/*
** 2001 September 16
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to particular operating
** systems. The purpose of this file is to provide a uniform abstract
** on which the rest of SQLite can operate.
*/
#include "sqliteInt.h"
#include "os.h"
#ifndef OS_UNIX
# ifndef OS_WIN
# define OS_UNIX 1
# else
# define OS_UNIX 0
# endif
#endif
#ifndef OS_WIN
# define OS_WIN 0
#endif
#if OS_UNIX
# include <unistd.h>
# include <fcntl.h>
# include <sys/stat.h>
# include <time.h>
#endif
#if OS_WIN
# include <winbase.h>
#endif
#if OS_UNIX
/*
** An instance of the following structure serves as the key used
** to locate a particular lockInfo structure given its inode.
*/
struct inodeKey {
dev_t dev; /* Device number */
ino_t ino; /* Inode number */
};
/*
** An instance of the following structure is allocated for each inode.
** A single inode can have multiple file descriptors, so each OsFile structure
** contains a pointer to an instance of this object.
*/
struct lockInfo {
struct inodeKey key; /* The lookup key */
int cnt; /* 0: unlocked. -1: write lock. >=1: read lock */
int nRef; /* Number of pointers to this structure */
};
/*
** This hash table maps inodes (in the form of inodeKey structures) into
** pointers to lockInfo structures.
*/
static Hash lockHash = { SQLITE_HASH_BINARY, 0, 0, 0, 0, 0 };
/*
** Given a file descriptor, locate a lockInfo structure that describes
** that file descriptor. Create a new one if necessary.
*/
static struct lockInfo *findLockInfo(int fd){
int rc;
struct inodeKey key;
struct stat statbuf;
struct lockInfo *pInfo;
rc = fstat(fd, &statbuf);
if( rc!=0 ) return 0;
key.dev = statbuf.st_dev;
key.ino = statbuf.st_ino;
pInfo = (struct lockInfo*)sqliteHashFind(&lockHash, &key, sizeof(key));
if( pInfo==0 ){
pInfo = sqliteMalloc( sizeof(*pInfo) );
pInfo->key = key;
pInfo->nRef = 1;
pInfo->cnt = 0;
sqliteHashInsert(&lockHash, &pInfo->key, sizeof(key), pInfo);
}else{
pInfo->nRef++;
}
return pInfo;
}
/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pInfo){
pInfo->nRef--;
if( pInfo->nRef==0 ){
sqliteHashInsert(&lockHash, &pInfo->key, sizeof(pInfo->key), 0);
sqliteFree(pInfo);
}
}
#endif
/*
** Delete the named file
*/
int sqliteOsDelete(const char *zFilename){
#if OS_UNIX
unlink(zFilename);
#endif
#if OS_WIN
DeleteFile(zFilename);
#endif
return SQLITE_OK;
}
/*
** Return TRUE if the named file exists.
*/
int sqliteOsFileExists(const char *zFilename){
#if OS_UNIX
return access(zFilename, 0)==0;
#endif
#if OS_WIN
HANDLE h;
h = CreateFile(zFilename,
GENERIC_READ,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h!=INVALID_HANDLE_VALUE ){
CloseHandle(h);
return 1;
}
return 0;
#endif
}
/*
** 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 *pResult
** 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
** *pResulst and *pReadonly unchanged.
*/
int sqliteOsOpenReadWrite(
const char *zFilename,
OsFile *pResult,
int *pReadonly
){
#if OS_UNIX
OsFile s;
s.fd = open(zFilename, O_RDWR|O_CREAT, 0644);
if( s.fd<0 ){
s.fd = open(zFilename, O_RDONLY);
if( s.fd<0 ){
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
*pReadonly = 0;
}
sqliteOsEnterMutex();
s.pLock = findLockInfo(s.fd);
sqliteOsLeaveMutex();
if( s.pLock==0 ){
close(s.fd);
return SQLITE_NOMEM;
}
*pResult = s;
return SQLITE_OK;
#endif
#if OS_WIN
HANDLE h = CreateFile(zFilename,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
HANDLE h = CreateFile(zFilename,
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
*pReadonly = 0;
}
*pResult = h;
return SQLITE_OK;
#endif
}
/*
** 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.
**
** On success, write the file handle into *pResult and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenExclusive(const char *zFilename, OsFile *pResult){
#if OS_UNIX
OsFile s;
if( access(zFilename, 0)==0 ){
return SQLITE_CANTOPEN;
}
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
s.fd = open(zFilename, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, 0600);
if( s.fd<0 ){
return SQLITE_CANTOPEN;
}
sqliteOsEnterMutex();
s.pLock = findLockInfo(s.fd);
sqliteOsLeaveMutex();
if( s.pLock==0 ){
close(s.fd);
return SQLITE_NOMEM;
}
*pResult = s;
return SQLITE_OK;
#endif
#if OS_WIN
HANDLE h = CreateFile(zFilename,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
*pResult = h;
return SQLITE_OK;
#endif
}
/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *pResult and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenReadOnly(const char *zFilename, OsFile *pResult){
#if OS_UNIX
OsFile s;
s.fd = open(zFilename, O_RDONLY);
if( s.fd<0 ){
return SQLITE_CANTOPEN;
}
sqliteOsEnterMutex();
s.pLock = findLockInfo(s.fd);
sqliteOsLeaveMutex();
if( s.pLock==0 ){
close(s.fd);
return SQLITE_NOMEM;
}
*pResult = s;
return SQLITE_OK;
#endif
#if OS_WIN
HANDLE h = CreateFile(zFilename,
GENERIC_READ,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
NULL
);
if( h==INVALID_HANDLE_VALUE ){
return SQLITE_CANTOPEN;
}
*pResult = h;
return SQLITE_OK;
#endif
}
/*
** Create a temporary file name in zBuf. zBuf must be big enough to
** hold at least SQLITE_TEMPNAME_SIZE characters.
*/
int sqliteOsTempFileName(char *zBuf){
#if OS_UNIX
static const char *azDirs[] = {
".",
"/var/tmp",
"/usr/tmp",
"/tmp",
};
static char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
int i, j;
struct stat buf;
const char *zDir = ".";
for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
if( stat(azDirs[i], &buf) ) continue;
if( !S_ISDIR(buf.st_mode) ) continue;
if( access(azDirs[i], 07) ) continue;
zDir = azDirs[i];
break;
}
do{
sprintf(zBuf, "%s/sqlite_", zDir);
j = strlen(zBuf);
for(i=0; i<15; i++){
int n = sqliteRandomByte() % (sizeof(zChars)-1);
zBuf[j++] = zChars[n];
}
zBuf[j] = 0;
}while( access(zBuf,0)==0 );
#endif
#if OS_WIN
static char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
int i, j;
char zTempPath[SQLITE_TEMPNAME_SIZE];
GetTempPath(SQLITE_TEMPNAME_SIZE-30, zTempPath);
for(;;){
sprintf(zBuf, "%s/sqlite_", zTempPath);
j = strlen(zBuf);
for(i=0; i<15; i++){
int n = sqliteRandomByte() % sizeof(zChars);
zBuf[j++] = zChars[n];
}
zBuf[j] = 0;
if( !sqliteOsFileExists(zBuf) ) break;
}
#endif
return SQLITE_OK;
}
/*
** Close a file
*/
int sqliteOsClose(OsFile id){
#if OS_UNIX
close(id.fd);
sqliteOsEnterMutex();
releaseLockInfo(id.pLock);
sqliteOsLeaveMutex();
return SQLITE_OK;
#endif
#if OS_WIN
CloseHandle(id);
return SQLITE_OK;
#endif
}
/*
** Read data from a file into a buffer. Return the number of
** bytes actually read.
*/
int sqliteOsRead(OsFile id, void *pBuf, int amt){
#if OS_UNIX
int got;
got = read(id.fd, pBuf, amt);
if( got<0 ) got = 0;
return got==amt ? SQLITE_OK : SQLITE_IOERR;
#endif
#if OS_WIN
DWORD got;
if( !ReadFile(id, pBuf, amt, &got, 0) ){
got = 0;
}
return got==amt ? SQLITE_OK : SQLITE_IOERR;
#endif
}
/*
** Write data from a buffer into a file. Return SQLITE_OK on success
** or some other error code on failure.
*/
int sqliteOsWrite(OsFile id, const void *pBuf, int amt){
#if OS_UNIX
int wrote;
wrote = write(id.fd, pBuf, amt);
if( wrote<amt ) return SQLITE_FULL;
return SQLITE_OK;
#endif
#if OS_WIN
DWORD wrote;
if( !WriteFile(id, pBuf, amt, &wrote, 0) || wrote<amt ){
return SQLITE_FULL;
}
return SQLITE_OK;
#endif
}
/*
** Move the read/write pointer in a file.
*/
int sqliteOsSeek(OsFile id, int offset){
#if OS_UNIX
lseek(id.fd, offset, SEEK_SET);
return SQLITE_OK;
#endif
#if OS_WIN
SetFilePointer(id, offset, 0, FILE_BEGIN);
return SQLITE_OK;
#endif
}
/*
** Make sure all writes to a particular file are committed to disk.
*/
int sqliteOsSync(OsFile id){
#if OS_UNIX
return fsync(id.fd)==0 ? SQLITE_OK : SQLITE_IOERR;
#endif
#if OS_WIN
return FlushFileBuffers(id) ? SQLITE_OK : SQLITE_IOERR;
#endif
}
/*
** Truncate an open file to a specified size
*/
int sqliteOsTruncate(OsFile id, int nByte){
#if OS_UNIX
return ftruncate(id.fd, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
#endif
#if OS_WIN
SetFilePointer(id, nByte, 0, FILE_BEGIN);
SetEndOfFile(id);
return SQLITE_OK;
#endif
}
/*
** Determine the current size of a file in bytes
*/
int sqliteOsFileSize(OsFile id, int *pSize){
#if OS_UNIX
struct stat buf;
if( fstat(id.fd, &buf)!=0 ){
return SQLITE_IOERR;
}
*pSize = buf.st_size;
return SQLITE_OK;
#endif
#if OS_WIN
*pSize = GetFileSize(id, 0);
return SQLITE_OK;
#endif
}
/*
** Get a read or write lock on a file.
*/
int sqliteOsLock(OsFile id, int wrlock){
#if OS_UNIX
int rc;
int needSysLock;
sqliteOsEnterMutex();
if( wrlock ){
if( id.pLock->cnt!=0 ){
rc = SQLITE_BUSY;
}else{
rc = SQLITE_OK;
id.pLock->cnt = -1;
needSysLock = 1;
}
}else{
if( id.pLock<0 ){
rc = SQLITE_BUSY;
}else{
rc = SQLITE_OK;
needSysLock = id.pLock->cnt==0;
id.pLock->cnt++;
}
}
sqliteOsLeaveMutex();
if( rc==SQLITE_OK && needSysLock ){
struct flock lock;
lock.l_type = wrlock ? F_WRLCK : F_RDLCK;
lock.l_whence = SEEK_SET;
lock.l_start = lock.l_len = 0L;
rc = fcntl(id.fd, F_SETLK, &lock)==0 ? SQLITE_OK : SQLITE_BUSY;
}
return rc;
#endif
#if OS_WIN
if( !LockFile(id, 0, 0, 1024, 0) ){
return SQLITE_BUSY;
}
return SQLITE_OK;
#endif
}
/*
** Release the read or write lock from a file.
*/
int sqliteOsUnlock(OsFile id){
#if OS_UNIX
int rc;
int needSysUnlock;
sqliteOsEnterMutex();
if( id.pLock->cnt<0 ){
needSysUnlock = 1;
id.pLock->cnt = 0;
}else if( id.pLock->cnt>0 ){
id.pLock->cnt--;
needSysUnlock = id.pLock->cnt==0;
}else{
rc = SQLITE_OK;
needSysUnlock = 0;
}
sqliteOsLeaveMutex();
if( needSysUnlock ){
struct flock lock;
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = lock.l_len = 0L;
rc = fcntl(id.fd, F_SETLK, &lock)==0 ? SQLITE_OK : SQLITE_IOERR;
}
return rc;
#endif
#if OS_WIN
return UnlockFile(id, 0, 0, 1024, 0) ? SQLITE_OK : SQLITE_IOERR;
#endif
}
/*
** Get information to seed the random number generator.
*/
int sqliteOsRandomSeed(char *zBuf){
static int once = 1;
#if OS_UNIX
int pid;
time((time_t*)zBuf);
pid = getpid();
memcpy(&zBuf[sizeof(time_t)], &pid, sizeof(pid));
#endif
#if OS_WIN
GetSystemTime((LPSYSTEMTIME)zBuf);
#endif
if( once ){
int seed;
memcpy(&seed, zBuf, sizeof(seed));
srand(seed);
once = 0;
}
return SQLITE_OK;
}
/*
** Sleep for a little while. Return the amount of time slept.
*/
int sqliteOsSleep(int ms){
#if OS_UNIX
#if defined(HAVE_USLEEP) && HAVE_USLEEP
usleep(ms*1000);
return ms;
#else
sleep((ms+999)/1000);
return 1000*((ms+999)/1000);
#endif
#endif
#if OS_WIN
Sleep(ms);
return ms;
#endif
}
/*
** The following pair of routine implement mutual exclusion for
** multi-threaded processes. Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex. There is not much critical
** code and what little there is executes quickly and without blocking.
**
****** TBD: The mutex is currently unimplemented. Until it is
****** implemented, SQLite is not threadsafe.
*/
static int inMutex = 0;
void sqliteOsEnterMutex(){
assert( !inMutex );
inMutex = 1;
}
void sqliteOsLeaveMutex(){
assert( inMutex );
inMutex = 0;
}