yaffsfs.c

yaffs2 lastest sourcecode~~

/*
 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2007 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * Created by Charles Manning <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "yaffsfs.h"
#include "yaffs_guts.h"
#include "yaffscfg.h"
#include <string.h> // for memset
#include "yportenv.h"

#define YAFFSFS_MAX_SYMLINK_DEREFERENCES 5

#ifndef NULL
#define NULL ((void *)0)
#endif


const char *yaffsfs_c_version="$Id: yaffsfs.c,v 1.25 2009/03/05 01:47:17 charles Exp $";

// configurationList is the list of devices that are supported
static yaffsfs_DeviceConfiguration *yaffsfs_configurationList;


/* Some forward references */
static yaffs_Object *yaffsfs_FindObject(yaffs_Object *relativeDirectory, const YCHAR *path, int symDepth);
static void yaffsfs_RemoveObjectCallback(yaffs_Object *obj);


// Handle management.
//


unsigned int yaffs_wr_attempts;

typedef struct
{
	__u8  inUse:1;		// this handle is in use
	__u8  readOnly:1;	// this handle is read only
	__u8  append:1;		// append only
	__u8  exclusive:1;	// exclusive
	__u32 position;		// current position in file
	yaffs_Object *obj;	// the object
}yaffsfs_Handle;


static yaffsfs_Handle yaffsfs_handle[YAFFSFS_N_HANDLES];

// yaffsfs_InitHandle
/// Inilitalise handles on start-up.
//
static int yaffsfs_InitHandles(void)
{
	int i;
	for(i = 0; i < YAFFSFS_N_HANDLES; i++)
	{
		yaffsfs_handle[i].inUse = 0;
		yaffsfs_handle[i].obj = NULL;
	}
	return 0;
}

yaffsfs_Handle *yaffsfs_GetHandlePointer(int h)
{
	if(h < 0 || h >= YAFFSFS_N_HANDLES)
	{
		return NULL;
	}

	return &yaffsfs_handle[h];
}

yaffs_Object *yaffsfs_GetHandleObject(int handle)
{
	yaffsfs_Handle *h = yaffsfs_GetHandlePointer(handle);

	if(h && h->inUse)
	{
		return h->obj;
	}

	return NULL;
}


//yaffsfs_GetHandle
// Grab a handle (when opening a file)
//

static int yaffsfs_GetHandle(void)
{
	int i;
	yaffsfs_Handle *h;

	for(i = 0; i < YAFFSFS_N_HANDLES; i++)
	{
		h = yaffsfs_GetHandlePointer(i);
		if(!h)
		{
			// todo bug: should never happen
		}
		if(!h->inUse)
		{
			memset(h,0,sizeof(yaffsfs_Handle));
			h->inUse=1;
			return i;
		}
	}
	return -1;
}

// yaffs_PutHandle
// Let go of a handle (when closing a file)
//
static int yaffsfs_PutHandle(int handle)
{
	yaffsfs_Handle *h = yaffsfs_GetHandlePointer(handle);

	if(h)
	{
		h->inUse = 0;
		h->obj = NULL;
	}
	return 0;
}



// Stuff to search for a directory from a path


int yaffsfs_Match(YCHAR a, YCHAR b)
{
	// case sensitive
	return (a == b);
}

int yaffsfs_IsPathDivider(YCHAR ch)
{
	YCHAR *str = YAFFS_PATH_DIVIDERS;

	while(*str){
		if(*str == ch)
			return 1;
		str++;
	}

	return 0;
}

// yaffsfs_FindDevice
// yaffsfs_FindRoot
// Scan the configuration list to find the root.
// Curveballs: Should match paths that end in '/' too
// Curveball2 Might have "/x/ and "/x/y". Need to return the longest match
static yaffs_Device *yaffsfs_FindDevice(const YCHAR *path, YCHAR **restOfPath)
{
	yaffsfs_DeviceConfiguration *cfg = yaffsfs_configurationList;
	const YCHAR *leftOver;
	const YCHAR *p;
	yaffs_Device *retval = NULL;
	int thisMatchLength;
	int longestMatch = -1;
	int matching;

	// Check all configs, choose the one that:
	// 1) Actually matches a prefix (ie /a amd /abc will not match
	// 2) Matches the longest.
	while(cfg && cfg->prefix && cfg->dev)
	{
		leftOver = path;
		p = cfg->prefix;
		thisMatchLength = 0;
		matching = 1;


		while(matching && *p && *leftOver){
			// Skip over any /s
			while(yaffsfs_IsPathDivider(*p))
			      p++;

			// Skip over any /s
			while(yaffsfs_IsPathDivider(*leftOver))
		              leftOver++;

			// Now match the text part
		        while(matching &&
		              *p && !yaffsfs_IsPathDivider(*p) &&
		              *leftOver && !yaffsfs_IsPathDivider(*leftOver)){
			      	if(yaffsfs_Match(*p,*leftOver)){
			      		p++;
			      		leftOver++;
			      		thisMatchLength++;
				} else {
					matching = 0;
				}
			}
		}

		// Skip over any /s in leftOver
		while(yaffsfs_IsPathDivider(*leftOver))
	              leftOver++;
		

		if( matching && (thisMatchLength > longestMatch))
		{
			// Matched prefix
			*restOfPath = (YCHAR *)leftOver;
			retval = cfg->dev;
			longestMatch = thisMatchLength;
		}

		cfg++;
	}
	return retval;
}

#if 0
static yaffs_Device *yaffsfs_FindDevice(const YCHAR *path, YCHAR **restOfPath)
{
	yaffsfs_DeviceConfiguration *cfg = yaffsfs_configurationList;
	const YCHAR *leftOver;
	const YCHAR *p;
	yaffs_Device *retval = NULL;
	int thisMatchLength;
	int longestMatch = -1;

	// Check all configs, choose the one that:
	// 1) Actually matches a prefix (ie /a amd /abc will not match
	// 2) Matches the longest.
	while(cfg && cfg->prefix && cfg->dev)
	{
		leftOver = path;
		p = cfg->prefix;
		thisMatchLength = 0;

		while(*p &&  //unmatched part of prefix
		      !(yaffsfs_IsPathDivider(*p) && (p[1] == 0)) && // the rest of the prefix is not / (to catch / at end)
		      *leftOver &&
		      yaffsfs_Match(*p,*leftOver))
		{
			p++;
			leftOver++;
			thisMatchLength++;
		}


		if((!*p || (yaffsfs_IsPathDivider(*p) && (p[1] == 0))) &&      // end of prefix
		   (!*leftOver || yaffsfs_IsPathDivider(*leftOver)) && // no more in this path name part
		   (thisMatchLength > longestMatch))
		{
			// Matched prefix
			*restOfPath = (YCHAR *)leftOver;
			retval = cfg->dev;
			longestMatch = thisMatchLength;
		}
		cfg++;
	}
	return retval;
}
#endif

static yaffs_Object *yaffsfs_FindRoot(const YCHAR *path, YCHAR **restOfPath)
{

	yaffs_Device *dev;

	dev= yaffsfs_FindDevice(path,restOfPath);
	if(dev && dev->isMounted)
	{
		return dev->rootDir;
	}
	return NULL;
}

static yaffs_Object *yaffsfs_FollowLink(yaffs_Object *obj,int symDepth)
{

	while(obj && obj->variantType == YAFFS_OBJECT_TYPE_SYMLINK)
	{
		YCHAR *alias = obj->variant.symLinkVariant.alias;

		if(yaffsfs_IsPathDivider(*alias))
		{
			// Starts with a /, need to scan from root up
			obj = yaffsfs_FindObject(NULL,alias,symDepth++);
		}
		else
		{
			// Relative to here, so use the parent of the symlink as a start
			obj = yaffsfs_FindObject(obj->parent,alias,symDepth++);
		}
	}
	return obj;
}


// yaffsfs_FindDirectory
// Parse a path to determine the directory and the name within the directory.
//
// eg. "/data/xx/ff" --> puts name="ff" and returns the directory "/data/xx"
static yaffs_Object *yaffsfs_DoFindDirectory(yaffs_Object *startDir,const YCHAR *path,YCHAR **name,int symDepth)
{
	yaffs_Object *dir;
	YCHAR *restOfPath;
	YCHAR str[YAFFS_MAX_NAME_LENGTH+1];
	int i;

	if(symDepth > YAFFSFS_MAX_SYMLINK_DEREFERENCES)
	{
		return NULL;
	}

	if(startDir)
	{
		dir = startDir;
		restOfPath = (YCHAR *)path;
	}
	else
	{
		dir = yaffsfs_FindRoot(path,&restOfPath);
	}

	while(dir)
	{
		// parse off /.
		// curve ball: also throw away surplus '/'
		// eg. "/ram/x////ff" gets treated the same as "/ram/x/ff"
		while(yaffsfs_IsPathDivider(*restOfPath))
		{
			restOfPath++; // get rid of '/'
		}

		*name = restOfPath;
		i = 0;

		while(*restOfPath && !yaffsfs_IsPathDivider(*restOfPath))
		{
			if (i < YAFFS_MAX_NAME_LENGTH)
			{
				str[i] = *restOfPath;
				str[i+1] = '\0';
				i++;
			}
			restOfPath++;
		}

		if(!*restOfPath)
		{
			// got to the end of the string
			return dir;
		}
		else
		{
			if(yaffs_strcmp(str,_Y(".")) == 0)
			{
				// Do nothing
			}
			else if(yaffs_strcmp(str,_Y("..")) == 0)
			{
				dir = dir->parent;
			}
			else
			{
				dir = yaffs_FindObjectByName(dir,str);

				while(dir && dir->variantType == YAFFS_OBJECT_TYPE_SYMLINK)
				{

					dir = yaffsfs_FollowLink(dir,symDepth);

				}

				if(dir && dir->variantType != YAFFS_OBJECT_TYPE_DIRECTORY)
				{
					dir = NULL;
				}
			}
		}
	}
	// directory did not exist.
	return NULL;
}

static yaffs_Object *yaffsfs_FindDirectory(yaffs_Object *relativeDirectory,const YCHAR *path,YCHAR **name,int symDepth)
{
	return yaffsfs_DoFindDirectory(relativeDirectory,path,name,symDepth);
}

// yaffsfs_FindObject turns a path for an existing object into the object
//
static yaffs_Object *yaffsfs_FindObject(yaffs_Object *relativeDirectory, const YCHAR *path,int symDepth)
{
	yaffs_Object *dir;
	YCHAR *name;

	dir = yaffsfs_FindDirectory(relativeDirectory,path,&name,symDepth);

	if(dir && *name)
	{
		return yaffs_FindObjectByName(dir,name);
	}

	return dir;
}


int yaffs_dup(int fd)
{
	int newHandle = -1;
	yaffsfs_Handle *oldPtr = NULL;
	yaffsfs_Handle *newPtr = NULL;

	yaffsfs_Lock();

	oldPtr = yaffsfs_GetHandlePointer(fd);
	if(oldPtr && oldPtr->inUse)
		newHandle = yaffsfs_GetHandle();
	if(newHandle >= 0)
		newPtr = yaffsfs_GetHandlePointer(newHandle);

	if(newPtr){
		*newPtr = *oldPtr;
		return newHandle;
	}

	if(!oldPtr)
		yaffsfs_SetError(-EBADF);
	else
		yaffsfs_SetError(-ENOMEM);

	return -1;

}

int yaffs_open(const YCHAR *path, int oflag, int mode)
{
	yaffs_Object *obj = NULL;
	yaffs_Object *dir = NULL;
	YCHAR *name;
	int handle = -1;
	yaffsfs_Handle *h = NULL;
	int alreadyOpen = 0;
	int alreadyExclusive = 0;
	int openDenied = 0;
	int symDepth = 0;
	int errorReported = 0;

	int i;


	// todo sanity check oflag (eg. can't have O_TRUNC without WRONLY or RDWR


	yaffsfs_Lock();

	handle = yaffsfs_GetHandle();

	if(handle >= 0)
	{

		h = yaffsfs_GetHandlePointer(handle);


		// try to find the exisiting object
		obj = yaffsfs_FindObject(NULL,path,0);

		if(obj && obj->variantType == YAFFS_OBJECT_TYPE_SYMLINK)
		{

			obj = yaffsfs_FollowLink(obj,symDepth++);
		}

		if(obj && obj->variantType != YAFFS_OBJECT_TYPE_FILE)
		{
			obj = NULL;
		}

		if(obj)
		{
			// Check if the object is already in use
			alreadyOpen = alreadyExclusive = 0;

			for(i = 0; i < YAFFSFS_N_HANDLES; i++)
			{

				if(i != handle &&
				   yaffsfs_handle[i].inUse &&
				    obj == yaffsfs_handle[i].obj)
				 {
				 	alreadyOpen = 1;
					if(yaffsfs_handle[i].exclusive)
					{
						alreadyExclusive = 1;
					}
				 }
			}

			if(((oflag & O_EXCL) && alreadyOpen) || alreadyExclusive)
			{
				openDenied = 1;
			}

			// Open should fail if O_CREAT and O_EXCL are specified
			if((oflag & O_EXCL) && (oflag & O_CREAT))
			{
				openDenied = 1;
				yaffsfs_SetError(-EEXIST);
				errorReported = 1;
			}

			// Check file permissions
			if( (oflag & (O_RDWR | O_WRONLY)) == 0 &&     // ie O_RDONLY
			   !(obj->yst_mode & S_IREAD))
			{
				openDenied = 1;
			}

			if( (oflag & O_RDWR) &&
			   !(obj->yst_mode & S_IREAD))
			{
				openDenied = 1;
			}

			if( (oflag & (O_RDWR | O_WRONLY)) &&
			   !(obj->yst_mode & S_IWRITE))
			{
				openDenied = 1;
			}

		}

		else if((oflag & O_CREAT))
		{
			// Let's see if we can create this file
			dir = yaffsfs_FindDirectory(NULL,path,&name,0);
			if(dir)
			{
				obj = yaffs_MknodFile(dir,name,mode,0,0);
			}
			else
			{
				yaffsfs_SetError(-ENOTDIR);
				errorReported = 1;
			}
		}

		if(obj && !openDenied)
		{
			h->obj = obj;
			h->inUse = 1;
	    	h->readOnly = (oflag & (O_WRONLY | O_RDWR)) ? 0 : 1;
			h->append =  (oflag & O_APPEND) ? 1 : 0;
			h->exclusive = (oflag & O_EXCL) ? 1 : 0;
			h->position = 0;

                        obj->inUse++;
                        if((oflag & O_TRUNC) && !h->readOnly)
                        {
                                yaffs_ResizeFile(obj,0);
                        }

		}
		else
		{
			yaffsfs_PutHandle(handle);
			if(!errorReported)
			{
				yaffsfs_SetError(-EACCES);
				errorReported = 1;
			}
			handle = -1;
		}

	}

	yaffsfs_Unlock();

	return handle;
}

int yaffs_flush(int fd)
{
	yaffsfs_Handle *h = NULL;
	int retVal = 0;

	yaffsfs_Lock();

	h = yaffsfs_GetHandlePointer(fd);

	if(h && h->inUse)
	{
		// flush the file
		yaffs_FlushFile(h->obj,1);
	}
	else
	{
		// bad handle
		yaffsfs_SetError(-EBADF);
		retVal = -1;
	}

	yaffsfs_Unlock();

	return retVal;
}


int yaffs_close(int fd)
{
	yaffsfs_Handle *h = NULL;
	int retVal = 0;

	yaffsfs_Lock();

	h = yaffsfs_GetHandlePointer(fd);

	if(h && h->inUse)
	{
		// clean up
		yaffs_FlushFile(h->obj,1);
		h->obj->inUse--;
		if(h->obj->inUse <= 0 && h->obj->unlinked)
		{
			yaffs_DeleteObject(h->obj);
		}
		yaffsfs_PutHandle(fd);
		retVal = 0;
	}
	else
	{
		// bad handle
		yaffsfs_SetError(-EBADF);
		retVal = -1;
	}

	yaffsfs_Unlock();

	return retVal;
}

int yaffs_read(int fd, void *buf, unsigned int nbyte)
{
	yaffsfs_Handle *h = NULL;
	yaffs_Object *obj = NULL;
	int pos = 0;
	int nRead = -1;
	unsigned int maxRead;

	yaffsfs_Lock();
	h = yaffsfs_GetHandlePointer(fd);
	obj = yaffsfs_GetHandleObject(fd);

	if(!h || !obj)
	{
		// bad handle
		yaffsfs_SetError(-EBADF);
	}
	else if( h && obj)