/* * M A I N . C * * A file maintenance utility to decompress files; compatible with the * public domain COMPRESS v4.0 utility by Spencer W. Thomas, et al. * * Algorithm from "A Technique for High Performance Data Compression", * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19. * * The impetus for this program comes from a desire to decompress files * in an MS-DOS environment with 16-bit codes using fewer machine * resources than the public domain COMPRESS utility. Memory usage * for MS-DOS is less than 250 kbytes for 16-bit codes. * * The code uses many ANSI-C style contructs with no apologies. *----------------------------------------------------------------------- * Authors: Lyle V. Rains * based on the source of COMPRESS v4.0 by Spencer Thomas, et al. *----------------------------------------------------------------------- * Revision History: */ #define MAIN #include "main.h" char *myname = MYNAME; static char *stdinname = STDIN; static char *stdoutname = STDOUT; /* Magic 2-byte file header */ static char header[] = {0x1F, 0x9D}; static char xbuf[XBUFSIZE]; /* Big buffers for setvbuf()*/ static char zbuf[ZBUFSIZE]; static void usage(all) int all; { U(" Usage: %s [%ch(elp)] [%ccko] [%cf] [files ...]\n", myname, SW, SW, SW); if (!all) return; #ifdef __DATE__ U("\n Version %s, %s\n", VERSION, __DATE__); #else U("\n Version %s\n", VERSION); #endif U(" Decompresses files in a method compatible with COMPRESS V4.0\n"); U(" INITIAL PUBLIC RELEASE. Please send feedback and bug reports to:\n"); U(" Lyle Rains, Compuserve User ID 71250,324\n"); U("\n Switches:\n"); U(" %ch this help message.\n", SW); U(" %cc concatenate output to stdout.\n", SW); #if KILL == YES U(" %ck keep input file (default: delete).\n", SW); #else U(" %ck kill input file (default: keep).\n", SW); #endif U(" %co overwrite pre-existing output file.\n", SW); U(" %cf filter (%s stdin to stdout; ignore additional args).\n", SW, myname); #if DEBUGOUT U(" %cd print debug info to stderr.\n", SW); #endif U(" File arguments:\n"); U(" infile %s infile (e.g., FOO.C%s) to default outfile (FOO.C)\n", myname, ZSUFFIX); U(" outfile %s to outfile (e.g., FOO.C) from default infile (FOO.C%s)\n", myname, ZSUFFIX); U(" in%cout %s infile to outfile (overrides %cc and defaults).\n", TO, myname, SW); return; } static int do_expand(); main(argc, argv) int argc; char *argv[]; { char **nextarg; int argsleft; char *arg, *out; int kill, overwrite, cat; char name_tmp[NAMEBUFSIZ]; FILE *infile, *outfile; char userinput[2]; if ((argsleft = argc) <= 1) { # if FILTER == YES do_expand(stdin, stdout, stdinname, stdoutname); exit (NORMAL); # else /* No arguments -- give short usage message and exit with error */ usage(QUICK); exit (ERROR); # endif } kill = KILL; cat = NO; overwrite = NO; /* Process command line arguments */ nextarg = argv; while (--argsleft > 0) { if (*(arg = *++nextarg) == SW) { /* Process command switches */ while (*++arg) { switch (*arg) { case 'h': case 'H': case '?': usage(ALL); exit (NORMAL); case 'f': case 'F': do_expand(stdin, stdout, stdinname, stdoutname); exit (NORMAL); case 'c': case 'C': cat = !cat; break; case 'o': case 'O': overwrite = !overwrite; break; case 'k': case 'K': kill = !kill; break; default: eprintf("%s: bad switch '-%c'.\n", myname, *arg); usage(QUICK); exit (ERROR); # if DEBUGOUT case 'd': case 'D': debug = !debug; break; # endif } } } else if (*arg == TO) { /* Inappropriate place to name output file. Find file name. */ if (!*++arg) arg = --argsleft ? *++nextarg : ""; errexit(("%s: no input file for output '=%s'.\n", myname, arg), ERROR); } else { /* Get input/output filespecs and open them for processing. * Note: filename processing is necessarily system dependent. * I am providing suitable routines for MS-DOS, but you must * supply your own routines as necessary for other systems. * * First check to see if there is an output file spec. If the * output prefix character isn't in the current argument, check * the beginning of the next arg, in case the user added whitespace. */ if ( (out = strchr(arg, TO)) != 0 || ( (argsleft > 1) && (out = (**(nextarg + 1) == TO) ? (--argsleft, *++nextarg) : NULL) != 0 ) ) { /* We found the prefix character. Now find the output * filespec, again allowing for the possible inclusion of * whitespace after the prefix character. */ *out = '\0'; if ( !*++out && (out = --argsleft ? *++nextarg : NULL) == 0 ) { errexit(("%s: missing output filespec for '%s='.\n", myname, arg),ERROR); } } else if (cat) out = stdoutname; else { /* Create a default output filespec, trying the following: * 1. If the input filespec file extension ends with ZSUFFIX, * then default output spec is the same as the input, with * ZSUFFIX removed. * 2. If the input doesn't end in ZSUFFIX, assume that the * user is really giving the desired output spec, and try to * create a default input spec by appending ZSUFFIX to * the filespec and seeing if any such input file exists. * 3. Give up (we really tried!), print an error and continue. */ out = strcpy(name_tmp, arg); if (!to_xname(out)) { out = arg; arg = name_tmp; to_zname(arg); } } if (!overwrite && out != stdoutname && (outfile = fopen(out, "r")) != 0) { eprintf("%s: output '%s' exists. Overwrite? ", myname, out); if (fgets(userinput, 2, stdin) && tolower(*userinput) == 'y') fclose(outfile); else exit (ERROR); } if ((outfile = (out == stdoutname) ? (FILE *)stdout : fopen(out, "w")) == 0) { errexit(("%s: can't open output '%s'.\n", myname, out), ERROR); } if ((infile = fopen(arg, "r")) == 0) { errexit(("%s: can't open input '%s'.\n", myname, arg), ERROR); } eprintf("expanding '%s' to '%s'.\n", arg, out); DBG(("\t overwrite = %d, cat = %d, kill = %d\n", overwrite, cat, kill)); do_expand(infile, outfile, arg, out); if (kill) unlink(arg); } } } static int do_expand(in, out, inname, outname) FILE *in; FILE *out; char *inname; char *outname; { int maxbits; int clearmode; setvbuf(in, zbuf, _IOFBF, ZBUFSIZE); setvbuf(out, xbuf, _IOFBF, XBUFSIZE); setbinary(in); /* Some systems require this */ setbinary(out); /* Check for the magic number header */ if ((char)getc(in) != header[0] || (char)getc(in) != header[1]) { errexit(("%s: '%s' not in compressed format.\n", myname, inname), ERROR); } maxbits = getc(in); clearmode = maxbits & BLOCK_MASK; if ((maxbits &= BIT_MASK) > Maxbits) { errexit(("%s: '%s' uses %d-bit compression (%s allows %d-bits maximum).\n", myname, inname, maxbits, myname, Maxbits), ERROR); } switch (expand(in, out, maxbits, clearmode)) { case OK: fclose(in); if (out != stdout) fclose(out); else fflush(out); return (OK); case NOMEM: errexit(("%s: not enough memory to expand '%s'.\n", myname, inname), ERROR); case TOKTOOBIG: errexit(("%s: token too long in '%s'.\n", myname, inname), ERROR); case READERR: errexit(("%s: read error on input '%s'.\n", myname, inname), ERROR); case WRITEERR: errexit(("%s: write error on output '%s'.\n", myname, outname), ERROR); case CODEBAD: errexit(("%s: illegal code found in '%s'.\n", myname, inname), ERROR); case TABLEBAD: errexit(("%s: internal error -- tables corrupted.\n", myname), ERROR); default: errexit(("%s: internal error -- illegal return value.\n", myname), ERROR); } }