82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
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/* first we need to create an I/O object that the parser will use to read the
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* source file
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*/
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struct StdIoStream {
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struct InputStream base;
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FILE *fp;
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int error;
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};
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typedef struct StdIoStream StdIoStream;
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#define CACHESIZE 65536
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/* StdIoStream methods */
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/* read count bytes into buffer starting at file position pos
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* return the number of bytes read, -1 on error or 0 on EOF
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*/
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int StdIoRead(StdIoStream *st, ulonglong pos, void *buffer, int count) {
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size_t rd;
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if (fseek(st->fp, pos, SEEK_SET)) {
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st->error = errno;
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return -1;
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}
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rd = fread(buffer, 1, count, st->fp);
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if (rd == 0) {
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if (feof(st->fp))
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return 0;
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st->error = errno;
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return -1;
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}
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return rd;
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}
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/* scan for a signature sig(big-endian) starting at file position pos
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* return position of the first byte of signature or -1 if error/not found
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*/
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longlong StdIoScan(StdIoStream *st, ulonglong start, unsigned signature) {
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int c;
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unsigned cmp = 0;
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FILE *fp = st->fp;
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if (fseek(fp, start, SEEK_SET))
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return -1;
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while ((c = getc(fp)) != EOF) {
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cmp = ((cmp << 8) | c) & 0xffffffff;
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if (cmp == signature)
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return ftell(fp) - 4;
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}
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return -1;
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}
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/* return cache size, this is used to limit readahead */
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unsigned StdIoGetCacheSize(StdIoStream *st) {
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return CACHESIZE;
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}
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/* return last error message */
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const char *StdIoGetLastError(StdIoStream *st) {
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return strerror(st->error);
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}
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/* memory allocation, this is done via stdlib */
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void *StdIoMalloc(StdIoStream *st, size_t size) {
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return malloc(size);
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}
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void *StdIoRealloc(StdIoStream *st, void *mem, size_t size) {
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return realloc(mem,size);
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}
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void StdIoFree(StdIoStream *st, void *mem) {
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free(mem);
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}
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/* progress report handler for lengthy operations
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* returns 0 to abort operation, nonzero to continue
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*/
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int StdIoProgress(StdIoStream *st, ulonglong cur, ulonglong max) {
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return 1;
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}
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