330 lines
6.7 KiB
C
Executable file
330 lines
6.7 KiB
C
Executable file
#include "sysincludes.h"
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#include "vfat.h"
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#include "dirCache.h"
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void myfree(void *a)
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{
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free(a);
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}
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#define free myfree
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#define BITS_PER_INT (sizeof(unsigned int) * 8)
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static inline unsigned int rol(unsigned int arg, int shift)
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{
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arg &= 0xffffffff; /* for 64 bit machines */
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return (arg << shift) | (arg >> (32 - shift));
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}
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static int calcHash(char *name)
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{
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unsigned long hash;
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int i;
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unsigned char c;
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hash = 0;
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i = 0;
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while(*name) {
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/* rotate it */
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hash = rol(hash,5); /* a shift of 5 makes sure we spread quickly
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* over the whole width, moreover, 5 is
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* prime with 32, which makes sure that
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* successive letters cannot cover each
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* other easily */
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c = toupper(*name);
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hash ^= (c * (c+2)) ^ (i * (i+2));
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hash &= 0xffffffff;
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i++, name++;
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}
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hash = hash * (hash + 2);
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/* the following two xors make sure all info is spread evenly over all
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* bytes. Important if we only keep the low order bits later on */
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hash ^= (hash & 0xfff) << 12;
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hash ^= (hash & 0xff000) << 24;
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return hash;
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}
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static int addBit(unsigned int *bitmap, int hash, int checkOnly)
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{
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int bit, entry;
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bit = 1 << (hash % BITS_PER_INT);
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entry = (hash / BITS_PER_INT) % DC_BITMAP_SIZE;
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if(checkOnly)
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return bitmap[entry] & bit;
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else {
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bitmap[entry] |= bit;
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return 1;
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}
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}
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static int _addHash(dirCache_t *cache, unsigned int hash, int checkOnly)
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{
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return
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addBit(cache->bm0, hash, checkOnly) &&
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addBit(cache->bm1, rol(hash,12), checkOnly) &&
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addBit(cache->bm2, rol(hash,24), checkOnly);
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}
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static void addNameToHash(dirCache_t *cache, char *name)
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{
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_addHash(cache, calcHash(name), 0);
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}
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static void hashDce(dirCache_t *cache, dirCacheEntry_t *dce)
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{
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if(dce->beginSlot != cache->nrHashed)
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return;
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cache->nrHashed = dce->endSlot;
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if(dce->longName)
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addNameToHash(cache, dce->longName);
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addNameToHash(cache, dce->shortName);
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}
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int isHashed(dirCache_t *cache, char *name)
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{
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int ret;
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ret = _addHash(cache, calcHash(name), 1);
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return ret;
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}
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void checkXYZ(dirCache_t *cache)
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{
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if(cache->entries[2])
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printf(" at 2 = %d\n", cache->entries[2]->beginSlot);
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}
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int growDirCache(dirCache_t *cache, int slot)
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{
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if(slot < 0) {
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fprintf(stderr, "Bad slot %d\n", slot);
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exit(1);
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}
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if( cache->nr_entries <= slot) {
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int i;
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cache->entries = realloc(cache->entries,
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(slot+1) * 2 *
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sizeof(dirCacheEntry_t *));
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if(!cache->entries)
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return -1;
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for(i= cache->nr_entries; i < (slot+1) * 2; i++) {
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cache->entries[i] = 0;
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}
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cache->nr_entries = (slot+1) * 2;
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}
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return 0;
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}
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dirCache_t *allocDirCache(Stream_t *Stream, int slot)
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{
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dirCache_t **dcp;
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if(slot < 0) {
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fprintf(stderr, "Bad slot %d\n", slot);
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exit(1);
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}
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dcp = getDirCacheP(Stream);
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if(!*dcp) {
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*dcp = New(dirCache_t);
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if(!*dcp)
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return 0;
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(*dcp)->entries = NewArray((slot+1)*2+5, dirCacheEntry_t *);
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if(!(*dcp)->entries) {
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free(*dcp);
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return 0;
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}
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(*dcp)->nr_entries = (slot+1) * 2;
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memset( (*dcp)->bm0, 0, DC_BITMAP_SIZE);
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memset( (*dcp)->bm1, 0, DC_BITMAP_SIZE);
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memset( (*dcp)->bm2, 0, DC_BITMAP_SIZE);
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(*dcp)->nrHashed = 0;
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} else
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if(growDirCache(*dcp, slot) < 0)
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return 0;
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return *dcp;
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}
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static void freeDirCacheRange(dirCache_t *cache, int beginSlot, int endSlot)
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{
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dirCacheEntry_t *entry;
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int clearBegin;
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int clearEnd;
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int i;
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if(endSlot < beginSlot) {
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fprintf(stderr, "Bad slots %d %d in free range\n",
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beginSlot, endSlot);
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exit(1);
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}
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while(beginSlot < endSlot) {
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entry = cache->entries[beginSlot];
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if(!entry) {
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beginSlot++;
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continue;
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}
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clearEnd = entry->endSlot;
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if(clearEnd > endSlot)
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clearEnd = endSlot;
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clearBegin = beginSlot;
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for(i = clearBegin; i <clearEnd; i++)
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cache->entries[i] = 0;
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if(entry->endSlot == endSlot)
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entry->endSlot = beginSlot;
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else if(entry->beginSlot == beginSlot)
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entry->beginSlot = endSlot;
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else {
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fprintf(stderr,
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"Internal error, non contiguous de-allocation\n");
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fprintf(stderr, "%d %d\n", beginSlot, endSlot);
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fprintf(stderr, "%d %d\n", entry->beginSlot,
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entry->endSlot);
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exit(1);
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}
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if(entry->beginSlot == entry->endSlot) {
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if(entry->longName)
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free(entry->longName);
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if(entry->shortName)
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free(entry->shortName);
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free(entry);
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}
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beginSlot = clearEnd;
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}
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}
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static dirCacheEntry_t *allocDirCacheEntry(dirCache_t *cache, int beginSlot,
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int endSlot,
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dirCacheEntryType_t type)
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{
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dirCacheEntry_t *entry;
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int i;
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if(growDirCache(cache, endSlot) < 0)
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return 0;
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entry = New(dirCacheEntry_t);
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if(!entry)
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return 0;
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entry->type = type;
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entry->longName = 0;
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entry->shortName = 0;
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entry->beginSlot = beginSlot;
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entry->endSlot = endSlot;
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freeDirCacheRange(cache, beginSlot, endSlot);
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for(i=beginSlot; i<endSlot; i++) {
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cache->entries[i] = entry;
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}
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return entry;
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}
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dirCacheEntry_t *addUsedEntry(dirCache_t *cache, int beginSlot, int endSlot,
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char *longName, char *shortName,
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struct directory *dir)
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{
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dirCacheEntry_t *entry;
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if(endSlot < beginSlot) {
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fprintf(stderr,
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"Bad slots %d %d in add used entry\n",
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beginSlot, endSlot);
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exit(1);
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}
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entry = allocDirCacheEntry(cache, beginSlot, endSlot, DCET_USED);
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if(!entry)
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return 0;
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entry->beginSlot = beginSlot;
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entry->endSlot = endSlot;
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if(longName)
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entry->longName = strdup(longName);
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entry->shortName = strdup(shortName);
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entry->dir = *dir;
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hashDce(cache, entry);
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return entry;
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}
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static void mergeFreeSlots(dirCache_t *cache, int slot)
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{
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dirCacheEntry_t *previous, *next;
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int i;
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if(slot == 0)
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return;
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previous = cache->entries[slot-1];
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next = cache->entries[slot];
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if(next && next->type == DCET_FREE &&
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previous && previous->type == DCET_FREE) {
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for(i=next->beginSlot; i < next->endSlot; i++)
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cache->entries[i] = previous;
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previous->endSlot = next->endSlot;
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free(next);
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}
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}
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dirCacheEntry_t *addFreeEntry(dirCache_t *cache, int beginSlot, int endSlot)
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{
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dirCacheEntry_t *entry;
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if(beginSlot < cache->nrHashed)
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cache->nrHashed = beginSlot;
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if(endSlot < beginSlot) {
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fprintf(stderr, "Bad slots %d %d in add free entry\n",
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beginSlot, endSlot);
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exit(1);
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}
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if(endSlot == beginSlot)
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return 0;
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entry = allocDirCacheEntry(cache, beginSlot, endSlot, DCET_FREE);
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mergeFreeSlots(cache, beginSlot);
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mergeFreeSlots(cache, endSlot);
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return cache->entries[beginSlot];
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}
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dirCacheEntry_t *addEndEntry(dirCache_t *cache, int pos)
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{
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return allocDirCacheEntry(cache, pos, pos+1, DCET_END);
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}
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dirCacheEntry_t *lookupInDircache(dirCache_t *cache, int pos)
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{
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if(growDirCache(cache, pos+1) < 0)
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return 0;
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return cache->entries[pos];
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}
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void freeDirCache(Stream_t *Stream)
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{
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dirCache_t *cache, **dcp;
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dcp = getDirCacheP(Stream);
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cache = *dcp;
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if(cache) {
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freeDirCacheRange(cache, 0, cache->nr_entries);
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free(cache);
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*dcp = 0;
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}
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}
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