vfsmemory.cpp@ 42599

Last change on this file since 42599 was 40292, checked in by vboxsync, 13 years ago
RTVfsMemFile bugfix: rtVfsMemFile_Write regression from previous fix.
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File size: 23.6 KB

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1	/* $Id: vfsmemory.cpp 40292 2012-02-29 11:29:35Z vboxsync $ */
2	/** @file
3	* IPRT - Virtual File System, Memory Backed VFS.
4	*/
5
6	/*
7	* Copyright (C) 2010-2012 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* The contents of this file may alternatively be used under the terms
18	* of the Common Development and Distribution License Version 1.0
19	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20	* VirtualBox OSE distribution, in which case the provisions of the
21	* CDDL are applicable instead of those of the GPL.
22	*
23	* You may elect to license modified versions of this file under the
24	* terms and conditions of either the GPL or the CDDL or both.
25	*/
26
27
28	/*******************************************************************************
29	* Header Files *
30	*******************************************************************************/
31	#include "internal/iprt.h"
32	#include <iprt/vfs.h>
33
34	#include <iprt/asm.h>
35	#include <iprt/assert.h>
36	#include <iprt/err.h>
37	#include <iprt/file.h>
38	#include <iprt/list.h>
39	#include <iprt/poll.h>
40	#include <iprt/string.h>
41	#include <iprt/vfslowlevel.h>
42
43
44
45	/*******************************************************************************
46	* Header Files *
47	*******************************************************************************/
48	#include "internal/iprt.h"
49	#include <iprt/vfs.h>
50
51	#include <iprt/err.h>
52	#include <iprt/mem.h>
53
54
55	/*******************************************************************************
56	* Defined Constants And Macros *
57	*******************************************************************************/
58	/** The max extent size. */
59	#define RTVFSMEM_MAX_EXTENT_SIZE _2M
60
61
62	/*******************************************************************************
63	* Structures and Typedefs *
64	*******************************************************************************/
65
66	/**
67	* Memory base object info.
68	*/
69	typedef struct RTVFSMEMBASE
70	{
71	/** The basic object info. */
72	RTFSOBJINFO ObjInfo;
73	} RTVFSMEMBASE;
74
75
76	/**
77	* Memory file extent.
78	*
79	* This stores part of the file content.
80	*/
81	typedef struct RTVFSMEMEXTENT
82	{
83	/** Extent list entry. */
84	RTLISTNODE Entry;
85	/** The offset of this extent within the file. */
86	uint64_t off;
87	/** The size of the this extent. */
88	uint32_t cb;
89	/** The data. */
90	uint8_t abData[1];
91	} RTVFSMEMEXTENT;
92	/** Pointer to a memory file extent. */
93	typedef RTVFSMEMEXTENT *PRTVFSMEMEXTENT;
94
95	/**
96	* Memory file.
97	*/
98	typedef struct RTVFSMEMFILE
99	{
100	/** The base info. */
101	RTVFSMEMBASE Base;
102	/** The current file position. */
103	uint64_t offCurPos;
104	/** Pointer to the current file extent. */
105	PRTVFSMEMEXTENT pCurExt;
106	/** Linked list of file extents - RTVFSMEMEXTENT. */
107	RTLISTANCHOR ExtentHead;
108	/** The current extent size.
109	* This is slowly grown to RTVFSMEM_MAX_EXTENT_SIZE as the file grows. */
110	uint32_t cbExtent;
111	} RTVFSMEMFILE;
112	/** Pointer to a memory file. */
113	typedef RTVFSMEMFILE *PRTVFSMEMFILE;
114
115
116
117	/**
118	* @interface_method_impl{RTVFSOBJOPS,pfnClose}
119	*/
120	static DECLCALLBACK(int) rtVfsMemFile_Close(void *pvThis)
121	{
122	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
123
124	/*
125	* Free the extent list.
126	*/
127	PRTVFSMEMEXTENT pCur, pNext;
128	RTListForEachSafe(&pThis->ExtentHead, pCur, pNext, RTVFSMEMEXTENT, Entry)
129	{
130	pCur->off = RTFOFF_MAX;
131	pCur->cb = UINT32_MAX;
132	RTListNodeRemove(&pCur->Entry);
133	RTMemFree(pCur);
134	}
135	pThis->pCurExt = NULL;
136
137	return VINF_SUCCESS;
138	}
139
140
141	/**
142	* @interface_method_impl{RTVFSOBJOPS,pfnQueryInfo}
143	*/
144	static DECLCALLBACK(int) rtVfsMemFile_QueryInfo(void *pvThis, PRTFSOBJINFO pObjInfo, RTFSOBJATTRADD enmAddAttr)
145	{
146	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
147	switch (enmAddAttr)
148	{
149	case RTFSOBJATTRADD_NOTHING:
150	case RTFSOBJATTRADD_UNIX:
151	*pObjInfo = pThis->Base.ObjInfo;
152	return VINF_SUCCESS;
153
154	default:
155	return VERR_NOT_SUPPORTED;
156	}
157	}
158
159
160	/**
161	* The slow paths of rtVfsMemFile_LocateExtent.
162	*
163	* @copydoc rtVfsMemFile_LocateExtent
164	*/
165	static PRTVFSMEMEXTENT rtVfsMemFile_LocateExtentSlow(PRTVFSMEMFILE pThis, uint64_t off, bool *pfHit)
166	{
167	/*
168	* Search from the start or the previously used extent. The heuristics
169	* are very very simple, but whatever.
170	*/
171	PRTVFSMEMEXTENT pExtent = pThis->pCurExt;
172	if (!pExtent \|\| pExtent->off < off)
173	{
174	/* Consider the last entry first (for writes). */
175	pExtent = RTListGetLast(&pThis->ExtentHead, RTVFSMEMEXTENT, Entry);
176	if (!pExtent)
177	{
178	*pfHit = false;
179	return NULL;
180	}
181	if (off - pExtent->off < pExtent->cb)
182	{
183	*pfHit = true;
184	pThis->pCurExt = pExtent;
185	return pExtent;
186	}
187
188	/* Otherwise, start from the head. */
189	pExtent = RTListGetFirst(&pThis->ExtentHead, RTVFSMEMEXTENT, Entry);
190	}
191
192	while (off - pExtent->off >= pExtent->cb)
193	{
194	Assert(pExtent->off <= off);
195	PRTVFSMEMEXTENT pNext = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
196	if ( !pNext
197	\|\| pNext->off > off)
198	{
199	*pfHit = false;
200	return pNext;
201	}
202
203	pExtent = pNext;
204	}
205
206	*pfHit = true;
207	pThis->pCurExt = pExtent;
208	return pExtent;
209	}
210
211
212	/**
213	* Locates the extent covering the specified offset, or the one after it.
214	*
215	* @returns The closest extent. NULL if off is 0 and there are no extent
216	* covering byte 0 yet.
217	* @param pThis The memory file.
218	* @param off The offset (0-positive).
219	* @param pfHit Where to indicate whether the extent is a
220	* direct hit (@c true) or just a closest match
221	* (@c false).
222	*/
223	DECLINLINE(PRTVFSMEMEXTENT) rtVfsMemFile_LocateExtent(PRTVFSMEMFILE pThis, uint64_t off, bool *pfHit)
224	{
225	/*
226	* The most likely case is that we're hitting the extent we used in the
227	* previous access or the one immediately following it.
228	*/
229	PRTVFSMEMEXTENT pExtent = pThis->pCurExt;
230	if (!pExtent)
231	return rtVfsMemFile_LocateExtentSlow(pThis, off, pfHit);
232
233	if (off - pExtent->off >= pExtent->cb)
234	{
235	pExtent = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
236	if ( !pExtent
237	\|\| off - pExtent->off >= pExtent->cb)
238	return rtVfsMemFile_LocateExtentSlow(pThis, off, pfHit);
239	pThis->pCurExt = pExtent;
240	}
241
242	*pfHit = true;
243	return pExtent;
244	}
245
246
247	/**
248	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnRead}
249	*/
250	static DECLCALLBACK(int) rtVfsMemFile_Read(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbRead)
251	{
252	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
253
254	Assert(pSgBuf->cSegs == 1);
255	Assert(off < 0);
256	NOREF(fBlocking);
257
258	/*
259	* Find the current position and check if it's within the file.
260	*/
261	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
262	if (offUnsigned >= (uint64_t)pThis->Base.ObjInfo.cbObject)
263	{
264	if (pcbRead)
265	{
266	*pcbRead = 0;
267	pThis->offCurPos = offUnsigned;
268	return VINF_EOF;
269	}
270	return VERR_EOF;
271	}
272
273	size_t cbLeftToRead;
274	if (offUnsigned + pSgBuf->paSegs[0].cbSeg > (uint64_t)pThis->Base.ObjInfo.cbObject)
275	{
276	if (!pcbRead)
277	return VERR_EOF;
278	*pcbRead = cbLeftToRead = (size_t)((uint64_t)pThis->Base.ObjInfo.cbObject - offUnsigned);
279	}
280	else
281	{
282	cbLeftToRead = pSgBuf->paSegs[0].cbSeg;
283	if (pcbRead)
284	*pcbRead = cbLeftToRead;
285	}
286
287	/*
288	* Ok, we've got a valid stretch within the file. Do the reading.
289	*/
290	if (cbLeftToRead > 0)
291	{
292	uint8_t pbDst = (uint8_t )pSgBuf->paSegs[0].pvSeg;
293	bool fHit;
294	PRTVFSMEMEXTENT pExtent = rtVfsMemFile_LocateExtent(pThis, offUnsigned, &fHit);
295	for (;;)
296	{
297	size_t cbThisRead;
298
299	/*
300	* Do we hit an extent covering the current file surface?
301	*/
302	if (fHit)
303	{
304	/* Yes, copy the data. */
305	Assert(offUnsigned - pExtent->off < pExtent->cb);
306	size_t const offExtent = (size_t)(offUnsigned - pExtent->off);
307	cbThisRead = pExtent->cb - offExtent;
308	if (cbThisRead >= cbLeftToRead)
309	cbThisRead = cbLeftToRead;
310
311	memcpy(pbDst, &pExtent->abData[offUnsigned - pExtent->off], cbThisRead);
312
313	offUnsigned += cbThisRead;
314	cbLeftToRead -= cbThisRead;
315	if (!cbLeftToRead)
316	break;
317	pbDst += cbThisRead;
318
319	/* Advance, looping immediately if not sparse. */
320	PRTVFSMEMEXTENT pNext = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
321	if ( pNext
322	&& pNext->off == pExtent->off + pExtent->cb)
323	{
324	pExtent = pNext;
325	continue;
326	}
327
328	Assert(!pNext \|\| pNext->off > pExtent->off);
329	pExtent = pNext;
330	fHit = false;
331	}
332	else
333	Assert(!pExtent \|\| pExtent->off > offUnsigned);
334
335	/*
336	* No extent of this portion (sparse file) - Read zeros.
337	*/
338	if ( !pExtent
339	\|\| offUnsigned + cbLeftToRead <= pExtent->off)
340	cbThisRead = cbLeftToRead;
341	else
342	cbThisRead = (size_t)(pExtent->off - offUnsigned);
343
344	RT_BZERO(pbDst, cbThisRead);
345
346	offUnsigned += cbThisRead;
347	cbLeftToRead -= cbThisRead;
348	if (!cbLeftToRead)
349	break;
350	pbDst += cbThisRead;
351
352	/* Go on and read content from the next extent. */
353	fHit = true;
354	}
355	}
356
357	pThis->offCurPos = offUnsigned;
358	return VINF_SUCCESS;
359	}
360
361
362	/**
363	* Allocates a new extent covering the ground at @a offUnsigned.
364	*
365	* @returns Pointer to the new extent on success, NULL if we're out of memory.
366	* @param pThis The memory file.
367	* @param offUnsigned The location to allocate the extent at.
368	* @param cbToWrite The number of bytes we're interested in writing
369	* starting at @a offUnsigned.
370	* @param pNext The extention after @a offUnsigned. NULL if
371	* none, i.e. we're allocating space at the end of
372	* the file.
373	*/
374	static PRTVFSMEMEXTENT rtVfsMemFile_AllocExtent(PRTVFSMEMFILE pThis, uint64_t offUnsigned, size_t cbToWrite,
375	PRTVFSMEMEXTENT pNext)
376	{
377	/*
378	* Adjust the extent size if we haven't reached the max size yet.
379	*/
380	if (pThis->cbExtent != RTVFSMEM_MAX_EXTENT_SIZE)
381	{
382	if (cbToWrite >= RTVFSMEM_MAX_EXTENT_SIZE)
383	pThis->cbExtent = RTVFSMEM_MAX_EXTENT_SIZE;
384	else if (!RTListIsEmpty(&pThis->ExtentHead))
385	{
386	uint32_t cbNextExtent = pThis->cbExtent;
387	if (RT_IS_POWER_OF_TWO(cbNextExtent))
388	cbNextExtent *= 2;
389	else
390	{
391	/* Make it a power of two (seeRTVfsMemorizeIoStreamAsFile). */
392	cbNextExtent = _4K;
393	while (cbNextExtent < pThis->cbExtent)
394	cbNextExtent *= 2;
395	}
396	if (((pThis->Base.ObjInfo.cbAllocated + cbNextExtent) & (cbNextExtent - 1)) == 0)
397	pThis->cbExtent = cbNextExtent;
398	}
399	}
400
401	/*
402	* Figure out the size and position of the extent we're adding.
403	*/
404	uint64_t offExtent = offUnsigned & ~(uint64_t)(pThis->cbExtent - 1);
405	uint32_t cbExtent = pThis->cbExtent;
406
407	PRTVFSMEMEXTENT pPrev = pNext
408	? RTListGetPrev(&pThis->ExtentHead, pNext, RTVFSMEMEXTENT, Entry)
409	: RTListGetLast(&pThis->ExtentHead, RTVFSMEMEXTENT, Entry);
410	uint64_t const offPrev = pPrev ? pPrev->off + pPrev->cb : 0;
411	if (offExtent < offPrev)
412	offExtent = offPrev;
413
414	if (pNext)
415	{
416	uint64_t cbMaxExtent = pNext->off - offExtent;
417	if (cbMaxExtent < cbExtent)
418	cbExtent = (uint32_t)cbMaxExtent;
419	}
420
421	/*
422	* Allocate, initialize and insert the new extent.
423	*/
424	PRTVFSMEMEXTENT pNew = (PRTVFSMEMEXTENT)RTMemAllocZ(RT_OFFSETOF(RTVFSMEMEXTENT, abData[cbExtent]));
425	if (pNew)
426	{
427	pNew->off = offExtent;
428	pNew->cb = cbExtent;
429	if (pPrev)
430	RTListNodeInsertAfter(&pPrev->Entry, &pNew->Entry);
431	else
432	RTListPrepend(&pThis->ExtentHead, &pNew->Entry);
433
434	pThis->Base.ObjInfo.cbAllocated += cbExtent;
435	}
436	/** @todo retry with minimum size. */
437
438	return pNew;
439	}
440
441
442	/**
443	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnWrite}
444	*/
445	static DECLCALLBACK(int) rtVfsMemFile_Write(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbWritten)
446	{
447	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
448
449	Assert(pSgBuf->cSegs == 1);
450	Assert(off < 0);
451	NOREF(fBlocking);
452
453	/*
454	* Validate the write and set up the write loop.
455	*/
456	size_t cbLeftToWrite = pSgBuf->paSegs[0].cbSeg;
457	if (!cbLeftToWrite)
458	return VINF_SUCCESS; /* pcbWritten is already 0. */
459	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
460	if (offUnsigned + cbLeftToWrite >= (uint64_t)RTFOFF_MAX)
461	return VERR_OUT_OF_RANGE;
462
463	int rc = VINF_SUCCESS;
464	uint8_t const pbSrc = (uint8_t const )pSgBuf->paSegs[0].pvSeg;
465	bool fHit;
466	PRTVFSMEMEXTENT pExtent = rtVfsMemFile_LocateExtent(pThis, offUnsigned, &fHit);
467	for (;;)
468	{
469	/*
470	* If we didn't hit an extent, allocate one (unless it's all zeros).
471	*/
472	if (!fHit)
473	{
474	Assert(!pExtent \|\| pExtent->off > offUnsigned);
475
476	/* Skip leading zeros if there is a whole bunch of them. */
477	uint8_t const pbSrcNZ = (uint8_t const )ASMMemIsAll8(pbSrc, cbLeftToWrite, 0);
478	size_t cbZeros = pbSrcNZ ? pbSrcNZ - pbSrc : cbLeftToWrite;
479	if (cbZeros)
480	{
481	uint64_t const cbToNext = pExtent ? pExtent->off - offUnsigned : UINT64_MAX;
482	if (cbZeros > cbToNext)
483	cbZeros = (size_t)cbToNext;
484	offUnsigned += cbZeros;
485	cbLeftToWrite -= cbZeros;
486	if (!cbLeftToWrite)
487	break;
488
489	Assert(!pExtent \|\| offUnsigned <= pExtent->off);
490	if (pExtent && pExtent->off == offUnsigned)
491	{
492	fHit = true;
493	continue;
494	}
495	}
496
497	fHit = true;
498	pExtent = rtVfsMemFile_AllocExtent(pThis, offUnsigned, cbLeftToWrite, pExtent);
499	if (!pExtent)
500	{
501	rc = VERR_NO_MEMORY;
502	break;
503	}
504	}
505	Assert(offUnsigned - pExtent->off < pExtent->cb);
506
507	/*
508	* Copy the source data into the current extent.
509	*/
510	uint32_t const offDst = (uint32_t)(offUnsigned - pExtent->off);
511	uint32_t cbThisWrite = pExtent->cb - offDst;
512	if (cbThisWrite > cbLeftToWrite)
513	cbThisWrite = (uint32_t)cbLeftToWrite;
514	memcpy(&pExtent->abData[offDst], pbSrc, cbThisWrite);
515
516	offUnsigned += cbLeftToWrite;
517	cbLeftToWrite -= cbThisWrite;
518	if (!cbLeftToWrite)
519	break;
520	pbSrc += cbThisWrite;
521	Assert(offUnsigned == pExtent->off + pExtent->cb);
522
523	/*
524	* Advance to the next extent (emulate the lookup).
525	*/
526	pExtent = RTListGetNext(&pThis->ExtentHead, pExtent, RTVFSMEMEXTENT, Entry);
527	fHit = pExtent && (offUnsigned - pExtent->off < pExtent->cb);
528	}
529
530	/*
531	* Update the state, set return value and return.
532	* Note! There must be no alternative exit path from the loop above.
533	*/
534	pThis->offCurPos = offUnsigned;
535	if ((uint64_t)pThis->Base.ObjInfo.cbObject < offUnsigned)
536	pThis->Base.ObjInfo.cbObject = offUnsigned;
537
538	if (pcbWritten)
539	*pcbWritten = pSgBuf->paSegs[0].cbSeg - cbLeftToWrite;
540	return rc;
541	}
542
543
544	/**
545	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnFlush}
546	*/
547	static DECLCALLBACK(int) rtVfsMemFile_Flush(void *pvThis)
548	{
549	NOREF(pvThis);
550	return VINF_SUCCESS;
551	}
552
553
554	/**
555	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnPollOne}
556	*/
557	static DECLCALLBACK(int) rtVfsMemFile_PollOne(void *pvThis, uint32_t fEvents, RTMSINTERVAL cMillies, bool fIntr,
558	uint32_t *pfRetEvents)
559	{
560	NOREF(pvThis);
561	int rc;
562	if (fEvents != RTPOLL_EVT_ERROR)
563	{
564	*pfRetEvents = fEvents & ~RTPOLL_EVT_ERROR;
565	rc = VINF_SUCCESS;
566	}
567	else
568	rc = RTVfsUtilDummyPollOne(fEvents, cMillies, fIntr, pfRetEvents);
569	return rc;
570	}
571
572
573	/**
574	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnTell}
575	*/
576	static DECLCALLBACK(int) rtVfsMemFile_Tell(void *pvThis, PRTFOFF poffActual)
577	{
578	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
579	*poffActual = pThis->offCurPos;
580	return VINF_SUCCESS;
581	}
582
583
584	/**
585	* @interface_method_impl{RTVFSOBJSETOPS,pfnMode}
586	*/
587	static DECLCALLBACK(int) rtVfsMemFile_SetMode(void *pvThis, RTFMODE fMode, RTFMODE fMask)
588	{
589	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
590	pThis->Base.ObjInfo.Attr.fMode = (pThis->Base.ObjInfo.Attr.fMode & ~fMask) \| fMode;
591	return VINF_SUCCESS;
592	}
593
594
595	/**
596	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetTimes}
597	*/
598	static DECLCALLBACK(int) rtVfsMemFile_SetTimes(void *pvThis, PCRTTIMESPEC pAccessTime, PCRTTIMESPEC pModificationTime,
599	PCRTTIMESPEC pChangeTime, PCRTTIMESPEC pBirthTime)
600	{
601	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
602
603	if (pAccessTime)
604	pThis->Base.ObjInfo.AccessTime = *pAccessTime;
605	if (pModificationTime)
606	pThis->Base.ObjInfo.ModificationTime = *pModificationTime;
607	if (pChangeTime)
608	pThis->Base.ObjInfo.ChangeTime = *pChangeTime;
609	if (pBirthTime)
610	pThis->Base.ObjInfo.BirthTime = *pBirthTime;
611
612	return VINF_SUCCESS;
613	}
614
615
616	/**
617	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetOwner}
618	*/
619	static DECLCALLBACK(int) rtVfsMemFile_SetOwner(void *pvThis, RTUID uid, RTGID gid)
620	{
621	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
622
623	if (uid != NIL_RTUID)
624	pThis->Base.ObjInfo.Attr.u.Unix.uid = uid;
625	if (gid != NIL_RTUID)
626	pThis->Base.ObjInfo.Attr.u.Unix.gid = gid;
627
628	return VINF_SUCCESS;
629	}
630
631
632	/**
633	* @interface_method_impl{RTVFSFILEOPS,pfnSeek}
634	*/
635	static DECLCALLBACK(int) rtVfsMemFile_Seek(void *pvThis, RTFOFF offSeek, unsigned uMethod, PRTFOFF poffActual)
636	{
637	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
638
639	/*
640	* Seek relative to which position.
641	*/
642	uint64_t offWrt;
643	switch (uMethod)
644	{
645	case RTFILE_SEEK_BEGIN:
646	offWrt = 0;
647	break;
648
649	case RTFILE_SEEK_CURRENT:
650	offWrt = pThis->offCurPos;
651	break;
652
653	case RTFILE_SEEK_END:
654	offWrt = pThis->Base.ObjInfo.cbObject;
655	break;
656
657	default:
658	return VERR_INTERNAL_ERROR_5;
659	}
660
661	/*
662	* Calc new position, take care to stay without bounds.
663	*/
664	uint64_t offNew;
665	if (offSeek == 0)
666	offNew = offWrt;
667	else if (offSeek > 0)
668	{
669	offNew = offWrt + offSeek;
670	if ( offNew < offWrt
671	\|\| offNew > RTFOFF_MAX)
672	offNew = RTFOFF_MAX;
673	}
674	else if ((uint64_t)-offSeek < offWrt)
675	offNew = offWrt + offSeek;
676	else
677	offNew = 0;
678
679	/*
680	* Update the state and set return value.
681	*/
682	if ( pThis->pCurExt
683	&& pThis->pCurExt->off - offNew >= pThis->pCurExt->cb)
684	pThis->pCurExt = NULL;
685	pThis->offCurPos = offNew;
686
687	*poffActual = offNew;
688	return VINF_SUCCESS;
689	}
690
691
692	/**
693	* @interface_method_impl{RTVFSFILEOPS,pfnQuerySize}
694	*/
695	static DECLCALLBACK(int) rtVfsMemFile_QuerySize(void pvThis, uint64_t pcbFile)
696	{
697	PRTVFSMEMFILE pThis = (PRTVFSMEMFILE)pvThis;
698	*pcbFile = pThis->Base.ObjInfo.cbObject;
699	return VINF_SUCCESS;
700	}
701
702
703	/**
704	* Standard file operations.
705	*/
706	DECL_HIDDEN_CONST(const RTVFSFILEOPS) g_rtVfsStdFileOps =
707	{
708	{ /* Stream */
709	{ /* Obj */
710	RTVFSOBJOPS_VERSION,
711	RTVFSOBJTYPE_FILE,
712	"MemFile",
713	rtVfsMemFile_Close,
714	rtVfsMemFile_QueryInfo,
715	RTVFSOBJOPS_VERSION
716	},
717	RTVFSIOSTREAMOPS_VERSION,
718	RTVFSIOSTREAMOPS_FEAT_NO_SG,
719	rtVfsMemFile_Read,
720	rtVfsMemFile_Write,
721	rtVfsMemFile_Flush,
722	rtVfsMemFile_PollOne,
723	rtVfsMemFile_Tell,
724	NULL /Skip/,
725	NULL /ZeroFill/,
726	RTVFSIOSTREAMOPS_VERSION,
727	},
728	RTVFSFILEOPS_VERSION,
729	/RTVFSIOFILEOPS_FEAT_NO_AT_OFFSET/ 0,
730	{ /* ObjSet */
731	RTVFSOBJSETOPS_VERSION,
732	RT_OFFSETOF(RTVFSFILEOPS, Stream.Obj) - RT_OFFSETOF(RTVFSFILEOPS, ObjSet),
733	rtVfsMemFile_SetMode,
734	rtVfsMemFile_SetTimes,
735	rtVfsMemFile_SetOwner,
736	RTVFSOBJSETOPS_VERSION
737	},
738	rtVfsMemFile_Seek,
739	rtVfsMemFile_QuerySize,
740	RTVFSFILEOPS_VERSION
741	};
742
743
744
745
746
747	RTDECL(int) RTVfsMemorizeIoStreamAsFile(RTVFSIOSTREAM hVfsIos, uint32_t fFlags, PRTVFSFILE phVfsFile)
748	{
749	/*
750	* Create a memory file instance and try set the extension size to match
751	* the length of the I/O stream.
752	*/
753	RTFSOBJINFO ObjInfo;
754	int rc = RTVfsIoStrmQueryInfo(hVfsIos, &ObjInfo, RTFSOBJATTRADD_UNIX);
755	if (RT_SUCCESS(rc))
756	{
757	RTVFSFILE hVfsFile;
758	PRTVFSMEMFILE pThis;
759	rc = RTVfsNewFile(&g_rtVfsStdFileOps, sizeof(*pThis), fFlags \| RTFILE_O_WRITE, NIL_RTVFS, NIL_RTVFSLOCK,
760	&hVfsFile, (void **)&pThis);
761	if (RT_SUCCESS(rc))
762	{
763	pThis->Base.ObjInfo = ObjInfo;
764	pThis->offCurPos = 0;
765	pThis->pCurExt = NULL;
766	RTListInit(&pThis->ExtentHead);
767	if (ObjInfo.cbObject <= 0)
768	pThis->cbExtent = _4K;
769	else if (ObjInfo.cbObject < RTVFSMEM_MAX_EXTENT_SIZE)
770	pThis->cbExtent = _4K /* ObjInfo.cbObject */;
771	else
772	pThis->cbExtent = RTVFSMEM_MAX_EXTENT_SIZE;
773
774	/*
775	* Copy the stream.
776	*/
777	RTVFSIOSTREAM hVfsIosDst = RTVfsFileToIoStream(hVfsFile);
778	rc = RTVfsUtilPumpIoStreams(hVfsIos, hVfsIosDst, pThis->cbExtent);
779	RTVfsIoStrmRelease(hVfsIosDst);
780	if (RT_SUCCESS(rc))
781	{
782	pThis->pCurExt = RTListGetFirst(&pThis->ExtentHead, RTVFSMEMEXTENT, Entry);
783	pThis->offCurPos = 0;
784
785	if (!(fFlags & RTFILE_O_WRITE))
786	{
787	/** @todo clear RTFILE_O_WRITE from the resulting. */
788	}
789	*phVfsFile = hVfsFile;
790	return VINF_SUCCESS;
791	}
792	RTVfsFileRelease(hVfsFile);
793	}
794	}
795	return rc;
796	}

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source: vbox/trunk/src/VBox/Runtime/common/vfs/vfsmemory.cpp@ 42599

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