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/* minigzip.c -- simulate gzip using the zlib compression library
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* Copyright (C) 1995-2005 Jean-loup Gailly.
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* For conditions of distribution and use, see copyright notice in zlib.h
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* minigzip is a minimal implementation of the gzip utility. This is
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* only an example of using zlib and isn't meant to replace the
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* full-featured gzip. No attempt is made to deal with file systems
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* limiting names to 14 or 8+3 characters, etc... Error checking is
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* very limited. So use minigzip only for testing; use gzip for the
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* real thing. On MSDOS, use only on file names without extension
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# include <sys/types.h>
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# include <sys/mman.h>
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# include <sys/stat.h>
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#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
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# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
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# define SET_BINARY_MODE(file)
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# define unlink delete
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# define GZ_SUFFIX "-gz"
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# define unlink remove
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# define GZ_SUFFIX "-gz"
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# define fileno(file) file->__file
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#if defined(__MWERKS__) && __dest_os != __be_os && __dest_os != __win32_os
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# include <unix.h> /* for fileno */
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#ifndef WIN32 /* unlink already in stdio.h for WIN32 */
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extern int unlink OF((const char *));
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# define GZ_SUFFIX ".gz"
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#define SUFFIX_LEN (sizeof(GZ_SUFFIX)-1)
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#define MAX_NAME_LEN 1024
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/* Needed for systems with limitation on stack size. */
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void error OF((const char *msg));
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void gz_compress OF((FILE *in, gzFile out));
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int gz_compress_mmap OF((FILE *in, gzFile out));
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void gz_uncompress OF((gzFile in, FILE *out));
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void file_compress OF((char *file, char *mode));
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void file_uncompress OF((char *file));
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int main OF((int argc, char *argv[]));
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/* ===========================================================================
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* Display error message and exit
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fprintf(stderr, "%s: %s\n", prog, msg);
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/* ===========================================================================
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* Compress input to output then close both files.
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void gz_compress(in, out)
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local char buf[BUFLEN];
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/* Try first compressing with mmap. If mmap fails (minigzip used in a
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* pipe), use the normal fread loop.
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if (gz_compress_mmap(in, out) == Z_OK) return;
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len = (int)fread(buf, 1, sizeof(buf), in);
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if (gzwrite(out, buf, (unsigned)len) != len) error(gzerror(out, &err));
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if (gzclose(out) != Z_OK) error("failed gzclose");
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#ifdef USE_MMAP /* MMAP version, Miguel Albrecht <malbrech@eso.org> */
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/* Try compressing the input file at once using mmap. Return Z_OK if
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* if success, Z_ERRNO otherwise.
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int gz_compress_mmap(in, out)
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int ifd = fileno(in);
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caddr_t buf; /* mmap'ed buffer for the entire input file */
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off_t buf_len; /* length of the input file */
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/* Determine the size of the file, needed for mmap: */
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if (fstat(ifd, &sb) < 0) return Z_ERRNO;
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buf_len = sb.st_size;
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if (buf_len <= 0) return Z_ERRNO;
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/* Now do the actual mmap: */
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buf = mmap((caddr_t) 0, buf_len, PROT_READ, MAP_SHARED, ifd, (off_t)0);
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if (buf == (caddr_t)(-1)) return Z_ERRNO;
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/* Compress the whole file at once: */
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len = gzwrite(out, (char *)buf, (unsigned)buf_len);
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if (len != (int)buf_len) error(gzerror(out, &err));
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munmap(buf, buf_len);
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if (gzclose(out) != Z_OK) error("failed gzclose");
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#endif /* USE_MMAP */
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/* ===========================================================================
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* Uncompress input to output then close both files.
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void gz_uncompress(in, out)
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local char buf[BUFLEN];
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len = gzread(in, buf, sizeof(buf));
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if (len < 0) error (gzerror(in, &err));
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if ((int)fwrite(buf, 1, (unsigned)len, out) != len) {
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error("failed fwrite");
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if (fclose(out)) error("failed fclose");
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if (gzclose(in) != Z_OK) error("failed gzclose");
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/* ===========================================================================
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* Compress the given file: create a corresponding .gz file and remove the
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void file_compress(file, mode)
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local char outfile[MAX_NAME_LEN];
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strcpy(outfile, file);
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strcat(outfile, GZ_SUFFIX);
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in = fopen(file, "rb");
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out = gzopen(outfile, mode);
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fprintf(stderr, "%s: can't gzopen %s\n", prog, outfile);
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gz_compress(in, out);
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/* ===========================================================================
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* Uncompress the given file and remove the original.
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void file_uncompress(file)
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local char buf[MAX_NAME_LEN];
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char *infile, *outfile;
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uInt len = (uInt)strlen(file);
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if (len > SUFFIX_LEN && strcmp(file+len-SUFFIX_LEN, GZ_SUFFIX) == 0) {
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outfile[len-3] = '\0';
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strcat(infile, GZ_SUFFIX);
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in = gzopen(infile, "rb");
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fprintf(stderr, "%s: can't gzopen %s\n", prog, infile);
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out = fopen(outfile, "wb");
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gz_uncompress(in, out);
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/* ===========================================================================
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* Usage: minigzip [-d] [-f] [-h] [-r] [-1 to -9] [files...]
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* -f : compress with Z_FILTERED
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* -h : compress with Z_HUFFMAN_ONLY
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* -r : compress with Z_RLE
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* -1 to -9 : compression level
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strcpy(outmode, "wb6 ");
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if (strcmp(*argv, "-d") == 0)
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else if (strcmp(*argv, "-f") == 0)
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else if (strcmp(*argv, "-h") == 0)
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else if (strcmp(*argv, "-r") == 0)
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else if ((*argv)[0] == '-' && (*argv)[1] >= '1' && (*argv)[1] <= '9' &&
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outmode[2] = (*argv)[1];
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if (outmode[3] == ' ')
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SET_BINARY_MODE(stdin);
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SET_BINARY_MODE(stdout);
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file = gzdopen(fileno(stdin), "rb");
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if (file == NULL) error("can't gzdopen stdin");
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gz_uncompress(file, stdout);
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file = gzdopen(fileno(stdout), outmode);
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if (file == NULL) error("can't gzdopen stdout");
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gz_compress(stdin, file);
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file_uncompress(*argv);
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file_compress(*argv, outmode);
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} while (argv++, --argc);
added
removed
zlib-1.2.3/minigzip.c
