/*
** Reset the automatic extension loading mechanism.
*/
void sqlite3_reset_auto_extension(void){
sqlite3OsEnterMutex();
sqliteFree(aAutoExtension);
aAutoExtension = 0;
nAutoExtension = 0;
sqlite3OsLeaveMutex();
}
/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero. If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
int sqlite3OsCheckReservedLock(OsFile *id){
int r = 0;
assert( id->isOpen );
sqlite3OsEnterMutex(); /* Needed because id->pLock is shared across threads */
/* Check if a thread in this process holds such a lock */
if( id->pLock->locktype>SHARED_LOCK ){
r = 1;
}
/* Otherwise see if some other process holds it.
*/
if( !r ){
struct flock lock;
lock.l_whence = SEEK_SET;
lock.l_start = RESERVED_BYTE;
lock.l_len = 1;
lock.l_type = F_WRLCK;
fcntl(id->h, F_GETLK, &lock);
if( lock.l_type!=F_UNLCK ){
r = 1;
}
}
sqlite3OsLeaveMutex();
TRACE3("TEST WR-LOCK %d %d\n", id->h, r);
return r;
}
/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing. To avoid
** a potential security problem, we do not allow the file to have
** previously existed. Nor do we allow the file to be a symbolic
** link.
**
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3OsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
int rc;
assert( !id->isOpen );
if( access(zFilename, 0)==0 ){
return SQLITE_CANTOPEN;
}
id->dirfd = -1;
id->h = open(zFilename,
O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY, 0600);
if( id->h<0 ){
return SQLITE_CANTOPEN;
}
sqlite3OsEnterMutex();
rc = findLockInfo(id->h, &id->pLock, &id->pOpen);
sqlite3OsLeaveMutex();
if( rc ){
close(id->h);
unlink(zFilename);
return SQLITE_NOMEM;
}
id->locktype = 0;
id->isOpen = 1;
if( delFlag ){
unlink(zFilename);
}
TRACE3("OPEN-EX %-3d %s\n", id->h, zFilename);
OpenCounter(+1);
return SQLITE_OK;
}
/*
** Set the value of the two crash parameters.
*/
void sqlite3SetCrashParams(int iDelay, char const *zFile){
sqlite3OsEnterMutex();
assert( strlen(zFile)<256 );
strcpy(zCrashFile, zFile);
iCrashDelay = iDelay;
sqlite3OsLeaveMutex();
}
/*
** Close a file.
*/
int sqlite3OsClose(OsFile *id){
if( !id->isOpen ) return SQLITE_OK;
sqlite3OsUnlock(id, NO_LOCK);
if( id->dirfd>=0 ) close(id->dirfd);
id->dirfd = -1;
sqlite3OsEnterMutex();
if( id->pOpen->nLock ){
/* If there are outstanding locks, do not actually close the file just
** yet because that would clear those locks. Instead, add the file
** descriptor to pOpen->aPending. It will be automatically closed when
** the last lock is cleared.
*/
int *aNew;
struct openCnt *pOpen = id->pOpen;
pOpen->nPending++;
aNew = sqliteRealloc( pOpen->aPending, pOpen->nPending*sizeof(int) );
if( aNew==0 ){
/* If a malloc fails, just leak the file descriptor */
}else{
pOpen->aPending = aNew;
pOpen->aPending[pOpen->nPending-1] = id->h;
}
}else{
/* There are no outstanding locks so we can close the file immediately */
close(id->h);
}
releaseLockInfo(id->pLock);
releaseOpenCnt(id->pOpen);
sqlite3OsLeaveMutex();
id->isOpen = 0;
TRACE2("CLOSE %-3d\n", id->h);
OpenCounter(-1);
return SQLITE_OK;
}
/*
** This function looks up an identifier to determine if it is a
** keyword. If it is a keyword, the token code of that keyword is
** returned. If the input is not a keyword, TK_ID is returned.
*/
int sqlite3KeywordCode(const char *z, int n){
int h, i;
Keyword *p;
static char needInit = 1;
if( needInit ){
/* Initialize the keyword hash table */
sqlite3OsEnterMutex();
if( needInit ){
int nk;
nk = sizeof(aKeywordTable)/sizeof(aKeywordTable[0]);
for(i=0; i<nk; i++){
aKeywordTable[i].len = strlen(aKeywordTable[i].zName);
h = sqlite3HashNoCase(aKeywordTable[i].zName, aKeywordTable[i].len);
h %= KEY_HASH_SIZE;
aKeywordTable[i].iNext = aiHashTable[h];
aiHashTable[h] = i+1;
}
needInit = 0;
}
sqlite3OsLeaveMutex();
}
h = sqlite3HashNoCase(z, n) % KEY_HASH_SIZE;
for(i=aiHashTable[h]; i; i=p->iNext){
p = &aKeywordTable[i-1];
if( p->len==n && sqlite3StrNICmp(p->zName, z, n)==0 ){
return p->tokenType;
}
}
return TK_ID;
}
/*
** If the library is compiled to omit the full-scale date and time
** handling (to get a smaller binary), the following minimal version
** of the functions current_time(), current_date() and current_timestamp()
** are included instead. This is to support column declarations that
** include "DEFAULT CURRENT_TIME" etc.
**
** This function uses the C-library functions time(), gmtime()
** and strftime(). The format string to pass to strftime() is supplied
** as the user-data for the function.
*/
static void currentTimeFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
time_t t;
char *zFormat = (char *)sqlite3_user_data(context);
char zBuf[20];
time(&t);
#ifdef SQLITE_TEST
{
extern int sqlite3_current_time; /* See os_XXX.c */
if( sqlite3_current_time ){
t = sqlite3_current_time;
}
}
#endif
sqlite3OsEnterMutex();
strftime(zBuf, 20, zFormat, gmtime(&t));
sqlite3OsLeaveMutex();
sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
/*
** Load all automatic extensions.
*/
int sqlite3AutoLoadExtensions(sqlite3 *db){
int i;
int go = 1;
int rc = SQLITE_OK;
int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
if( nAutoExtension==0 ){
/* Common case: early out without every having to acquire a mutex */
return SQLITE_OK;
}
for(i=0; go; i++){
char *zErrmsg = 0;
sqlite3OsEnterMutex();
if( i>=nAutoExtension ){
xInit = 0;
go = 0;
}else{
xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
aAutoExtension[i];
}
sqlite3OsLeaveMutex();
if( xInit && xInit(db, &zErrmsg, &sqlite3_apis) ){
sqlite3Error(db, SQLITE_ERROR,
"automatic extension loading failed: %s", zErrmsg);
go = 0;
rc = SQLITE_ERROR;
}
}
return rc;
}
/*
** Return N random bytes.
*/
void sqlite3Randomness(int N, void *pBuf){
unsigned char *zBuf = pBuf;
sqlite3OsEnterMutex();
while( N-- ){
*(zBuf++) = randomByte();
}
sqlite3OsLeaveMutex();
}
/*
** This is the test layer's wrapper around sqlite3OsFree(). The argument is a
** pointer to the space allocated for the application to use.
*/
static void OSFREE(void *pFree){
u32 *p; /* Pointer to the OS-layer allocation */
sqlite3OsEnterMutex();
p = (u32 *)getOsPointer(pFree);
checkGuards(p);
unlinkAlloc(p);
memset(pFree, 0x55, OSSIZEOF(pFree));
sqlite3OsFree(p);
sqlite3_nFree++;
sqlite3OsLeaveMutex();
}
/*
** This is the test layer's wrapper around sqlite3OsMalloc().
*/
static void * OSMALLOC(int n){
sqlite3OsEnterMutex();
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
sqlite3_nMaxAlloc =
MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
assert( !sqlite3_mallocDisallowed );
if( !sqlite3TestMallocFail() ){
u32 *p;
p = (u32 *)sqlite3OsMalloc(n + TESTALLOC_OVERHEAD);
assert(p);
sqlite3_nMalloc++;
applyGuards(p);
linkAlloc(p);
sqlite3OsLeaveMutex();
return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
}
sqlite3OsLeaveMutex();
return 0;
}
/*
** File zPath is being sync()ed. Return non-zero if this should
** cause a crash.
*/
static int crashRequired(char const *zPath){
int r;
int n;
sqlite3OsEnterMutex();
n = strlen(zCrashFile);
if( zCrashFile[n-1]=='*' ){
n--;
}else if( strlen(zPath)>n ){
n = strlen(zPath);
}
r = 0;
if( iCrashDelay>0 && strncmp(zPath, zCrashFile, n)==0 ){
iCrashDelay--;
if( iCrashDelay<=0 ){
r = 1;
}
}
sqlite3OsLeaveMutex();
return r;
}
/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqlite3OsOpenReadOnly(const char *zFilename, OsFile *id){
int rc;
assert( !id->isOpen );
id->dirfd = -1;
id->h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
if( id->h<0 ){
return SQLITE_CANTOPEN;
}
sqlite3OsEnterMutex();
rc = findLockInfo(id->h, &id->pLock, &id->pOpen);
sqlite3OsLeaveMutex();
if( rc ){
close(id->h);
return SQLITE_NOMEM;
}
id->locktype = 0;
id->isOpen = 1;
TRACE3("OPEN-RO %-3d %s\n", id->h, zFilename);
OpenCounter(+1);
return SQLITE_OK;
}
/*
** Register a statically linked extension that is automatically
** loaded by every new database connection.
*/
int sqlite3_auto_extension(void *xInit){
int i;
int rc = SQLITE_OK;
sqlite3OsEnterMutex();
for(i=0; i<nAutoExtension; i++){
if( aAutoExtension[i]==xInit ) break;
}
if( i==nAutoExtension ){
nAutoExtension++;
aAutoExtension = sqlite3Realloc( aAutoExtension,
nAutoExtension*sizeof(aAutoExtension[0]) );
if( aAutoExtension==0 ){
nAutoExtension = 0;
rc = SQLITE_NOMEM;
}else{
aAutoExtension[nAutoExtension-1] = xInit;
}
}
sqlite3OsLeaveMutex();
return rc;
}
/*
** Attempt to open a file for both reading and writing. If that
** fails, try opening it read-only. If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only. The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
int sqlite3OsOpenReadWrite(
const char *zFilename,
OsFile *id,
int *pReadonly
){
int rc;
assert( !id->isOpen );
id->dirfd = -1;
id->h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
SQLITE_DEFAULT_FILE_PERMISSIONS);
if( id->h<0 ){
#ifdef EISDIR
if( errno==EISDIR ){
return SQLITE_CANTOPEN;
}
#endif
id->h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
if( id->h<0 ){
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
*pReadonly = 0;
}
sqlite3OsEnterMutex();
rc = findLockInfo(id->h, &id->pLock, &id->pOpen);
sqlite3OsLeaveMutex();
if( rc ){
close(id->h);
return SQLITE_NOMEM;
}
id->locktype = 0;
id->isOpen = 1;
TRACE3("OPEN %-3d %s\n", id->h, zFilename);
OpenCounter(+1);
return SQLITE_OK;
}
/*
** This routine does the work of opening a database on behalf of
** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"
** is UTF-8 encoded.
*/
static int openDatabase(
const char *zFilename, /* Database filename UTF-8 encoded */
sqlite3 **ppDb /* OUT: Returned database handle */
){
sqlite3 *db;
int rc, i;
/* Allocate the sqlite data structure */
db = sqliteMalloc( sizeof(sqlite3) );
if( db==0 ) goto opendb_out;
db->priorNewRowid = 0;
db->magic = SQLITE_MAGIC_BUSY;
db->nDb = 2;
db->aDb = db->aDbStatic;
db->enc = SQLITE_UTF8;
db->autoCommit = 1;
db->flags |= SQLITE_ShortColNames;
sqlite3HashInit(&db->aFunc, SQLITE_HASH_STRING, 0);
sqlite3HashInit(&db->aCollSeq, SQLITE_HASH_STRING, 0);
for(i=0; i<db->nDb; i++){
sqlite3HashInit(&db->aDb[i].tblHash, SQLITE_HASH_STRING, 0);
sqlite3HashInit(&db->aDb[i].idxHash, SQLITE_HASH_STRING, 0);
sqlite3HashInit(&db->aDb[i].trigHash, SQLITE_HASH_STRING, 0);
sqlite3HashInit(&db->aDb[i].aFKey, SQLITE_HASH_STRING, 1);
}
/* Add the default collation sequence BINARY. BINARY works for both UTF-8
** and UTF-16, so add a version for each to avoid any unnecessary
** conversions. The only error that can occur here is a malloc() failure.
*/
if( sqlite3_create_collation(db, "BINARY", SQLITE_UTF8, 0,binCollFunc) ||
sqlite3_create_collation(db, "BINARY", SQLITE_UTF16, 0,binCollFunc) ||
!(db->pDfltColl = sqlite3FindCollSeq(db, db->enc, "BINARY", 6, 0)) ){
rc = db->errCode;
assert( rc!=SQLITE_OK );
db->magic = SQLITE_MAGIC_CLOSED;
goto opendb_out;
}
/* Also add a UTF-8 case-insensitive collation sequence. */
sqlite3_create_collation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc);
/* Open the backend database driver */
rc = sqlite3BtreeFactory(db, zFilename, 0, MAX_PAGES, &db->aDb[0].pBt);
if( rc!=SQLITE_OK ){
sqlite3Error(db, rc, 0);
db->magic = SQLITE_MAGIC_CLOSED;
goto opendb_out;
}
/* The default safety_level for the main database is 'full'; for the temp
** database it is 'NONE'. This matches the pager layer defaults.
*/
db->aDb[0].zName = "main";
db->aDb[0].safety_level = 3;
#ifndef SQLITE_OMIT_TEMPDB
db->aDb[1].zName = "temp";
db->aDb[1].safety_level = 1;
#endif
/* Register all built-in functions, but do not attempt to read the
** database schema yet. This is delayed until the first time the database
** is accessed.
*/
sqlite3RegisterBuiltinFunctions(db);
sqlite3Error(db, SQLITE_OK, 0);
db->magic = SQLITE_MAGIC_OPEN;
opendb_out:
if( sqlite3_errcode(db)==SQLITE_OK && sqlite3_malloc_failed ){
sqlite3Error(db, SQLITE_NOMEM, 0);
}
*ppDb = db;
#ifndef SQLITE_OMIT_GLOBALRECOVER
if( db ){
sqlite3OsEnterMutex();
db->pNext = pDbList;
pDbList = db;
sqlite3OsLeaveMutex();
}
#endif
return sqlite3_errcode(db);
}
/*
** Lower the locking level on file descriptor id to locktype. locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK. If the second argument is SHARED_LOCK, this routine
** might return SQLITE_IOERR instead of SQLITE_OK.
*/
int sqlite3OsUnlock(OsFile *id, int locktype){
struct lockInfo *pLock;
struct flock lock;
int rc = SQLITE_OK;
assert( id->isOpen );
TRACE7("UNLOCK %d %d was %d(%d,%d) pid=%d\n", id->h, locktype, id->locktype,
id->pLock->locktype, id->pLock->cnt, getpid());
assert( locktype<=SHARED_LOCK );
if( id->locktype<=locktype ){
return SQLITE_OK;
}
sqlite3OsEnterMutex();
pLock = id->pLock;
assert( pLock->cnt!=0 );
if( id->locktype>SHARED_LOCK ){
assert( pLock->locktype==id->locktype );
if( locktype==SHARED_LOCK ){
lock.l_type = F_RDLCK;
lock.l_whence = SEEK_SET;
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
if( fcntl(id->h, F_SETLK, &lock)!=0 ){
/* This should never happen */
rc = SQLITE_IOERR;
}
}
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = PENDING_BYTE;
lock.l_len = 2L; assert( PENDING_BYTE+1==RESERVED_BYTE );
fcntl(id->h, F_SETLK, &lock);
pLock->locktype = SHARED_LOCK;
}
if( locktype==NO_LOCK ){
struct openCnt *pOpen;
/* Decrement the shared lock counter. Release the lock using an
** OS call only when all threads in this same process have released
** the lock.
*/
pLock->cnt--;
if( pLock->cnt==0 ){
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = lock.l_len = 0L;
fcntl(id->h, F_SETLK, &lock);
pLock->locktype = NO_LOCK;
}
/* Decrement the count of locks against this same file. When the
** count reaches zero, close any other file descriptors whose close
** was deferred because of outstanding locks.
*/
pOpen = id->pOpen;
pOpen->nLock--;
assert( pOpen->nLock>=0 );
if( pOpen->nLock==0 && pOpen->nPending>0 ){
int i;
for(i=0; i<pOpen->nPending; i++){
close(pOpen->aPending[i]);
}
sqliteFree(pOpen->aPending);
pOpen->nPending = 0;
pOpen->aPending = 0;
}
}
sqlite3OsLeaveMutex();
id->locktype = locktype;
return rc;
}
/*
** Close an existing SQLite database
*/
int sqlite3_close(sqlite3 *db){
HashElem *i;
int j;
if( !db ){
return SQLITE_OK;
}
if( sqlite3SafetyCheck(db) ){
return SQLITE_MISUSE;
}
#ifdef SQLITE_SSE
sqlite3_finalize(db->pFetch);
#endif
/* If there are any outstanding VMs, return SQLITE_BUSY. */
if( db->pVdbe ){
sqlite3Error(db, SQLITE_BUSY,
"Unable to close due to unfinalised statements");
return SQLITE_BUSY;
}
assert( !sqlite3SafetyCheck(db) );
/* FIX ME: db->magic may be set to SQLITE_MAGIC_CLOSED if the database
** cannot be opened for some reason. So this routine needs to run in
** that case. But maybe there should be an extra magic value for the
** "failed to open" state.
*/
if( db->magic!=SQLITE_MAGIC_CLOSED && sqlite3SafetyOn(db) ){
/* printf("DID NOT CLOSE\n"); fflush(stdout); */
return SQLITE_ERROR;
}
for(j=0; j<db->nDb; j++){
struct Db *pDb = &db->aDb[j];
if( pDb->pBt ){
sqlite3BtreeClose(pDb->pBt);
pDb->pBt = 0;
}
}
sqlite3ResetInternalSchema(db, 0);
assert( db->nDb<=2 );
assert( db->aDb==db->aDbStatic );
for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
FuncDef *pFunc, *pNext;
for(pFunc = (FuncDef*)sqliteHashData(i); pFunc; pFunc=pNext){
pNext = pFunc->pNext;
sqliteFree(pFunc);
}
}
for(i=sqliteHashFirst(&db->aCollSeq); i; i=sqliteHashNext(i)){
CollSeq *pColl = (CollSeq *)sqliteHashData(i);
sqliteFree(pColl);
}
sqlite3HashClear(&db->aCollSeq);
sqlite3HashClear(&db->aFunc);
sqlite3Error(db, SQLITE_OK, 0); /* Deallocates any cached error strings. */
if( db->pValue ){
sqlite3ValueFree(db->pValue);
}
if( db->pErr ){
sqlite3ValueFree(db->pErr);
}
#ifndef SQLITE_OMIT_GLOBALRECOVER
{
sqlite3 *pPrev;
sqlite3OsEnterMutex();
pPrev = pDbList;
while( pPrev && pPrev->pNext!=db ){
pPrev = pPrev->pNext;
}
if( pPrev ){
pPrev->pNext = db->pNext;
}else{
assert( pDbList==db );
pDbList = db->pNext;
}
sqlite3OsLeaveMutex();
}
#endif
db->magic = SQLITE_MAGIC_ERROR;
sqliteFree(db);
return SQLITE_OK;
}
/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
int sqlite3OsLock(OsFile *id, int locktype){
/* The following describes the implementation of the various locks and
** lock transitions in terms of the POSIX advisory shared and exclusive
** lock primitives (called read-locks and write-locks below, to avoid
** confusion with SQLite lock names). The algorithms are complicated
** slightly in order to be compatible with windows systems simultaneously
** accessing the same database file, in case that is ever required.
**
** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
** byte', each single bytes at well known offsets, and the 'shared byte
** range', a range of 510 bytes at a well known offset.
**
** To obtain a SHARED lock, a read-lock is obtained on the 'pending
** byte'. If this is successful, a random byte from the 'shared byte
** range' is read-locked and the lock on the 'pending byte' released.
**
** A process may only obtain a RESERVED lock after it has a SHARED lock.
** A RESERVED lock is implemented by grabbing a write-lock on the
** 'reserved byte'.
**
** A process may only obtain a PENDING lock after it has obtained a
** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
** on the 'pending byte'. This ensures that no new SHARED locks can be
** obtained, but existing SHARED locks are allowed to persist. A process
** does not have to obtain a RESERVED lock on the way to a PENDING lock.
** This property is used by the algorithm for rolling back a journal file
** after a crash.
**
** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
** implemented by obtaining a write-lock on the entire 'shared byte
** range'. Since all other locks require a read-lock on one of the bytes
** within this range, this ensures that no other locks are held on the
** database.
**
** The reason a single byte cannot be used instead of the 'shared byte
** range' is that some versions of windows do not support read-locks. By
** locking a random byte from a range, concurrent SHARED locks may exist
** even if the locking primitive used is always a write-lock.
*/
int rc = SQLITE_OK;
struct lockInfo *pLock = id->pLock;
struct flock lock;
int s;
assert( id->isOpen );
TRACE7("LOCK %d %s was %s(%s,%d) pid=%d\n", id->h, locktypeName(locktype),
locktypeName(id->locktype), locktypeName(pLock->locktype), pLock->cnt
,getpid() );
/* If there is already a lock of this type or more restrictive on the
** OsFile, do nothing. Don't use the end_lock: exit path, as
** sqlite3OsEnterMutex() hasn't been called yet.
*/
if( id->locktype>=locktype ){
TRACE3("LOCK %d %s ok (already held)\n", id->h, locktypeName(locktype));
return SQLITE_OK;
}
/* Make sure the locking sequence is correct
*/
assert( id->locktype!=NO_LOCK || locktype==SHARED_LOCK );
assert( locktype!=PENDING_LOCK );
assert( locktype!=RESERVED_LOCK || id->locktype==SHARED_LOCK );
/* This mutex is needed because id->pLock is shared across threads
*/
sqlite3OsEnterMutex();
/* If some thread using this PID has a lock via a different OsFile*
** handle that precludes the requested lock, return BUSY.
*/
if( (id->locktype!=pLock->locktype &&
(pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK))
){
rc = SQLITE_BUSY;
goto end_lock;
}
/* If a SHARED lock is requested, and some thread using this PID already
** has a SHARED or RESERVED lock, then increment reference counts and
** return SQLITE_OK.
*/
if( locktype==SHARED_LOCK &&
(pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
assert( locktype==SHARED_LOCK );
assert( id->locktype==0 );
assert( pLock->cnt>0 );
id->locktype = SHARED_LOCK;
pLock->cnt++;
id->pOpen->nLock++;
goto end_lock;
}
lock.l_len = 1L;
lock.l_whence = SEEK_SET;
/* A PENDING lock is needed before acquiring a SHARED lock and before
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
** be released.
*/
if( locktype==SHARED_LOCK
|| (locktype==EXCLUSIVE_LOCK && id->locktype<PENDING_LOCK)
){
lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
lock.l_start = PENDING_BYTE;
s = fcntl(id->h, F_SETLK, &lock);
if( s ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
goto end_lock;
}
}
/* If control gets to this point, then actually go ahead and make
** operating system calls for the specified lock.
*/
if( locktype==SHARED_LOCK ){
assert( pLock->cnt==0 );
assert( pLock->locktype==0 );
/* Now get the read-lock */
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
s = fcntl(id->h, F_SETLK, &lock);
/* Drop the temporary PENDING lock */
lock.l_start = PENDING_BYTE;
lock.l_len = 1L;
lock.l_type = F_UNLCK;
fcntl(id->h, F_SETLK, &lock);
if( s ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
}else{
id->locktype = SHARED_LOCK;
id->pOpen->nLock++;
pLock->cnt = 1;
}
}else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
/* We are trying for an exclusive lock but another thread in this
** same process is still holding a shared lock. */
rc = SQLITE_BUSY;
}else{
/* The request was for a RESERVED or EXCLUSIVE lock. It is
** assumed that there is a SHARED or greater lock on the file
** already.
*/
assert( 0!=id->locktype );
lock.l_type = F_WRLCK;
switch( locktype ){
case RESERVED_LOCK:
lock.l_start = RESERVED_BYTE;
break;
case EXCLUSIVE_LOCK:
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
break;
default:
assert(0);
}
s = fcntl(id->h, F_SETLK, &lock);
if( s ){
rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
}
}
if( rc==SQLITE_OK ){
id->locktype = locktype;
pLock->locktype = locktype;
}else if( locktype==EXCLUSIVE_LOCK ){
id->locktype = PENDING_LOCK;
pLock->locktype = PENDING_LOCK;
}
end_lock:
sqlite3OsLeaveMutex();
TRACE4("LOCK %d %s %s\n", id->h, locktypeName(locktype),
rc==SQLITE_OK ? "ok" : "failed");
return rc;
}
