SQLite

#include "os.h"

#if OS_UNIX
# include <unistd.h>
# include <fcntl.h>
# include <sys/stat.h>
# include <time.h>
# ifndef O_LARGEFILE
#  define O_LARGEFILE 0
# endif
# ifndef O_NOFOLLOW
#  define O_NOFOLLOW 0
# endif
#endif

#if OS_WIN
# include <winbase.h>
#endif

/*
** Macros for performance tracing.  Normally turned off
*/

*/
int sqliteOsOpenReadWrite(
  const char *zFilename,
  OsFile *id,
  int *pReadonly
){
#if OS_UNIX
  id->fd = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE, 0644);
  if( id->fd<0 ){
    id->fd = open(zFilename, O_RDONLY|O_LARGEFILE);
    if( id->fd<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }

** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
#if OS_UNIX
  if( access(zFilename, 0)==0 ){
    return SQLITE_CANTOPEN;
  }



  id->fd = open(zFilename, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE, 0600);
  if( id->fd<0 ){
    return SQLITE_CANTOPEN;
  }
  sqliteOsEnterMutex();
  id->pLock = findLockInfo(id->fd);
  sqliteOsLeaveMutex();
  if( id->pLock==0 ){

**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenReadOnly(const char *zFilename, OsFile *id){
#if OS_UNIX
  id->fd = open(zFilename, O_RDONLY|O_LARGEFILE);
  if( id->fd<0 ){
    return SQLITE_CANTOPEN;
  }
  sqliteOsEnterMutex();
  id->pLock = findLockInfo(id->fd);
  sqliteOsLeaveMutex();
  if( id->pLock==0 ){

  return SQLITE_OK;
#endif
}

/*
** Move the read/write pointer in a file.
*/
int sqliteOsSeek(OsFile *id, off_t offset){
  SEEK(offset/1024 + 1);
#if OS_UNIX
  lseek(id->fd, offset, SEEK_SET);
  return SQLITE_OK;
#endif
#if OS_WIN
  SetFilePointer(id->h, offset, 0, FILE_BEGIN);

  }
#endif
}

/*
** Truncate an open file to a specified size
*/
int sqliteOsTruncate(OsFile *id, off_t nByte){
  SimulateIOError(SQLITE_IOERR);
#if OS_UNIX
  return ftruncate(id->fd, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
#endif
#if OS_WIN
  SetFilePointer(id->h, nByte, 0, FILE_BEGIN);
  SetEndOfFile(id->h);
  return SQLITE_OK;
#endif
}

/*
** Determine the current size of a file in bytes
*/
int sqliteOsFileSize(OsFile *id, off_t *pSize){
#if OS_UNIX
  struct stat buf;
  SimulateIOError(SQLITE_IOERR);
  if( fstat(id->fd, &buf)!=0 ){
    return SQLITE_IOERR;
  }
  *pSize = buf.st_size;

#include <windows.h>
#include <winbase.h>
  typedef struct OsFile OsFile;
  struct OsFile {
    HANDLE h;               /* Handle for accessing the file */
    int locked;             /* 0: unlocked, <0: write lock, >0: read lock */
  };
  typedef int off_t;
# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
# define SQLITE_MIN_SLEEP_MS 1
#endif

int sqliteOsDelete(const char*);
int sqliteOsFileExists(const char*);
int sqliteOsOpenReadWrite(const char*, OsFile*, int*);
int sqliteOsOpenExclusive(const char*, OsFile*, int);
int sqliteOsOpenReadOnly(const char*, OsFile*);
int sqliteOsTempFileName(char*);
int sqliteOsClose(OsFile*);
int sqliteOsRead(OsFile*, void*, int amt);
int sqliteOsWrite(OsFile*, const void*, int amt);
int sqliteOsSeek(OsFile*, off_t offset);
int sqliteOsSync(OsFile*);
int sqliteOsTruncate(OsFile*, off_t size);
int sqliteOsFileSize(OsFile*, off_t *pSize);
int sqliteOsReadLock(OsFile*);
int sqliteOsWriteLock(OsFile*);
int sqliteOsUnlock(OsFile*);
int sqliteOsRandomSeed(char*);
int sqliteOsSleep(int ms);
void sqliteOsEnterMutex(void);
void sqliteOsLeaveMutex(void);

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.54 2002/11/05 23:03:03 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "os.h"
#include <assert.h>
#include <string.h>

struct Pager {
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  OsFile fd, jfd;             /* File descriptors for database and journal */
  OsFile cpfd;                /* File descriptor for the checkpoint journal */
  int dbSize;                 /* Number of pages in the file */
  int origDbSize;             /* dbSize before the current change */
  int ckptSize;               /* Size of database (in pages) at ckpt_begin() */
  off_t ckptJSize;            /* Size of journal at ckpt_begin() */
  int nExtra;                 /* Add this many bytes to each in-memory page */
  void (*xDestructor)(void*); /* Call this routine when freeing pages */
  int nPage;                  /* Total number of in-memory pages */
  int nRef;                   /* Number of in-memory pages with PgHdr.nRef>0 */
  int mxPage;                 /* Maximum number of pages to hold in cache */
  int nHit, nMiss, nOvfl;     /* Cache hits, missing, and LRU overflows */
  u8 journalOpen;             /* True if journal file descriptors is valid */

** at the beginning) then this routine returns SQLITE_PROTOCOL.
** If any other errors occur during playback, the database will
** likely be corrupted, so the PAGER_ERR_CORRUPT bit is set in
** pPager->errMask and SQLITE_CORRUPT is returned.  If it all
** works, then this routine returns SQLITE_OK.
*/
static int pager_playback(Pager *pPager){
  off_t nRec;              /* Number of Records */
  int i;                   /* Loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  unsigned char aMagic[sizeof(aJournalMagic)];
  int rc;

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( pPager->journalOpen );
  sqliteOsSeek(&pPager->jfd, 0);
  rc = sqliteOsFileSize(&pPager->jfd, &nRec);
  if( rc!=SQLITE_OK ){
    goto end_playback;
  }
  if( nRec <= sizeof(aMagic)+sizeof(Pgno) ){

    goto end_playback;
  }
  nRec = (nRec - (sizeof(aMagic)+sizeof(Pgno))) / sizeof(PageRecord);

  /* Read the beginning of the journal and truncate the
  ** database file back to its original size.
  */
  rc = sqliteOsRead(&pPager->jfd, aMagic, sizeof(aMagic));
  if( rc!=SQLITE_OK ){
    rc = SQLITE_PROTOCOL;

    rc = SQLITE_PROTOCOL;
    goto end_playback;
  }
  rc = read32bits(pPager, &pPager->jfd, &mxPg);
  if( rc!=SQLITE_OK ){
    goto end_playback;
  }
  rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)mxPg);
  if( rc!=SQLITE_OK ){
    goto end_playback;
  }
  pPager->dbSize = mxPg;
  
  /* Copy original pages out of the journal and back into the database file.
  */

**         journal file itself.
**
**    (2)  In addition to playing back the checkpoint journal, also
**         playback all pages of the transaction journal beginning
**         at offset pPager->ckptJSize.
*/
static int pager_ckpt_playback(Pager *pPager){
  off_t nRec;              /* Number of Records */
  int i;                   /* Loop counter */
  int rc;

  /* Truncate the database back to its original size.
  */
  rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)pPager->ckptSize);
  pPager->dbSize = pPager->ckptSize;

  /* Figure out how many records are in the checkpoint journal.
  */
  assert( pPager->ckptInUse && pPager->journalOpen );
  sqliteOsSeek(&pPager->cpfd, 0);
  rc = sqliteOsFileSize(&pPager->cpfd, &nRec);

}

/*
** Return the total number of pages in the disk file associated with
** pPager.
*/
int sqlitepager_pagecount(Pager *pPager){
  off_t n;
  assert( pPager!=0 );
  if( pPager->dbSize>=0 ){
    return pPager->dbSize;
  }
  if( sqliteOsFileSize(&pPager->fd, &n)!=SQLITE_OK ){
    pPager->errMask |= PAGER_ERR_DISK;
    return 0;

    if( pPager->dbSize<(int)pgno ){
      memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE);
    }else{
      int rc;
      sqliteOsSeek(&pPager->fd, (pgno-1)*SQLITE_PAGE_SIZE);
      rc = sqliteOsRead(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE);
      if( rc!=SQLITE_OK ){
        off_t fileSize;
        if( sqliteOsFileSize(&pPager->fd,&fileSize)!=SQLITE_OK
               || fileSize>=pgno*SQLITE_PAGE_SIZE ){
          return rc;
        }else{
          memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE);
        }
      }