/* alock.c - access lock library */ /* $OpenLDAP$ */ /* This work is part of OpenLDAP Software . * * Copyright 2005-2015 The OpenLDAP Foundation. * Portions Copyright 2004-2005 Symas Corporation. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted only as authorized by the OpenLDAP * Public License. * * A copy of this license is available in the file LICENSE in the * top-level directory of the distribution or, alternatively, at * . */ /* ACKNOWLEDGEMENTS: * This work was initially developed by Emily Backes at Symas * Corporation for inclusion in OpenLDAP Software. */ #include "portable.h" #if SLAPD_BDB || SLAPD_HDB #include #include "alock.h" #include "lutil.h" #include #include #include #include #include #include #include #ifdef HAVE_SYS_FILE_H #include #endif #include #ifdef _WIN32 #include #include #include #endif static int alock_grab_lock ( int fd, int slot ) { int res; #if defined( HAVE_LOCKF ) res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET); if (res == -1) return -1; res = lockf (fd, F_LOCK, (off_t) ALOCK_SLOT_SIZE); #elif defined( HAVE_FCNTL ) struct flock lock_info; (void) memset ((void *) &lock_info, 0, sizeof (struct flock)); lock_info.l_type = F_WRLCK; lock_info.l_whence = SEEK_SET; lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot); lock_info.l_len = (off_t) ALOCK_SLOT_SIZE; res = fcntl (fd, F_SETLKW, &lock_info); #elif defined( _WIN32 ) OVERLAPPED ov; HANDLE hh = _get_osfhandle ( fd ); ov.hEvent = 0; ov.Offset = ALOCK_SLOT_SIZE*slot; ov.OffsetHigh = 0; res = LockFileEx( hh, LOCKFILE_EXCLUSIVE_LOCK, 0, ALOCK_SLOT_SIZE, 0, &ov ) ? 0 : -1; #else # error alock needs lockf, fcntl, or LockFile[Ex] #endif if (res == -1) { assert (errno != EDEADLK); return -1; } return 0; } static int alock_release_lock ( int fd, int slot ) { int res; #if defined( HAVE_LOCKF ) res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET); if (res == -1) return -1; res = lockf (fd, F_ULOCK, (off_t) ALOCK_SLOT_SIZE); if (res == -1) return -1; #elif defined ( HAVE_FCNTL ) struct flock lock_info; (void) memset ((void *) &lock_info, 0, sizeof (struct flock)); lock_info.l_type = F_UNLCK; lock_info.l_whence = SEEK_SET; lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot); lock_info.l_len = (off_t) ALOCK_SLOT_SIZE; res = fcntl (fd, F_SETLKW, &lock_info); if (res == -1) return -1; #elif defined( _WIN32 ) HANDLE hh = _get_osfhandle ( fd ); if ( !UnlockFile ( hh, ALOCK_SLOT_SIZE*slot, 0, ALOCK_SLOT_SIZE, 0 )) return -1; #else # error alock needs lockf, fcntl, or LockFile[Ex] #endif return 0; } static int alock_share_lock ( int fd, int slot ) { int res; #if defined( HAVE_LOCKF ) res = 0; /* lockf has no shared locks */ #elif defined ( HAVE_FCNTL ) struct flock lock_info; (void) memset ((void *) &lock_info, 0, sizeof (struct flock)); /* The shared lock replaces the existing lock */ lock_info.l_type = F_RDLCK; lock_info.l_whence = SEEK_SET; lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot); lock_info.l_len = (off_t) ALOCK_SLOT_SIZE; res = fcntl (fd, F_SETLK, &lock_info); if (res == -1) return -1; #elif defined( _WIN32 ) OVERLAPPED ov; HANDLE hh = _get_osfhandle ( fd ); /* Windows locks are mandatory, not advisory. * We must downgrade the lock to allow future * callers to read the slot data. * * First acquire a shared lock. Unlock will * release the existing exclusive lock. */ ov.hEvent = 0; ov.Offset = ALOCK_SLOT_SIZE*slot; ov.OffsetHigh = 0; LockFileEx (hh, 0, 0, ALOCK_SLOT_SIZE, 0, &ov); UnlockFile (hh, ALOCK_SLOT_SIZE*slot, 0, ALOCK_SLOT_SIZE, 0); #else # error alock needs lockf, fcntl, or LockFile[Ex] #endif return 0; } static int alock_test_lock ( int fd, int slot ) { int res; #if defined( HAVE_LOCKF ) res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET); if (res == -1) return -1; res = lockf (fd, F_TEST, (off_t) ALOCK_SLOT_SIZE); if (res == -1) { if (errno == EACCES || errno == EAGAIN) { return ALOCK_LOCKED; } else { return -1; } } #elif defined( HAVE_FCNTL ) struct flock lock_info; (void) memset ((void *) &lock_info, 0, sizeof (struct flock)); lock_info.l_type = F_WRLCK; lock_info.l_whence = SEEK_SET; lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot); lock_info.l_len = (off_t) ALOCK_SLOT_SIZE; res = fcntl (fd, F_GETLK, &lock_info); if (res == -1) return -1; if (lock_info.l_type != F_UNLCK) return ALOCK_LOCKED; #elif defined( _WIN32 ) OVERLAPPED ov; HANDLE hh = _get_osfhandle ( fd ); ov.hEvent = 0; ov.Offset = ALOCK_SLOT_SIZE*slot; ov.OffsetHigh = 0; if( !LockFileEx( hh, LOCKFILE_EXCLUSIVE_LOCK|LOCKFILE_FAIL_IMMEDIATELY, 0, ALOCK_SLOT_SIZE, 0, &ov )) { int err = GetLastError(); if ( err == ERROR_LOCK_VIOLATION ) return ALOCK_LOCKED; else return -1; } #else # error alock needs lockf, fcntl, or LockFile #endif return 0; } /* Read a 64bit LE value */ static unsigned long int alock_read_iattr ( unsigned char * bufptr ) { unsigned long int val = 0; int count; assert (bufptr != NULL); bufptr += sizeof (unsigned long int); for (count=0; count <= (int) sizeof (unsigned long int); ++count) { val <<= 8; val += (unsigned long int) *bufptr--; } return val; } /* Write a 64bit LE value */ static void alock_write_iattr ( unsigned char * bufptr, unsigned long int val ) { int count; assert (bufptr != NULL); for (count=0; count < 8; ++count) { *bufptr++ = (unsigned char) (val & 0xff); val >>= 8; } } static int alock_read_slot ( alock_info_t * info, alock_slot_t * slot_data ) { unsigned char slotbuf [ALOCK_SLOT_SIZE]; int res, size, size_total, err; assert (info != NULL); assert (slot_data != NULL); assert (info->al_slot > 0); res = lseek (info->al_fd, (off_t) (ALOCK_SLOT_SIZE * info->al_slot), SEEK_SET); if (res == -1) return -1; size_total = 0; while (size_total < ALOCK_SLOT_SIZE) { size = read (info->al_fd, slotbuf + size_total, ALOCK_SLOT_SIZE - size_total); if (size == 0) return -1; if (size < 0) { err = errno; if (err != EINTR && err != EAGAIN) return -1; } else { size_total += size; } } if (alock_read_iattr (slotbuf) != ALOCK_MAGIC) { return -1; } slot_data->al_lock = alock_read_iattr (slotbuf+8); slot_data->al_stamp = alock_read_iattr (slotbuf+16); slot_data->al_pid = alock_read_iattr (slotbuf+24); if (slot_data->al_appname) ber_memfree (slot_data->al_appname); slot_data->al_appname = ber_memcalloc (1, ALOCK_MAX_APPNAME); if (slot_data->al_appname == NULL) { return -1; } strncpy (slot_data->al_appname, (char *)slotbuf+32, ALOCK_MAX_APPNAME-1); (slot_data->al_appname) [ALOCK_MAX_APPNAME-1] = '\0'; return 0; } static int alock_write_slot ( alock_info_t * info, alock_slot_t * slot_data ) { unsigned char slotbuf [ALOCK_SLOT_SIZE]; int res, size, size_total, err; assert (info != NULL); assert (slot_data != NULL); assert (info->al_slot > 0); (void) memset ((void *) slotbuf, 0, ALOCK_SLOT_SIZE); alock_write_iattr (slotbuf, ALOCK_MAGIC); assert (alock_read_iattr (slotbuf) == ALOCK_MAGIC); alock_write_iattr (slotbuf+8, slot_data->al_lock); alock_write_iattr (slotbuf+16, slot_data->al_stamp); alock_write_iattr (slotbuf+24, slot_data->al_pid); if (slot_data->al_appname) strncpy ((char *)slotbuf+32, slot_data->al_appname, ALOCK_MAX_APPNAME-1); slotbuf[ALOCK_SLOT_SIZE-1] = '\0'; res = lseek (info->al_fd, (off_t) (ALOCK_SLOT_SIZE * info->al_slot), SEEK_SET); if (res == -1) return -1; size_total = 0; while (size_total < ALOCK_SLOT_SIZE) { size = write (info->al_fd, slotbuf + size_total, ALOCK_SLOT_SIZE - size_total); if (size == 0) return -1; if (size < 0) { err = errno; if (err != EINTR && err != EAGAIN) return -1; } else { size_total += size; } } return 0; } static int alock_query_slot ( alock_info_t * info ) { int res, nosave; alock_slot_t slot_data; assert (info != NULL); assert (info->al_slot > 0); (void) memset ((void *) &slot_data, 0, sizeof (alock_slot_t)); alock_read_slot (info, &slot_data); if (slot_data.al_appname != NULL) ber_memfree (slot_data.al_appname); slot_data.al_appname = NULL; nosave = slot_data.al_lock & ALOCK_NOSAVE; if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNLOCKED) return slot_data.al_lock; res = alock_test_lock (info->al_fd, info->al_slot); if (res < 0) return -1; if (res > 0) { if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNIQUE) { return slot_data.al_lock; } else { return ALOCK_LOCKED | nosave; } } return ALOCK_DIRTY | nosave; } int alock_open ( alock_info_t * info, const char * appname, const char * envdir, int locktype ) { struct stat statbuf; alock_info_t scan_info; alock_slot_t slot_data; char * filename; int res, max_slot; int dirty_count, live_count, nosave; char *ptr; assert (info != NULL); assert (appname != NULL); assert (envdir != NULL); assert ((locktype & ALOCK_SMASK) >= 1 && (locktype & ALOCK_SMASK) <= 2); slot_data.al_lock = locktype; slot_data.al_stamp = time(NULL); slot_data.al_pid = getpid(); slot_data.al_appname = ber_memcalloc (1, ALOCK_MAX_APPNAME); if (slot_data.al_appname == NULL) { return ALOCK_UNSTABLE; } strncpy (slot_data.al_appname, appname, ALOCK_MAX_APPNAME-1); slot_data.al_appname [ALOCK_MAX_APPNAME-1] = '\0'; filename = ber_memcalloc (1, strlen (envdir) + strlen ("/alock") + 1); if (filename == NULL ) { ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } ptr = lutil_strcopy(filename, envdir); lutil_strcopy(ptr, "/alock"); #ifdef _WIN32 { HANDLE handle = CreateFile (filename, GENERIC_READ|GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); info->al_fd = _open_osfhandle (handle, 0); } #else info->al_fd = open (filename, O_CREAT|O_RDWR, 0666); #endif ber_memfree (filename); if (info->al_fd < 0) { ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } info->al_slot = 0; res = alock_grab_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } res = fstat (info->al_fd, &statbuf); if (res == -1) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE; dirty_count = 0; live_count = 0; nosave = 0; scan_info.al_fd = info->al_fd; for (scan_info.al_slot = 1; scan_info.al_slot < max_slot; ++ scan_info.al_slot) { if (scan_info.al_slot != info->al_slot) { res = alock_query_slot (&scan_info); if (res & ALOCK_NOSAVE) { nosave = ALOCK_NOSAVE; res ^= ALOCK_NOSAVE; } if (res == ALOCK_UNLOCKED && info->al_slot == 0) { info->al_slot = scan_info.al_slot; } else if (res == ALOCK_LOCKED) { ++live_count; } else if (res == ALOCK_UNIQUE && (( locktype & ALOCK_SMASK ) == ALOCK_UNIQUE || nosave )) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_BUSY; } else if (res == ALOCK_DIRTY) { ++dirty_count; } else if (res == -1) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } } } if (dirty_count && live_count) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } if (info->al_slot == 0) info->al_slot = max_slot + 1; res = alock_grab_lock (info->al_fd, info->al_slot); if (res == -1) { close (info->al_fd); ber_memfree (slot_data.al_appname); return ALOCK_UNSTABLE; } res = alock_write_slot (info, &slot_data); ber_memfree (slot_data.al_appname); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } alock_share_lock (info->al_fd, info->al_slot); res = alock_release_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } if (dirty_count) return ALOCK_RECOVER | nosave; return ALOCK_CLEAN | nosave; } int alock_scan ( alock_info_t * info ) { struct stat statbuf; alock_info_t scan_info; int res, max_slot; int dirty_count, live_count, nosave; assert (info != NULL); scan_info.al_fd = info->al_fd; res = alock_grab_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } res = fstat (info->al_fd, &statbuf); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE; dirty_count = 0; live_count = 0; nosave = 0; for (scan_info.al_slot = 1; scan_info.al_slot < max_slot; ++ scan_info.al_slot) { if (scan_info.al_slot != info->al_slot) { res = alock_query_slot (&scan_info); if (res & ALOCK_NOSAVE) { nosave = ALOCK_NOSAVE; res ^= ALOCK_NOSAVE; } if (res == ALOCK_LOCKED) { ++live_count; } else if (res == ALOCK_DIRTY) { ++dirty_count; } else if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } } } res = alock_release_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } if (dirty_count) { if (live_count) { close (info->al_fd); return ALOCK_UNSTABLE; } else { return ALOCK_RECOVER | nosave; } } return ALOCK_CLEAN | nosave; } int alock_close ( alock_info_t * info, int nosave ) { alock_slot_t slot_data; int res; if ( !info->al_slot ) return ALOCK_CLEAN; (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t)); res = alock_grab_lock (info->al_fd, 0); if (res == -1) { fail: /* Windows doesn't clean up locks immediately when a process exits. * Make sure we release our locks, to prevent stale locks from * hanging around. */ alock_release_lock (info->al_fd, 0); close (info->al_fd); return ALOCK_UNSTABLE; } /* mark our slot as clean */ res = alock_read_slot (info, &slot_data); if (res == -1) { if (slot_data.al_appname != NULL) ber_memfree (slot_data.al_appname); goto fail; } slot_data.al_lock = ALOCK_UNLOCKED; if ( nosave ) slot_data.al_lock |= ALOCK_NOSAVE; /* since we have slot 0 locked, we don't need our slot lock */ res = alock_release_lock (info->al_fd, info->al_slot); if (res == -1) { goto fail; } res = alock_write_slot (info, &slot_data); if (res == -1) { if (slot_data.al_appname != NULL) ber_memfree (slot_data.al_appname); goto fail; } if (slot_data.al_appname != NULL) { ber_memfree (slot_data.al_appname); slot_data.al_appname = NULL; } res = alock_release_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } res = close (info->al_fd); if (res == -1) return ALOCK_UNSTABLE; return ALOCK_CLEAN; } int alock_recover ( alock_info_t * info ) { struct stat statbuf; alock_slot_t slot_data; alock_info_t scan_info; int res, max_slot; assert (info != NULL); scan_info.al_fd = info->al_fd; (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t)); res = alock_grab_lock (info->al_fd, 0); if (res == -1) { goto fail; } res = fstat (info->al_fd, &statbuf); if (res == -1) { goto fail; } max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE; for (scan_info.al_slot = 1; scan_info.al_slot < max_slot; ++ scan_info.al_slot) { if (scan_info.al_slot != info->al_slot) { res = alock_query_slot (&scan_info) & ~ALOCK_NOSAVE; if (res == ALOCK_LOCKED || res == ALOCK_UNIQUE) { /* recovery attempt on an active db? */ goto fail; } else if (res == ALOCK_DIRTY) { /* mark it clean */ res = alock_read_slot (&scan_info, &slot_data); if (res == -1) { goto fail; } slot_data.al_lock = ALOCK_UNLOCKED; res = alock_write_slot (&scan_info, &slot_data); if (res == -1) { if (slot_data.al_appname != NULL) ber_memfree (slot_data.al_appname); goto fail; } if (slot_data.al_appname != NULL) { ber_memfree (slot_data.al_appname); slot_data.al_appname = NULL; } } else if (res == -1) { goto fail; } } } res = alock_release_lock (info->al_fd, 0); if (res == -1) { close (info->al_fd); return ALOCK_UNSTABLE; } return ALOCK_CLEAN; fail: alock_release_lock (info->al_fd, 0); close (info->al_fd); return ALOCK_UNSTABLE; } #endif /* SLAPD_BDB || SLAPD_HDB */