file.c

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#include "sysincludes.h"
#include "msdos.h"
#include "stream.h"
#include "mtools.h"
#include "fsP.h"
#include "file.h"
#include "htable.h"
#include "dirCache.h"

typedef struct File_t {
        Class_t *Class;
        int refs;
        struct Fs_t *Fs;        /* Filesystem that this fat file belongs to */
        Stream_t *Buffer;

        int (*map)(struct File_t *this, off_t where, size_t *len, int mode,
                           mt_off_t *res);
        size_t FileSize;

        size_t preallocatedSize;
        int preallocatedClusters;

        /* Absolute position of first cluster of file */
        unsigned int FirstAbsCluNr;

        /* Absolute position of previous cluster */
        unsigned int PreviousAbsCluNr;

        /* Relative position of previous cluster */
        unsigned int PreviousRelCluNr;
        direntry_t direntry;
        int hint;
        struct dirCache_t *dcp;

        unsigned int loopDetectRel;
        unsigned int loopDetectAbs;
} File_t;

static Class_t FileClass;
T_HashTable *filehash;

static File_t *getUnbufferedFile(Stream_t *Stream)
{
        while(Stream->Class != &FileClass)
                Stream = Stream->Next;
        return (File_t *) Stream;
}

Fs_t *getFs(Stream_t *Stream)
{
        return getUnbufferedFile(Stream)->Fs;
}

struct dirCache_t **getDirCacheP(Stream_t *Stream)
{
        return &getUnbufferedFile(Stream)->dcp;
}

direntry_t *getDirentry(Stream_t *Stream)
{
        return &getUnbufferedFile(Stream)->direntry;
}


static int recalcPreallocSize(File_t *This)
{
        size_t currentClusters, neededClusters;
        int clus_size;
        int neededPrealloc;
        Fs_t *Fs = This->Fs;
        int r;

        if(This->FileSize & 0xc0000000) {
                fprintf(stderr, "Bad filesize\n");
        }
        if(This->preallocatedSize & 0xc0000000) {
                fprintf(stderr, "Bad preallocated size %x\n", 
                                (int) This->preallocatedSize);
        }

        clus_size = Fs->cluster_size * Fs->sector_size;

        currentClusters = (This->FileSize + clus_size - 1) / clus_size;
        neededClusters = (This->preallocatedSize + clus_size - 1) / clus_size;
        neededPrealloc = neededClusters - currentClusters;
        if(neededPrealloc < 0)
                neededPrealloc = 0;
        r = fsPreallocateClusters(Fs, neededPrealloc - This->preallocatedClusters);
        if(r)
                return r;
        This->preallocatedClusters = neededPrealloc;
        return 0;
}

static int _loopDetect(unsigned int *oldrel, unsigned int rel, 
                                           unsigned int *oldabs, unsigned int abs)
{
        if(*oldrel && rel > *oldrel && abs == *oldabs) {
                fprintf(stderr, "loop detected! oldrel=%d newrel=%d abs=%d\n",
                                *oldrel, rel, abs);
                return -1;
        }

        if(rel >= 2 * *oldrel + 1) {
                *oldrel = rel;
                *oldabs = abs;
        }
        return 0;
}


static int loopDetect(File_t *This, unsigned int rel, unsigned int abs)
{
        return _loopDetect(&This->loopDetectRel, rel, &This->loopDetectAbs, abs);
}

static unsigned int _countBlocks(Fs_t *This, unsigned int block)
{
        unsigned int blocks;
        unsigned int rel, oldabs, oldrel;

        blocks = 0;
        
        oldabs = oldrel = rel = 0;

        while (block <= This->last_fat && block != 1 && block) {
                blocks++;
                block = fatDecode(This, block);
                rel++;
                if(_loopDetect(&oldrel, rel, &oldabs, block) < 0)
                        block = -1;
        }
        return blocks;
}

unsigned int countBlocks(Stream_t *Dir, unsigned int block)
{
        Stream_t *Stream = GetFs(Dir);
        DeclareThis(Fs_t);

        return _countBlocks(This, block);
}

/* returns number of bytes in a directory.  Represents a file size, and
 * can hence be not bigger than 2^32
 */
static size_t countBytes(Stream_t *Dir, unsigned int block)
{
        Stream_t *Stream = GetFs(Dir);
        DeclareThis(Fs_t);

        return _countBlocks(This, block) * 
                This->sector_size * This->cluster_size;
}

void printFat(Stream_t *Stream)
{
        File_t *This = getUnbufferedFile(Stream);
        unsigned long n;
        int rel;
        unsigned long begin, end;
        int first;

        n = This->FirstAbsCluNr;
        if(!n) {
                printf("Root directory or empty file\n");
                return;
        }

        rel = 0;
        first = 1;
        begin = end = 0;
        do {
                if (first || n != end+1) {
                        if (!first) {
                                if (begin != end)
                                        printf("-%lu", end);
                                printf("> ");
                        }
                        begin = end = n;
                        printf("<%lu", begin);
                } else {
                        end++;
                }
                first = 0;
                n = fatDecode(This->Fs, n);
                rel++;
                if(loopDetect(This, rel, n) < 0)
                        n = 1;
        } while (n <= This->Fs->last_fat && n != 1);
        if(!first) {
                if (begin != end)
                        printf("-%lu", end);
                printf(">");
        }
}

static int normal_map(File_t *This, off_t where, size_t *len, int mode,
                                                   mt_off_t *res)
{
        int offset;
        off_t end;
        int NrClu; /* number of clusters to read */
        unsigned int RelCluNr;
        unsigned int CurCluNr;
        unsigned int NewCluNr;
        unsigned int AbsCluNr;
        int clus_size;
        Fs_t *Fs = This->Fs;

        *res = 0;
        clus_size = Fs->cluster_size * Fs->sector_size;
        offset = where % clus_size;

        if (mode == MT_READ)
                maximize(*len, This->FileSize - where);
        if (*len == 0 )
                return 0;

        if (This->FirstAbsCluNr < 2){
                if( mode == MT_READ || *len == 0){
                        *len = 0;
                        return 0;
                }
                NewCluNr = get_next_free_cluster(This->Fs, 1);
                if (NewCluNr == 1 ){
                        errno = ENOSPC;
                        return -2;
                }
                hash_remove(filehash, (void *) This, This->hint);
                This->FirstAbsCluNr = NewCluNr;
                hash_add(filehash, (void *) This, &This->hint);
                fatAllocate(This->Fs, NewCluNr, Fs->end_fat);
        }

        RelCluNr = where / clus_size;
        
        if (RelCluNr >= This->PreviousRelCluNr){
                CurCluNr = This->PreviousRelCluNr;
                AbsCluNr = This->PreviousAbsCluNr;
        } else {
                CurCluNr = 0;
                AbsCluNr = This->FirstAbsCluNr;
        }


        NrClu = (offset + *len - 1) / clus_size;
        while (CurCluNr <= RelCluNr + NrClu){
                if (CurCluNr == RelCluNr){
                        /* we have reached the beginning of our zone. Save
                         * coordinates */
                        This->PreviousRelCluNr = RelCluNr;
                        This->PreviousAbsCluNr = AbsCluNr;
                }
                NewCluNr = fatDecode(This->Fs, AbsCluNr);
                if (NewCluNr == 1 || NewCluNr == 0){
                        fprintf(stderr,"Fat problem while decoding %d %x\n", 
                                AbsCluNr, NewCluNr);
                        exit(1);
                }
                if(CurCluNr == RelCluNr + NrClu)                        
                        break;
                if (NewCluNr > Fs->last_fat && mode == MT_WRITE){
                        /* if at end, and writing, extend it */
                        NewCluNr = get_next_free_cluster(This->Fs, AbsCluNr);
                        if (NewCluNr == 1 ){ /* no more space */
                                errno = ENOSPC;
                                return -2;
                        }
                        fatAppend(This->Fs, AbsCluNr, NewCluNr);
                }

                if (CurCluNr < RelCluNr && NewCluNr > Fs->last_fat){
                        *len = 0;
                        return 0;
                }

                if (CurCluNr >= RelCluNr && NewCluNr != AbsCluNr + 1)
                        break;
                CurCluNr++;
                AbsCluNr = NewCluNr;
                if(loopDetect(This, CurCluNr, AbsCluNr)) {
                        errno = EIO;
                        return -2;
                }
        }

        maximize(*len, (1 + CurCluNr - RelCluNr) * clus_size - offset);
        
        end = where + *len;
        if(batchmode && mode == MT_WRITE && end >= This->FileSize) {
                *len += ROUND_UP(end, clus_size) - end;
        }

        if((*len + offset) / clus_size + This->PreviousAbsCluNr-2 >
                Fs->num_clus) {
                fprintf(stderr, "cluster too big\n");
                exit(1);
        }

        *res = sectorsToBytes((Stream_t*)Fs, 
                                                  (This->PreviousAbsCluNr-2) * Fs->cluster_size +
                                                  Fs->clus_start) + offset;
        return 1;
}


static int root_map(File_t *This, off_t where, size_t *len, int mode,
                                        mt_off_t *res)
{
        Fs_t *Fs = This->Fs;

        if(Fs->dir_len * Fs->sector_size < where) {
                *len = 0;
                errno = ENOSPC;
                return -2;
        }

        maximize(*len, Fs->dir_len * Fs->sector_size - where);
        if (*len == 0)
            return 0;
        
        *res = sectorsToBytes((Stream_t*)Fs, Fs->dir_start) + where;
        return 1;
}
        

static int read_file(Stream_t *Stream, char *buf, mt_off_t iwhere, 
                                         size_t len)
{
        DeclareThis(File_t);
        mt_off_t pos;
        int err;
        off_t where = truncBytes32(iwhere);

        Stream_t *Disk = This->Fs->Next;
        
        err = This->map(This, where, &len, MT_READ, &pos);
        if(err <= 0)
                return err;
        return READS(Disk, buf, pos, len);
}

static int write_file(Stream_t *Stream, char *buf, mt_off_t iwhere, size_t len)
{
        DeclareThis(File_t);
        mt_off_t pos;
        int ret;
        size_t requestedLen;
        Stream_t *Disk = This->Fs->Next;
        off_t where = truncBytes32(iwhere);
        int err;

        requestedLen = len;
        err = This->map(This, where, &len, MT_WRITE, &pos);
        if( err <= 0)
                return err;
        if(batchmode)
                ret = force_write(Disk, buf, pos, len);
        else
                ret = WRITES(Disk, buf, pos, len);
        if(ret > requestedLen)
                ret = requestedLen;
        if (ret > 0 && where + ret > This->FileSize )
                This->FileSize = where + ret;
        recalcPreallocSize(This);
        return ret;
}


/*
 * Convert an MSDOS time & date stamp to the Unix time() format
 */

static int month[] = {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
                                          0, 0, 0 };
static inline time_t conv_stamp(struct directory *dir)
{
        struct tm *tmbuf;
        long tzone, dst;
        time_t accum, tmp;

        accum = DOS_YEAR(dir) - 1970; /* years past */

        /* days passed */
        accum = accum * 365L + month[DOS_MONTH(dir)-1] + DOS_DAY(dir);

        /* leap years */
        accum += (DOS_YEAR(dir) - 1972) / 4L;

        /* back off 1 day if before 29 Feb */
        if (!(DOS_YEAR(dir) % 4) && DOS_MONTH(dir) < 3)
                accum--;
        accum = accum * 24L + DOS_HOUR(dir); /* hours passed */
        accum = accum * 60L + DOS_MINUTE(dir); /* minutes passed */
        accum = accum * 60L + DOS_SEC(dir); /* seconds passed */

#ifndef OS_Minix
        /* correct for Time Zone */
#ifdef HAVE_GETTIMEOFDAY
        {
                struct timeval tv;
                struct timezone tz;
                
                gettimeofday(&tv, &tz);
                tzone = tz.tz_minuteswest * 60L;
        }
#else
#ifdef HAVE_TZSET
        {
#ifndef OS_ultrix
                /* Ultrix defines this to be a different type */
                extern long timezone;
#endif
                tzset();
                tzone = (long) timezone;
        }
#else
        tzone = 0;
#endif /* HAVE_TZSET */
#endif /* HAVE_GETTIMEOFDAY */

        accum += tzone;
#endif /* OS_Minix */

        /* correct for Daylight Saving Time */
        tmp = accum;
        tmbuf = localtime(&tmp);
#ifndef OS_Minix
        dst = (tmbuf->tm_isdst) ? (-60L * 60L) : 0L;
        accum += dst;
#endif
        
        return accum;
}


static int get_file_data(Stream_t *Stream, time_t *date, mt_size_t *size,
                         int *type, int *address)
{
        DeclareThis(File_t);

        if(date)
                *date = conv_stamp(& This->direntry.dir);
        if(size)
                *size = (mt_size_t) This->FileSize;
        if(type)
                *type = This->direntry.dir.attr & ATTR_DIR;
        if(address)
                *address = This->FirstAbsCluNr;
        return 0;
}


static int free_file(Stream_t *Stream)
{
        DeclareThis(File_t);
        Fs_t *Fs = This->Fs;
        fsPreallocateClusters(Fs, -This->preallocatedClusters);       
        FREE(&This->direntry.Dir);
        freeDirCache(Stream);
        return hash_remove(filehash, (void *) Stream, This->hint);
}


static int flush_file(Stream_t *Stream)
{
        DeclareThis(File_t);
        direntry_t *entry = &This->direntry;

        if(isRootDir(Stream)) {
                return 0;
        }

        if(This->FirstAbsCluNr != getStart(entry->Dir, &entry->dir)) {
                set_word(entry->dir.start, This->FirstAbsCluNr & 0xffff);
                set_word(entry->dir.startHi, This->FirstAbsCluNr >> 16);
                dir_write(entry);
        }
        return 0;
}


static int pre_allocate_file(Stream_t *Stream, mt_size_t isize)
{
        DeclareThis(File_t);

        size_t size = truncBytes32(isize);

        if(size > This->FileSize &&
           size > This->preallocatedSize) {
                This->preallocatedSize = size;
                return recalcPreallocSize(This);
        } else
                return 0;
}

static Class_t FileClass = {
        read_file, 
        write_file, 
        flush_file, /* flush */
        free_file, /* free */
        0, /* get_geom */
        get_file_data,
        pre_allocate_file
};

static unsigned int getAbsCluNr(File_t *This)
{
        if(This->FirstAbsCluNr)
                return This->FirstAbsCluNr;
        if(isRootDir((Stream_t *) This))
                return 0;
        return 1;
}

static unsigned int func1(void *Stream)
{
        DeclareThis(File_t);

        return getAbsCluNr(This) ^ (long) This->Fs;
}

static unsigned int func2(void *Stream)
{
        DeclareThis(File_t);

        return getAbsCluNr(This);
}

static int comp(void *Stream, void *Stream2)
{
        DeclareThis(File_t);

        File_t *This2 = (File_t *) Stream2;

        return This->Fs != This2->Fs ||
                getAbsCluNr(This) != getAbsCluNr(This2);
}

static void init_hash(void)
{
        static int is_initialised=0;
        
        if(!is_initialised){
                make_ht(func1, func2, comp, 20, &filehash);
                is_initialised = 1;
        }
}


static Stream_t *_internalFileOpen(Stream_t *Dir, unsigned int first, 
                                   size_t size, direntry_t *entry)
{
        Stream_t *Stream = GetFs(Dir);
        DeclareThis(Fs_t);
        File_t Pattern;
        File_t *File;

        init_hash();
        This->refs++;

        if(first != 1){
                /* we use the illegal cluster 1 to mark newly created files.
                 * do not manage those by hashtable */
                Pattern.Fs = This;
                Pattern.Class = &FileClass;
                if(first || (entry && !IS_DIR(entry)))
                        Pattern.map = normal_map;
                else
                        Pattern.map = root_map;
                Pattern.FirstAbsCluNr = first;
                Pattern.loopDetectRel = 0;
                Pattern.loopDetectAbs = first;
                if(!hash_lookup(filehash, (T_HashTableEl) &Pattern, 
                                (T_HashTableEl **)&File, 0)){
                        File->refs++;
                        This->refs--;
                        return (Stream_t *) File;
                }
        }

        File = New(File_t);
        if (!File)
                return NULL;
        File->dcp = 0;
        File->preallocatedClusters = 0;
        File->preallocatedSize = 0;
        /* memorize dir for date and attrib */
        File->direntry = *entry;
        if(entry->entry == -3)
                File->direntry.Dir = (Stream_t *) File; /* root directory */
        else
                COPY(File->direntry.Dir);

        File->Class = &FileClass;
        File->Fs = This;
        if(first || (entry && !IS_DIR(entry)))
                File->map = normal_map;
        else
                File->map = root_map; /* FAT 12/16 root directory */
        if(first == 1)
                File->FirstAbsCluNr = 0;
        else
                File->FirstAbsCluNr = first;

        File->loopDetectRel = 0;
        File->loopDetectAbs = 0;

        File->PreviousRelCluNr = 0xffff;
        File->FileSize = size;
        File->refs = 1;
        File->Buffer = 0;
        hash_add(filehash, (void *) File, &File->hint);
        return (Stream_t *) File;
}

Stream_t *OpenRoot(Stream_t *Dir)
{
        unsigned int num;
        direntry_t entry;
        size_t size;
        Stream_t *file;

        memset(&entry, 0, sizeof(direntry_t));

        num = fat32RootCluster(Dir);

        /* make the directory entry */
        entry.entry = -3;
        entry.name[0] = '\0';
        mk_entry("/", ATTR_DIR, num, 0, 0, &entry.dir);

        if(num)
                size = countBytes(Dir, num);
        else {
                Fs_t *Fs = (Fs_t *) GetFs(Dir);
                size = Fs->dir_len * Fs->sector_size;
        }
        file = _internalFileOpen(Dir, num, size, &entry);
        bufferize(&file);
        return file;
}


Stream_t *OpenFileByDirentry(direntry_t *entry)
{
        Stream_t *file;
        unsigned int first;
        size_t size;

        first = getStart(entry->Dir, &entry->dir);

        if(!first && IS_DIR(entry))
                return OpenRoot(entry->Dir);
        if (IS_DIR(entry))
                size = countBytes(entry->Dir, first);
        else 
                size = FILE_SIZE(&entry->dir);
        file = _internalFileOpen(entry->Dir, first, size, entry);
        if(IS_DIR(entry)) {
                bufferize(&file);
                if(first == 1)
                        dir_grow(file, 0);
        }

        return file;
}


int isRootDir(Stream_t *Stream)
{
        File_t *This = getUnbufferedFile(Stream);

        return This->map == root_map;
}

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