153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/*
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** compress.c - Main compression routine for LZA file compression program.
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**
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** Author: DavidDi
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*/
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// Headers
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///////////
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#ifndef LZA_DLL
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#include <dos.h>
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#include <errno.h>
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#include <io.h>
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#include <stdio.h>
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#include <string.h>
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#endif
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#include "lz_common.h"
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#include "lzcommon.h"
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#include "lz_buffers.h"
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#include "lz_header.h"
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/*
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** N.b., one reason DOS file handles are used for file references in this
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** module is that using FILE *'s for file references poses a problem.
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** fclose()'ing a file which was fopen()'ed in write "w" or append "a" mode
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** stamps the file with the current date. This undoes the intended effect of
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** CopyDateTimeStamp(). We could also get around this fclose() problem by
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** first fclose()'ing the file, and then fopen()'ing it again in read "r"
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** mode.
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**
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** Using file handles also allows us to bypass stream buffering, so reads and
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** writes may be done with whatever buffer size we choose. Also, the
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** lower-level DOS file handle functions are faster than their stream
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** counterparts.
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*/
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/*
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** int Compress(char ARG_PTR *pszSource, char ARG_PTR *pszDest,
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** BYTE byteAlgorithm, BYTE byteExtensionChar);
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**
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** Compress one file to another.
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**
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** Arguments: pszSource - name of file to compress
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** pszDest - name of compressed output file
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** byteAlgorithm - compression algorithm to use
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** byteExtensionChar - compressed file name extension character
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**
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** Returns: int - TRUE if compression finished successfully. One of the
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** LZERROR_ codes if not.
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**
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** Globals: none
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*/
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INT Compress(
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NOTIFYPROC pfnNotify,
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CHAR ARG_PTR *pszSource,
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CHAR ARG_PTR *pszDest,
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BYTE byteAlgorithm,
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BOOL bDoRename,
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PLZINFO pLZI)
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{
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INT doshSource, // input file handle
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doshDest, // output file handle
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nRetVal = TRUE;
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FH FHOut; // compressed header info struct
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CHAR szDestFileName[MAX_PATH];
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BYTE byteExtensionChar;
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// Sanity check
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if (!pLZI) {
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return(LZERROR_GLOBLOCK);
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}
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// Set up input file handle. Set cblInSize to length of input file.
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if ((nRetVal = GetIOHandle(pszSource, READ_IT, & doshSource, &pLZI->cblInSize)) != TRUE)
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return(nRetVal);
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// Rewind input file.
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if (FSEEK(doshSource, 0L, SEEK_SET) != 0L)
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{
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FCLOSE(doshSource);
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return(LZERROR_BADINHANDLE);
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}
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// Create destination file name.
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STRCPY(szDestFileName, pszDest);
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if (bDoRename == TRUE)
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// Rename output file.
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byteExtensionChar = MakeCompressedName(szDestFileName);
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else
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byteExtensionChar = '\0';
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// Ask if we should compress this file.
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if (! (*pfnNotify)(pszSource, szDestFileName, NOTIFY_START_COMPRESS))
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{
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// Don't compress file. This error condition should be handled in
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// pfnNotify, so indicate that it is not necessary for the caller to
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// display an error message.
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FCLOSE(doshSource);
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return(BLANK_ERROR);
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}
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// Set up output file handle.
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if ((nRetVal = GetIOHandle(szDestFileName, WRITE_IT, & doshDest, &pLZI->cblInSize)) != TRUE)
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{
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FCLOSE(doshSource);
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return(nRetVal);
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}
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// Fill in compressed file header.
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MakeHeader(& FHOut, byteAlgorithm, byteExtensionChar, pLZI);
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// Write compressed file header to output file.
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if ((nRetVal = WriteHdr(& FHOut, doshDest, pLZI)) != TRUE)
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goto COMPRESS_EXIT;
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// Compress input file into output file.
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switch (byteAlgorithm)
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{
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case ALG_FIRST:
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#if 0
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case ALG_LZ:
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#endif
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nRetVal = LZEncode(doshSource, doshDest, pLZI);
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break;
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default:
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nRetVal = LZERROR_UNKNOWNALG;
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break;
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}
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if (nRetVal != TRUE)
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goto COMPRESS_EXIT;
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// Copy date and time stamp from source file to destination file.
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nRetVal = CopyDateTimeStamp(doshSource, doshDest);
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COMPRESS_EXIT:
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// Close files.
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FCLOSE(doshSource);
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FCLOSE(doshDest);
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return(nRetVal);
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}
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