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metaforce/hecl/lib/database/sqlite_hecl_mem_vfs.c

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#include "sqlite_hecl_vfs.h"
#include "sqlite3.h"
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/*
* Modified test_onefile.c VFS for sqlite3
*
* This VFS gets registered with sqlite to access an in-memory,
* block-compressed LBA. It's designed for read-only access of
* a packed object-database.
*
* Journal and temp read/write is unsupported and will call abort
* if attempted.
*/
/*
* App-supplied callback called when file is closed (ready to access)
*/
static TCloseCallback CLOSE_CALLBACK = NULL;
static void* CLOSE_CTX = NULL;
typedef struct mem_file mem_file;
struct mem_file
{
sqlite3_file base;
int nSize;
int nAlloc;
char* zAlloc;
};
/*
** Method declarations for mem_file.
*/
static int memClose(sqlite3_file*);
static int memRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int memWrite(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
static int memTruncate(sqlite3_file*, sqlite3_int64 size);
static int memSync(sqlite3_file*, int flags);
static int memFileSize(sqlite3_file*, sqlite3_int64* pSize);
static int memLock(sqlite3_file*, int);
static int memUnlock(sqlite3_file*, int);
static int memCheckReservedLock(sqlite3_file*, int* pResOut);
static int memFileControl(sqlite3_file*, int op, void* pArg);
static int memSectorSize(sqlite3_file*);
static int memDeviceCharacteristics(sqlite3_file*);
/*
** Method declarations for fs_vfs.
*/
static int memOpen(sqlite3_vfs*, const char*, sqlite3_file*, int , int*);
static int memDelete(sqlite3_vfs*, const char* zName, int syncDir);
static int memAccess(sqlite3_vfs*, const char* zName, int flags, int*);
static int memFullPathname(sqlite3_vfs*, const char* zName, int nOut, char* zOut);
static void* memDlOpen(sqlite3_vfs*, const char* zFilename);
static void memDlError(sqlite3_vfs*, int nByte, char* zErrMsg);
static void (*memDlSym(sqlite3_vfs*, void*, const char* zSymbol))(void);
static void memDlClose(sqlite3_vfs*, void*);
static int memRandomness(sqlite3_vfs*, int nByte, char* zOut);
static int memSleep(sqlite3_vfs*, int microseconds);
static int memCurrentTime(sqlite3_vfs*, double*);
static sqlite3_vfs mem_vfs =
{
1, /* iVersion */
0, /* szOsFile */
0, /* mxPathname */
0, /* pNext */
"hecl_mem", /* zName */
0, /* pAppData */
memOpen, /* xOpen */
memDelete, /* xDelete */
memAccess, /* xAccess */
memFullPathname, /* xFullPathname */
memDlOpen, /* xDlOpen */
memDlError, /* xDlError */
memDlSym, /* xDlSym */
memDlClose, /* xDlClose */
memRandomness, /* xRandomness */
memSleep, /* xSleep */
memCurrentTime, /* xCurrentTime */
0 /* xCurrentTimeInt64 */
};
static sqlite3_io_methods mem_io_methods =
{
1, /* iVersion */
memClose, /* xClose */
memRead, /* xRead */
memWrite, /* xWrite */
memTruncate, /* xTruncate */
memSync, /* xSync */
memFileSize, /* xFileSize */
memLock, /* xLock */
memUnlock, /* xUnlock */
memCheckReservedLock, /* xCheckReservedLock */
memFileControl, /* xFileControl */
memSectorSize, /* xSectorSize */
memDeviceCharacteristics, /* xDeviceCharacteristics */
0, /* xShmMap */
0, /* xShmLock */
0, /* xShmBarrier */
0, /* xShmUnmap */
0,
0
};
/* Useful macros used in several places */
#define MIN(x,y) ((x)<(y)?(x):(y))
#define MAX(x,y) ((x)>(y)?(x):(y))
/*
** Close a mem-file.
*/
static int memClose(sqlite3_file* pFile)
{
mem_file* pTmp = (mem_file*)pFile;
if(CLOSE_CALLBACK)
CLOSE_CALLBACK(pTmp->zAlloc, pTmp->nSize, CLOSE_CTX);
else
sqlite3_free(pTmp->zAlloc);
return SQLITE_OK;
}
/*
** Read data from a mem-file.
*/
static int memRead(
sqlite3_file* pFile,
void* zBuf,
int iAmt,
sqlite_int64 iOfst
)
{
mem_file* pTmp = (mem_file*)pFile;
if((iAmt + iOfst) > pTmp->nSize)
return SQLITE_IOERR_SHORT_READ;
memcpy(zBuf, &pTmp->zAlloc[iOfst], iAmt);
return SQLITE_OK;
}
/*
** Write data to a mem-file.
*/
static int memWrite(
sqlite3_file* pFile,
const void* zBuf,
int iAmt,
sqlite_int64 iOfst
)
{
mem_file* pTmp = (mem_file*)pFile;
if((iAmt + iOfst) > pTmp->nAlloc)
{
int nNew = (int)(2 * (iAmt + iOfst + pTmp->nAlloc));
char* zNew = sqlite3_realloc(pTmp->zAlloc, nNew);
if(!zNew)
return SQLITE_NOMEM;
pTmp->zAlloc = zNew;
pTmp->nAlloc = nNew;
}
memcpy(&pTmp->zAlloc[iOfst], zBuf, iAmt);
pTmp->nSize = (int)MAX(pTmp->nSize, iOfst + iAmt);
return SQLITE_OK;
}
/*
** Truncate a mem-file.
*/
static int memTruncate(sqlite3_file* pFile, sqlite_int64 size)
{
mem_file* pTmp = (mem_file*)pFile;
pTmp->nSize = (int)MIN(pTmp->nSize, size);
return SQLITE_OK;
}
/*
** Sync a mem-file.
*/
static int memSync(sqlite3_file* pFile, int flags)
{
return SQLITE_OK;
}
/*
** Return the current file-size of a mem-file.
*/
static int memFileSize(sqlite3_file* pFile, sqlite_int64* pSize)
{
mem_file* pTmp = (mem_file*)pFile;
*pSize = pTmp->nSize;
return SQLITE_OK;
}
/*
** Lock a mem-file.
*/
static int memLock(sqlite3_file* pFile, int eLock)
{
return SQLITE_OK;
}
/*
** Unlock a mem-file.
*/
static int memUnlock(sqlite3_file* pFile, int eLock)
{
return SQLITE_OK;
}
/*
** Check if another file-handle holds a RESERVED lock on a mem-file.
*/
static int memCheckReservedLock(sqlite3_file* pFile, int* pResOut)
{
*pResOut = 0;
return SQLITE_OK;
}
/*
** File control method. For custom operations on a mem-file.
*/
static int memFileControl(sqlite3_file* pFile, int op, void* pArg)
{
return SQLITE_OK;
}
/*
** Return the sector-size in bytes for a mem-file.
*/
static int memSectorSize(sqlite3_file* pFile)
{
return 0;
}
/*
** Return the device characteristic flags supported by a mem-file.
*/
static int memDeviceCharacteristics(sqlite3_file* pFile)
{
return 0;
}
/*
** Open an mem file handle.
*/
static int memOpen(
sqlite3_vfs* pVfs,
const char* zName,
sqlite3_file* pFile,
int flags,
int* pOutFlags
)
{
if ((flags & SQLITE_OPEN_MAIN_DB) != SQLITE_OPEN_MAIN_DB)
{
fprintf(stderr, "the sqlite hecl mem VFS only supports main-db reading/writing\n");
return SQLITE_CANTOPEN;
}
mem_file* p2 = (mem_file*)pFile;
memset(p2, 0, sizeof(*p2));
p2->base.pMethods = &mem_io_methods;
return SQLITE_OK;
}
/*
** Delete the file located at zPath. If the dirSync argument is true,
** ensure the file-system modifications are synced to disk before
** returning.
*/
static int memDelete(sqlite3_vfs* pVfs, const char* zPath, int dirSync)
{
return SQLITE_OK;
}
/*
** Test for access permissions. Return true if the requested permission
** is available, or false otherwise.
*/
static int memAccess(
sqlite3_vfs* pVfs,
const char* zPath,
int flags,
int* pResOut
)
{
if(flags & SQLITE_ACCESS_READ | SQLITE_ACCESS_READWRITE)
return 1;
return 0;
}
/*
** Populate buffer zOut with the full canonical pathname corresponding
** to the pathname in zPath. zOut is guaranteed to point to a buffer
** of at least (FS_MAX_PATHNAME+1) bytes.
*/
static int memFullPathname(
sqlite3_vfs* pVfs, /* Pointer to vfs object */
const char* zPath, /* Possibly relative input path */
int nOut, /* Size of output buffer in bytes */
char* zOut) /* Output buffer */
{
strncpy(zOut, zPath, nOut);
return SQLITE_OK;
}
/*
** Open the dynamic library located at zPath and return a handle.
*/
static void* memDlOpen(sqlite3_vfs* pVfs, const char* zPath)
{
return NULL;
}
/*
** Populate the buffer zErrMsg (size nByte bytes) with a human readable
** utf-8 string describing the most recent error encountered associated
** with dynamic libraries.
*/
static void memDlError(sqlite3_vfs* pVfs, int nByte, char* zErrMsg)
{
}
/*
** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
*/
static void (*memDlSym(sqlite3_vfs* pVfs, void* pH, const char* zSym))(void)
{
}
/*
** Close the dynamic library handle pHandle.
*/
static void memDlClose(sqlite3_vfs* pVfs, void* pHandle)
{
}
/*
** Populate the buffer pointed to by zBufOut with nByte bytes of
** random data.
*/
static int memRandomness(sqlite3_vfs* pVfs, int nByte, char* zBufOut)
{
for(int i = 0 ; i < nByte ; ++i)
zBufOut[i] = rand();
return nByte;
}
/*
** Sleep for nMicro microseconds. Return the number of microseconds
** actually slept.
*/
static int memSleep(sqlite3_vfs* pVfs, int nMicro)
{
int seconds = (nMicro + 999999) / 1000000;
sleep(seconds);
return seconds * 1000000;
}
/*
** Return the current time as a Julian Day number in *pTimeOut.
*/
static int memCurrentTime(sqlite3_vfs* pVfs, double* pTimeOut)
{
*pTimeOut = 0.0;
return 0;
}
/*
** This procedure registers the mem vfs with SQLite. If the argument is
** true, the mem vfs becomes the new default vfs. It is the only publicly
** available function in this file.
*/
int sqlite_hecl_mem_vfs_register(TCloseCallback closeCb, void* ctx)
{
CLOSE_CALLBACK = closeCb;
CLOSE_CTX = ctx;
if(mem_vfs.szOsFile) return SQLITE_OK;
mem_vfs.szOsFile = sizeof(mem_file);
return sqlite3_vfs_register(&mem_vfs, 0);
}
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