *next);
216 : extern bbstreamer *bbstreamer_tar_parser_new(bbstreamer *next);
217 : extern bbstreamer *bbstreamer_tar_terminator_new(bbstreamer *next);
218 : extern bbstreamer *bbstreamer_tar_archiver_new(bbstreamer *next);
219 :
220 : extern bbstreamer *bbstreamer_recovery_injector_new(bbstreamer *next,
221 : bool is_recovery_guc_supported,
222 : PQExpBuffer recoveryconfcontents);
223 : extern void bbstreamer_inject_file(bbstreamer *streamer, char *pathname,
224 : char *data, int len);
225 :
226 : #endif
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