xref: /sqlite-3.40.0/src/test_vfs.c (revision e8f2c9dc)
1 /*
2 ** 2010 May 05
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 ******************************************************************************
12 **
13 ** This file contains the implementation of the Tcl [testvfs] command,
14 ** used to create SQLite VFS implementations with various properties and
15 ** instrumentation to support testing SQLite.
16 **
17 **   testvfs VFSNAME ?OPTIONS?
18 **
19 ** Available options are:
20 **
21 **   -noshm      BOOLEAN        (True to omit shm methods. Default false)
22 **   -default    BOOLEAN        (True to make the vfs default. Default false)
23 **   -szosfile   INTEGER        (Value for sqlite3_vfs.szOsFile)
24 **   -mxpathname INTEGER        (Value for sqlite3_vfs.mxPathname)
25 **   -iversion   INTEGER        (Value for sqlite3_vfs.iVersion)
26 */
27 #if SQLITE_TEST          /* This file is used for testing only */
28 
29 #include "sqlite3.h"
30 #include "sqliteInt.h"
31 #include <tcl.h>
32 
33 typedef struct Testvfs Testvfs;
34 typedef struct TestvfsShm TestvfsShm;
35 typedef struct TestvfsBuffer TestvfsBuffer;
36 typedef struct TestvfsFile TestvfsFile;
37 typedef struct TestvfsFd TestvfsFd;
38 
39 /*
40 ** An open file handle.
41 */
42 struct TestvfsFile {
43   sqlite3_file base;              /* Base class.  Must be first */
44   TestvfsFd *pFd;                 /* File data */
45 };
46 #define tvfsGetFd(pFile) (((TestvfsFile *)pFile)->pFd)
47 
48 struct TestvfsFd {
49   sqlite3_vfs *pVfs;              /* The VFS */
50   const char *zFilename;          /* Filename as passed to xOpen() */
51   sqlite3_file *pReal;            /* The real, underlying file descriptor */
52   Tcl_Obj *pShmId;                /* Shared memory id for Tcl callbacks */
53 
54   TestvfsBuffer *pShm;            /* Shared memory buffer */
55   u32 excllock;                   /* Mask of exclusive locks */
56   u32 sharedlock;                 /* Mask of shared locks */
57   TestvfsFd *pNext;               /* Next handle opened on the same file */
58 };
59 
60 
61 #define FAULT_INJECT_NONE       0
62 #define FAULT_INJECT_TRANSIENT  1
63 #define FAULT_INJECT_PERSISTENT 2
64 
65 typedef struct TestFaultInject TestFaultInject;
66 struct TestFaultInject {
67   int iCnt;                       /* Remaining calls before fault injection */
68   int eFault;                     /* A FAULT_INJECT_* value */
69   int nFail;                      /* Number of faults injected */
70 };
71 
72 /*
73 ** An instance of this structure is allocated for each VFS created. The
74 ** sqlite3_vfs.pAppData field of the VFS structure registered with SQLite
75 ** is set to point to it.
76 */
77 struct Testvfs {
78   char *zName;                    /* Name of this VFS */
79   sqlite3_vfs *pParent;           /* The VFS to use for file IO */
80   sqlite3_vfs *pVfs;              /* The testvfs registered with SQLite */
81   Tcl_Interp *interp;             /* Interpreter to run script in */
82   Tcl_Obj *pScript;               /* Script to execute */
83   TestvfsBuffer *pBuffer;         /* List of shared buffers */
84   int isNoshm;
85   int isFullshm;
86 
87   int mask;                       /* Mask controlling [script] and [ioerr] */
88 
89   TestFaultInject ioerr_err;
90   TestFaultInject full_err;
91   TestFaultInject cantopen_err;
92 
93 #if 0
94   int iIoerrCnt;
95   int ioerr;
96   int nIoerrFail;
97   int iFullCnt;
98   int fullerr;
99   int nFullFail;
100 #endif
101 
102   int iDevchar;
103   int iSectorsize;
104 };
105 
106 /*
107 ** The Testvfs.mask variable is set to a combination of the following.
108 ** If a bit is clear in Testvfs.mask, then calls made by SQLite to the
109 ** corresponding VFS method is ignored for purposes of:
110 **
111 **   + Simulating IO errors, and
112 **   + Invoking the Tcl callback script.
113 */
114 #define TESTVFS_SHMOPEN_MASK      0x00000001
115 #define TESTVFS_SHMLOCK_MASK      0x00000010
116 #define TESTVFS_SHMMAP_MASK       0x00000020
117 #define TESTVFS_SHMBARRIER_MASK   0x00000040
118 #define TESTVFS_SHMCLOSE_MASK     0x00000080
119 
120 #define TESTVFS_OPEN_MASK         0x00000100
121 #define TESTVFS_SYNC_MASK         0x00000200
122 #define TESTVFS_DELETE_MASK       0x00000400
123 #define TESTVFS_CLOSE_MASK        0x00000800
124 #define TESTVFS_WRITE_MASK        0x00001000
125 #define TESTVFS_TRUNCATE_MASK     0x00002000
126 #define TESTVFS_ACCESS_MASK       0x00004000
127 #define TESTVFS_FULLPATHNAME_MASK 0x00008000
128 #define TESTVFS_READ_MASK         0x00010000
129 #define TESTVFS_UNLOCK_MASK       0x00020000
130 #define TESTVFS_LOCK_MASK         0x00040000
131 #define TESTVFS_CKLOCK_MASK       0x00080000
132 
133 #define TESTVFS_ALL_MASK          0x000FFFFF
134 
135 
136 #define TESTVFS_MAX_PAGES 1024
137 
138 /*
139 ** A shared-memory buffer. There is one of these objects for each shared
140 ** memory region opened by clients. If two clients open the same file,
141 ** there are two TestvfsFile structures but only one TestvfsBuffer structure.
142 */
143 struct TestvfsBuffer {
144   char *zFile;                    /* Associated file name */
145   int pgsz;                       /* Page size */
146   u8 *aPage[TESTVFS_MAX_PAGES];   /* Array of ckalloc'd pages */
147   TestvfsFd *pFile;               /* List of open handles */
148   TestvfsBuffer *pNext;           /* Next in linked list of all buffers */
149 };
150 
151 
152 #define PARENTVFS(x) (((Testvfs *)((x)->pAppData))->pParent)
153 
154 #define TESTVFS_MAX_ARGS 12
155 
156 
157 /*
158 ** Method declarations for TestvfsFile.
159 */
160 static int tvfsClose(sqlite3_file*);
161 static int tvfsRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
162 static int tvfsWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst);
163 static int tvfsTruncate(sqlite3_file*, sqlite3_int64 size);
164 static int tvfsSync(sqlite3_file*, int flags);
165 static int tvfsFileSize(sqlite3_file*, sqlite3_int64 *pSize);
166 static int tvfsLock(sqlite3_file*, int);
167 static int tvfsUnlock(sqlite3_file*, int);
168 static int tvfsCheckReservedLock(sqlite3_file*, int *);
169 static int tvfsFileControl(sqlite3_file*, int op, void *pArg);
170 static int tvfsSectorSize(sqlite3_file*);
171 static int tvfsDeviceCharacteristics(sqlite3_file*);
172 
173 /*
174 ** Method declarations for tvfs_vfs.
175 */
176 static int tvfsOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *);
177 static int tvfsDelete(sqlite3_vfs*, const char *zName, int syncDir);
178 static int tvfsAccess(sqlite3_vfs*, const char *zName, int flags, int *);
179 static int tvfsFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
180 #ifndef SQLITE_OMIT_LOAD_EXTENSION
181 static void *tvfsDlOpen(sqlite3_vfs*, const char *zFilename);
182 static void tvfsDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
183 static void (*tvfsDlSym(sqlite3_vfs*,void*, const char *zSymbol))(void);
184 static void tvfsDlClose(sqlite3_vfs*, void*);
185 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
186 static int tvfsRandomness(sqlite3_vfs*, int nByte, char *zOut);
187 static int tvfsSleep(sqlite3_vfs*, int microseconds);
188 static int tvfsCurrentTime(sqlite3_vfs*, double*);
189 
190 static int tvfsShmOpen(sqlite3_file*);
191 static int tvfsShmLock(sqlite3_file*, int , int, int);
192 static int tvfsShmMap(sqlite3_file*,int,int,int, void volatile **);
193 static void tvfsShmBarrier(sqlite3_file*);
194 static int tvfsShmUnmap(sqlite3_file*, int);
195 
196 static int tvfsFetch(sqlite3_file*, sqlite3_int64, int, void**);
197 static int tvfsUnfetch(sqlite3_file*, sqlite3_int64, void*);
198 
199 static sqlite3_io_methods tvfs_io_methods = {
200   3,                              /* iVersion */
201   tvfsClose,                      /* xClose */
202   tvfsRead,                       /* xRead */
203   tvfsWrite,                      /* xWrite */
204   tvfsTruncate,                   /* xTruncate */
205   tvfsSync,                       /* xSync */
206   tvfsFileSize,                   /* xFileSize */
207   tvfsLock,                       /* xLock */
208   tvfsUnlock,                     /* xUnlock */
209   tvfsCheckReservedLock,          /* xCheckReservedLock */
210   tvfsFileControl,                /* xFileControl */
211   tvfsSectorSize,                 /* xSectorSize */
212   tvfsDeviceCharacteristics,      /* xDeviceCharacteristics */
213   tvfsShmMap,                     /* xShmMap */
214   tvfsShmLock,                    /* xShmLock */
215   tvfsShmBarrier,                 /* xShmBarrier */
216   tvfsShmUnmap,                   /* xShmUnmap */
217   tvfsFetch,
218   tvfsUnfetch
219 };
220 
221 static int tvfsResultCode(Testvfs *p, int *pRc){
222   struct errcode {
223     int eCode;
224     const char *zCode;
225   } aCode[] = {
226     { SQLITE_OK,     "SQLITE_OK"     },
227     { SQLITE_ERROR,  "SQLITE_ERROR"  },
228     { SQLITE_IOERR,  "SQLITE_IOERR"  },
229     { SQLITE_LOCKED, "SQLITE_LOCKED" },
230     { SQLITE_BUSY,   "SQLITE_BUSY"   },
231   };
232 
233   const char *z;
234   int i;
235 
236   z = Tcl_GetStringResult(p->interp);
237   for(i=0; i<ArraySize(aCode); i++){
238     if( 0==strcmp(z, aCode[i].zCode) ){
239       *pRc = aCode[i].eCode;
240       return 1;
241     }
242   }
243 
244   return 0;
245 }
246 
247 static int tvfsInjectFault(TestFaultInject *p){
248   int ret = 0;
249   if( p->eFault ){
250     p->iCnt--;
251     if( p->iCnt==0 || (p->iCnt<0 && p->eFault==FAULT_INJECT_PERSISTENT ) ){
252       ret = 1;
253       p->nFail++;
254     }
255   }
256   return ret;
257 }
258 
259 
260 static int tvfsInjectIoerr(Testvfs *p){
261   return tvfsInjectFault(&p->ioerr_err);
262 }
263 
264 static int tvfsInjectFullerr(Testvfs *p){
265   return tvfsInjectFault(&p->full_err);
266 }
267 static int tvfsInjectCantopenerr(Testvfs *p){
268   return tvfsInjectFault(&p->cantopen_err);
269 }
270 
271 
272 static void tvfsExecTcl(
273   Testvfs *p,
274   const char *zMethod,
275   Tcl_Obj *arg1,
276   Tcl_Obj *arg2,
277   Tcl_Obj *arg3,
278   Tcl_Obj *arg4
279 ){
280   int rc;                         /* Return code from Tcl_EvalObj() */
281   Tcl_Obj *pEval;
282   assert( p->pScript );
283 
284   assert( zMethod );
285   assert( p );
286   assert( arg2==0 || arg1!=0 );
287   assert( arg3==0 || arg2!=0 );
288 
289   pEval = Tcl_DuplicateObj(p->pScript);
290   Tcl_IncrRefCount(p->pScript);
291   Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj(zMethod, -1));
292   if( arg1 ) Tcl_ListObjAppendElement(p->interp, pEval, arg1);
293   if( arg2 ) Tcl_ListObjAppendElement(p->interp, pEval, arg2);
294   if( arg3 ) Tcl_ListObjAppendElement(p->interp, pEval, arg3);
295   if( arg4 ) Tcl_ListObjAppendElement(p->interp, pEval, arg4);
296 
297   rc = Tcl_EvalObjEx(p->interp, pEval, TCL_EVAL_GLOBAL);
298   if( rc!=TCL_OK ){
299     Tcl_BackgroundError(p->interp);
300     Tcl_ResetResult(p->interp);
301   }
302 }
303 
304 
305 /*
306 ** Close an tvfs-file.
307 */
308 static int tvfsClose(sqlite3_file *pFile){
309   int rc;
310   TestvfsFile *pTestfile = (TestvfsFile *)pFile;
311   TestvfsFd *pFd = pTestfile->pFd;
312   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
313 
314   if( p->pScript && p->mask&TESTVFS_CLOSE_MASK ){
315     tvfsExecTcl(p, "xClose",
316         Tcl_NewStringObj(pFd->zFilename, -1), pFd->pShmId, 0, 0
317     );
318   }
319 
320   if( pFd->pShmId ){
321     Tcl_DecrRefCount(pFd->pShmId);
322     pFd->pShmId = 0;
323   }
324   if( pFile->pMethods ){
325     ckfree((char *)pFile->pMethods);
326   }
327   rc = sqlite3OsClose(pFd->pReal);
328   ckfree((char *)pFd);
329   pTestfile->pFd = 0;
330   return rc;
331 }
332 
333 /*
334 ** Read data from an tvfs-file.
335 */
336 static int tvfsRead(
337   sqlite3_file *pFile,
338   void *zBuf,
339   int iAmt,
340   sqlite_int64 iOfst
341 ){
342   int rc = SQLITE_OK;
343   TestvfsFd *pFd = tvfsGetFd(pFile);
344   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
345   if( p->pScript && p->mask&TESTVFS_READ_MASK ){
346     tvfsExecTcl(p, "xRead",
347         Tcl_NewStringObj(pFd->zFilename, -1), pFd->pShmId, 0, 0
348     );
349     tvfsResultCode(p, &rc);
350   }
351   if( rc==SQLITE_OK && p->mask&TESTVFS_READ_MASK && tvfsInjectIoerr(p) ){
352     rc = SQLITE_IOERR;
353   }
354   if( rc==SQLITE_OK ){
355     rc = sqlite3OsRead(pFd->pReal, zBuf, iAmt, iOfst);
356   }
357   return rc;
358 }
359 
360 /*
361 ** Write data to an tvfs-file.
362 */
363 static int tvfsWrite(
364   sqlite3_file *pFile,
365   const void *zBuf,
366   int iAmt,
367   sqlite_int64 iOfst
368 ){
369   int rc = SQLITE_OK;
370   TestvfsFd *pFd = tvfsGetFd(pFile);
371   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
372 
373   if( p->pScript && p->mask&TESTVFS_WRITE_MASK ){
374     tvfsExecTcl(p, "xWrite",
375         Tcl_NewStringObj(pFd->zFilename, -1), pFd->pShmId,
376         Tcl_NewWideIntObj(iOfst), Tcl_NewIntObj(iAmt)
377     );
378     tvfsResultCode(p, &rc);
379   }
380 
381   if( rc==SQLITE_OK && tvfsInjectFullerr(p) ){
382     rc = SQLITE_FULL;
383   }
384   if( rc==SQLITE_OK && p->mask&TESTVFS_WRITE_MASK && tvfsInjectIoerr(p) ){
385     rc = SQLITE_IOERR;
386   }
387 
388   if( rc==SQLITE_OK ){
389     rc = sqlite3OsWrite(pFd->pReal, zBuf, iAmt, iOfst);
390   }
391   return rc;
392 }
393 
394 /*
395 ** Truncate an tvfs-file.
396 */
397 static int tvfsTruncate(sqlite3_file *pFile, sqlite_int64 size){
398   int rc = SQLITE_OK;
399   TestvfsFd *pFd = tvfsGetFd(pFile);
400   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
401 
402   if( p->pScript && p->mask&TESTVFS_TRUNCATE_MASK ){
403     tvfsExecTcl(p, "xTruncate",
404         Tcl_NewStringObj(pFd->zFilename, -1), pFd->pShmId, 0, 0
405     );
406     tvfsResultCode(p, &rc);
407   }
408 
409   if( rc==SQLITE_OK ){
410     rc = sqlite3OsTruncate(pFd->pReal, size);
411   }
412   return rc;
413 }
414 
415 /*
416 ** Sync an tvfs-file.
417 */
418 static int tvfsSync(sqlite3_file *pFile, int flags){
419   int rc = SQLITE_OK;
420   TestvfsFd *pFd = tvfsGetFd(pFile);
421   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
422 
423   if( p->pScript && p->mask&TESTVFS_SYNC_MASK ){
424     char *zFlags;
425 
426     switch( flags ){
427       case SQLITE_SYNC_NORMAL:
428         zFlags = "normal";
429         break;
430       case SQLITE_SYNC_FULL:
431         zFlags = "full";
432         break;
433       case SQLITE_SYNC_NORMAL|SQLITE_SYNC_DATAONLY:
434         zFlags = "normal|dataonly";
435         break;
436       case SQLITE_SYNC_FULL|SQLITE_SYNC_DATAONLY:
437         zFlags = "full|dataonly";
438         break;
439       default:
440         assert(0);
441     }
442 
443     tvfsExecTcl(p, "xSync",
444         Tcl_NewStringObj(pFd->zFilename, -1), pFd->pShmId,
445         Tcl_NewStringObj(zFlags, -1), 0
446     );
447     tvfsResultCode(p, &rc);
448   }
449 
450   if( rc==SQLITE_OK && tvfsInjectFullerr(p) ) rc = SQLITE_FULL;
451 
452   if( rc==SQLITE_OK ){
453     rc = sqlite3OsSync(pFd->pReal, flags);
454   }
455 
456   return rc;
457 }
458 
459 /*
460 ** Return the current file-size of an tvfs-file.
461 */
462 static int tvfsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
463   TestvfsFd *p = tvfsGetFd(pFile);
464   return sqlite3OsFileSize(p->pReal, pSize);
465 }
466 
467 /*
468 ** Lock an tvfs-file.
469 */
470 static int tvfsLock(sqlite3_file *pFile, int eLock){
471   TestvfsFd *pFd = tvfsGetFd(pFile);
472   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
473   if( p->pScript && p->mask&TESTVFS_LOCK_MASK ){
474     char zLock[30];
475     sqlite3_snprintf(sizeof(zLock),zLock,"%d",eLock);
476     tvfsExecTcl(p, "xLock", Tcl_NewStringObj(pFd->zFilename, -1),
477                    Tcl_NewStringObj(zLock, -1), 0, 0);
478   }
479   return sqlite3OsLock(pFd->pReal, eLock);
480 }
481 
482 /*
483 ** Unlock an tvfs-file.
484 */
485 static int tvfsUnlock(sqlite3_file *pFile, int eLock){
486   TestvfsFd *pFd = tvfsGetFd(pFile);
487   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
488   if( p->pScript && p->mask&TESTVFS_UNLOCK_MASK ){
489     char zLock[30];
490     sqlite3_snprintf(sizeof(zLock),zLock,"%d",eLock);
491     tvfsExecTcl(p, "xUnlock", Tcl_NewStringObj(pFd->zFilename, -1),
492                    Tcl_NewStringObj(zLock, -1), 0, 0);
493   }
494   if( p->mask&TESTVFS_WRITE_MASK && tvfsInjectIoerr(p) ){
495     return SQLITE_IOERR_UNLOCK;
496   }
497   return sqlite3OsUnlock(pFd->pReal, eLock);
498 }
499 
500 /*
501 ** Check if another file-handle holds a RESERVED lock on an tvfs-file.
502 */
503 static int tvfsCheckReservedLock(sqlite3_file *pFile, int *pResOut){
504   TestvfsFd *pFd = tvfsGetFd(pFile);
505   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
506   if( p->pScript && p->mask&TESTVFS_CKLOCK_MASK ){
507     tvfsExecTcl(p, "xCheckReservedLock", Tcl_NewStringObj(pFd->zFilename, -1),
508                    0, 0, 0);
509   }
510   return sqlite3OsCheckReservedLock(pFd->pReal, pResOut);
511 }
512 
513 /*
514 ** File control method. For custom operations on an tvfs-file.
515 */
516 static int tvfsFileControl(sqlite3_file *pFile, int op, void *pArg){
517   TestvfsFd *p = tvfsGetFd(pFile);
518   if( op==SQLITE_FCNTL_PRAGMA ){
519     char **argv = (char**)pArg;
520     if( sqlite3_stricmp(argv[1],"error")==0 ){
521       int rc = SQLITE_ERROR;
522       if( argv[2] ){
523         const char *z = argv[2];
524         int x = atoi(z);
525         if( x ){
526           rc = x;
527           while( sqlite3Isdigit(z[0]) ){ z++; }
528           while( sqlite3Isspace(z[0]) ){ z++; }
529         }
530         if( z[0] ) argv[0] = sqlite3_mprintf("%s", z);
531       }
532       return rc;
533     }
534     if( sqlite3_stricmp(argv[1], "filename")==0 ){
535       argv[0] = sqlite3_mprintf("%s", p->zFilename);
536       return SQLITE_OK;
537     }
538   }
539   return sqlite3OsFileControl(p->pReal, op, pArg);
540 }
541 
542 /*
543 ** Return the sector-size in bytes for an tvfs-file.
544 */
545 static int tvfsSectorSize(sqlite3_file *pFile){
546   TestvfsFd *pFd = tvfsGetFd(pFile);
547   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
548   if( p->iSectorsize>=0 ){
549     return p->iSectorsize;
550   }
551   return sqlite3OsSectorSize(pFd->pReal);
552 }
553 
554 /*
555 ** Return the device characteristic flags supported by an tvfs-file.
556 */
557 static int tvfsDeviceCharacteristics(sqlite3_file *pFile){
558   TestvfsFd *pFd = tvfsGetFd(pFile);
559   Testvfs *p = (Testvfs *)pFd->pVfs->pAppData;
560   if( p->iDevchar>=0 ){
561     return p->iDevchar;
562   }
563   return sqlite3OsDeviceCharacteristics(pFd->pReal);
564 }
565 
566 /*
567 ** Open an tvfs file handle.
568 */
569 static int tvfsOpen(
570   sqlite3_vfs *pVfs,
571   const char *zName,
572   sqlite3_file *pFile,
573   int flags,
574   int *pOutFlags
575 ){
576   int rc;
577   TestvfsFile *pTestfile = (TestvfsFile *)pFile;
578   TestvfsFd *pFd;
579   Tcl_Obj *pId = 0;
580   Testvfs *p = (Testvfs *)pVfs->pAppData;
581 
582   pFd = (TestvfsFd *)ckalloc(sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
583   memset(pFd, 0, sizeof(TestvfsFd) + PARENTVFS(pVfs)->szOsFile);
584   pFd->pShm = 0;
585   pFd->pShmId = 0;
586   pFd->zFilename = zName;
587   pFd->pVfs = pVfs;
588   pFd->pReal = (sqlite3_file *)&pFd[1];
589   memset(pTestfile, 0, sizeof(TestvfsFile));
590   pTestfile->pFd = pFd;
591 
592   /* Evaluate the Tcl script:
593   **
594   **   SCRIPT xOpen FILENAME KEY-VALUE-ARGS
595   **
596   ** If the script returns an SQLite error code other than SQLITE_OK, an
597   ** error is returned to the caller. If it returns SQLITE_OK, the new
598   ** connection is named "anon". Otherwise, the value returned by the
599   ** script is used as the connection name.
600   */
601   Tcl_ResetResult(p->interp);
602   if( p->pScript && p->mask&TESTVFS_OPEN_MASK ){
603     Tcl_Obj *pArg = Tcl_NewObj();
604     Tcl_IncrRefCount(pArg);
605     if( flags&SQLITE_OPEN_MAIN_DB ){
606       const char *z = &zName[strlen(zName)+1];
607       while( *z ){
608         Tcl_ListObjAppendElement(0, pArg, Tcl_NewStringObj(z, -1));
609         z += strlen(z) + 1;
610         Tcl_ListObjAppendElement(0, pArg, Tcl_NewStringObj(z, -1));
611         z += strlen(z) + 1;
612       }
613     }
614     tvfsExecTcl(p, "xOpen", Tcl_NewStringObj(pFd->zFilename, -1), pArg, 0, 0);
615     Tcl_DecrRefCount(pArg);
616     if( tvfsResultCode(p, &rc) ){
617       if( rc!=SQLITE_OK ) return rc;
618     }else{
619       pId = Tcl_GetObjResult(p->interp);
620     }
621   }
622 
623   if( (p->mask&TESTVFS_OPEN_MASK) &&  tvfsInjectIoerr(p) ) return SQLITE_IOERR;
624   if( tvfsInjectCantopenerr(p) ) return SQLITE_CANTOPEN;
625   if( tvfsInjectFullerr(p) ) return SQLITE_FULL;
626 
627   if( !pId ){
628     pId = Tcl_NewStringObj("anon", -1);
629   }
630   Tcl_IncrRefCount(pId);
631   pFd->pShmId = pId;
632   Tcl_ResetResult(p->interp);
633 
634   rc = sqlite3OsOpen(PARENTVFS(pVfs), zName, pFd->pReal, flags, pOutFlags);
635   if( pFd->pReal->pMethods ){
636     sqlite3_io_methods *pMethods;
637     int nByte;
638 
639     if( pVfs->iVersion>1 ){
640       nByte = sizeof(sqlite3_io_methods);
641     }else{
642       nByte = offsetof(sqlite3_io_methods, xShmMap);
643     }
644 
645     pMethods = (sqlite3_io_methods *)ckalloc(nByte);
646     memcpy(pMethods, &tvfs_io_methods, nByte);
647     pMethods->iVersion = pFd->pReal->pMethods->iVersion;
648     if( pMethods->iVersion>pVfs->iVersion ){
649       pMethods->iVersion = pVfs->iVersion;
650     }
651     if( pVfs->iVersion>1 && ((Testvfs *)pVfs->pAppData)->isNoshm ){
652       pMethods->xShmUnmap = 0;
653       pMethods->xShmLock = 0;
654       pMethods->xShmBarrier = 0;
655       pMethods->xShmMap = 0;
656     }
657     pFile->pMethods = pMethods;
658   }
659 
660   return rc;
661 }
662 
663 /*
664 ** Delete the file located at zPath. If the dirSync argument is true,
665 ** ensure the file-system modifications are synced to disk before
666 ** returning.
667 */
668 static int tvfsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
669   int rc = SQLITE_OK;
670   Testvfs *p = (Testvfs *)pVfs->pAppData;
671 
672   if( p->pScript && p->mask&TESTVFS_DELETE_MASK ){
673     tvfsExecTcl(p, "xDelete",
674         Tcl_NewStringObj(zPath, -1), Tcl_NewIntObj(dirSync), 0, 0
675     );
676     tvfsResultCode(p, &rc);
677   }
678   if( rc==SQLITE_OK ){
679     rc = sqlite3OsDelete(PARENTVFS(pVfs), zPath, dirSync);
680   }
681   return rc;
682 }
683 
684 /*
685 ** Test for access permissions. Return true if the requested permission
686 ** is available, or false otherwise.
687 */
688 static int tvfsAccess(
689   sqlite3_vfs *pVfs,
690   const char *zPath,
691   int flags,
692   int *pResOut
693 ){
694   Testvfs *p = (Testvfs *)pVfs->pAppData;
695   if( p->pScript && p->mask&TESTVFS_ACCESS_MASK ){
696     int rc;
697     char *zArg = 0;
698     if( flags==SQLITE_ACCESS_EXISTS ) zArg = "SQLITE_ACCESS_EXISTS";
699     if( flags==SQLITE_ACCESS_READWRITE ) zArg = "SQLITE_ACCESS_READWRITE";
700     if( flags==SQLITE_ACCESS_READ ) zArg = "SQLITE_ACCESS_READ";
701     tvfsExecTcl(p, "xAccess",
702         Tcl_NewStringObj(zPath, -1), Tcl_NewStringObj(zArg, -1), 0, 0
703     );
704     if( tvfsResultCode(p, &rc) ){
705       if( rc!=SQLITE_OK ) return rc;
706     }else{
707       Tcl_Interp *interp = p->interp;
708       if( TCL_OK==Tcl_GetBooleanFromObj(0, Tcl_GetObjResult(interp), pResOut) ){
709         return SQLITE_OK;
710       }
711     }
712   }
713   return sqlite3OsAccess(PARENTVFS(pVfs), zPath, flags, pResOut);
714 }
715 
716 /*
717 ** Populate buffer zOut with the full canonical pathname corresponding
718 ** to the pathname in zPath. zOut is guaranteed to point to a buffer
719 ** of at least (DEVSYM_MAX_PATHNAME+1) bytes.
720 */
721 static int tvfsFullPathname(
722   sqlite3_vfs *pVfs,
723   const char *zPath,
724   int nOut,
725   char *zOut
726 ){
727   Testvfs *p = (Testvfs *)pVfs->pAppData;
728   if( p->pScript && p->mask&TESTVFS_FULLPATHNAME_MASK ){
729     int rc;
730     tvfsExecTcl(p, "xFullPathname", Tcl_NewStringObj(zPath, -1), 0, 0, 0);
731     if( tvfsResultCode(p, &rc) ){
732       if( rc!=SQLITE_OK ) return rc;
733     }
734   }
735   return sqlite3OsFullPathname(PARENTVFS(pVfs), zPath, nOut, zOut);
736 }
737 
738 #ifndef SQLITE_OMIT_LOAD_EXTENSION
739 /*
740 ** Open the dynamic library located at zPath and return a handle.
741 */
742 static void *tvfsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
743   return sqlite3OsDlOpen(PARENTVFS(pVfs), zPath);
744 }
745 
746 /*
747 ** Populate the buffer zErrMsg (size nByte bytes) with a human readable
748 ** utf-8 string describing the most recent error encountered associated
749 ** with dynamic libraries.
750 */
751 static void tvfsDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
752   sqlite3OsDlError(PARENTVFS(pVfs), nByte, zErrMsg);
753 }
754 
755 /*
756 ** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
757 */
758 static void (*tvfsDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){
759   return sqlite3OsDlSym(PARENTVFS(pVfs), p, zSym);
760 }
761 
762 /*
763 ** Close the dynamic library handle pHandle.
764 */
765 static void tvfsDlClose(sqlite3_vfs *pVfs, void *pHandle){
766   sqlite3OsDlClose(PARENTVFS(pVfs), pHandle);
767 }
768 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
769 
770 /*
771 ** Populate the buffer pointed to by zBufOut with nByte bytes of
772 ** random data.
773 */
774 static int tvfsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
775   return sqlite3OsRandomness(PARENTVFS(pVfs), nByte, zBufOut);
776 }
777 
778 /*
779 ** Sleep for nMicro microseconds. Return the number of microseconds
780 ** actually slept.
781 */
782 static int tvfsSleep(sqlite3_vfs *pVfs, int nMicro){
783   return sqlite3OsSleep(PARENTVFS(pVfs), nMicro);
784 }
785 
786 /*
787 ** Return the current time as a Julian Day number in *pTimeOut.
788 */
789 static int tvfsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
790   return PARENTVFS(pVfs)->xCurrentTime(PARENTVFS(pVfs), pTimeOut);
791 }
792 
793 static int tvfsShmOpen(sqlite3_file *pFile){
794   Testvfs *p;
795   int rc = SQLITE_OK;             /* Return code */
796   TestvfsBuffer *pBuffer;         /* Buffer to open connection to */
797   TestvfsFd *pFd;                 /* The testvfs file structure */
798 
799   pFd = tvfsGetFd(pFile);
800   p = (Testvfs *)pFd->pVfs->pAppData;
801   assert( 0==p->isFullshm );
802   assert( pFd->pShmId && pFd->pShm==0 && pFd->pNext==0 );
803 
804   /* Evaluate the Tcl script:
805   **
806   **   SCRIPT xShmOpen FILENAME
807   */
808   Tcl_ResetResult(p->interp);
809   if( p->pScript && p->mask&TESTVFS_SHMOPEN_MASK ){
810     tvfsExecTcl(p, "xShmOpen", Tcl_NewStringObj(pFd->zFilename, -1), 0, 0, 0);
811     if( tvfsResultCode(p, &rc) ){
812       if( rc!=SQLITE_OK ) return rc;
813     }
814   }
815 
816   assert( rc==SQLITE_OK );
817   if( p->mask&TESTVFS_SHMOPEN_MASK && tvfsInjectIoerr(p) ){
818     return SQLITE_IOERR;
819   }
820 
821   /* Search for a TestvfsBuffer. Create a new one if required. */
822   for(pBuffer=p->pBuffer; pBuffer; pBuffer=pBuffer->pNext){
823     if( 0==strcmp(pFd->zFilename, pBuffer->zFile) ) break;
824   }
825   if( !pBuffer ){
826     int nByte = sizeof(TestvfsBuffer) + (int)strlen(pFd->zFilename) + 1;
827     pBuffer = (TestvfsBuffer *)ckalloc(nByte);
828     memset(pBuffer, 0, nByte);
829     pBuffer->zFile = (char *)&pBuffer[1];
830     strcpy(pBuffer->zFile, pFd->zFilename);
831     pBuffer->pNext = p->pBuffer;
832     p->pBuffer = pBuffer;
833   }
834 
835   /* Connect the TestvfsBuffer to the new TestvfsShm handle and return. */
836   pFd->pNext = pBuffer->pFile;
837   pBuffer->pFile = pFd;
838   pFd->pShm = pBuffer;
839   return SQLITE_OK;
840 }
841 
842 static void tvfsAllocPage(TestvfsBuffer *p, int iPage, int pgsz){
843   assert( iPage<TESTVFS_MAX_PAGES );
844   if( p->aPage[iPage]==0 ){
845     p->aPage[iPage] = (u8 *)ckalloc(pgsz);
846     memset(p->aPage[iPage], 0, pgsz);
847     p->pgsz = pgsz;
848   }
849 }
850 
851 static int tvfsShmMap(
852   sqlite3_file *pFile,            /* Handle open on database file */
853   int iPage,                      /* Page to retrieve */
854   int pgsz,                       /* Size of pages */
855   int isWrite,                    /* True to extend file if necessary */
856   void volatile **pp              /* OUT: Mapped memory */
857 ){
858   int rc = SQLITE_OK;
859   TestvfsFd *pFd = tvfsGetFd(pFile);
860   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
861 
862   if( p->isFullshm ){
863     return sqlite3OsShmMap(pFd->pReal, iPage, pgsz, isWrite, pp);
864   }
865 
866   if( 0==pFd->pShm ){
867     rc = tvfsShmOpen(pFile);
868     if( rc!=SQLITE_OK ){
869       return rc;
870     }
871   }
872 
873   if( p->pScript && p->mask&TESTVFS_SHMMAP_MASK ){
874     Tcl_Obj *pArg = Tcl_NewObj();
875     Tcl_IncrRefCount(pArg);
876     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(iPage));
877     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(pgsz));
878     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(isWrite));
879     tvfsExecTcl(p, "xShmMap",
880         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, pArg, 0
881     );
882     tvfsResultCode(p, &rc);
883     Tcl_DecrRefCount(pArg);
884   }
885   if( rc==SQLITE_OK && p->mask&TESTVFS_SHMMAP_MASK && tvfsInjectIoerr(p) ){
886     rc = SQLITE_IOERR;
887   }
888 
889   if( rc==SQLITE_OK && isWrite && !pFd->pShm->aPage[iPage] ){
890     tvfsAllocPage(pFd->pShm, iPage, pgsz);
891   }
892   *pp = (void volatile *)pFd->pShm->aPage[iPage];
893 
894   return rc;
895 }
896 
897 
898 static int tvfsShmLock(
899   sqlite3_file *pFile,
900   int ofst,
901   int n,
902   int flags
903 ){
904   int rc = SQLITE_OK;
905   TestvfsFd *pFd = tvfsGetFd(pFile);
906   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
907   int nLock;
908   char zLock[80];
909 
910   if( p->isFullshm ){
911     return sqlite3OsShmLock(pFd->pReal, ofst, n, flags);
912   }
913 
914   if( p->pScript && p->mask&TESTVFS_SHMLOCK_MASK ){
915     sqlite3_snprintf(sizeof(zLock), zLock, "%d %d", ofst, n);
916     nLock = (int)strlen(zLock);
917     if( flags & SQLITE_SHM_LOCK ){
918       strcpy(&zLock[nLock], " lock");
919     }else{
920       strcpy(&zLock[nLock], " unlock");
921     }
922     nLock += (int)strlen(&zLock[nLock]);
923     if( flags & SQLITE_SHM_SHARED ){
924       strcpy(&zLock[nLock], " shared");
925     }else{
926       strcpy(&zLock[nLock], " exclusive");
927     }
928     tvfsExecTcl(p, "xShmLock",
929         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId,
930         Tcl_NewStringObj(zLock, -1), 0
931     );
932     tvfsResultCode(p, &rc);
933   }
934 
935   if( rc==SQLITE_OK && p->mask&TESTVFS_SHMLOCK_MASK && tvfsInjectIoerr(p) ){
936     rc = SQLITE_IOERR;
937   }
938 
939   if( rc==SQLITE_OK ){
940     int isLock = (flags & SQLITE_SHM_LOCK);
941     int isExcl = (flags & SQLITE_SHM_EXCLUSIVE);
942     u32 mask = (((1<<n)-1) << ofst);
943     if( isLock ){
944       TestvfsFd *p2;
945       for(p2=pFd->pShm->pFile; p2; p2=p2->pNext){
946         if( p2==pFd ) continue;
947         if( (p2->excllock&mask) || (isExcl && p2->sharedlock&mask) ){
948           rc = SQLITE_BUSY;
949           break;
950         }
951       }
952       if( rc==SQLITE_OK ){
953         if( isExcl )  pFd->excllock |= mask;
954         if( !isExcl ) pFd->sharedlock |= mask;
955       }
956     }else{
957       if( isExcl )  pFd->excllock &= (~mask);
958       if( !isExcl ) pFd->sharedlock &= (~mask);
959     }
960   }
961 
962   return rc;
963 }
964 
965 static void tvfsShmBarrier(sqlite3_file *pFile){
966   TestvfsFd *pFd = tvfsGetFd(pFile);
967   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
968 
969   if( p->isFullshm ){
970     sqlite3OsShmBarrier(pFd->pReal);
971     return;
972   }
973 
974   if( p->pScript && p->mask&TESTVFS_SHMBARRIER_MASK ){
975     tvfsExecTcl(p, "xShmBarrier",
976         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0, 0
977     );
978   }
979 }
980 
981 static int tvfsShmUnmap(
982   sqlite3_file *pFile,
983   int deleteFlag
984 ){
985   int rc = SQLITE_OK;
986   TestvfsFd *pFd = tvfsGetFd(pFile);
987   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
988   TestvfsBuffer *pBuffer = pFd->pShm;
989   TestvfsFd **ppFd;
990 
991   if( p->isFullshm ){
992     return sqlite3OsShmUnmap(pFd->pReal, deleteFlag);
993   }
994 
995   if( !pBuffer ) return SQLITE_OK;
996   assert( pFd->pShmId && pFd->pShm );
997 
998   if( p->pScript && p->mask&TESTVFS_SHMCLOSE_MASK ){
999     tvfsExecTcl(p, "xShmUnmap",
1000         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0, 0
1001     );
1002     tvfsResultCode(p, &rc);
1003   }
1004 
1005   for(ppFd=&pBuffer->pFile; *ppFd!=pFd; ppFd=&((*ppFd)->pNext));
1006   assert( (*ppFd)==pFd );
1007   *ppFd = pFd->pNext;
1008   pFd->pNext = 0;
1009 
1010   if( pBuffer->pFile==0 ){
1011     int i;
1012     TestvfsBuffer **pp;
1013     for(pp=&p->pBuffer; *pp!=pBuffer; pp=&((*pp)->pNext));
1014     *pp = (*pp)->pNext;
1015     for(i=0; pBuffer->aPage[i]; i++){
1016       ckfree((char *)pBuffer->aPage[i]);
1017     }
1018     ckfree((char *)pBuffer);
1019   }
1020   pFd->pShm = 0;
1021 
1022   return rc;
1023 }
1024 
1025 static int tvfsFetch(
1026     sqlite3_file *pFile,
1027     sqlite3_int64 iOfst,
1028     int iAmt,
1029     void **pp
1030 ){
1031   TestvfsFd *pFd = tvfsGetFd(pFile);
1032   return sqlite3OsFetch(pFd->pReal, iOfst, iAmt, pp);
1033 }
1034 
1035 static int tvfsUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *p){
1036   TestvfsFd *pFd = tvfsGetFd(pFile);
1037   return sqlite3OsUnfetch(pFd->pReal, iOfst, p);
1038 }
1039 
1040 static int testvfs_obj_cmd(
1041   ClientData cd,
1042   Tcl_Interp *interp,
1043   int objc,
1044   Tcl_Obj *CONST objv[]
1045 ){
1046   Testvfs *p = (Testvfs *)cd;
1047 
1048   enum DB_enum {
1049     CMD_SHM, CMD_DELETE, CMD_FILTER, CMD_IOERR, CMD_SCRIPT,
1050     CMD_DEVCHAR, CMD_SECTORSIZE, CMD_FULLERR, CMD_CANTOPENERR
1051   };
1052   struct TestvfsSubcmd {
1053     char *zName;
1054     enum DB_enum eCmd;
1055   } aSubcmd[] = {
1056     { "shm",         CMD_SHM         },
1057     { "delete",      CMD_DELETE      },
1058     { "filter",      CMD_FILTER      },
1059     { "ioerr",       CMD_IOERR       },
1060     { "fullerr",     CMD_FULLERR     },
1061     { "cantopenerr", CMD_CANTOPENERR },
1062     { "script",      CMD_SCRIPT      },
1063     { "devchar",     CMD_DEVCHAR     },
1064     { "sectorsize",  CMD_SECTORSIZE  },
1065     { 0, 0 }
1066   };
1067   int i;
1068 
1069   if( objc<2 ){
1070     Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
1071     return TCL_ERROR;
1072   }
1073   if( Tcl_GetIndexFromObjStruct(
1074         interp, objv[1], aSubcmd, sizeof(aSubcmd[0]), "subcommand", 0, &i)
1075   ){
1076     return TCL_ERROR;
1077   }
1078   Tcl_ResetResult(interp);
1079 
1080   switch( aSubcmd[i].eCmd ){
1081     case CMD_SHM: {
1082       Tcl_Obj *pObj;
1083       int i, rc;
1084       TestvfsBuffer *pBuffer;
1085       char *zName;
1086       if( objc!=3 && objc!=4 ){
1087         Tcl_WrongNumArgs(interp, 2, objv, "FILE ?VALUE?");
1088         return TCL_ERROR;
1089       }
1090       zName = ckalloc(p->pParent->mxPathname);
1091       rc = p->pParent->xFullPathname(
1092           p->pParent, Tcl_GetString(objv[2]),
1093           p->pParent->mxPathname, zName
1094       );
1095       if( rc!=SQLITE_OK ){
1096         Tcl_AppendResult(interp, "failed to get full path: ",
1097                          Tcl_GetString(objv[2]), 0);
1098         ckfree(zName);
1099         return TCL_ERROR;
1100       }
1101       for(pBuffer=p->pBuffer; pBuffer; pBuffer=pBuffer->pNext){
1102         if( 0==strcmp(pBuffer->zFile, zName) ) break;
1103       }
1104       ckfree(zName);
1105       if( !pBuffer ){
1106         Tcl_AppendResult(interp, "no such file: ", Tcl_GetString(objv[2]), 0);
1107         return TCL_ERROR;
1108       }
1109       if( objc==4 ){
1110         int n;
1111         u8 *a = Tcl_GetByteArrayFromObj(objv[3], &n);
1112         int pgsz = pBuffer->pgsz;
1113         if( pgsz==0 ) pgsz = 65536;
1114         for(i=0; i*pgsz<n; i++){
1115           int nByte = pgsz;
1116           tvfsAllocPage(pBuffer, i, pgsz);
1117           if( n-i*pgsz<pgsz ){
1118             nByte = n;
1119           }
1120           memcpy(pBuffer->aPage[i], &a[i*pgsz], nByte);
1121         }
1122       }
1123 
1124       pObj = Tcl_NewObj();
1125       for(i=0; pBuffer->aPage[i]; i++){
1126         int pgsz = pBuffer->pgsz;
1127         if( pgsz==0 ) pgsz = 65536;
1128         Tcl_AppendObjToObj(pObj, Tcl_NewByteArrayObj(pBuffer->aPage[i], pgsz));
1129       }
1130       Tcl_SetObjResult(interp, pObj);
1131       break;
1132     }
1133 
1134     /*  TESTVFS filter METHOD-LIST
1135     **
1136     **     Activate special processing for those methods contained in the list
1137     */
1138     case CMD_FILTER: {
1139       static struct VfsMethod {
1140         char *zName;
1141         int mask;
1142       } vfsmethod [] = {
1143         { "xShmOpen",           TESTVFS_SHMOPEN_MASK },
1144         { "xShmLock",           TESTVFS_SHMLOCK_MASK },
1145         { "xShmBarrier",        TESTVFS_SHMBARRIER_MASK },
1146         { "xShmUnmap",          TESTVFS_SHMCLOSE_MASK },
1147         { "xShmMap",            TESTVFS_SHMMAP_MASK },
1148         { "xSync",              TESTVFS_SYNC_MASK },
1149         { "xDelete",            TESTVFS_DELETE_MASK },
1150         { "xWrite",             TESTVFS_WRITE_MASK },
1151         { "xRead",              TESTVFS_READ_MASK },
1152         { "xTruncate",          TESTVFS_TRUNCATE_MASK },
1153         { "xOpen",              TESTVFS_OPEN_MASK },
1154         { "xClose",             TESTVFS_CLOSE_MASK },
1155         { "xAccess",            TESTVFS_ACCESS_MASK },
1156         { "xFullPathname",      TESTVFS_FULLPATHNAME_MASK },
1157         { "xUnlock",            TESTVFS_UNLOCK_MASK },
1158         { "xLock",              TESTVFS_LOCK_MASK },
1159         { "xCheckReservedLock", TESTVFS_CKLOCK_MASK },
1160       };
1161       Tcl_Obj **apElem = 0;
1162       int nElem = 0;
1163       int i;
1164       int mask = 0;
1165       if( objc!=3 ){
1166         Tcl_WrongNumArgs(interp, 2, objv, "LIST");
1167         return TCL_ERROR;
1168       }
1169       if( Tcl_ListObjGetElements(interp, objv[2], &nElem, &apElem) ){
1170         return TCL_ERROR;
1171       }
1172       Tcl_ResetResult(interp);
1173       for(i=0; i<nElem; i++){
1174         int iMethod;
1175         char *zElem = Tcl_GetString(apElem[i]);
1176         for(iMethod=0; iMethod<ArraySize(vfsmethod); iMethod++){
1177           if( strcmp(zElem, vfsmethod[iMethod].zName)==0 ){
1178             mask |= vfsmethod[iMethod].mask;
1179             break;
1180           }
1181         }
1182         if( iMethod==ArraySize(vfsmethod) ){
1183           Tcl_AppendResult(interp, "unknown method: ", zElem, 0);
1184           return TCL_ERROR;
1185         }
1186       }
1187       p->mask = mask;
1188       break;
1189     }
1190 
1191     /*
1192     **  TESTVFS script ?SCRIPT?
1193     **
1194     **  Query or set the script to be run when filtered VFS events
1195     **  occur.
1196     */
1197     case CMD_SCRIPT: {
1198       if( objc==3 ){
1199         int nByte;
1200         if( p->pScript ){
1201           Tcl_DecrRefCount(p->pScript);
1202           p->pScript = 0;
1203         }
1204         Tcl_GetStringFromObj(objv[2], &nByte);
1205         if( nByte>0 ){
1206           p->pScript = Tcl_DuplicateObj(objv[2]);
1207           Tcl_IncrRefCount(p->pScript);
1208         }
1209       }else if( objc!=2 ){
1210         Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
1211         return TCL_ERROR;
1212       }
1213 
1214       Tcl_ResetResult(interp);
1215       if( p->pScript ) Tcl_SetObjResult(interp, p->pScript);
1216 
1217       break;
1218     }
1219 
1220     /*
1221     ** TESTVFS ioerr ?IFAIL PERSIST?
1222     **
1223     **   Where IFAIL is an integer and PERSIST is boolean.
1224     */
1225     case CMD_CANTOPENERR:
1226     case CMD_IOERR:
1227     case CMD_FULLERR: {
1228       TestFaultInject *pTest;
1229       int iRet;
1230 
1231       switch( aSubcmd[i].eCmd ){
1232         case CMD_IOERR: pTest = &p->ioerr_err; break;
1233         case CMD_FULLERR: pTest = &p->full_err; break;
1234         case CMD_CANTOPENERR: pTest = &p->cantopen_err; break;
1235         default: assert(0);
1236       }
1237       iRet = pTest->nFail;
1238       pTest->nFail = 0;
1239       pTest->eFault = 0;
1240       pTest->iCnt = 0;
1241 
1242       if( objc==4 ){
1243         int iCnt, iPersist;
1244         if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iCnt)
1245          || TCL_OK!=Tcl_GetBooleanFromObj(interp, objv[3], &iPersist)
1246         ){
1247           return TCL_ERROR;
1248         }
1249         pTest->eFault = iPersist?FAULT_INJECT_PERSISTENT:FAULT_INJECT_TRANSIENT;
1250         pTest->iCnt = iCnt;
1251       }else if( objc!=2 ){
1252         Tcl_WrongNumArgs(interp, 2, objv, "?CNT PERSIST?");
1253         return TCL_ERROR;
1254       }
1255       Tcl_SetObjResult(interp, Tcl_NewIntObj(iRet));
1256       break;
1257     }
1258 
1259     case CMD_DELETE: {
1260       Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
1261       break;
1262     }
1263 
1264     case CMD_DEVCHAR: {
1265       struct DeviceFlag {
1266         char *zName;
1267         int iValue;
1268       } aFlag[] = {
1269         { "default",               -1 },
1270         { "atomic",                SQLITE_IOCAP_ATOMIC                },
1271         { "atomic512",             SQLITE_IOCAP_ATOMIC512             },
1272         { "atomic1k",              SQLITE_IOCAP_ATOMIC1K              },
1273         { "atomic2k",              SQLITE_IOCAP_ATOMIC2K              },
1274         { "atomic4k",              SQLITE_IOCAP_ATOMIC4K              },
1275         { "atomic8k",              SQLITE_IOCAP_ATOMIC8K              },
1276         { "atomic16k",             SQLITE_IOCAP_ATOMIC16K             },
1277         { "atomic32k",             SQLITE_IOCAP_ATOMIC32K             },
1278         { "atomic64k",             SQLITE_IOCAP_ATOMIC64K             },
1279         { "sequential",            SQLITE_IOCAP_SEQUENTIAL            },
1280         { "safe_append",           SQLITE_IOCAP_SAFE_APPEND           },
1281         { "undeletable_when_open", SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN },
1282         { "powersafe_overwrite",   SQLITE_IOCAP_POWERSAFE_OVERWRITE   },
1283         { "immutable",             SQLITE_IOCAP_IMMUTABLE             },
1284         { 0, 0 }
1285       };
1286       Tcl_Obj *pRet;
1287       int iFlag;
1288 
1289       if( objc>3 ){
1290         Tcl_WrongNumArgs(interp, 2, objv, "?ATTR-LIST?");
1291         return TCL_ERROR;
1292       }
1293       if( objc==3 ){
1294         int j;
1295         int iNew = 0;
1296         Tcl_Obj **flags = 0;
1297         int nFlags = 0;
1298 
1299         if( Tcl_ListObjGetElements(interp, objv[2], &nFlags, &flags) ){
1300           return TCL_ERROR;
1301         }
1302 
1303         for(j=0; j<nFlags; j++){
1304           int idx = 0;
1305           if( Tcl_GetIndexFromObjStruct(interp, flags[j], aFlag,
1306                 sizeof(aFlag[0]), "flag", 0, &idx)
1307           ){
1308             return TCL_ERROR;
1309           }
1310           if( aFlag[idx].iValue<0 && nFlags>1 ){
1311             Tcl_AppendResult(interp, "bad flags: ", Tcl_GetString(objv[2]), 0);
1312             return TCL_ERROR;
1313           }
1314           iNew |= aFlag[idx].iValue;
1315         }
1316 
1317         p->iDevchar = iNew| 0x10000000;
1318       }
1319 
1320       pRet = Tcl_NewObj();
1321       for(iFlag=0; iFlag<sizeof(aFlag)/sizeof(aFlag[0]); iFlag++){
1322         if( p->iDevchar & aFlag[iFlag].iValue ){
1323           Tcl_ListObjAppendElement(
1324               interp, pRet, Tcl_NewStringObj(aFlag[iFlag].zName, -1)
1325           );
1326         }
1327       }
1328       Tcl_SetObjResult(interp, pRet);
1329 
1330       break;
1331     }
1332 
1333     case CMD_SECTORSIZE: {
1334       if( objc>3 ){
1335         Tcl_WrongNumArgs(interp, 2, objv, "?VALUE?");
1336         return TCL_ERROR;
1337       }
1338       if( objc==3 ){
1339         int iNew = 0;
1340         if( Tcl_GetIntFromObj(interp, objv[2], &iNew) ){
1341           return TCL_ERROR;
1342         }
1343         p->iSectorsize = iNew;
1344       }
1345       Tcl_SetObjResult(interp, Tcl_NewIntObj(p->iSectorsize));
1346       break;
1347     }
1348   }
1349 
1350   return TCL_OK;
1351 }
1352 
1353 static void testvfs_obj_del(ClientData cd){
1354   Testvfs *p = (Testvfs *)cd;
1355   if( p->pScript ) Tcl_DecrRefCount(p->pScript);
1356   sqlite3_vfs_unregister(p->pVfs);
1357   ckfree((char *)p->pVfs);
1358   ckfree((char *)p);
1359 }
1360 
1361 /*
1362 ** Usage:  testvfs VFSNAME ?SWITCHES?
1363 **
1364 ** Switches are:
1365 **
1366 **   -noshm   BOOLEAN             (True to omit shm methods. Default false)
1367 **   -default BOOLEAN             (True to make the vfs default. Default false)
1368 **
1369 ** This command creates two things when it is invoked: an SQLite VFS, and
1370 ** a Tcl command. Both are named VFSNAME. The VFS is installed. It is not
1371 ** installed as the default VFS.
1372 **
1373 ** The VFS passes all file I/O calls through to the underlying VFS.
1374 **
1375 ** Whenever the xShmMap method of the VFS
1376 ** is invoked, the SCRIPT is executed as follows:
1377 **
1378 **   SCRIPT xShmMap    FILENAME ID
1379 **
1380 ** The value returned by the invocation of SCRIPT above is interpreted as
1381 ** an SQLite error code and returned to SQLite. Either a symbolic
1382 ** "SQLITE_OK" or numeric "0" value may be returned.
1383 **
1384 ** The contents of the shared-memory buffer associated with a given file
1385 ** may be read and set using the following command:
1386 **
1387 **   VFSNAME shm FILENAME ?NEWVALUE?
1388 **
1389 ** When the xShmLock method is invoked by SQLite, the following script is
1390 ** run:
1391 **
1392 **   SCRIPT xShmLock    FILENAME ID LOCK
1393 **
1394 ** where LOCK is of the form "OFFSET NBYTE lock/unlock shared/exclusive"
1395 */
1396 static int testvfs_cmd(
1397   ClientData cd,
1398   Tcl_Interp *interp,
1399   int objc,
1400   Tcl_Obj *CONST objv[]
1401 ){
1402   static sqlite3_vfs tvfs_vfs = {
1403     3,                            /* iVersion */
1404     0,                            /* szOsFile */
1405     0,                            /* mxPathname */
1406     0,                            /* pNext */
1407     0,                            /* zName */
1408     0,                            /* pAppData */
1409     tvfsOpen,                     /* xOpen */
1410     tvfsDelete,                   /* xDelete */
1411     tvfsAccess,                   /* xAccess */
1412     tvfsFullPathname,             /* xFullPathname */
1413 #ifndef SQLITE_OMIT_LOAD_EXTENSION
1414     tvfsDlOpen,                   /* xDlOpen */
1415     tvfsDlError,                  /* xDlError */
1416     tvfsDlSym,                    /* xDlSym */
1417     tvfsDlClose,                  /* xDlClose */
1418 #else
1419     0,                            /* xDlOpen */
1420     0,                            /* xDlError */
1421     0,                            /* xDlSym */
1422     0,                            /* xDlClose */
1423 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
1424     tvfsRandomness,               /* xRandomness */
1425     tvfsSleep,                    /* xSleep */
1426     tvfsCurrentTime,              /* xCurrentTime */
1427     0,                            /* xGetLastError */
1428     0,                            /* xCurrentTimeInt64 */
1429     0,                            /* xSetSystemCall */
1430     0,                            /* xGetSystemCall */
1431     0,                            /* xNextSystemCall */
1432   };
1433 
1434   Testvfs *p;                     /* New object */
1435   sqlite3_vfs *pVfs;              /* New VFS */
1436   char *zVfs;
1437   int nByte;                      /* Bytes of space to allocate at p */
1438 
1439   int i;
1440   int isNoshm = 0;                /* True if -noshm is passed */
1441   int isFullshm = 0;              /* True if -fullshm is passed */
1442   int isDefault = 0;              /* True if -default is passed */
1443   int szOsFile = 0;               /* Value passed to -szosfile */
1444   int mxPathname = -1;            /* Value passed to -mxpathname */
1445   int iVersion = 3;               /* Value passed to -iversion */
1446 
1447   if( objc<2 || 0!=(objc%2) ) goto bad_args;
1448   for(i=2; i<objc; i += 2){
1449     int nSwitch;
1450     char *zSwitch;
1451     zSwitch = Tcl_GetStringFromObj(objv[i], &nSwitch);
1452 
1453     if( nSwitch>2 && 0==strncmp("-noshm", zSwitch, nSwitch) ){
1454       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isNoshm) ){
1455         return TCL_ERROR;
1456       }
1457       if( isNoshm ) isFullshm = 0;
1458     }
1459     else if( nSwitch>2 && 0==strncmp("-default", zSwitch, nSwitch) ){
1460       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isDefault) ){
1461         return TCL_ERROR;
1462       }
1463     }
1464     else if( nSwitch>2 && 0==strncmp("-szosfile", zSwitch, nSwitch) ){
1465       if( Tcl_GetIntFromObj(interp, objv[i+1], &szOsFile) ){
1466         return TCL_ERROR;
1467       }
1468     }
1469     else if( nSwitch>2 && 0==strncmp("-mxpathname", zSwitch, nSwitch) ){
1470       if( Tcl_GetIntFromObj(interp, objv[i+1], &mxPathname) ){
1471         return TCL_ERROR;
1472       }
1473     }
1474     else if( nSwitch>2 && 0==strncmp("-iversion", zSwitch, nSwitch) ){
1475       if( Tcl_GetIntFromObj(interp, objv[i+1], &iVersion) ){
1476         return TCL_ERROR;
1477       }
1478     }
1479     else if( nSwitch>2 && 0==strncmp("-fullshm", zSwitch, nSwitch) ){
1480       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isFullshm) ){
1481         return TCL_ERROR;
1482       }
1483       if( isFullshm ) isNoshm = 0;
1484     }
1485     else{
1486       goto bad_args;
1487     }
1488   }
1489 
1490   if( szOsFile<sizeof(TestvfsFile) ){
1491     szOsFile = sizeof(TestvfsFile);
1492   }
1493 
1494   zVfs = Tcl_GetString(objv[1]);
1495   nByte = sizeof(Testvfs) + (int)strlen(zVfs)+1;
1496   p = (Testvfs *)ckalloc(nByte);
1497   memset(p, 0, nByte);
1498   p->iDevchar = -1;
1499   p->iSectorsize = -1;
1500 
1501   /* Create the new object command before querying SQLite for a default VFS
1502   ** to use for 'real' IO operations. This is because creating the new VFS
1503   ** may delete an existing [testvfs] VFS of the same name. If such a VFS
1504   ** is currently the default, the new [testvfs] may end up calling the
1505   ** methods of a deleted object.
1506   */
1507   Tcl_CreateObjCommand(interp, zVfs, testvfs_obj_cmd, p, testvfs_obj_del);
1508   p->pParent = sqlite3_vfs_find(0);
1509   p->interp = interp;
1510 
1511   p->zName = (char *)&p[1];
1512   memcpy(p->zName, zVfs, strlen(zVfs)+1);
1513 
1514   pVfs = (sqlite3_vfs *)ckalloc(sizeof(sqlite3_vfs));
1515   memcpy(pVfs, &tvfs_vfs, sizeof(sqlite3_vfs));
1516   pVfs->pAppData = (void *)p;
1517   pVfs->iVersion = iVersion;
1518   pVfs->zName = p->zName;
1519   pVfs->mxPathname = p->pParent->mxPathname;
1520   if( mxPathname>=0 && mxPathname<pVfs->mxPathname ){
1521     pVfs->mxPathname = mxPathname;
1522   }
1523   pVfs->szOsFile = szOsFile;
1524   p->pVfs = pVfs;
1525   p->isNoshm = isNoshm;
1526   p->isFullshm = isFullshm;
1527   p->mask = TESTVFS_ALL_MASK;
1528 
1529   sqlite3_vfs_register(pVfs, isDefault);
1530 
1531   return TCL_OK;
1532 
1533  bad_args:
1534   Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-default BOOL? ?-mxpathname INT? ?-szosfile INT? ?-iversion INT?");
1535   return TCL_ERROR;
1536 }
1537 
1538 int Sqlitetestvfs_Init(Tcl_Interp *interp){
1539   Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);
1540   return TCL_OK;
1541 }
1542 
1543 #endif
1544