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Diffstat (limited to 'winsup/cygwin/flock.cc')
| -rw-r--r-- | winsup/cygwin/flock.cc | 1504 |
1 files changed, 0 insertions, 1504 deletions
diff --git a/winsup/cygwin/flock.cc b/winsup/cygwin/flock.cc deleted file mode 100644 index 24907b674..000000000 --- a/winsup/cygwin/flock.cc +++ /dev/null @@ -1,1504 +0,0 @@ -/* flock.cc. NT specific implementation of advisory file locking. - - Copyright 2003, 2008 Red Hat, Inc. - - This file is part of Cygwin. - - This software is a copyrighted work licensed under the terms of the - Cygwin license. Please consult the file "CYGWIN_LICENSE" for - details. */ - -/* The basic mechanism as well as the datastructures used in the below - implementation are taken from the FreeBSD repository on 2008-03-18. - The essential code of the lf_XXX functions has been taken from the - module src/sys/kern/kern_lockf.c. It has been adapted to use NT - global namespace subdirs and event objects for synchronization - purposes. - - So, the following copyright applies to most of the code in the lf_XXX - functions. - - * Copyright (c) 1982, 1986, 1989, 1993 - * The Regents of the University of California. All rights reserved. - * - * This code is derived from software contributed to Berkeley by - * Scooter Morris at Genentech Inc. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 4. Neither the name of the University nor the names of its contributors - * may be used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - * - * @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94 -*/ - -/* - * The flock() function is based upon source taken from the Red Hat - * implementation used in their imap-2002d SRPM. - * - * $RH: flock.c,v 1.2 2000/08/23 17:07:00 nalin Exp $ - */ - -/* The lockf function is based upon FreeBSD sources with the following - * copyright. - * - * Copyright (c) 1997 The NetBSD Foundation, Inc. - * All rights reserved. - * - * This code is derived from software contributed to The NetBSD Foundation - * by Klaus Klein. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. All advertising materials mentioning features or use of this software - * must display the following acknowledgement: - * This product includes software developed by the NetBSD - * Foundation, Inc. and its contributors. - * 4. Neither the name of The NetBSD Foundation nor the names of its - * contributors may be used to endorse or promote products derived - * from this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS - * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED - * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR - * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS - * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR - * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF - * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS - * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN - * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) - * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE - * POSSIBILITY OF SUCH DAMAGE. - * - * - * $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $ -*/ - -#include "winsup.h" -#include <assert.h> -#include <sys/file.h> -#include <unistd.h> -#include <stdlib.h> -#include "cygerrno.h" -#include "security.h" -#include "shared_info.h" -#include "path.h" -#include "fhandler.h" -#include "dtable.h" -#include "cygheap.h" -#include "pinfo.h" -#include "sigproc.h" -#include "cygtls.h" -#include "tls_pbuf.h" -#include "ntdll.h" -#include <sys/queue.h> -#include <wchar.h> - -#define F_WAIT 0x10 /* Wait until lock is granted */ -#define F_FLOCK 0x20 /* Use flock(2) semantics for lock */ -#define F_POSIX 0x40 /* Use POSIX semantics for lock */ - -#ifndef OFF_MAX -#define OFF_MAX LLONG_MAX -#endif - -static NO_COPY muto lockf_guard; - -#define INODE_LIST_LOCK() (lockf_guard.init ("lockf_guard")->acquire ()) -#define INODE_LIST_UNLOCK() (lockf_guard.release ()) - -#define LOCK_OBJ_NAME_LEN 64 - -#define FLOCK_INODE_DIR_ACCESS (DIRECTORY_QUERY \ - | DIRECTORY_TRAVERSE \ - | DIRECTORY_CREATE_OBJECT \ - | READ_CONTROL) - -#define FLOCK_EVENT_ACCESS (EVENT_QUERY_STATE \ - | SYNCHRONIZE \ - | READ_CONTROL) - -/* This function takes the own process security descriptor DACL and adds - SYNCHRONIZE permissions for everyone. This allows all processes - to wait for this process to die when blocking in a F_SETLKW on a lock - which is hold by this process. */ -static void -allow_others_to_sync () -{ - static NO_COPY bool done; - - if (done) - return; - - NTSTATUS status; - PACL dacl; - LPVOID ace; - ULONG len; - - /* Get this process DACL. We use a temporary path buffer in TLS space - to avoid having to alloc 64K from the stack. */ - tmp_pathbuf tp; - PSECURITY_DESCRIPTOR sd = (PSECURITY_DESCRIPTOR) tp.w_get (); - status = NtQuerySecurityObject (hMainProc, DACL_SECURITY_INFORMATION, sd, - NT_MAX_PATH * sizeof (WCHAR), &len); - if (!NT_SUCCESS (status)) - { - debug_printf ("NtQuerySecurityObject: %p", status); - return; - } - /* Create a valid dacl pointer and set it's size to be as big as - there's room in the temporary buffer. Note that the descriptor - is in self-relative format. */ - dacl = (PACL) ((char *) sd + (uintptr_t) sd->Dacl); - dacl->AclSize = NT_MAX_PATH * sizeof (WCHAR) - ((char *) dacl - (char *) sd); - /* Allow everyone to SYNCHRONIZE with this process. */ - if (!AddAccessAllowedAce (dacl, ACL_REVISION, SYNCHRONIZE, - well_known_world_sid)) - { - debug_printf ("AddAccessAllowedAce: %lu", GetLastError ()); - return; - } - /* Set the size of the DACL correctly. */ - if (!FindFirstFreeAce (dacl, &ace)) - { - debug_printf ("FindFirstFreeAce: %lu", GetLastError ()); - return; - } - dacl->AclSize = (char *) ace - (char *) dacl; - /* Write the DACL back. */ - status = NtSetSecurityObject (hMainProc, DACL_SECURITY_INFORMATION, sd); - if (!NT_SUCCESS (status)) - { - debug_printf ("NtSetSecurityObject: %p", status); - return; - } - done = true; -} - -/* Get the handle count of an object. */ -static ULONG -get_obj_handle_count (HANDLE h) -{ - OBJECT_BASIC_INFORMATION obi; - NTSTATUS status; - ULONG hdl_cnt = 0; - - status = NtQueryObject (h, ObjectBasicInformation, &obi, sizeof obi, NULL); - if (!NT_SUCCESS (status)) - debug_printf ("NtQueryObject: %p\n", status); - else - hdl_cnt = obi.HandleCount; - return hdl_cnt; -} - -/* Per lock class. */ -class lockf_t -{ - public: - short lf_flags; /* Semantics: F_POSIX, F_FLOCK, F_WAIT */ - short lf_type; /* Lock type: F_RDLCK, F_WRLCK */ - _off64_t lf_start; /* Byte # of the start of the lock */ - _off64_t lf_end; /* Byte # of the end of the lock (-1=EOF) */ - long long lf_id; /* Cygwin PID for POSIX locks, a unique id per - file table entry for BSD flock locks. */ - DWORD lf_wid; /* Win PID of the resource holding the lock */ - class lockf_t **lf_head; /* Back pointer to the head of the lockf_t list */ - class inode_t *lf_inode; /* Back pointer to the inode_t */ - class lockf_t *lf_next; /* Pointer to the next lock on this inode_t */ - HANDLE lf_obj; /* Handle to the lock event object. */ - - lockf_t () - : lf_flags (0), lf_type (0), lf_start (0), lf_end (0), lf_id (0), - lf_wid (0), lf_head (NULL), lf_inode (NULL), - lf_next (NULL), lf_obj (NULL) - {} - lockf_t (class inode_t *node, class lockf_t **head, short flags, short type, - _off64_t start, _off64_t end, long long id, DWORD wid) - : lf_flags (flags), lf_type (type), lf_start (start), lf_end (end), - lf_id (id), lf_wid (wid), lf_head (head), lf_inode (node), - lf_next (NULL), lf_obj (NULL) - {} - ~lockf_t (); - - /* Used to create all locks list in a given TLS buffer. */ - void *operator new (size_t size, void *p) - { return p; } - /* Used to store own lock list in the cygheap. */ - void *operator new (size_t size) - { return cmalloc (HEAP_FHANDLER, sizeof (lockf_t)); } - /* Never call on node->i_all_lf! */ - void operator delete (void *p) - { cfree (p); } - - void create_lock_obj (); - bool open_lock_obj (); - void del_lock_obj (HANDLE fhdl, bool signal = false); -}; - -/* Per inode_t class */ -class inode_t -{ - friend class lockf_t; - - public: - LIST_ENTRY (inode_t) i_next; - lockf_t *i_lockf; /* List of locks of this process. */ - lockf_t *i_all_lf; /* Temp list of all locks for this file. */ - - __dev32_t i_dev; /* Device ID */ - __ino64_t i_ino; /* inode number */ - - private: - HANDLE i_dir; - HANDLE i_mtx; - - public: - inode_t (__dev32_t dev, __ino64_t ino); - ~inode_t (); - - void *operator new (size_t size) - { return cmalloc (HEAP_FHANDLER, sizeof (inode_t)); } - void operator delete (void *p) - { cfree (p); } - - static inode_t *get (__dev32_t dev, __ino64_t ino, bool create_if_missing); - - void LOCK () { WaitForSingleObject (i_mtx, INFINITE); } - void UNLOCK () { ReleaseMutex (i_mtx); } - - lockf_t *get_all_locks_list (); - - bool del_my_locks (long long id, HANDLE fhdl); -}; - -inode_t::~inode_t () -{ - lockf_t *lock, *n_lock; - for (lock = i_lockf; lock && (n_lock = lock->lf_next, 1); lock = n_lock) - delete lock; - NtClose (i_mtx); - NtClose (i_dir); -} - -bool -inode_t::del_my_locks (long long id, HANDLE fhdl) -{ - lockf_t *lock, *n_lock; - lockf_t **prev = &i_lockf; - int lc = 0; - for (lock = *prev; lock && (n_lock = lock->lf_next, 1); lock = n_lock) - { - if (lock->lf_flags & F_POSIX) - { - /* Delete all POSIX locks. */ - *prev = n_lock; - ++lc; - delete lock; - } - else if (id && lock->lf_id == id) - { - int cnt = 0; - cygheap_fdenum cfd (true); - while (cfd.next () >= 0) - if (cfd->get_unique_id () == lock->lf_id && ++cnt > 1) - break; - /* Delete BSD flock lock when no other fd in this process references - it anymore. */ - if (cnt <= 1) - { - *prev = n_lock; - lock->del_lock_obj (fhdl); - delete lock; - } - } - else - prev = &lock->lf_next; - } - return i_lockf == NULL; -} - -/* Used to delete the locks on a file hold by this process. Called from - close(2) and fixup_after_fork, as well as from fixup_after_exec in - case the close_on_exec flag is set. The whole inode is deleted as - soon as no lock exists on it anymore. */ -void -fhandler_base::del_my_locks (bool after_fork) -{ - INODE_LIST_LOCK (); - inode_t *node = inode_t::get (get_dev (), get_ino (), false); - if (node) - { - bool no_locks_left = - node->del_my_locks (after_fork ? 0 : get_unique_id (), get_handle ()); - if (no_locks_left) - { - LIST_REMOVE (node, i_next); - node->UNLOCK (); - delete node; - } - else - node->UNLOCK (); - } - INODE_LIST_UNLOCK (); -} - -/* Called in an execed child. The exec'ed process must allow SYNCHRONIZE - access to everyone if at least one inode exists. - The lock owner's Windows PID changed and all POSIX lock event objects - have to be relabeled so that waiting processes know which process to - wait on. If the node has been abandoned due to close_on_exec on the - referencing fhandlers, remove the inode entirely. */ -void -fixup_lockf_after_exec () -{ - inode_t *node, *next_node; - - INODE_LIST_LOCK (); - if (LIST_FIRST (&cygheap->inode_list)) - allow_others_to_sync (); - LIST_FOREACH_SAFE (node, &cygheap->inode_list, i_next, next_node) - { - int cnt = 0; - cygheap_fdenum cfd (true); - while (cfd.next () >= 0) - if (cfd->get_dev () == node->i_dev - && cfd->get_ino () == node->i_ino - && ++cnt > 1) - break; - if (cnt == 0) - { - LIST_REMOVE (node, i_next); - delete node; - } - else - { - node->LOCK (); - for (lockf_t *lock = node->i_lockf; lock; lock = lock->lf_next) - if (lock->lf_flags & F_POSIX) - { - lock->del_lock_obj (NULL); - lock->lf_wid = myself->dwProcessId; - lock->create_lock_obj (); - } - node->UNLOCK (); - } - } - INODE_LIST_UNLOCK (); -} - -/* static method to return a pointer to the inode_t structure for a specific - file. The file is specified by the device and inode_t number. If inode_t - doesn't exist, create it. */ -inode_t * -inode_t::get (__dev32_t dev, __ino64_t ino, bool create_if_missing) -{ - inode_t *node; - - INODE_LIST_LOCK (); - LIST_FOREACH (node, &cygheap->inode_list, i_next) - if (node->i_dev == dev && node->i_ino == ino) - break; - if (!node && create_if_missing) - { - node = new inode_t (dev, ino); - if (node) - LIST_INSERT_HEAD (&cygheap->inode_list, node, i_next); - } - if (node) - node->LOCK (); - INODE_LIST_UNLOCK (); - return node; -} - -inode_t::inode_t (__dev32_t dev, __ino64_t ino) -: i_lockf (NULL), i_all_lf (NULL), i_dev (dev), i_ino (ino) -{ - HANDLE parent_dir; - WCHAR name[48]; - UNICODE_STRING uname; - OBJECT_ATTRIBUTES attr; - NTSTATUS status; - - parent_dir = get_shared_parent_dir (); - /* Create a subdir which is named after the device and inode_t numbers - of the given file, in hex notation. */ - int len = __small_swprintf (name, L"flock-%08x-%016X", dev, ino); - RtlInitCountedUnicodeString (&uname, name, len * sizeof (WCHAR)); - InitializeObjectAttributes (&attr, &uname, OBJ_INHERIT | OBJ_OPENIF, - parent_dir, everyone_sd (FLOCK_INODE_DIR_ACCESS)); - status = NtCreateDirectoryObject (&i_dir, FLOCK_INODE_DIR_ACCESS, &attr); - if (!NT_SUCCESS (status)) - api_fatal ("NtCreateDirectoryObject(inode): %p", status); - /* Create a mutex object in the file specific dir, which is used for - access synchronization on the dir and its objects. */ - RtlInitUnicodeString (&uname, L"mtx"); - InitializeObjectAttributes (&attr, &uname, OBJ_INHERIT | OBJ_OPENIF, i_dir, - everyone_sd (CYG_MUTANT_ACCESS)); - status = NtCreateMutant (&i_mtx, CYG_MUTANT_ACCESS, &attr, FALSE); - if (!NT_SUCCESS (status)) - api_fatal ("NtCreateMutant(inode): %p", status); -} - -/* Enumerate all lock event objects for this file and create a lockf_t - list in the i_all_lf member. This list is searched in lf_getblock - for locks which potentially block our lock request. */ - -/* Number of lockf_t structs which fit in the temporary buffer. */ -#define MAX_LOCKF_CNT ((intptr_t)((NT_MAX_PATH * sizeof (WCHAR)) \ - / sizeof (lockf_t))) - -lockf_t * -inode_t::get_all_locks_list () -{ - struct fdbi - { - DIRECTORY_BASIC_INFORMATION dbi; - WCHAR buf[2][NAME_MAX + 1]; - } f; - ULONG context; - NTSTATUS status; - lockf_t *lock = i_all_lf; - - for (BOOLEAN restart = TRUE; - NT_SUCCESS (status = NtQueryDirectoryObject (i_dir, &f, sizeof f, TRUE, - restart, &context, NULL)); - restart = FALSE) - { - if (f.dbi.ObjectName.Length != LOCK_OBJ_NAME_LEN * sizeof (WCHAR)) - continue; - wchar_t *wc = f.dbi.ObjectName.Buffer, *endptr; - /* "%02x-%01x-%016X-%016X-%016X-%08x", - lf_flags, lf_type, lf_start, lf_end, lf_id, lf_wid */ - wc[LOCK_OBJ_NAME_LEN] = L'\0'; - short flags = wcstol (wc, &endptr, 16); - if ((flags & ~(F_FLOCK | F_POSIX)) != 0 - || ((flags & (F_FLOCK | F_POSIX)) == (F_FLOCK | F_POSIX))) - continue; - short type = wcstol (endptr + 1, &endptr, 16); - if ((type != F_RDLCK && type != F_WRLCK) || !endptr || *endptr != L'-') - continue; - _off64_t start = (_off64_t) wcstoull (endptr + 1, &endptr, 16); - if (start < 0 || !endptr || *endptr != L'-') - continue; - _off64_t end = (_off64_t) wcstoull (endptr + 1, &endptr, 16); - if (end < -1LL || (end > 0 && end < start) || !endptr || *endptr != L'-') - continue; - long long id = wcstoll (endptr + 1, &endptr, 16); - if (!endptr || *endptr != L'-' - || ((flags & F_POSIX) && (id < 1 || id > ULONG_MAX))) - continue; - DWORD wid = wcstoul (endptr + 1, &endptr, 16); - if (endptr && *endptr != L'\0') - continue; - if (lock - i_all_lf >= MAX_LOCKF_CNT) - { - system_printf ("Warning, can't handle more than %d locks per file.", - MAX_LOCKF_CNT); - break; - } - if (lock > i_all_lf) - lock[-1].lf_next = lock; - new (lock++) lockf_t (this, &i_all_lf, flags, type, start, end, id, wid); - } - /* If no lock has been found, return NULL. */ - if (lock == i_all_lf) - return NULL; - return i_all_lf; -} - -/* Create the lock event object in the file's subdir in the NT global - namespace. The name is constructed from the lock properties which - identify it uniquely, all values in hex. See the __small_swprintf - call right at the start. */ -void -lockf_t::create_lock_obj () -{ - WCHAR name[LOCK_OBJ_NAME_LEN + 1]; - UNICODE_STRING uname; - OBJECT_ATTRIBUTES attr; - NTSTATUS status; - - __small_swprintf (name, L"%02x-%01x-%016X-%016X-%016X-%08x", - lf_flags & (F_POSIX | F_FLOCK), lf_type, lf_start, - lf_end, lf_id, lf_wid); - RtlInitCountedUnicodeString (&uname, name, - LOCK_OBJ_NAME_LEN * sizeof (WCHAR)); - InitializeObjectAttributes (&attr, &uname, OBJ_INHERIT, lf_inode->i_dir, - everyone_sd (FLOCK_EVENT_ACCESS)); - status = NtCreateEvent (&lf_obj, CYG_EVENT_ACCESS, &attr, - NotificationEvent, FALSE); - if (!NT_SUCCESS (status)) - api_fatal ("NtCreateEvent(lock): %p", status); -} - -/* Open a lock event object for SYNCHRONIZE access (to wait for it). */ -bool -lockf_t::open_lock_obj () -{ - WCHAR name[LOCK_OBJ_NAME_LEN + 1]; - UNICODE_STRING uname; - OBJECT_ATTRIBUTES attr; - NTSTATUS status; - - __small_swprintf (name, L"%02x-%01x-%016X-%016X-%016X-%08x", - lf_flags & (F_POSIX | F_FLOCK), lf_type, lf_start, - lf_end, lf_id, lf_wid); - RtlInitCountedUnicodeString (&uname, name, - LOCK_OBJ_NAME_LEN * sizeof (WCHAR)); - InitializeObjectAttributes (&attr, &uname, 0, lf_inode->i_dir, NULL); - status = NtOpenEvent (&lf_obj, FLOCK_EVENT_ACCESS, &attr); - if (!NT_SUCCESS (status)) - { - SetLastError (RtlNtStatusToDosError (status)); - lf_obj = NULL; /* Paranoia... */ - } - return lf_obj != NULL; -} - -/* Close a lock event handle. The important thing here is to signal it - before closing the handle. This way all threads waiting for this - lock can wake up. */ -void -lockf_t::del_lock_obj (HANDLE fhdl, bool signal) -{ - if (lf_obj) - { - /* Only signal the event if it's either a POSIX lock, or, in case of - BSD flock locks, if it's an explicit unlock or if the calling fhandler - holds the last reference to the file table entry. The file table - entry in UNIX terms is equivalent to the FILE_OBJECT in Windows NT - terms. It's what the handle/descriptor references when calling - CreateFile/open. Calling DuplicateHandle/dup only creates a new - handle/descriptor to the same FILE_OBJECT/file table entry. */ - if ((lf_flags & F_POSIX) || signal - || (fhdl && get_obj_handle_count (fhdl) <= 1)) - SetEvent (lf_obj); - NtClose (lf_obj); - lf_obj = NULL; - } -} - -lockf_t::~lockf_t () -{ - del_lock_obj (NULL); -} - -/* - * This variable controls the maximum number of processes that will - * be checked in doing deadlock detection. - */ -#ifndef __CYGWIN__ -#define MAXDEPTH 50 -static int maxlockdepth = MAXDEPTH; -#endif - -#define NOLOCKF (struct lockf_t *)0 -#define SELF 0x1 -#define OTHERS 0x2 -static int lf_clearlock (lockf_t *, lockf_t **, HANDLE); -static int lf_findoverlap (lockf_t *, lockf_t *, int, lockf_t ***, lockf_t **); -static lockf_t *lf_getblock (lockf_t *, inode_t *node); -static int lf_getlock (lockf_t *, inode_t *, struct __flock64 *); -static int lf_setlock (lockf_t *, inode_t *, lockf_t **, HANDLE); -static void lf_split (lockf_t *, lockf_t *, lockf_t **); -static void lf_wakelock (lockf_t *, HANDLE); - -int -fhandler_disk_file::lock (int a_op, struct __flock64 *fl) -{ - _off64_t start, end, oadd; - lockf_t *n; - int error = 0; - - short a_flags = fl->l_type & (F_POSIX | F_FLOCK); - short type = fl->l_type & (F_RDLCK | F_WRLCK | F_UNLCK); - - if (!a_flags) - a_flags = F_POSIX; /* default */ - if (a_op == F_SETLKW) - { - a_op = F_SETLK; - a_flags |= F_WAIT; - } - if (a_op == F_SETLK) - switch (type) - { - case F_UNLCK: - a_op = F_UNLCK; - break; - case F_RDLCK: - if (!(get_access () & GENERIC_READ)) - { - set_errno (EBADF); - return -1; - } - break; - case F_WRLCK: - if (!(get_access () & GENERIC_WRITE)) - { - set_errno (EBADF); - return -1; - } - break; - default: - set_errno (EINVAL); - return -1; - } - - /* - * Convert the flock structure into a start and end. - */ - switch (fl->l_whence) - { - case SEEK_SET: - start = fl->l_start; - break; - - case SEEK_CUR: - if ((start = lseek (0, SEEK_CUR)) == ILLEGAL_SEEK) - return -1; - break; - - case SEEK_END: - { - NTSTATUS status; - IO_STATUS_BLOCK io; - FILE_STANDARD_INFORMATION fsi; - - status = NtQueryInformationFile (get_handle (), &io, &fsi, sizeof fsi, - FileStandardInformation); - if (!NT_SUCCESS (status)) - { - __seterrno_from_nt_status (status); - return -1; - } - if (fl->l_start > 0 && fsi.EndOfFile.QuadPart > OFF_MAX - fl->l_start) - { - set_errno (EOVERFLOW); - return -1; - } - start = fsi.EndOfFile.QuadPart + fl->l_start; - } - break; - - default: - return (EINVAL); - } - if (start < 0) - { - set_errno (EINVAL); - return -1; - } - if (fl->l_len < 0) - { - if (start == 0) - { - set_errno (EINVAL); - return -1; - } - end = start - 1; - start += fl->l_len; - if (start < 0) - { - set_errno (EINVAL); - return -1; - } - } - else if (fl->l_len == 0) - end = -1; - else - { - oadd = fl->l_len - 1; - if (oadd > OFF_MAX - start) - { - set_errno (EOVERFLOW); - return -1; - } - end = start + oadd; - } - - inode_t *node = inode_t::get (get_dev (), get_ino (), true); - if (!node) - { - set_errno (ENOLCK); - return -1; - } - need_fork_fixup (true); - - /* Unlock the fd table which has been locked in fcntl_worker/lock_worker, - otherwise a blocking F_SETLKW never wakes up on a signal. */ - cygheap->fdtab.unlock (); - - lockf_t **head = &node->i_lockf; - - /* - * Avoid the common case of unlocking when inode_t has no locks. - */ - if (*head == NULL) - { - if (a_op != F_SETLK) - { - node->UNLOCK (); - fl->l_type = F_UNLCK; - return 0; - } - } - /* - * Allocate a spare structure in case we have to split. - */ - lockf_t *clean = NULL; - if (a_op == F_SETLK || a_op == F_UNLCK) - { - clean = new lockf_t (); - if (!clean) - { - node->UNLOCK (); - set_errno (ENOLCK); - return -1; - } - } - /* - * Create the lockf_t structure - */ - lockf_t *lock = new lockf_t (node, head, a_flags, type, start, end, - (a_flags & F_FLOCK) ? get_unique_id () - : getpid (), - myself->dwProcessId); - if (!lock) - { - node->UNLOCK (); - set_errno (ENOLCK); - return -1; - } - - switch (a_op) - { - case F_SETLK: - error = lf_setlock (lock, node, &clean, get_handle ()); - break; - - case F_UNLCK: - error = lf_clearlock (lock, &clean, get_handle ()); - lock->lf_next = clean; - clean = lock; - break; - - case F_GETLK: - error = lf_getlock (lock, node, fl); - lock->lf_next = clean; - clean = lock; - break; - - default: - lock->lf_next = clean; - clean = lock; - error = EINVAL; - break; - } - for (lock = clean; lock != NULL; ) - { - n = lock->lf_next; - lock->del_lock_obj (get_handle (), a_op == F_UNLCK); - delete lock; - lock = n; - } - if (node->i_lockf == NULL) - { - INODE_LIST_LOCK (); - LIST_REMOVE (node, i_next); - node->UNLOCK (); - delete node; - INODE_LIST_UNLOCK (); - } - else - node->UNLOCK (); - if (error) - { - set_errno (error); - return -1; - } - return 0; -} - -/* - * Set a byte-range lock. - */ -static int -lf_setlock (lockf_t *lock, inode_t *node, lockf_t **clean, HANDLE fhdl) -{ - lockf_t *block; - lockf_t **head = lock->lf_head; - lockf_t **prev, *overlap; - int ovcase, priority, old_prio, needtolink; - tmp_pathbuf tp; - - /* - * Set the priority - */ - priority = old_prio = GetThreadPriority (GetCurrentThread ()); - if (lock->lf_type == F_WRLCK && priority <= THREAD_PRIORITY_ABOVE_NORMAL) - priority = THREAD_PRIORITY_HIGHEST; - /* - * Scan lock list for this file looking for locks that would block us. - */ - /* Create temporary space for the all locks list. */ - node->i_all_lf = (lockf_t *) tp.w_get (); - while ((block = lf_getblock(lock, node))) - { - DWORD ret; - HANDLE obj = block->lf_obj; - block->lf_obj = NULL; - - /* - * Free the structure and return if nonblocking. - */ - if ((lock->lf_flags & F_WAIT) == 0) - { - lock->lf_next = *clean; - *clean = lock; - if (obj) - NtClose (obj); - return EAGAIN; - } - /* - * We are blocked. Since flock style locks cover - * the whole file, there is no chance for deadlock. - * For byte-range locks we must check for deadlock. - * - * Deadlock detection is done by looking through the - * wait channels to see if there are any cycles that - * involve us. MAXDEPTH is set just to make sure we - * do not go off into neverland. - */ - /* FIXME: We check the handle count of all the lock event objects - this process holds. If it's > 1, another process is - waiting for one of our locks. This method isn't overly - intelligent. If it turns out to be too dumb, we might - have to remove it or to find another method. */ - for (lockf_t *lk = node->i_lockf; lk; lk = lk->lf_next) - if ((lk->lf_flags & F_POSIX) && get_obj_handle_count (lk->lf_obj) > 1) - { - if (obj) - NtClose (obj); - return EDEADLK; - } - - /* - * For flock type locks, we must first remove - * any shared locks that we hold before we sleep - * waiting for an exclusive lock. - */ - if ((lock->lf_flags & F_FLOCK) && lock->lf_type == F_WRLCK) - { - lock->lf_type = F_UNLCK; - (void) lf_clearlock (lock, clean, fhdl); - lock->lf_type = F_WRLCK; - } - - /* - * Add our lock to the blocked list and sleep until we're free. - * Remember who blocked us (for deadlock detection). - */ - /* Cygwin: No locked list. See deadlock recognition above. */ - - /* Wait for the blocking object and its holding process. */ - if (!obj) - { - /* We can't synchronize on the lock event object. - Treat this as a deadlock-like situation for now. */ - system_printf ("Can't sync with lock object hold by " - "Win32 pid %lu: %E", block->lf_wid); - return EDEADLK; - } - SetThreadPriority (GetCurrentThread (), priority); - if (lock->lf_flags & F_POSIX) - { - HANDLE proc = OpenProcess (SYNCHRONIZE, FALSE, block->lf_wid); - if (!proc) - { - /* If we can't synchronize on the process holding the lock, - we will never recognize when the lock has been abandoned. - Treat this as a deadlock-like situation for now. */ - system_printf ("Can't sync with process holding a lock " - "(Win32 pid %lu): %E", block->lf_wid); - NtClose (obj); - return EDEADLK; - } - HANDLE w4[3] = { obj, proc, signal_arrived }; - node->UNLOCK (); - ret = WaitForMultipleObjects (3, w4, FALSE, INFINITE); - CloseHandle (proc); - } - else - { - HANDLE w4[2] = { obj, signal_arrived }; - node->UNLOCK (); - /* Unfortunately, since BSD flock locks are not attached to a - specific process, we can't recognize an abandoned lock by - sync'ing with a process. We have to find out if we're the only - process left accessing this event object. */ - do - { - ret = WaitForMultipleObjects (2, w4, FALSE, 100L); - } - while (ret == WAIT_TIMEOUT && get_obj_handle_count (obj) > 1); - } - node->LOCK (); - NtClose (obj); - SetThreadPriority (GetCurrentThread (), old_prio); - switch (ret) - { - case WAIT_OBJECT_0: - /* The lock object has been set to signalled. */ - break; - case WAIT_OBJECT_0 + 1: - /* For POSIX locks, the process holding the lock has exited. */ - if (lock->lf_flags & F_POSIX) - break; - /*FALLTHRU*/ - case WAIT_OBJECT_0 + 2: - /* A signal came in. */ - _my_tls.call_signal_handler (); - return EINTR; - default: - return geterrno_from_win_error (); - } - } - allow_others_to_sync (); - /* - * No blocks!! Add the lock. Note that we will - * downgrade or upgrade any overlapping locks this - * process already owns. - * - * Handle any locks that overlap. - */ - prev = head; - block = *head; - needtolink = 1; - for (;;) - { - ovcase = lf_findoverlap (block, lock, SELF, &prev, &overlap); - if (ovcase) - block = overlap->lf_next; - /* - * Six cases: - * 0) no overlap - * 1) overlap == lock - * 2) overlap contains lock - * 3) lock contains overlap - * 4) overlap starts before lock - * 5) overlap ends after lock - */ - switch (ovcase) - { - case 0: /* no overlap */ - if (needtolink) - { - *prev = lock; - lock->lf_next = overlap; - lock->create_lock_obj (); - } - break; - - case 1: /* overlap == lock */ - /* - * If downgrading lock, others may be - * able to acquire it. - * Cygwin: Always wake lock. - */ - lf_wakelock (overlap, fhdl); - overlap->lf_type = lock->lf_type; - overlap->create_lock_obj (); - lock->lf_next = *clean; - *clean = lock; - break; - - case 2: /* overlap contains lock */ - /* - * Check for common starting point and different types. - */ - if (overlap->lf_type == lock->lf_type) - { - lock->lf_next = *clean; - *clean = lock; - break; - } - if (overlap->lf_start == lock->lf_start) - { - *prev = lock; - lock->lf_next = overlap; - overlap->lf_start = lock->lf_end + 1; - } - else - lf_split (overlap, lock, clean); - lf_wakelock (overlap, fhdl); - overlap->create_lock_obj (); - lock->create_lock_obj (); - if (lock->lf_next && !lock->lf_next->lf_obj) - lock->lf_next->create_lock_obj (); - break; - - case 3: /* lock contains overlap */ - /* - * If downgrading lock, others may be able to - * acquire it, otherwise take the list. - * Cygwin: Always wake old lock and create new lock. - */ - lf_wakelock (overlap, fhdl); - /* - * Add the new lock if necessary and delete the overlap. - */ - if (needtolink) - { - *prev = lock; - lock->lf_next = overlap->lf_next; - prev = &lock->lf_next; - lock->create_lock_obj (); - needtolink = 0; - } - else - *prev = overlap->lf_next; - overlap->lf_next = *clean; - *clean = overlap; - continue; - - case 4: /* overlap starts before lock */ - /* - * Add lock after overlap on the list. - */ - lock->lf_next = overlap->lf_next; - overlap->lf_next = lock; - overlap->lf_end = lock->lf_start - 1; - prev = &lock->lf_next; - lf_wakelock (overlap, fhdl); - overlap->create_lock_obj (); - lock->create_lock_obj (); - needtolink = 0; - continue; - - case 5: /* overlap ends after lock */ - /* - * Add the new lock before overlap. - */ - if (needtolink) { - *prev = lock; - lock->lf_next = overlap; - } - overlap->lf_start = lock->lf_end + 1; - lf_wakelock (overlap, fhdl); - lock->create_lock_obj (); - overlap->create_lock_obj (); - break; - } - break; - } - return 0; -} - -/* - * Remove a byte-range lock on an inode_t. - * - * Generally, find the lock (or an overlap to that lock) - * and remove it (or shrink it), then wakeup anyone we can. - */ -static int -lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl) -{ - lockf_t **head = unlock->lf_head; - lockf_t *lf = *head; - lockf_t *overlap, **prev; - int ovcase; - - if (lf == NOLOCKF) - return 0; - prev = head; - while ((ovcase = lf_findoverlap (lf, unlock, SELF, &prev, &overlap))) - { - /* - * Wakeup the list of locks to be retried. - */ - lf_wakelock (overlap, fhdl); - - switch (ovcase) - { - case 1: /* overlap == lock */ - *prev = overlap->lf_next; - overlap->lf_next = *clean; - *clean = overlap; - break; - - case 2: /* overlap contains lock: split it */ - if (overlap->lf_start == unlock->lf_start) - { - overlap->lf_start = unlock->lf_end + 1; - overlap->create_lock_obj (); - break; - } - lf_split (overlap, unlock, clean); - overlap->lf_next = unlock->lf_next; - overlap->create_lock_obj (); - if (overlap->lf_next && !overlap->lf_next->lf_obj) - overlap->lf_next->create_lock_obj (); - break; - - case 3: /* lock contains overlap */ - *prev = overlap->lf_next; - lf = overlap->lf_next; - overlap->lf_next = *clean; - *clean = overlap; - continue; - - case 4: /* overlap starts before lock */ - overlap->lf_end = unlock->lf_start - 1; - prev = &overlap->lf_next; - lf = overlap->lf_next; - overlap->create_lock_obj (); - continue; - - case 5: /* overlap ends after lock */ - overlap->lf_start = unlock->lf_end + 1; - overlap->create_lock_obj (); - break; - } - break; - } - return 0; -} - -/* - * Check whether there is a blocking lock, - * and if so return its process identifier. - */ -static int -lf_getlock (lockf_t *lock, inode_t *node, struct __flock64 *fl) -{ - lockf_t *block; - tmp_pathbuf tp; - - /* Create temporary space for the all locks list. */ - node->i_all_lf = (lockf_t *) tp.w_get (); - if ((block = lf_getblock (lock, node))) - { - if (block->lf_obj) - NtClose (block->lf_obj); - fl->l_type = block->lf_type; - fl->l_whence = SEEK_SET; - fl->l_start = block->lf_start; - if (block->lf_end == -1) - fl->l_len = 0; - else - fl->l_len = block->lf_end - block->lf_start + 1; - if (block->lf_flags & F_POSIX) - fl->l_pid = (pid_t) block->lf_id; - else - fl->l_pid = -1; - } - else - fl->l_type = F_UNLCK; - return 0; -} - -/* - * Walk the list of locks for an inode_t and - * return the first blocking lock. - */ -static lockf_t * -lf_getblock (lockf_t *lock, inode_t *node) -{ - lockf_t **prev, *overlap; - lockf_t *lf = node->get_all_locks_list (); - int ovcase; - NTSTATUS status; - EVENT_BASIC_INFORMATION ebi; - - prev = lock->lf_head; - while ((ovcase = lf_findoverlap (lf, lock, OTHERS, &prev, &overlap))) - { - /* - * We've found an overlap, see if it blocks us - */ - if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK)) - { - /* Open the event object for synchronization. */ - if (!overlap->open_lock_obj () || (overlap->lf_flags & F_POSIX)) - return overlap; - /* In case of BSD flock locks, check if the event object is - signalled. If so, the overlap doesn't actually exist anymore. - There are just a few open handles left. */ - status = NtQueryEvent (overlap->lf_obj, EventBasicInformation, - &ebi, sizeof ebi, NULL); - if (!NT_SUCCESS (status) || ebi.SignalState == 0) - return overlap; - NtClose (overlap->lf_obj); - overlap->lf_obj = NULL; - } - /* - * Nope, point to the next one on the list and - * see if it blocks us - */ - lf = overlap->lf_next; - } - return NOLOCKF; -} - -/* - * Walk the list of locks for an inode_t to - * find an overlapping lock (if any). - * - * NOTE: this returns only the FIRST overlapping lock. There - * may be more than one. - */ -static int -lf_findoverlap (lockf_t *lf, lockf_t *lock, int type, lockf_t ***prev, - lockf_t **overlap) -{ - _off64_t start, end; - - *overlap = lf; - if (lf == NOLOCKF) - return 0; - - start = lock->lf_start; - end = lock->lf_end; - while (lf != NOLOCKF) - { - if (((type & OTHERS) && lf->lf_id == lock->lf_id) - /* As on Linux: POSIX locks and BSD flock locks don't interact. */ - || (lf->lf_flags & (F_POSIX | F_FLOCK)) - != (lock->lf_flags & (F_POSIX | F_FLOCK))) - { - *prev = &lf->lf_next; - *overlap = lf = lf->lf_next; - continue; - } - /* - * OK, check for overlap - * - * Six cases: - * 0) no overlap - * 1) overlap == lock - * 2) overlap contains lock - * 3) lock contains overlap - * 4) overlap starts before lock - * 5) overlap ends after lock - */ - if ((lf->lf_end != -1 && start > lf->lf_end) || - (end != -1 && lf->lf_start > end)) - { - /* Case 0 */ - if ((type & SELF) && end != -1 && lf->lf_start > end) - return 0; - *prev = &lf->lf_next; - *overlap = lf = lf->lf_next; - continue; - } - if ((lf->lf_start == start) && (lf->lf_end == end)) - { - /* Case 1 */ - return 1; - } - if ((lf->lf_start <= start) && (end != -1) && - ((lf->lf_end >= end) || (lf->lf_end == -1))) - { - /* Case 2 */ - return 2; - } - if (start <= lf->lf_start && (end == -1 || - (lf->lf_end != -1 && end >= lf->lf_end))) - { - /* Case 3 */ - return 3; - } - if ((lf->lf_start < start) && - ((lf->lf_end >= start) || (lf->lf_end == -1))) - { - /* Case 4 */ - return 4; - } - if ((lf->lf_start > start) && (end != -1) && - ((lf->lf_end > end) || (lf->lf_end == -1))) - { - /* Case 5 */ - return 5; - } - api_fatal ("lf_findoverlap: default\n"); - } - return 0; -} - -/* - * Split a lock and a contained region into - * two or three locks as necessary. - */ -static void -lf_split (lockf_t *lock1, lockf_t *lock2, lockf_t **split) -{ - lockf_t *splitlock; - - /* - * Check to see if spliting into only two pieces. - */ - if (lock1->lf_start == lock2->lf_start) - { - lock1->lf_start = lock2->lf_end + 1; - lock2->lf_next = lock1; - return; - } - if (lock1->lf_end == lock2->lf_end) - { - lock1->lf_end = lock2->lf_start - 1; - lock2->lf_next = lock1->lf_next; - lock1->lf_next = lock2; - return; - } - /* - * Make a new lock consisting of the last part of - * the encompassing lock. We use the preallocated - * splitlock so we don't have to block. - */ - splitlock = *split; - assert (splitlock != NULL); - *split = splitlock->lf_next; - memcpy (splitlock, lock1, sizeof *splitlock); - /* We have to unset the obj HANDLE here which has been copied by the - above memcpy, so that the calling function recognizes the new object. - See post-lf_split handling in lf_setlock and lf_clearlock. */ - splitlock->lf_obj = NULL; - splitlock->lf_start = lock2->lf_end + 1; - lock1->lf_end = lock2->lf_start - 1; - /* - * OK, now link it in - */ - splitlock->lf_next = lock1->lf_next; - lock2->lf_next = splitlock; - lock1->lf_next = lock2; -} - -/* - * Wakeup a blocklist - * Cygwin: Just signal the lock which gets removed. This unblocks - * all threads waiting for this lock. - */ -static void -lf_wakelock (lockf_t *listhead, HANDLE fhdl) -{ - listhead->del_lock_obj (fhdl, true); -} - -extern "C" int -flock (int fd, int operation) -{ - int res = -1; - int cmd; - struct __flock64 fl = { 0, SEEK_SET, 0, 0, 0 }; - - myfault efault; - if (efault.faulted (EFAULT)) - return -1; - - cygheap_fdget cfd (fd, true); - if (cfd < 0) - goto done; - - cmd = (operation & LOCK_NB) ? F_SETLK : F_SETLKW; - switch (operation & (~LOCK_NB)) - { - case LOCK_EX: - fl.l_type = F_WRLCK | F_FLOCK; - break; - case LOCK_SH: - fl.l_type = F_RDLCK | F_FLOCK; - break; - case LOCK_UN: - fl.l_type = F_UNLCK | F_FLOCK; - break; - default: - set_errno (EINVAL); - goto done; - } - res = cfd->lock (cmd, &fl); - if ((res == -1) && ((get_errno () == EAGAIN) || (get_errno () == EACCES))) - set_errno (EWOULDBLOCK); -done: - syscall_printf ("%d = flock (%d, %d)", res, fd, operation); - return res; -} - -extern "C" int -lockf (int filedes, int function, _off64_t size) -{ - int res = -1; - int cmd; - struct __flock64 fl; - - myfault efault; - if (efault.faulted (EFAULT)) - return -1; - - cygheap_fdget cfd (filedes, true); - if (cfd < 0) - goto done; - - fl.l_start = 0; - fl.l_len = size; - fl.l_whence = SEEK_CUR; - - switch (function) - { - case F_ULOCK: - cmd = F_SETLK; - fl.l_type = F_UNLCK; - break; - case F_LOCK: - cmd = F_SETLKW; - fl.l_type = F_WRLCK; - break; - case F_TLOCK: - cmd = F_SETLK; - fl.l_type = F_WRLCK; - break; - case F_TEST: - fl.l_type = F_WRLCK; - if (cfd->lock (F_GETLK, &fl) == -1) - goto done; - if (fl.l_type == F_UNLCK || fl.l_pid == getpid ()) - res = 0; - else - errno = EAGAIN; - goto done; - /* NOTREACHED */ - default: - errno = EINVAL; - goto done; - /* NOTREACHED */ - } - res = cfd->lock (cmd, &fl); -done: - syscall_printf ("%d = lockf (%d, %d, %D)", res, filedes, function, size); - return res; -} |