/*++ /* NAME /* mkmap_db 3 /* SUMMARY /* create or open database, DB style /* SYNOPSIS /* #include <mkmap.h> /* /* MKMAP *mkmap_hash_open(path) /* const char *path; /* /* MKMAP *mkmap_btree_open(path) /* const char *path; /* DESCRIPTION /* This module implements support for creating DB databases. /* /* mkmap_hash_open() and mkmap_btree_open() take a file name, /* append the ".db" suffix, and do whatever initialization is /* required before the Berkeley DB open routine is called. /* /* All errors are fatal. /* SEE ALSO /* dict_db(3), DB dictionary interface. /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include <sys_defs.h> #include <sys/stat.h> #include <unistd.h> #include <errno.h> /* Utility library. */ #include <msg.h> #include <mymalloc.h> #include <stringops.h> #include <dict.h> #include <dict_db.h> #include <myflock.h> #include <warn_stat.h> /* Global library. */ #include <mail_params.h> /* Application-specific. */ #include "mkmap.h" #ifdef HAS_DB #ifdef PATH_DB_H #include PATH_DB_H #else #include <db.h> #endif typedef struct MKMAP_DB { MKMAP mkmap; /* parent class */ char *lock_file; /* path name */ int lock_fd; /* -1 or open locked file */ } MKMAP_DB; /* mkmap_db_after_close - clean up after closing database */ static void mkmap_db_after_close(MKMAP *mp) { MKMAP_DB *mkmap = (MKMAP_DB *) mp; if (mkmap->lock_fd >= 0 && close(mkmap->lock_fd) < 0) msg_warn("close %s: %m", mkmap->lock_file); myfree(mkmap->lock_file); } /* mkmap_db_after_open - lock newly created database */ static void mkmap_db_after_open(MKMAP *mp) { MKMAP_DB *mkmap = (MKMAP_DB *) mp; if (mkmap->lock_fd < 0) { if ((mkmap->lock_fd = open(mkmap->lock_file, O_RDWR, 0644)) < 0) msg_fatal("open lockfile %s: %m", mkmap->lock_file); if (myflock(mkmap->lock_fd, INTERNAL_LOCK, MYFLOCK_OP_EXCLUSIVE) < 0) msg_fatal("lock %s: %m", mkmap->lock_file); } } /* mkmap_db_before_open - lock existing database */ static MKMAP *mkmap_db_before_open(const char *path, DICT *(*db_open) (const char *, int, int)) { MKMAP_DB *mkmap = (MKMAP_DB *) mymalloc(sizeof(*mkmap)); struct stat st; /* * Override the default per-table cache size for map (re)builds. * * db_cache_size" is defined in util/dict_db.c and defaults to 128kB, which * works well for the lookup code. * * We use a larger per-table cache when building ".db" files. For "hash" * files performance degrades rapidly unless the memory pool is O(file * size). * * For "btree" files peformance is good with sorted input even for small * memory pools, but with random input degrades rapidly unless the memory * pool is O(file size). * * XXX This should be specified via the DICT interface so that the buffer * size becomes an object property, instead of being specified by poking * a global variable so that it becomes a class property. */ dict_db_cache_size = var_db_create_buf; /* * Fill in the generic members. */ mkmap->lock_file = concatenate(path, ".db", (char *) 0); mkmap->mkmap.open = db_open; mkmap->mkmap.after_open = mkmap_db_after_open; mkmap->mkmap.after_close = mkmap_db_after_close; /* * Unfortunately, not all systems that might support db databases do * support locking on open(), so we open the file before updating it. * * XXX Berkeley DB 4.1 refuses to open a zero-length file. This means we can * open and lock only an existing file, and that we must not truncate it. */ if ((mkmap->lock_fd = open(mkmap->lock_file, O_RDWR, 0644)) < 0) { if (errno != ENOENT) msg_fatal("open %s: %m", mkmap->lock_file); } /* * Get an exclusive lock - we're going to change the database so we can't * have any spectators. * * XXX Horror. Berkeley DB 4.1 refuses to open a zero-length file. This * means that we must examine the size while the file is locked, and that * we must unlink a zero-length file while it is locked. Avoid a race * condition where two processes try to open the same zero-length file * and where the second process ends up deleting the wrong file. */ else { if (myflock(mkmap->lock_fd, INTERNAL_LOCK, MYFLOCK_OP_EXCLUSIVE) < 0) msg_fatal("lock %s: %m", mkmap->lock_file); if (fstat(mkmap->lock_fd, &st) < 0) msg_fatal("fstat %s: %m", mkmap->lock_file); if (st.st_size == 0) { if (st.st_nlink > 0) { if (unlink(mkmap->lock_file) < 0) msg_fatal("cannot remove zero-length database file %s: %m", mkmap->lock_file); msg_warn("removing zero-length database file: %s", mkmap->lock_file); } close(mkmap->lock_fd); mkmap->lock_fd = -1; } } return (&mkmap->mkmap); } /* mkmap_hash_open - create or open hashed DB file */ MKMAP *mkmap_hash_open(const char *path) { return (mkmap_db_before_open(path, dict_hash_open)); } /* mkmap_btree_open - create or open btree DB file */ MKMAP *mkmap_btree_open(const char *path) { return (mkmap_db_before_open(path, dict_btree_open)); } #endif