diff options
Diffstat (limited to 'src/backend/utils/init/postinit.c')
| -rw-r--r-- | src/backend/utils/init/postinit.c | 88 |
1 files changed, 65 insertions, 23 deletions
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c index 53eb47a97ec..d1479bbab77 100644 --- a/src/backend/utils/init/postinit.c +++ b/src/backend/utils/init/postinit.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.140 2005/02/20 21:46:49 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.141 2005/02/26 18:43:33 tgl Exp $ * * *------------------------------------------------------------------------- @@ -27,14 +27,16 @@ #include "catalog/pg_database.h" #include "catalog/pg_shadow.h" #include "catalog/pg_tablespace.h" +#include "libpq/hba.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "postmaster/postmaster.h" -#include "storage/backendid.h" +#include "storage/fd.h" #include "storage/ipc.h" #include "storage/proc.h" #include "storage/sinval.h" #include "storage/smgr.h" +#include "utils/flatfiles.h" #include "utils/fmgroids.h" #include "utils/guc.h" #include "utils/portal.h" @@ -42,6 +44,7 @@ #include "utils/syscache.h" +static bool FindMyDatabase(const char *name, Oid *db_id, Oid *db_tablespace); static void ReverifyMyDatabase(const char *name); static void InitCommunication(void); static void ShutdownPostgres(int code, Datum arg); @@ -51,18 +54,60 @@ static bool ThereIsAtLeastOneUser(void); /*** InitPostgres support ***/ -/* -------------------------------- - * ReverifyMyDatabase +/* + * FindMyDatabase -- get the critical info needed to locate my database * - * Since we are forced to fetch the database OID out of pg_database without - * benefit of locking or transaction ID checking (see utils/misc/database.c), - * we might have gotten a wrong answer. Or, we might have attached to a - * database that's in process of being destroyed by destroydb(). This - * routine is called after we have all the locking and other infrastructure - * running --- now we can check that we are really attached to a valid - * database. + * Find the named database in pg_database, return its database OID and the + * OID of its default tablespace. Return TRUE if found, FALSE if not. * - * In reality, if destroydb() is running in parallel with our startup, + * Since we are not yet up and running as a backend, we cannot look directly + * at pg_database (we can't obtain locks nor participate in transactions). + * So to get the info we need before starting up, we must look at the "flat + * file" copy of pg_database that is helpfully maintained by flatfiles.c. + * This is subject to various race conditions, so after we have the + * transaction infrastructure started, we have to recheck the information; + * see ReverifyMyDatabase. + */ +static bool +FindMyDatabase(const char *name, Oid *db_id, Oid *db_tablespace) +{ + bool result = false; + char *filename; + FILE *db_file; + char thisname[NAMEDATALEN]; + + filename = database_getflatfilename(); + db_file = AllocateFile(filename, "r"); + if (db_file == NULL) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", filename))); + + while (read_pg_database_line(db_file, thisname, db_id, db_tablespace)) + { + if (strcmp(thisname, name) == 0) + { + result = true; + break; + } + } + + FreeFile(db_file); + pfree(filename); + + return result; +} + +/* + * ReverifyMyDatabase -- recheck info obtained by FindMyDatabase + * + * Since FindMyDatabase cannot lock pg_database, the information it read + * could be stale; for example we might have attached to a database that's in + * process of being destroyed by dropdb(). This routine is called after + * we have all the locking and other infrastructure running --- now we can + * check that we are really attached to a valid database. + * + * In reality, if dropdb() is running in parallel with our startup, * it's pretty likely that we will have failed before now, due to being * unable to read some of the system tables within the doomed database. * This routine just exists to make *sure* we have not started up in an @@ -75,7 +120,6 @@ static bool ThereIsAtLeastOneUser(void); * To avoid having to read pg_database more times than necessary * during session startup, this place is also fitting to set up any * database-specific configuration variables. - * -------------------------------- */ static void ReverifyMyDatabase(const char *name) @@ -87,10 +131,10 @@ ReverifyMyDatabase(const char *name) Form_pg_database dbform; /* - * Because we grab AccessShareLock here, we can be sure that destroydb + * Because we grab RowShareLock here, we can be sure that dropdb() * is not running in parallel with us (any more). */ - pgdbrel = heap_openr(DatabaseRelationName, AccessShareLock); + pgdbrel = heap_openr(DatabaseRelationName, RowShareLock); ScanKeyInit(&key, Anum_pg_database_datname, @@ -104,7 +148,7 @@ ReverifyMyDatabase(const char *name) HeapTupleGetOid(tup) != MyDatabaseId) { /* OOPS */ - heap_close(pgdbrel, AccessShareLock); + heap_close(pgdbrel, RowShareLock); /* * The only real problem I could have created is to load dirty @@ -131,7 +175,7 @@ ReverifyMyDatabase(const char *name) name))); /* - * OK, we're golden. Only other to-do item is to save the encoding + * OK, we're golden. Next to-do item is to save the encoding * info out of the pg_database tuple. */ SetDatabaseEncoding(dbform->encoding); @@ -143,7 +187,7 @@ ReverifyMyDatabase(const char *name) PGC_BACKEND, PGC_S_DEFAULT); /* - * Set up database-specific configuration variables. + * Lastly, set up any database-specific configuration variables. */ if (IsUnderPostmaster) { @@ -161,7 +205,7 @@ ReverifyMyDatabase(const char *name) } heap_endscan(pgdbscan); - heap_close(pgdbrel, AccessShareLock); + heap_close(pgdbrel, RowShareLock); } @@ -261,11 +305,9 @@ InitPostgres(const char *dbname, const char *username) /* * Find oid and tablespace of the database we're about to open. * Since we're not yet up and running we have to use the hackish - * GetRawDatabaseInfo. + * FindMyDatabase. */ - GetRawDatabaseInfo(dbname, &MyDatabaseId, &MyDatabaseTableSpace); - - if (!OidIsValid(MyDatabaseId)) + if (!FindMyDatabase(dbname, &MyDatabaseId, &MyDatabaseTableSpace)) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", |