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changeset 131:b6b3f04a732f

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Cleaned up fs code init_fs actually uses the devnum passed to it rootLoc changed to RootLoc for consistency vint other variables Added comments on anything that was not instantly obvious to me TODO: multiple disks (oh, how I wish I had C++ classes for this... Oh well, I am now thinking of a fake OO interface where some structure is just required to be passed to every single function. I just do not know how well that would work with program-level stuff... I will think about it more...)
author Jonathan Pevarnek <pevarnj@gmail.com>
date Wed, 31 Aug 2011 23:58:33 -0400
parents 550840bcc140
children abf1f35f5935
files include/error.h include/os/fs.h src/os/fs.c
diffstat 3 files changed, 28 insertions(+), 18 deletions(-) [+]
line wrap: on
line diff
--- a/include/error.h	Wed Aug 31 16:11:06 2011 -0400
+++ b/include/error.h	Wed Aug 31 23:58:33 2011 -0400
@@ -29,6 +29,7 @@
 #define NOTINCACHE 8
 #define DISKFULL 9 //every block on the disk is currently set to be in use
 #define EXISTS 10 //the user tried to create a file that already exists
+#define SMALLCACHE 11 //the cache size is not large enough for the operation
 
 //Codes: Time of date
 #define UPTIME 1 //the actual time of date was not set in the system
--- a/include/os/fs.h	Wed Aug 31 16:11:06 2011 -0400
+++ b/include/os/fs.h	Wed Aug 31 23:58:33 2011 -0400
@@ -1,10 +1,10 @@
+#ifndef __FS_H
+#define __FS_H
+
 #include <std.h>
 #include <error.h>
 #include <os/fsStructs.h>
 
-#ifndef __FS_H
-#define __FS_H
-
 #define CACHESPACE 1 //percentage of heap to use for the FS Cache
 #define FSMAGICNUM 0x42420374
 #define DEPBLK (FSBLKSIZE / sizeof(Direntry)) //director entries per block
--- a/src/os/fs.c	Wed Aug 31 16:11:06 2011 -0400
+++ b/src/os/fs.c	Wed Aug 31 23:58:33 2011 -0400
@@ -22,7 +22,7 @@
 static FSBlk *FS_Cache = NULL; //A pointer to the actual cache
 static u32 *CacheLocs; //what location each block points to
 static u32 CacheNext; //the next location to toss a cached block into
-static u32 rootLoc;
+static u32 RootLoc;
 static u32 MaxBlocks;
 
 ErrCode init_fs(u32 devnum, u64 __memsize)
@@ -37,20 +37,20 @@
 	CacheSize = 0;
 	CacheNext = 0;
 
-	DevID = find_dev(0x100);
+	DevID = find_dev(devnum);
 	Superblock *sb;
-	sb = readFSBlock(1);
+	sb = readFSBlock(1); //second file system block has the superblock
 	if(!sb) return ERR_FSBLKREADFAIL;
 	if(sb->magic != FSMAGICNUM) return mkError(MODFS, MUGGLE, ERROR);
 	MaxBlocks = sb->nblocks;
-	rootLoc = sb->root_inode;
+	RootLoc = sb->root_inode;
 
 	return 0;
 }
 
 ErrCode getFInfo(u32 n, void* de)
 {
-	Inode *root = readFSBlock(rootLoc);
+	Inode *root = readFSBlock(RootLoc);
 	if(!root) return ERR_FSBLKREADFAIL;
 	if(n >= root->size/DEPBLK) return mkError(MODFS, OUTOFRANGE, WARN);
 	Direntry *dp = readFSBlock(root->blocks[n/DEPBLK]);
@@ -82,12 +82,13 @@
 ErrCode makeFile(char *fname, u32 *fid)
 {
 	ErrCode err;
+	//lookupFile should return the notfile erro as the file should not yet exist
 	if(!isError(err = lookupFile(fname, fid)))
 		return mkError(MODFS, EXISTS, ERROR); //the file should not exist
 	if(err != mkError(MODFS, NOTFILE, ERROR)) return err;
 	if(isError(err = nextFreeBlock(0, fid))) return err;
 
-	Inode nin;
+	Inode nin; //new inode
 	nin.size = 0;
 	nin.nblocks = 0;
 	if(isError(err = setTod(&nin))) return err;
@@ -98,7 +99,7 @@
 	Direntry de;
 	de.inode = *fid;
 	memcpy(de.fname, fname, FNAMELEN);
-	if(isError(err = fileAppend(rootLoc, &de, sizeof(Direntry)))) return err;
+	if(isError(err = fileAppend(RootLoc, &de, sizeof(Direntry)))) return err;
 
 	return 0;
 }
@@ -106,7 +107,7 @@
 ErrCode deleteFile(u32 fid)
 {
 	ErrCode err;
-	if(isError(err = setFileSize(fid, 0))) return err;
+	if(isError(err = setFileSize(fid, 0))) return err; //get rid of all the data
 	Direntry de;
 	u32 fileNo;
 	for(fileNo = 0; 1; fileNo++) {
@@ -114,7 +115,7 @@
 		else if(err == mkError(MODFS, OUTOFRANGE, WARN)) return mkError(MODFS, NOTFILE, ERROR);
 		if(de.inode == fid) break;
 	}
-	Inode *root = readFSBlock(rootLoc);
+	Inode *root = readFSBlock(RootLoc);
 	if(!root) return ERR_FSBLKREADFAIL;
 	u32 rootSize = root->size;
 	u32 numDE = rootSize/sizeof(Direntry);
@@ -124,16 +125,19 @@
 	if(!td) return ERR_FSBLKREADFAIL;
 	td += fileNo%DEPBLK;
 	Direntry *end = readFSBlock(endBlkNo);
+		//XXX HACK consider fixing
 		//this will fail if there is only space for one item in cache and the 2 DEs
-		//are in different blocks.  There will be no indication of failure
+		//are in different blocks.  The line below should detect this failure
+	if(end == td) return mkError(MODFS, SMALLCACHE, ERROR);
 	if(!end) return ERR_FSBLKREADFAIL;
 	end += numDE%DEPBLK - 1;
 	*td = *end;
-	if(isError(err = setFileSize(rootLoc, rootSize - sizeof(Direntry)))) return err;
+	if(isError(err = setFileSize(RootLoc, rootSize - sizeof(Direntry)))) return err;
 	if(isError(err = sync(toBlkNo))) return err; //end does not need to be synchronized
 	return 0;
 }
 
+//a simple wrapper for fileWrite that just appends the data to the file
 ErrCode fileAppend(u32 fid, void *data, u32 length)
 {
 	ErrCode err;
@@ -149,11 +153,13 @@
 	Inode *iptr = readFSBlock(fid);
 	if(!iptr) return ERR_FSBLKREADFAIL;
 	u32 oldSize = iptr->size;
-	u32 dataStop = offset + length;
-	if(dataStop > oldSize) {
+	u32 dataStop = offset + length; //where the new data will stop being added
+	if(dataStop > oldSize) { //if the file will need to be longer than it is, make it so
 		if(isError(err = setFileSize(fid, dataStop))) return err;
 	}
 
+	//I will be using the cache for the file contents so copy this out just in
+	//case it would be overwritten
 	Inode in;
 	if(isError(err = getBlockData(fid, &in))) return err;
 
@@ -165,8 +171,8 @@
 		u32 tcOS = currPos%FSBLKSIZE; //the current offset for the block
 		u32 tcSize = Min_u32(dataStop - currPos, FSBLKSIZE); //assume 0 offset
 		tcSize = (tcSize + tcOS > FSBLKSIZE)?FSBLKSIZE - tcOS:tcSize; //take into account the offset
-		memcpy(ptr + tcOS, data, tcSize);
-		if(isError(err = sync(currBlock))) return err;
+		memcpy(ptr + tcOS, data, tcSize); //copy the data into the cache
+		if(isError(err = sync(currBlock))) return err; //update the disk
 		data += tcSize;
 		currPos += tcSize;
 	}
@@ -291,6 +297,7 @@
 	return 0;
 }
 
+//copies the data from block blkno to the location specified by the user
 static ErrCode getBlockData(u32 blkno, void* ptr)
 {
 	Inode *temp = readFSBlock(blkno);
@@ -416,6 +423,8 @@
 	return ret;
 }
 
+
+//This function sets the modified time of the inode to be the current time
 //TODO consider what to do in other places if this returns a warning/error
 static ErrCode setTod(Inode *inPtr)
 {