perkeep/misc/sqlite/vfs.go

133 lines
2.6 KiB
Go

package sqlite
/*
#include <string.h>
#define SKIP_SQLITE_VERSION
#include "sqlite3.h"
*/
import "C"
import (
"os"
"sync"
"unsafe"
)
var file_map_mutex sync.Mutex
var file_map = make(map[int]*os.File)
func GetFile(fd int) (file *os.File) {
file_map_mutex.Lock()
defer file_map_mutex.Unlock()
return file_map[fd]
}
//export GoFileClose
// Returns 0 on success and -1 on error.
func GoFileClose(fd C.int) (int) {
file := GetFile(int(fd))
if file.Close() != nil {
return -1
}
return 0
}
//export GoFileRead
// Returns SQLite error codes to be returned by xRead:
// SQLITE_OK: read n bytes
// SQLITE_IOERR_READ: got error while reading
// SQLITE_IOERR_SHORT_READ: read fewer than n bytes; rest will be zeroed
func GoFileRead(fd C.int, dst *C.char, n C.int, offset C.long) (rv int) {
println("reading", n, "bytes at offset", offset, "from fd", fd);
defer func() {
println("read returning", rv);
}()
file := GetFile(int(fd))
if file == nil {
return C.SQLITE_IOERR_READ
}
buf := make([]byte, n)
curbuf := buf
for n > 0 {
read, err := file.ReadAt(curbuf, int64(offset))
curbuf = curbuf[read:]
n -= C.int(read)
if err == os.EOF {
break
}
if err != nil {
return C.SQLITE_IOERR_READ
}
}
C.memcpy(unsafe.Pointer(dst), unsafe.Pointer(&buf[0]), C.size_t(len(buf)))
if n != 0 {
return C.SQLITE_IOERR_SHORT_READ
}
return C.SQLITE_OK
}
//export GoFileFileSize
// return[0]: 0 on success and -1 on error.
// return[1]: size
func GoFileFileSize(fd C.int) (rv int, size C.long) {
println("getting file size for fd", fd);
defer func() {
println("returning", rv, "with size", size);
}()
file := GetFile(int(fd))
if file == nil {
return -1, 0
}
info, err := file.Stat()
if err != nil {
return -1, 0
}
return 0, C.long(info.Size)
}
//export GoVFSOpen
// fd is -1 on error.
func GoVFSOpen(filename *C.char, flags C.int) (fd int) {
println("opening", C.GoString(filename), "with flags", int(flags))
goflags := 0
if flags & C.SQLITE_OPEN_READONLY != 0 {
goflags |= os.O_RDONLY
}
if flags & C.SQLITE_OPEN_READWRITE != 0 {
goflags |= os.O_RDWR
}
if flags & C.SQLITE_OPEN_CREATE != 0 {
goflags |= os.O_RDWR | os.O_CREATE | os.O_TRUNC
}
if flags & C.SQLITE_OPEN_DELETEONCLOSE != 0 {
// TODO: Do something.
}
if flags & C.SQLITE_OPEN_EXCLUSIVE != 0{
goflags |= os.O_EXCL
}
file, err := os.OpenFile(C.GoString(filename), goflags, 0666)
defer func() {
if err != nil {
println("got error:", err.String())
}
println("returning fd", fd);
}()
if err != nil {
return -1
}
file_map_mutex.Lock()
defer file_map_mutex.Unlock()
file_map[file.Fd()] = file
return file.Fd()
}