Line data Source code
1 : /*-------------------------------------------------------------------------
2 : * relpath.c
3 : * Shared frontend/backend code to compute pathnames of relation files
4 : *
5 : * This module also contains some logic associated with fork names.
6 : *
7 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : * IDENTIFICATION
11 : * src/common/relpath.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #ifndef FRONTEND
16 : #include "postgres.h"
17 : #else
18 : #include "postgres_fe.h"
19 : #endif
20 :
21 : #include "catalog/pg_tablespace_d.h"
22 : #include "common/relpath.h"
23 : #include "storage/procnumber.h"
24 :
25 :
26 : /*
27 : * Lookup table of fork name by fork number.
28 : *
29 : * If you add a new entry, remember to update the errhint in
30 : * forkname_to_number() below, and update the SGML documentation for
31 : * pg_relation_size().
32 : */
33 : const char *const forkNames[] = {
34 : [MAIN_FORKNUM] = "main",
35 : [FSM_FORKNUM] = "fsm",
36 : [VISIBILITYMAP_FORKNUM] = "vm",
37 : [INIT_FORKNUM] = "init",
38 : };
39 :
40 : StaticAssertDecl(lengthof(forkNames) == (MAX_FORKNUM + 1),
41 : "array length mismatch");
42 :
43 : /*
44 : * forkname_to_number - look up fork number by name
45 : *
46 : * In backend, we throw an error for no match; in frontend, we just
47 : * return InvalidForkNumber.
48 : */
49 : ForkNumber
50 5766 : forkname_to_number(const char *forkName)
51 : {
52 : ForkNumber forkNum;
53 :
54 5802 : for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
55 5798 : if (strcmp(forkNames[forkNum], forkName) == 0)
56 5762 : return forkNum;
57 :
58 : #ifndef FRONTEND
59 2 : ereport(ERROR,
60 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
61 : errmsg("invalid fork name"),
62 : errhint("Valid fork names are \"main\", \"fsm\", "
63 : "\"vm\", and \"init\".")));
64 : #endif
65 :
66 2 : return InvalidForkNumber;
67 : }
68 :
69 : /*
70 : * forkname_chars
71 : * We use this to figure out whether a filename could be a relation
72 : * fork (as opposed to an oddly named stray file that somehow ended
73 : * up in the database directory). If the passed string begins with
74 : * a fork name (other than the main fork name), we return its length,
75 : * and set *fork (if not NULL) to the fork number. If not, we return 0.
76 : *
77 : * Note that the present coding assumes that there are no fork names which
78 : * are prefixes of other fork names.
79 : */
80 : int
81 396358 : forkname_chars(const char *str, ForkNumber *fork)
82 : {
83 : ForkNumber forkNum;
84 :
85 594392 : for (forkNum = 1; forkNum <= MAX_FORKNUM; forkNum++)
86 : {
87 594392 : int len = strlen(forkNames[forkNum]);
88 :
89 594392 : if (strncmp(forkNames[forkNum], str, len) == 0)
90 : {
91 396358 : if (fork)
92 396318 : *fork = forkNum;
93 396358 : return len;
94 : }
95 : }
96 0 : if (fork)
97 0 : *fork = InvalidForkNumber;
98 0 : return 0;
99 : }
100 :
101 :
102 : /*
103 : * GetDatabasePath - construct path to a database directory
104 : *
105 : * Result is a palloc'd string.
106 : *
107 : * XXX this must agree with GetRelationPath()!
108 : */
109 : char *
110 347820 : GetDatabasePath(Oid dbOid, Oid spcOid)
111 : {
112 347820 : if (spcOid == GLOBALTABLESPACE_OID)
113 : {
114 : /* Shared system relations live in {datadir}/global */
115 : Assert(dbOid == 0);
116 4 : return pstrdup("global");
117 : }
118 347816 : else if (spcOid == DEFAULTTABLESPACE_OID)
119 : {
120 : /* The default tablespace is {datadir}/base */
121 344986 : return psprintf("base/%u", dbOid);
122 : }
123 : else
124 : {
125 : /* All other tablespaces are accessed via symlinks */
126 2830 : return psprintf("%s/%u/%s/%u",
127 : PG_TBLSPC_DIR, spcOid,
128 : TABLESPACE_VERSION_DIRECTORY, dbOid);
129 : }
130 : }
131 :
132 : /*
133 : * GetRelationPath - construct path to a relation's file
134 : *
135 : * The result is returned in-place as a struct, to make it suitable for use in
136 : * critical sections etc.
137 : *
138 : * Note: ideally, procNumber would be declared as type ProcNumber, but
139 : * relpath.h would have to include a backend-only header to do that; doesn't
140 : * seem worth the trouble considering ProcNumber is just int anyway.
141 : */
142 : RelPathStr
143 3581122 : GetRelationPath(Oid dbOid, Oid spcOid, RelFileNumber relNumber,
144 : int procNumber, ForkNumber forkNumber)
145 : {
146 : RelPathStr rp;
147 :
148 3581122 : if (spcOid == GLOBALTABLESPACE_OID)
149 : {
150 : /* Shared system relations live in {datadir}/global */
151 : Assert(dbOid == 0);
152 : Assert(procNumber == INVALID_PROC_NUMBER);
153 176186 : if (forkNumber != MAIN_FORKNUM)
154 46256 : sprintf(rp.str, "global/%u_%s",
155 : relNumber, forkNames[forkNumber]);
156 : else
157 129930 : sprintf(rp.str, "global/%u",
158 : relNumber);
159 : }
160 3404936 : else if (spcOid == DEFAULTTABLESPACE_OID)
161 : {
162 : /* The default tablespace is {datadir}/base */
163 3394634 : if (procNumber == INVALID_PROC_NUMBER)
164 : {
165 3336576 : if (forkNumber != MAIN_FORKNUM)
166 : {
167 1348334 : sprintf(rp.str, "base/%u/%u_%s",
168 : dbOid, relNumber,
169 : forkNames[forkNumber]);
170 : }
171 : else
172 1988242 : sprintf(rp.str, "base/%u/%u",
173 : dbOid, relNumber);
174 : }
175 : else
176 : {
177 58058 : if (forkNumber != MAIN_FORKNUM)
178 30238 : sprintf(rp.str, "base/%u/t%d_%u_%s",
179 : dbOid, procNumber, relNumber,
180 : forkNames[forkNumber]);
181 : else
182 27820 : sprintf(rp.str, "base/%u/t%d_%u",
183 : dbOid, procNumber, relNumber);
184 : }
185 : }
186 : else
187 : {
188 : /* All other tablespaces are accessed via symlinks */
189 10302 : if (procNumber == INVALID_PROC_NUMBER)
190 : {
191 10182 : if (forkNumber != MAIN_FORKNUM)
192 4480 : sprintf(rp.str, "%s/%u/%s/%u/%u_%s",
193 : PG_TBLSPC_DIR, spcOid,
194 : TABLESPACE_VERSION_DIRECTORY,
195 : dbOid, relNumber,
196 : forkNames[forkNumber]);
197 : else
198 5702 : sprintf(rp.str, "%s/%u/%s/%u/%u",
199 : PG_TBLSPC_DIR, spcOid,
200 : TABLESPACE_VERSION_DIRECTORY,
201 : dbOid, relNumber);
202 : }
203 : else
204 : {
205 120 : if (forkNumber != MAIN_FORKNUM)
206 66 : sprintf(rp.str, "%s/%u/%s/%u/t%d_%u_%s",
207 : PG_TBLSPC_DIR, spcOid,
208 : TABLESPACE_VERSION_DIRECTORY,
209 : dbOid, procNumber, relNumber,
210 : forkNames[forkNumber]);
211 : else
212 54 : sprintf(rp.str, "%s/%u/%s/%u/t%d_%u",
213 : PG_TBLSPC_DIR, spcOid,
214 : TABLESPACE_VERSION_DIRECTORY,
215 : dbOid, procNumber, relNumber);
216 : }
217 : }
218 :
219 : Assert(strnlen(rp.str, REL_PATH_STR_MAXLEN + 1) <= REL_PATH_STR_MAXLEN);
220 :
221 3581122 : return rp;
222 : }
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