Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * bbstreamer_file.c
4 : *
5 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
6 : *
7 : * IDENTIFICATION
8 : * src/bin/pg_basebackup/bbstreamer_file.c
9 : *-------------------------------------------------------------------------
10 : */
11 :
12 : #include "postgres_fe.h"
13 :
14 : #include <unistd.h>
15 :
16 : #include "bbstreamer.h"
17 : #include "common/file_perm.h"
18 : #include "common/logging.h"
19 : #include "common/string.h"
20 :
21 : typedef struct bbstreamer_plain_writer
22 : {
23 : bbstreamer base;
24 : char *pathname;
25 : FILE *file;
26 : bool should_close_file;
27 : } bbstreamer_plain_writer;
28 :
29 : typedef struct bbstreamer_extractor
30 : {
31 : bbstreamer base;
32 : char *basepath;
33 : const char *(*link_map) (const char *);
34 : void (*report_output_file) (const char *);
35 : char filename[MAXPGPATH];
36 : FILE *file;
37 : } bbstreamer_extractor;
38 :
39 : static void bbstreamer_plain_writer_content(bbstreamer *streamer,
40 : bbstreamer_member *member,
41 : const char *data, int len,
42 : bbstreamer_archive_context context);
43 : static void bbstreamer_plain_writer_finalize(bbstreamer *streamer);
44 : static void bbstreamer_plain_writer_free(bbstreamer *streamer);
45 :
46 : const bbstreamer_ops bbstreamer_plain_writer_ops = {
47 : .content = bbstreamer_plain_writer_content,
48 : .finalize = bbstreamer_plain_writer_finalize,
49 : .free = bbstreamer_plain_writer_free
50 : };
51 :
52 : static void bbstreamer_extractor_content(bbstreamer *streamer,
53 : bbstreamer_member *member,
54 : const char *data, int len,
55 : bbstreamer_archive_context context);
56 : static void bbstreamer_extractor_finalize(bbstreamer *streamer);
57 : static void bbstreamer_extractor_free(bbstreamer *streamer);
58 : static void extract_directory(const char *filename, mode_t mode);
59 : static void extract_link(const char *filename, const char *linktarget);
60 : static FILE *create_file_for_extract(const char *filename, mode_t mode);
61 :
62 : const bbstreamer_ops bbstreamer_extractor_ops = {
63 : .content = bbstreamer_extractor_content,
64 : .finalize = bbstreamer_extractor_finalize,
65 : .free = bbstreamer_extractor_free
66 : };
67 :
68 : /*
69 : * Create a bbstreamer that just writes data to a file.
70 : *
71 : * The caller must specify a pathname and may specify a file. The pathname is
72 : * used for error-reporting purposes either way. If file is NULL, the pathname
73 : * also identifies the file to which the data should be written: it is opened
74 : * for writing and closed when done. If file is not NULL, the data is written
75 : * there.
76 : */
77 : bbstreamer *
78 20 : bbstreamer_plain_writer_new(char *pathname, FILE *file)
79 : {
80 : bbstreamer_plain_writer *streamer;
81 :
82 20 : streamer = palloc0(sizeof(bbstreamer_plain_writer));
83 20 : *((const bbstreamer_ops **) &streamer->base.bbs_ops) =
84 : &bbstreamer_plain_writer_ops;
85 :
86 20 : streamer->pathname = pstrdup(pathname);
87 20 : streamer->file = file;
88 :
89 20 : if (file == NULL)
90 : {
91 20 : streamer->file = fopen(pathname, "wb");
92 20 : if (streamer->file == NULL)
93 0 : pg_fatal("could not create file \"%s\": %m", pathname);
94 20 : streamer->should_close_file = true;
95 : }
96 :
97 20 : return &streamer->base;
98 : }
99 :
100 : /*
101 : * Write archive content to file.
102 : */
103 : static void
104 27168 : bbstreamer_plain_writer_content(bbstreamer *streamer,
105 : bbstreamer_member *member, const char *data,
106 : int len, bbstreamer_archive_context context)
107 : {
108 : bbstreamer_plain_writer *mystreamer;
109 :
110 27168 : mystreamer = (bbstreamer_plain_writer *) streamer;
111 :
112 27168 : if (len == 0)
113 0 : return;
114 :
115 27168 : errno = 0;
116 27168 : if (fwrite(data, len, 1, mystreamer->file) != 1)
117 : {
118 : /* if write didn't set errno, assume problem is no disk space */
119 0 : if (errno == 0)
120 0 : errno = ENOSPC;
121 0 : pg_fatal("could not write to file \"%s\": %m",
122 : mystreamer->pathname);
123 : }
124 : }
125 :
126 : /*
127 : * End-of-archive processing when writing to a plain file consists of closing
128 : * the file if we opened it, but not if the caller provided it.
129 : */
130 : static void
131 20 : bbstreamer_plain_writer_finalize(bbstreamer *streamer)
132 : {
133 : bbstreamer_plain_writer *mystreamer;
134 :
135 20 : mystreamer = (bbstreamer_plain_writer *) streamer;
136 :
137 20 : if (mystreamer->should_close_file && fclose(mystreamer->file) != 0)
138 0 : pg_fatal("could not close file \"%s\": %m",
139 : mystreamer->pathname);
140 :
141 20 : mystreamer->file = NULL;
142 20 : mystreamer->should_close_file = false;
143 20 : }
144 :
145 : /*
146 : * Free memory associated with this bbstreamer.
147 : */
148 : static void
149 20 : bbstreamer_plain_writer_free(bbstreamer *streamer)
150 : {
151 : bbstreamer_plain_writer *mystreamer;
152 :
153 20 : mystreamer = (bbstreamer_plain_writer *) streamer;
154 :
155 : Assert(!mystreamer->should_close_file);
156 : Assert(mystreamer->base.bbs_next == NULL);
157 :
158 20 : pfree(mystreamer->pathname);
159 20 : pfree(mystreamer);
160 20 : }
161 :
162 : /*
163 : * Create a bbstreamer that extracts an archive.
164 : *
165 : * All pathnames in the archive are interpreted relative to basepath.
166 : *
167 : * Unlike e.g. bbstreamer_plain_writer_new() we can't do anything useful here
168 : * with untyped chunks; we need typed chunks which follow the rules described
169 : * in bbstreamer.h. Assuming we have that, we don't need to worry about the
170 : * original archive format; it's enough to just look at the member information
171 : * provided and write to the corresponding file.
172 : *
173 : * 'link_map' is a function that will be applied to the target of any
174 : * symbolic link, and which should return a replacement pathname to be used
175 : * in its place. If NULL, the symbolic link target is used without
176 : * modification.
177 : *
178 : * 'report_output_file' is a function that will be called each time we open a
179 : * new output file. The pathname to that file is passed as an argument. If
180 : * NULL, the call is skipped.
181 : */
182 : bbstreamer *
183 298 : bbstreamer_extractor_new(const char *basepath,
184 : const char *(*link_map) (const char *),
185 : void (*report_output_file) (const char *))
186 : {
187 : bbstreamer_extractor *streamer;
188 :
189 298 : streamer = palloc0(sizeof(bbstreamer_extractor));
190 298 : *((const bbstreamer_ops **) &streamer->base.bbs_ops) =
191 : &bbstreamer_extractor_ops;
192 298 : streamer->basepath = pstrdup(basepath);
193 298 : streamer->link_map = link_map;
194 298 : streamer->report_output_file = report_output_file;
195 :
196 298 : return &streamer->base;
197 : }
198 :
199 : /*
200 : * Extract archive contents to the filesystem.
201 : */
202 : static void
203 928578 : bbstreamer_extractor_content(bbstreamer *streamer, bbstreamer_member *member,
204 : const char *data, int len,
205 : bbstreamer_archive_context context)
206 : {
207 928578 : bbstreamer_extractor *mystreamer = (bbstreamer_extractor *) streamer;
208 : int fnamelen;
209 :
210 : Assert(member != NULL || context == BBSTREAMER_ARCHIVE_TRAILER);
211 : Assert(context != BBSTREAMER_UNKNOWN);
212 :
213 928578 : switch (context)
214 : {
215 245232 : case BBSTREAMER_MEMBER_HEADER:
216 : Assert(mystreamer->file == NULL);
217 :
218 : /* Prepend basepath. */
219 245232 : snprintf(mystreamer->filename, sizeof(mystreamer->filename),
220 245232 : "%s/%s", mystreamer->basepath, member->pathname);
221 :
222 : /* Remove any trailing slash. */
223 245232 : fnamelen = strlen(mystreamer->filename);
224 245232 : if (mystreamer->filename[fnamelen - 1] == '/')
225 6422 : mystreamer->filename[fnamelen - 1] = '\0';
226 :
227 : /* Dispatch based on file type. */
228 245232 : if (member->is_directory)
229 6394 : extract_directory(mystreamer->filename, member->mode);
230 238838 : else if (member->is_link)
231 : {
232 28 : const char *linktarget = member->linktarget;
233 :
234 28 : if (mystreamer->link_map)
235 28 : linktarget = mystreamer->link_map(linktarget);
236 28 : extract_link(mystreamer->filename, linktarget);
237 : }
238 : else
239 238810 : mystreamer->file =
240 238810 : create_file_for_extract(mystreamer->filename,
241 : member->mode);
242 :
243 : /* Report output file change. */
244 245232 : if (mystreamer->report_output_file)
245 245232 : mystreamer->report_output_file(mystreamer->filename);
246 245232 : break;
247 :
248 437828 : case BBSTREAMER_MEMBER_CONTENTS:
249 437828 : if (mystreamer->file == NULL)
250 0 : break;
251 :
252 437828 : errno = 0;
253 437828 : if (len > 0 && fwrite(data, len, 1, mystreamer->file) != 1)
254 : {
255 : /* if write didn't set errno, assume problem is no disk space */
256 0 : if (errno == 0)
257 0 : errno = ENOSPC;
258 0 : pg_fatal("could not write to file \"%s\": %m",
259 : mystreamer->filename);
260 : }
261 437828 : break;
262 :
263 245226 : case BBSTREAMER_MEMBER_TRAILER:
264 245226 : if (mystreamer->file == NULL)
265 6422 : break;
266 238804 : fclose(mystreamer->file);
267 238804 : mystreamer->file = NULL;
268 238804 : break;
269 :
270 292 : case BBSTREAMER_ARCHIVE_TRAILER:
271 292 : break;
272 :
273 0 : default:
274 : /* Shouldn't happen. */
275 0 : pg_fatal("unexpected state while extracting archive");
276 : }
277 928578 : }
278 :
279 : /*
280 : * Should we tolerate an already-existing directory?
281 : *
282 : * When streaming WAL, pg_wal (or pg_xlog for pre-9.6 clusters) will have been
283 : * created by the wal receiver process. Also, when the WAL directory location
284 : * was specified, pg_wal (or pg_xlog) has already been created as a symbolic
285 : * link before starting the actual backup. So just ignore creation failures
286 : * on related directories.
287 : *
288 : * If in-place tablespaces are used, pg_tblspc and subdirectories may already
289 : * exist when we get here. So tolerate that case, too.
290 : */
291 : static bool
292 716 : should_allow_existing_directory(const char *pathname)
293 : {
294 716 : const char *filename = last_dir_separator(pathname) + 1;
295 :
296 716 : if (strcmp(filename, "pg_wal") == 0 ||
297 492 : strcmp(filename, "pg_xlog") == 0 ||
298 492 : strcmp(filename, "archive_status") == 0 ||
299 268 : strcmp(filename, "summaries") == 0 ||
300 44 : strcmp(filename, "pg_tblspc") == 0)
301 688 : return true;
302 :
303 28 : if (strspn(filename, "0123456789") == strlen(filename))
304 : {
305 28 : const char *pg_tblspc = strstr(pathname, "/pg_tblspc/");
306 :
307 28 : return pg_tblspc != NULL && pg_tblspc + 11 == filename;
308 : }
309 :
310 0 : return false;
311 : }
312 :
313 : /*
314 : * Create a directory.
315 : */
316 : static void
317 6394 : extract_directory(const char *filename, mode_t mode)
318 : {
319 6394 : if (mkdir(filename, pg_dir_create_mode) != 0 &&
320 716 : (errno != EEXIST || !should_allow_existing_directory(filename)))
321 0 : pg_fatal("could not create directory \"%s\": %m",
322 : filename);
323 :
324 : #ifndef WIN32
325 6394 : if (chmod(filename, mode))
326 0 : pg_fatal("could not set permissions on directory \"%s\": %m",
327 : filename);
328 : #endif
329 6394 : }
330 :
331 : /*
332 : * Create a symbolic link.
333 : *
334 : * It's most likely a link in pg_tblspc directory, to the location of a
335 : * tablespace. Apply any tablespace mapping given on the command line
336 : * (--tablespace-mapping). (We blindly apply the mapping without checking that
337 : * the link really is inside pg_tblspc. We don't expect there to be other
338 : * symlinks in a data directory, but if there are, you can call it an
339 : * undocumented feature that you can map them too.)
340 : */
341 : static void
342 28 : extract_link(const char *filename, const char *linktarget)
343 : {
344 28 : if (symlink(linktarget, filename) != 0)
345 0 : pg_fatal("could not create symbolic link from \"%s\" to \"%s\": %m",
346 : filename, linktarget);
347 28 : }
348 :
349 : /*
350 : * Create a regular file.
351 : *
352 : * Return the resulting handle so we can write the content to the file.
353 : */
354 : static FILE *
355 238810 : create_file_for_extract(const char *filename, mode_t mode)
356 : {
357 : FILE *file;
358 :
359 238810 : file = fopen(filename, "wb");
360 238810 : if (file == NULL)
361 0 : pg_fatal("could not create file \"%s\": %m", filename);
362 :
363 : #ifndef WIN32
364 238810 : if (chmod(filename, mode))
365 0 : pg_fatal("could not set permissions on file \"%s\": %m",
366 : filename);
367 : #endif
368 :
369 238810 : return file;
370 : }
371 :
372 : /*
373 : * End-of-stream processing for extracting an archive.
374 : *
375 : * There's nothing to do here but sanity checking.
376 : */
377 : static void
378 292 : bbstreamer_extractor_finalize(bbstreamer *streamer)
379 : {
380 292 : bbstreamer_extractor *mystreamer PG_USED_FOR_ASSERTS_ONLY
381 : = (bbstreamer_extractor *) streamer;
382 :
383 : Assert(mystreamer->file == NULL);
384 292 : }
385 :
386 : /*
387 : * Free memory.
388 : */
389 : static void
390 292 : bbstreamer_extractor_free(bbstreamer *streamer)
391 : {
392 292 : bbstreamer_extractor *mystreamer = (bbstreamer_extractor *) streamer;
393 :
394 292 : pfree(mystreamer->basepath);
395 292 : pfree(mystreamer);
396 292 : }
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