xref: /sqlite-3.40.0/src/test_vfs.c (revision c56fac74)
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 = 0;
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 szName = (int)strlen(pFd->zFilename);
827     int nByte = sizeof(TestvfsBuffer) + szName + 1;
828     pBuffer = (TestvfsBuffer *)ckalloc(nByte);
829     memset(pBuffer, 0, nByte);
830     pBuffer->zFile = (char *)&pBuffer[1];
831     memcpy(pBuffer->zFile, pFd->zFilename, szName+1);
832     pBuffer->pNext = p->pBuffer;
833     p->pBuffer = pBuffer;
834   }
835 
836   /* Connect the TestvfsBuffer to the new TestvfsShm handle and return. */
837   pFd->pNext = pBuffer->pFile;
838   pBuffer->pFile = pFd;
839   pFd->pShm = pBuffer;
840   return SQLITE_OK;
841 }
842 
843 static void tvfsAllocPage(TestvfsBuffer *p, int iPage, int pgsz){
844   assert( iPage<TESTVFS_MAX_PAGES );
845   if( p->aPage[iPage]==0 ){
846     p->aPage[iPage] = (u8 *)ckalloc(pgsz);
847     memset(p->aPage[iPage], 0, pgsz);
848     p->pgsz = pgsz;
849   }
850 }
851 
852 static int tvfsShmMap(
853   sqlite3_file *pFile,            /* Handle open on database file */
854   int iPage,                      /* Page to retrieve */
855   int pgsz,                       /* Size of pages */
856   int isWrite,                    /* True to extend file if necessary */
857   void volatile **pp              /* OUT: Mapped memory */
858 ){
859   int rc = SQLITE_OK;
860   TestvfsFd *pFd = tvfsGetFd(pFile);
861   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
862 
863   if( p->isFullshm ){
864     return sqlite3OsShmMap(pFd->pReal, iPage, pgsz, isWrite, pp);
865   }
866 
867   if( 0==pFd->pShm ){
868     rc = tvfsShmOpen(pFile);
869     if( rc!=SQLITE_OK ){
870       return rc;
871     }
872   }
873 
874   if( p->pScript && p->mask&TESTVFS_SHMMAP_MASK ){
875     Tcl_Obj *pArg = Tcl_NewObj();
876     Tcl_IncrRefCount(pArg);
877     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(iPage));
878     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(pgsz));
879     Tcl_ListObjAppendElement(p->interp, pArg, Tcl_NewIntObj(isWrite));
880     tvfsExecTcl(p, "xShmMap",
881         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, pArg, 0
882     );
883     tvfsResultCode(p, &rc);
884     Tcl_DecrRefCount(pArg);
885   }
886   if( rc==SQLITE_OK && p->mask&TESTVFS_SHMMAP_MASK && tvfsInjectIoerr(p) ){
887     rc = SQLITE_IOERR;
888   }
889 
890   if( rc==SQLITE_OK && isWrite && !pFd->pShm->aPage[iPage] ){
891     tvfsAllocPage(pFd->pShm, iPage, pgsz);
892   }
893   *pp = (void volatile *)pFd->pShm->aPage[iPage];
894 
895   return rc;
896 }
897 
898 
899 static int tvfsShmLock(
900   sqlite3_file *pFile,
901   int ofst,
902   int n,
903   int flags
904 ){
905   int rc = SQLITE_OK;
906   TestvfsFd *pFd = tvfsGetFd(pFile);
907   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
908   int nLock;
909   char zLock[80];
910 
911   if( p->isFullshm ){
912     return sqlite3OsShmLock(pFd->pReal, ofst, n, flags);
913   }
914 
915   if( p->pScript && p->mask&TESTVFS_SHMLOCK_MASK ){
916     sqlite3_snprintf(sizeof(zLock), zLock, "%d %d", ofst, n);
917     nLock = (int)strlen(zLock);
918     if( flags & SQLITE_SHM_LOCK ){
919       strcpy(&zLock[nLock], " lock");
920     }else{
921       strcpy(&zLock[nLock], " unlock");
922     }
923     nLock += (int)strlen(&zLock[nLock]);
924     if( flags & SQLITE_SHM_SHARED ){
925       strcpy(&zLock[nLock], " shared");
926     }else{
927       strcpy(&zLock[nLock], " exclusive");
928     }
929     tvfsExecTcl(p, "xShmLock",
930         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId,
931         Tcl_NewStringObj(zLock, -1), 0
932     );
933     tvfsResultCode(p, &rc);
934   }
935 
936   if( rc==SQLITE_OK && p->mask&TESTVFS_SHMLOCK_MASK && tvfsInjectIoerr(p) ){
937     rc = SQLITE_IOERR;
938   }
939 
940   if( rc==SQLITE_OK ){
941     int isLock = (flags & SQLITE_SHM_LOCK);
942     int isExcl = (flags & SQLITE_SHM_EXCLUSIVE);
943     u32 mask = (((1<<n)-1) << ofst);
944     if( isLock ){
945       TestvfsFd *p2;
946       for(p2=pFd->pShm->pFile; p2; p2=p2->pNext){
947         if( p2==pFd ) continue;
948         if( (p2->excllock&mask) || (isExcl && p2->sharedlock&mask) ){
949           rc = SQLITE_BUSY;
950           break;
951         }
952       }
953       if( rc==SQLITE_OK ){
954         if( isExcl )  pFd->excllock |= mask;
955         if( !isExcl ) pFd->sharedlock |= mask;
956       }
957     }else{
958       if( isExcl )  pFd->excllock &= (~mask);
959       if( !isExcl ) pFd->sharedlock &= (~mask);
960     }
961   }
962 
963   return rc;
964 }
965 
966 static void tvfsShmBarrier(sqlite3_file *pFile){
967   TestvfsFd *pFd = tvfsGetFd(pFile);
968   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
969 
970   if( p->pScript && p->mask&TESTVFS_SHMBARRIER_MASK ){
971     const char *z = pFd->pShm ? pFd->pShm->zFile : "";
972     tvfsExecTcl(p, "xShmBarrier", Tcl_NewStringObj(z, -1), pFd->pShmId, 0, 0);
973   }
974 
975   if( p->isFullshm ){
976     sqlite3OsShmBarrier(pFd->pReal);
977     return;
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 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 mask = 0;
1164       if( objc!=3 ){
1165         Tcl_WrongNumArgs(interp, 2, objv, "LIST");
1166         return TCL_ERROR;
1167       }
1168       if( Tcl_ListObjGetElements(interp, objv[2], &nElem, &apElem) ){
1169         return TCL_ERROR;
1170       }
1171       Tcl_ResetResult(interp);
1172       for(i=0; i<nElem; i++){
1173         int iMethod;
1174         char *zElem = Tcl_GetString(apElem[i]);
1175         for(iMethod=0; iMethod<ArraySize(vfsmethod); iMethod++){
1176           if( strcmp(zElem, vfsmethod[iMethod].zName)==0 ){
1177             mask |= vfsmethod[iMethod].mask;
1178             break;
1179           }
1180         }
1181         if( iMethod==ArraySize(vfsmethod) ){
1182           Tcl_AppendResult(interp, "unknown method: ", zElem, 0);
1183           return TCL_ERROR;
1184         }
1185       }
1186       p->mask = mask;
1187       break;
1188     }
1189 
1190     /*
1191     **  TESTVFS script ?SCRIPT?
1192     **
1193     **  Query or set the script to be run when filtered VFS events
1194     **  occur.
1195     */
1196     case CMD_SCRIPT: {
1197       if( objc==3 ){
1198         int nByte;
1199         if( p->pScript ){
1200           Tcl_DecrRefCount(p->pScript);
1201           p->pScript = 0;
1202         }
1203         Tcl_GetStringFromObj(objv[2], &nByte);
1204         if( nByte>0 ){
1205           p->pScript = Tcl_DuplicateObj(objv[2]);
1206           Tcl_IncrRefCount(p->pScript);
1207         }
1208       }else if( objc!=2 ){
1209         Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
1210         return TCL_ERROR;
1211       }
1212 
1213       Tcl_ResetResult(interp);
1214       if( p->pScript ) Tcl_SetObjResult(interp, p->pScript);
1215 
1216       break;
1217     }
1218 
1219     /*
1220     ** TESTVFS ioerr ?IFAIL PERSIST?
1221     **
1222     **   Where IFAIL is an integer and PERSIST is boolean.
1223     */
1224     case CMD_CANTOPENERR:
1225     case CMD_IOERR:
1226     case CMD_FULLERR: {
1227       TestFaultInject *pTest = 0;
1228       int iRet;
1229 
1230       switch( aSubcmd[i].eCmd ){
1231         case CMD_IOERR: pTest = &p->ioerr_err; break;
1232         case CMD_FULLERR: pTest = &p->full_err; break;
1233         case CMD_CANTOPENERR: pTest = &p->cantopen_err; break;
1234         default: assert(0);
1235       }
1236       iRet = pTest->nFail;
1237       pTest->nFail = 0;
1238       pTest->eFault = 0;
1239       pTest->iCnt = 0;
1240 
1241       if( objc==4 ){
1242         int iCnt, iPersist;
1243         if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &iCnt)
1244          || TCL_OK!=Tcl_GetBooleanFromObj(interp, objv[3], &iPersist)
1245         ){
1246           return TCL_ERROR;
1247         }
1248         pTest->eFault = iPersist?FAULT_INJECT_PERSISTENT:FAULT_INJECT_TRANSIENT;
1249         pTest->iCnt = iCnt;
1250       }else if( objc!=2 ){
1251         Tcl_WrongNumArgs(interp, 2, objv, "?CNT PERSIST?");
1252         return TCL_ERROR;
1253       }
1254       Tcl_SetObjResult(interp, Tcl_NewIntObj(iRet));
1255       break;
1256     }
1257 
1258     case CMD_DELETE: {
1259       Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
1260       break;
1261     }
1262 
1263     case CMD_DEVCHAR: {
1264       struct DeviceFlag {
1265         char *zName;
1266         int iValue;
1267       } aFlag[] = {
1268         { "default",               -1 },
1269         { "atomic",                SQLITE_IOCAP_ATOMIC                },
1270         { "atomic512",             SQLITE_IOCAP_ATOMIC512             },
1271         { "atomic1k",              SQLITE_IOCAP_ATOMIC1K              },
1272         { "atomic2k",              SQLITE_IOCAP_ATOMIC2K              },
1273         { "atomic4k",              SQLITE_IOCAP_ATOMIC4K              },
1274         { "atomic8k",              SQLITE_IOCAP_ATOMIC8K              },
1275         { "atomic16k",             SQLITE_IOCAP_ATOMIC16K             },
1276         { "atomic32k",             SQLITE_IOCAP_ATOMIC32K             },
1277         { "atomic64k",             SQLITE_IOCAP_ATOMIC64K             },
1278         { "sequential",            SQLITE_IOCAP_SEQUENTIAL            },
1279         { "safe_append",           SQLITE_IOCAP_SAFE_APPEND           },
1280         { "undeletable_when_open", SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN },
1281         { "powersafe_overwrite",   SQLITE_IOCAP_POWERSAFE_OVERWRITE   },
1282         { "immutable",             SQLITE_IOCAP_IMMUTABLE             },
1283         { 0, 0 }
1284       };
1285       Tcl_Obj *pRet;
1286       int iFlag;
1287 
1288       if( objc>3 ){
1289         Tcl_WrongNumArgs(interp, 2, objv, "?ATTR-LIST?");
1290         return TCL_ERROR;
1291       }
1292       if( objc==3 ){
1293         int j;
1294         int iNew = 0;
1295         Tcl_Obj **flags = 0;
1296         int nFlags = 0;
1297 
1298         if( Tcl_ListObjGetElements(interp, objv[2], &nFlags, &flags) ){
1299           return TCL_ERROR;
1300         }
1301 
1302         for(j=0; j<nFlags; j++){
1303           int idx = 0;
1304           if( Tcl_GetIndexFromObjStruct(interp, flags[j], aFlag,
1305                 sizeof(aFlag[0]), "flag", 0, &idx)
1306           ){
1307             return TCL_ERROR;
1308           }
1309           if( aFlag[idx].iValue<0 && nFlags>1 ){
1310             Tcl_AppendResult(interp, "bad flags: ", Tcl_GetString(objv[2]), 0);
1311             return TCL_ERROR;
1312           }
1313           iNew |= aFlag[idx].iValue;
1314         }
1315 
1316         p->iDevchar = iNew| 0x10000000;
1317       }
1318 
1319       pRet = Tcl_NewObj();
1320       for(iFlag=0; iFlag<sizeof(aFlag)/sizeof(aFlag[0]); iFlag++){
1321         if( p->iDevchar & aFlag[iFlag].iValue ){
1322           Tcl_ListObjAppendElement(
1323               interp, pRet, Tcl_NewStringObj(aFlag[iFlag].zName, -1)
1324           );
1325         }
1326       }
1327       Tcl_SetObjResult(interp, pRet);
1328 
1329       break;
1330     }
1331 
1332     case CMD_SECTORSIZE: {
1333       if( objc>3 ){
1334         Tcl_WrongNumArgs(interp, 2, objv, "?VALUE?");
1335         return TCL_ERROR;
1336       }
1337       if( objc==3 ){
1338         int iNew = 0;
1339         if( Tcl_GetIntFromObj(interp, objv[2], &iNew) ){
1340           return TCL_ERROR;
1341         }
1342         p->iSectorsize = iNew;
1343       }
1344       Tcl_SetObjResult(interp, Tcl_NewIntObj(p->iSectorsize));
1345       break;
1346     }
1347   }
1348 
1349   return TCL_OK;
1350 }
1351 
1352 static void testvfs_obj_del(ClientData cd){
1353   Testvfs *p = (Testvfs *)cd;
1354   if( p->pScript ) Tcl_DecrRefCount(p->pScript);
1355   sqlite3_vfs_unregister(p->pVfs);
1356   ckfree((char *)p->pVfs);
1357   ckfree((char *)p);
1358 }
1359 
1360 /*
1361 ** Usage:  testvfs VFSNAME ?SWITCHES?
1362 **
1363 ** Switches are:
1364 **
1365 **   -noshm   BOOLEAN             (True to omit shm methods. Default false)
1366 **   -default BOOLEAN             (True to make the vfs default. Default false)
1367 **
1368 ** This command creates two things when it is invoked: an SQLite VFS, and
1369 ** a Tcl command. Both are named VFSNAME. The VFS is installed. It is not
1370 ** installed as the default VFS.
1371 **
1372 ** The VFS passes all file I/O calls through to the underlying VFS.
1373 **
1374 ** Whenever the xShmMap method of the VFS
1375 ** is invoked, the SCRIPT is executed as follows:
1376 **
1377 **   SCRIPT xShmMap    FILENAME ID
1378 **
1379 ** The value returned by the invocation of SCRIPT above is interpreted as
1380 ** an SQLite error code and returned to SQLite. Either a symbolic
1381 ** "SQLITE_OK" or numeric "0" value may be returned.
1382 **
1383 ** The contents of the shared-memory buffer associated with a given file
1384 ** may be read and set using the following command:
1385 **
1386 **   VFSNAME shm FILENAME ?NEWVALUE?
1387 **
1388 ** When the xShmLock method is invoked by SQLite, the following script is
1389 ** run:
1390 **
1391 **   SCRIPT xShmLock    FILENAME ID LOCK
1392 **
1393 ** where LOCK is of the form "OFFSET NBYTE lock/unlock shared/exclusive"
1394 */
1395 static int testvfs_cmd(
1396   ClientData cd,
1397   Tcl_Interp *interp,
1398   int objc,
1399   Tcl_Obj *CONST objv[]
1400 ){
1401   static sqlite3_vfs tvfs_vfs = {
1402     3,                            /* iVersion */
1403     0,                            /* szOsFile */
1404     0,                            /* mxPathname */
1405     0,                            /* pNext */
1406     0,                            /* zName */
1407     0,                            /* pAppData */
1408     tvfsOpen,                     /* xOpen */
1409     tvfsDelete,                   /* xDelete */
1410     tvfsAccess,                   /* xAccess */
1411     tvfsFullPathname,             /* xFullPathname */
1412 #ifndef SQLITE_OMIT_LOAD_EXTENSION
1413     tvfsDlOpen,                   /* xDlOpen */
1414     tvfsDlError,                  /* xDlError */
1415     tvfsDlSym,                    /* xDlSym */
1416     tvfsDlClose,                  /* xDlClose */
1417 #else
1418     0,                            /* xDlOpen */
1419     0,                            /* xDlError */
1420     0,                            /* xDlSym */
1421     0,                            /* xDlClose */
1422 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
1423     tvfsRandomness,               /* xRandomness */
1424     tvfsSleep,                    /* xSleep */
1425     tvfsCurrentTime,              /* xCurrentTime */
1426     0,                            /* xGetLastError */
1427     0,                            /* xCurrentTimeInt64 */
1428     0,                            /* xSetSystemCall */
1429     0,                            /* xGetSystemCall */
1430     0,                            /* xNextSystemCall */
1431   };
1432 
1433   Testvfs *p;                     /* New object */
1434   sqlite3_vfs *pVfs;              /* New VFS */
1435   char *zVfs;
1436   int nByte;                      /* Bytes of space to allocate at p */
1437 
1438   int i;
1439   int isNoshm = 0;                /* True if -noshm is passed */
1440   int isFullshm = 0;              /* True if -fullshm is passed */
1441   int isDefault = 0;              /* True if -default is passed */
1442   int szOsFile = 0;               /* Value passed to -szosfile */
1443   int mxPathname = -1;            /* Value passed to -mxpathname */
1444   int iVersion = 3;               /* Value passed to -iversion */
1445 
1446   if( objc<2 || 0!=(objc%2) ) goto bad_args;
1447   for(i=2; i<objc; i += 2){
1448     int nSwitch;
1449     char *zSwitch;
1450     zSwitch = Tcl_GetStringFromObj(objv[i], &nSwitch);
1451 
1452     if( nSwitch>2 && 0==strncmp("-noshm", zSwitch, nSwitch) ){
1453       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isNoshm) ){
1454         return TCL_ERROR;
1455       }
1456       if( isNoshm ) isFullshm = 0;
1457     }
1458     else if( nSwitch>2 && 0==strncmp("-default", zSwitch, nSwitch) ){
1459       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isDefault) ){
1460         return TCL_ERROR;
1461       }
1462     }
1463     else if( nSwitch>2 && 0==strncmp("-szosfile", zSwitch, nSwitch) ){
1464       if( Tcl_GetIntFromObj(interp, objv[i+1], &szOsFile) ){
1465         return TCL_ERROR;
1466       }
1467     }
1468     else if( nSwitch>2 && 0==strncmp("-mxpathname", zSwitch, nSwitch) ){
1469       if( Tcl_GetIntFromObj(interp, objv[i+1], &mxPathname) ){
1470         return TCL_ERROR;
1471       }
1472     }
1473     else if( nSwitch>2 && 0==strncmp("-iversion", zSwitch, nSwitch) ){
1474       if( Tcl_GetIntFromObj(interp, objv[i+1], &iVersion) ){
1475         return TCL_ERROR;
1476       }
1477     }
1478     else if( nSwitch>2 && 0==strncmp("-fullshm", zSwitch, nSwitch) ){
1479       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isFullshm) ){
1480         return TCL_ERROR;
1481       }
1482       if( isFullshm ) isNoshm = 0;
1483     }
1484     else{
1485       goto bad_args;
1486     }
1487   }
1488 
1489   if( szOsFile<sizeof(TestvfsFile) ){
1490     szOsFile = sizeof(TestvfsFile);
1491   }
1492 
1493   zVfs = Tcl_GetString(objv[1]);
1494   nByte = sizeof(Testvfs) + (int)strlen(zVfs)+1;
1495   p = (Testvfs *)ckalloc(nByte);
1496   memset(p, 0, nByte);
1497   p->iDevchar = -1;
1498   p->iSectorsize = -1;
1499 
1500   /* Create the new object command before querying SQLite for a default VFS
1501   ** to use for 'real' IO operations. This is because creating the new VFS
1502   ** may delete an existing [testvfs] VFS of the same name. If such a VFS
1503   ** is currently the default, the new [testvfs] may end up calling the
1504   ** methods of a deleted object.
1505   */
1506   Tcl_CreateObjCommand(interp, zVfs, testvfs_obj_cmd, p, testvfs_obj_del);
1507   p->pParent = sqlite3_vfs_find(0);
1508   p->interp = interp;
1509 
1510   p->zName = (char *)&p[1];
1511   memcpy(p->zName, zVfs, strlen(zVfs)+1);
1512 
1513   pVfs = (sqlite3_vfs *)ckalloc(sizeof(sqlite3_vfs));
1514   memcpy(pVfs, &tvfs_vfs, sizeof(sqlite3_vfs));
1515   pVfs->pAppData = (void *)p;
1516   pVfs->iVersion = iVersion;
1517   pVfs->zName = p->zName;
1518   pVfs->mxPathname = p->pParent->mxPathname;
1519   if( mxPathname>=0 && mxPathname<pVfs->mxPathname ){
1520     pVfs->mxPathname = mxPathname;
1521   }
1522   pVfs->szOsFile = szOsFile;
1523   p->pVfs = pVfs;
1524   p->isNoshm = isNoshm;
1525   p->isFullshm = isFullshm;
1526   p->mask = TESTVFS_ALL_MASK;
1527 
1528   sqlite3_vfs_register(pVfs, isDefault);
1529 
1530   return TCL_OK;
1531 
1532  bad_args:
1533   Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-fullshm BOOL? ?-default BOOL? ?-mxpathname INT? ?-szosfile INT? ?-iversion INT?");
1534   return TCL_ERROR;
1535 }
1536 
1537 int Sqlitetestvfs_Init(Tcl_Interp *interp){
1538   Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);
1539   return TCL_OK;
1540 }
1541 
1542 #endif
1543