SQLite

#undef HAVE_MALLOC_H

/* Define to 1 if you have the `malloc_usable_size' function. */
#undef HAVE_MALLOC_USABLE_SIZE

/* Define to 1 if you have the <memory.h> header file. */
#undef HAVE_MEMORY_H

/* Define to 1 if you have the pread() function. */
#undef HAVE_PREAD

/* Define to 1 if you have the pread64() function. */
#undef HAVE_PREAD64

/* Define to 1 if you have the pwrite() function. */
#undef HAVE_PWRITE

/* Define to 1 if you have the pwrite64() function. */
#undef HAVE_PWRITE64

/* Define to 1 if you have the <stdint.h> header file. */
#undef HAVE_STDINT_H

/* Define to 1 if you have the <stdlib.h> header file. */
#undef HAVE_STDLIB_H

done


#########
# Figure out whether or not we have these functions
#
for ac_func in fdatasync gmtime_r isnan localtime_r localtime_s malloc_usable_size strchrnul usleep utime pread pread64 pwrite pwrite64
do :
  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
  cat >>confdefs.h <<_ACEOF
#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
_ACEOF

#########
# Check for needed/wanted headers
AC_CHECK_HEADERS([sys/types.h stdlib.h stdint.h inttypes.h malloc.h])

#########
# Figure out whether or not we have these functions
#
AC_CHECK_FUNCS([fdatasync gmtime_r isnan localtime_r localtime_s malloc_usable_size strchrnul usleep utime pread pread64 pwrite pwrite64])

#########
# By default, we use the amalgamation (this may be changed below...)
#
USE_AMALGAMATION=1

#########

#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
#  if defined(__APPLE__)
#    define SQLITE_ENABLE_LOCKING_STYLE 1
#  else
#    define SQLITE_ENABLE_LOCKING_STYLE 0
#  endif
#endif

/* Use pread() and pwrite() if they are available */
#if defined(HAVE_PREAD64) && defined(HAVE_PWRITE64)
# undef USE_PREAD
# undef USE_PWRITE
# define USE_PREAD64 1
# define USE_PWRITE64 1
#elif defined(HAVE_PREAD) && defined(HAVE_PWRITE)
# undef USE_PREAD
# undef USE_PWRITE
# define USE_PREAD64 1
# define USE_PWRITE64 1
#endif


/*
** standard include files.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

  unsigned short int ctrlFlags;       /* Behavioral bits.  UNIXFILE_* flags */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if !defined(USE_PREAD) && !defined(USE_PREAD64)
  off64_t iOfst;                      /* Current offset */
#endif
#if SQLITE_MAX_MMAP_SIZE>0
  int nFetchOut;                      /* Number of outstanding xFetch refs */
  sqlite3_int64 mmapSize;             /* Usable size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeActual;       /* Actual size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
  void *pMapRegion;                   /* Memory mapped region */
#endif

**
** To avoid stomping the errno value on a failed read the lastErrno value
** is set before returning.
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
  int got;
  int prior = 0;



  TIMER_START;
  assert( cnt==(cnt&0x1ffff) );
  assert( id->h>2 );
  do{
#if defined(USE_PREAD)
    got = osPread(id->h, pBuf, cnt, offset);
    SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
    got = osPread64(id->h, pBuf, cnt, offset);
    SimulateIOError( got = -1 );
#else
    if( offset!=id->iOfst ){
      id->iOfst = lseek(id->h, offset, SEEK_SET);
      SimulateIOError( id->iOfst = -1 );
      if( id->iOfst<0 ){
        storeLastErrno((unixFile*)id, errno);
        return -1;
      }
      got = osRead(id->h, pBuf, cnt);
      if( got>=0 ) id->iOfst += got;
#endif
    if( got==cnt ) break;
    if( got<0 ){
      if( errno==EINTR ){ got = 1; continue; }
      prior = 0;
      storeLastErrno((unixFile*)id,  errno);
      break;

#if defined(USE_PREAD)
  do{ rc = (int)osPwrite(fd, pBuf, nBuf, iOff); }while( rc<0 && errno==EINTR );
#elif defined(USE_PREAD64)
  do{ rc = (int)osPwrite64(fd, pBuf, nBuf, iOff);}while( rc<0 && errno==EINTR);
#else
  do{
    if( iOff!=fd
    i64 iSeek = lseek(fd, iOff, SEEK_SET);
    SimulateIOError( iSeek = -1 );
    if( iSeek<0 ){
      rc = -1;
      break;
    }
    rc = osWrite(fd, pBuf, nBuf);