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compress.c
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compress.c
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/* (N)compress.c - File compression ala IEEE Computer, Mar 1992.
*
* Authors:
* Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
* Jim McKie (decvax!mcvax!jim)
* Steve Davies (decvax!vax135!petsd!peora!srd)
* Ken Turkowski (decvax!decwrl!turtlevax!ken)
* James A. Woods (decvax!ihnp4!ames!jaw)
* Joe Orost (decvax!vax135!petsd!joe)
* Dave Mack (csu@alembic.acs.com)
* Peter Jannesen, Network Communication Systems
* (peter@ncs.nl)
* Mike Frysinger (vapier@gmail.com)
*/
#ifdef _MSC_VER
# define WINDOWS
#endif
#ifdef __MINGW32__
# define MINGW
#endif
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#if !defined(DOS) && !defined(WINDOWS)
# include <dirent.h>
# define RECURSIVE 1
# include <unistd.h>
#else
# include <io.h>
#endif
#ifdef UTIME_H
# include <utime.h>
#else
struct utimbuf {
time_t actime;
time_t modtime;
};
#endif
#ifndef SIG_TYPE
# define SIG_TYPE void (*)()
#endif
#if defined(AMIGA) || defined(DOS) || defined(MINGW) || defined(WINDOWS)
# define chmod(pathname, mode) 0
# define chown(pathname, owner, group) 0
# define utime(pathname, times) 0
#endif
#if defined(MINGW) || defined(WINDOWS)
# define isatty(fd) 0
# define open _open
# define close _close
# define read _read
# define strdup _strdup
# define unlink _unlink
# define write _write
#else
/* NB: macOS has a setmode() that is different from Windows. */
# define setmode(fd, mode)
#endif
#ifndef LSTAT
# define lstat stat
#endif
#if defined(DOS) || defined(WINDOWS)
# define F_OK 0
static inline int access(const char *pathname, int mode)
{
struct stat st;
return lstat(pathname, &st);
}
#endif
#include "patchlevel.h"
#undef min
#define min(a,b) ((a>b) ? b : a)
#ifndef IBUFSIZ
# define IBUFSIZ BUFSIZ /* Default input buffer size */
#endif
#ifndef OBUFSIZ
# define OBUFSIZ BUFSIZ /* Default output buffer size */
#endif
/* Defines for third byte of header */
#define MAGIC_1 (char_type)'\037'/* First byte of compressed file */
#define MAGIC_2 (char_type)'\235'/* Second byte of compressed file */
#define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
/* Masks 0x20 and 0x40 are free. */
/* I think 0x20 should mean that there is */
/* a fourth header byte (for expansion). */
#define BLOCK_MODE 0x80 /* Block compression if table is full and */
/* compression rate is dropping flush tables */
/* the next two codes should not be changed lightly, as they must not */
/* lie within the contiguous general code space. */
#define FIRST 257 /* first free entry */
#define CLEAR 256 /* table clear output code */
#define INIT_BITS 9 /* initial number of bits/code */
#ifndef SACREDMEM
/*
* SACREDMEM is the amount of physical memory saved for others; compress
* will hog the rest.
*/
# define SACREDMEM 0
#endif
#ifndef USERMEM
/*
* Set USERMEM to the maximum amount of physical user memory available
* in bytes. USERMEM is used to determine the maximum BITS that can be used
* for compression.
*/
# define USERMEM 450000 /* default user memory */
#endif
/*
* machine variants which require cc -Dmachine: pdp11, z8000, DOS
*/
#ifdef DOS /* PC/XT/AT (8088) processor */
# define BITS 16 /* 16-bits processor max 12 bits */
#endif /* DOS */
#ifndef O_BINARY
# define O_BINARY 0 /* System has no binary mode */
#endif
#ifdef M_XENIX /* Stupid compiler can't handle arrays with */
# if BITS > 13 /* Code only handles BITS = 12, 13, or 16 */
# define BITS 13
# endif
#endif
#ifndef BITS /* General processor calculate BITS */
# if USERMEM >= (800000+SACREDMEM)
# define FAST
# else
# if USERMEM >= (433484+SACREDMEM)
# define BITS 16
# else
# if USERMEM >= (229600+SACREDMEM)
# define BITS 15
# else
# if USERMEM >= (127536+SACREDMEM)
# define BITS 14
# else
# if USERMEM >= (73464+SACREDMEM)
# define BITS 13
# else
# define BITS 12
# endif
# endif
# endif
# endif
# endif
#endif /* BITS */
#ifdef FAST
# define HBITS 17 /* 50% occupancy */
# define HSIZE (1<<HBITS)
# define HMASK (HSIZE-1)
# define HPRIME 9941
# define BITS 16
#else
# if BITS == 16
# define HSIZE 69001 /* 95% occupancy */
# endif
# if BITS == 15
# define HSIZE 35023 /* 94% occupancy */
# endif
# if BITS == 14
# define HSIZE 18013 /* 91% occupancy */
# endif
# if BITS == 13
# define HSIZE 9001 /* 91% occupancy */
# endif
# if BITS <= 12
# define HSIZE 5003 /* 80% occupancy */
# endif
#endif
#define CHECK_GAP 10000
typedef long int code_int;
#ifdef SIGNED_COMPARE_SLOW
typedef unsigned long int count_int;
typedef unsigned short int count_short;
typedef unsigned long int cmp_code_int; /* Cast to make compare faster */
#else
typedef long int count_int;
typedef long int cmp_code_int;
#endif
typedef unsigned char char_type;
#define ARGVAL() (*++(*argv) || (--argc && *++argv))
#define MAXCODE(n) (1L << (n))
#define output(b,o,c,n) { char_type *p = &(b)[(o)>>3]; \
long i = ((long)(c))<<((o)&0x7); \
p[0] |= (char_type)(i); \
p[1] |= (char_type)(i>>8); \
p[2] |= (char_type)(i>>16); \
(o) += (n); \
}
#define input(b,o,c,n,m){ char_type *p = &(b)[(o)>>3]; \
(c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
((long)(p[2])<<16))>>((o)&0x7))&(m); \
(o) += (n); \
}
#define reset_n_bits_for_compressor(n_bits, stcode, free_ent, extcode, maxbits) { \
n_bits = INIT_BITS; \
stcode = 1; \
free_ent = FIRST; \
extcode = MAXCODE(n_bits); \
if (n_bits < maxbits) \
extcode++; \
}
#define reset_n_bits_for_decompressor(n_bits, bitmask, maxbits, maxcode, maxmaxcode) { \
n_bits = INIT_BITS; \
bitmask = (1<<n_bits)-1; \
if (n_bits == maxbits) \
maxcode = maxmaxcode; \
else \
maxcode = MAXCODE(n_bits)-1; \
}
char *progname; /* Program name */
int silent = 0; /* don't tell me about errors */
int quiet = 1; /* don't tell me about compression */
int do_decomp = 0; /* Decompress mode */
int force = 0; /* Force overwrite of files and links */
int keep = 0; /* Keep input files */
int nomagic = 0; /* Use a 3-byte magic number header, */
/* unless old file */
int maxbits = BITS; /* user settable max # bits/code */
int zcat_flg = 0; /* Write output on stdout, suppress messages */
int recursive = 0; /* compress directories */
int exit_code = -1; /* Exitcode of compress (-1 no file compressed) */
char_type inbuf[IBUFSIZ+64]; /* Input buffer */
char_type outbuf[OBUFSIZ+2048];/* Output buffer */
struct stat infstat; /* Input file status */
char *ifname; /* Input filename */
int remove_ofname = 0; /* Remove output file on a error */
char *ofname = NULL; /* Output filename */
int fgnd_flag = 0; /* Running in background (SIGINT=SIGIGN) */
long bytes_in; /* Total number of byte from input */
long bytes_out; /* Total number of byte to output */
count_int htab[HSIZE];
unsigned short codetab[HSIZE];
#define tab_prefixof(i) codetab[i]
#define tab_suffixof(i) ((char_type *)(htab))[i]
#define de_stack ((char_type *)&(htab[HSIZE-1]))
#define clear_htab() memset(htab, -1, sizeof(htab))
#define clear_tab_prefixof() memset(codetab, 0, 256);
#ifdef FAST
static const int primetab[256] = /* Special secudary hash table. */
{
1013, -1061, 1109, -1181, 1231, -1291, 1361, -1429,
1481, -1531, 1583, -1627, 1699, -1759, 1831, -1889,
1973, -2017, 2083, -2137, 2213, -2273, 2339, -2383,
2441, -2531, 2593, -2663, 2707, -2753, 2819, -2887,
2957, -3023, 3089, -3181, 3251, -3313, 3361, -3449,
3511, -3557, 3617, -3677, 3739, -3821, 3881, -3931,
4013, -4079, 4139, -4219, 4271, -4349, 4423, -4493,
4561, -4639, 4691, -4783, 4831, -4931, 4973, -5023,
5101, -5179, 5261, -5333, 5413, -5471, 5521, -5591,
5659, -5737, 5807, -5857, 5923, -6029, 6089, -6151,
6221, -6287, 6343, -6397, 6491, -6571, 6659, -6709,
6791, -6857, 6917, -6983, 7043, -7129, 7213, -7297,
7369, -7477, 7529, -7577, 7643, -7703, 7789, -7873,
7933, -8017, 8093, -8171, 8237, -8297, 8387, -8461,
8543, -8627, 8689, -8741, 8819, -8867, 8963, -9029,
9109, -9181, 9241, -9323, 9397, -9439, 9511, -9613,
9677, -9743, 9811, -9871, 9941,-10061,10111,-10177,
10259,-10321,10399,-10477,10567,-10639,10711,-10789,
10867,-10949,11047,-11113,11173,-11261,11329,-11423,
11491,-11587,11681,-11777,11827,-11903,11959,-12041,
12109,-12197,12263,-12343,12413,-12487,12541,-12611,
12671,-12757,12829,-12917,12979,-13043,13127,-13187,
13291,-13367,13451,-13523,13619,-13691,13751,-13829,
13901,-13967,14057,-14153,14249,-14341,14419,-14489,
14557,-14633,14717,-14767,14831,-14897,14983,-15083,
15149,-15233,15289,-15359,15427,-15497,15583,-15649,
15733,-15791,15881,-15937,16057,-16097,16189,-16267,
16363,-16447,16529,-16619,16691,-16763,16879,-16937,
17021,-17093,17183,-17257,17341,-17401,17477,-17551,
17623,-17713,17791,-17891,17957,-18041,18097,-18169,
18233,-18307,18379,-18451,18523,-18637,18731,-18803,
18919,-19031,19121,-19211,19273,-19381,19429,-19477
} ;
#endif
static void Usage(int);
static void comprexx(const char *);
static void compdir(char *);
static void compress(int, int);
static void decompress(int, int);
static void read_error(void);
static void write_error(void);
static void abort_compress(void);
static void prratio(FILE *, long, long);
static void about(void);
/*****************************************************************
* TAG( main )
*
* Algorithm from "A Technique for High Performance Data Compression",
* Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
*
* Usage: compress [-dfvc] [-b bits] [file ...]
* Inputs:
* -d: If given, decompression is done instead.
*
* -c: Write output on stdout, don't remove original.
*
* -b: Parameter limits the max number of bits/code.
*
* -f: Forces output file to be generated, even if one already
* exists, and even if no space is saved by compressing.
* If -f is not used, the user will be prompted if stdin is
* a tty, otherwise, the output file will not be overwritten.
*
* -v: Write compression statistics
*
* -r: Recursive. If a filename is a directory, descend
* into it and compress everything in it.
*
* file ...:
* Files to be compressed. If none specified, stdin is used.
* Outputs:
* file.Z: Compressed form of file with same mode, owner, and utimes
* or stdout (if stdin used as input)
*
* Assumptions:
* When filenames are given, replaces with the compressed version
* (.Z suffix) only if the file decreases in size.
*
* Algorithm:
* Modified Lempel-Ziv method (LZW). Basically finds common
* substrings and replaces them with a variable size code. This is
* deterministic, and can be done on the fly. Thus, the decompression
* procedure needs no input table, but tracks the way the table was built.
*/
int
main(int argc, char *argv[])
{
char **filelist;
char **fileptr;
int seen_double_dash = 0;
#ifdef SIGINT
if ((fgnd_flag = (signal(SIGINT, SIG_IGN)) != SIG_IGN))
signal(SIGINT, (SIG_TYPE)abort_compress);
#endif
#ifdef SIGTERM
signal(SIGTERM, (SIG_TYPE)abort_compress);
#endif
#ifdef SIGHUP
signal(SIGHUP, (SIG_TYPE)abort_compress);
#endif
#ifdef COMPATIBLE
nomagic = 1; /* Original didn't have a magic number */
#endif
filelist = (char **)malloc(argc*sizeof(char *));
if (filelist == NULL)
{
fprintf(stderr, "Cannot allocate memory for file list.\n");
exit (1);
}
fileptr = filelist;
*filelist = NULL;
if ((progname = strrchr(argv[0], '/')) != 0)
progname++;
else
progname = argv[0];
if (strcmp(progname, "uncompress") == 0)
do_decomp = 1;
else
if (strcmp(progname, "zcat") == 0)
do_decomp = zcat_flg = 1;
/* Argument Processing
* All flags are optional.
* -V => print Version; debug verbose
* -d => do_decomp
* -v => unquiet
* -f => force overwrite of output file
* -k => keep input files
* -n => no header: useful to uncompress old files
* -b maxbits => maxbits. If -b is specified, then maxbits MUST be given also.
* -c => cat all output to stdout
* -C => generate output compatible with compress 2.0.
* -r => recursively compress directories
* if a string is left, must be an input filename.
*/
for (argc--, argv++; argc > 0; argc--, argv++)
{
if (strcmp(*argv, "--") == 0)
{
seen_double_dash = 1;
continue;
}
if (seen_double_dash == 0 && **argv == '-')
{/* A flag argument */
while (*++(*argv))
{/* Process all flags in this arg */
switch (**argv)
{
case 'V':
about();
break;
case 's':
silent = 1;
quiet = 1;
break;
case 'v':
silent = 0;
quiet = 0;
break;
case 'd':
do_decomp = 1;
break;
case 'k':
keep = 1;
break;
case 'f':
case 'F':
force = 1;
break;
case 'n':
nomagic = 1;
break;
case 'b':
if (!ARGVAL())
{
fprintf(stderr, "Missing maxbits\n");
Usage(1);
}
maxbits = atoi(*argv);
goto nextarg;
case 'c':
zcat_flg = 1;
break;
case 'q':
quiet = 1;
break;
case 'r':
case 'R':
#ifdef RECURSIVE
recursive = 1;
#else
fprintf(stderr, "%s -r not available (due to missing directory functions)\n", *argv);
#endif
break;
case 'h':
Usage(0);
break;
default:
fprintf(stderr, "Unknown flag: '%c'; ", **argv);
Usage(1);
}
}
}
else
{
*fileptr++ = *argv; /* Build input file list */
*fileptr = NULL;
}
nextarg: continue;
}
if (maxbits < INIT_BITS) maxbits = INIT_BITS;
if (maxbits > BITS) maxbits = BITS;
if (*filelist != NULL)
{
for (fileptr = filelist; *fileptr; fileptr++)
comprexx(*fileptr);
}
else
{/* Standard input */
ifname = "";
exit_code = 0;
remove_ofname = 0;
setmode(0, O_BINARY);
setmode(1, O_BINARY);
if (do_decomp == 0)
{
compress(0, 1);
if (zcat_flg == 0 && !quiet)
{
fprintf(stderr, "Compression: ");
prratio(stderr, bytes_in-bytes_out, bytes_in);
fprintf(stderr, "\n");
}
if (bytes_out >= bytes_in && !(force))
exit_code = 2;
}
else
decompress(0, 1);
}
if (recursive && exit_code == -1) {
fprintf(stderr, "no files processed after recursive search\n");
}
exit((exit_code== -1) ? 1:exit_code);
}
void
Usage(int status)
{
fprintf(status ? stderr : stdout, "\
Usage: %s [-dfhvcVr] [-b maxbits] [--] [path ...]\n\
-- Halt option processing and treat all remaining args as paths.\n\
-d If given, decompression is done instead.\n\
-c Write output on stdout, don't remove original.\n\
-k Keep input files (do not automatically remove).\n\
-b Parameter limits the max number of bits/code.\n\
-f Forces output file to be generated, even if one already.\n\
exists, and even if no space is saved by compressing.\n\
If -f is not used, the user will be prompted if stdin is.\n\
a tty, otherwise, the output file will not be overwritten.\n\
-h This help output.\n\
-v Write compression statistics.\n\
-V Output version and compile options.\n\
-r Recursive. If a path is a directory, compress everything in it.\n",
progname);
exit(status);
}
void
comprexx(const char *fileptr)
{
int fdin = -1;
int fdout = -1;
int has_z_suffix;
char *tempname;
unsigned long namesize = strlen(fileptr);
/* Create a temp buffer to add/remove the .Z suffix. */
tempname = malloc(namesize + 3);
if (tempname == NULL)
{
perror("malloc");
goto error;
}
strcpy(tempname,fileptr);
has_z_suffix = (namesize >= 2 && strcmp(&tempname[namesize - 2], ".Z") == 0);
errno = 0;
if (lstat(tempname,&infstat) == -1)
{
if (do_decomp)
{
switch (errno)
{
case ENOENT: /* file doesn't exist */
/*
** if the given name doesn't end with .Z, try appending one
** This is obviously the wrong thing to do if it's a
** directory, but it shouldn't do any harm.
*/
if (!has_z_suffix)
{
memcpy(&tempname[namesize], ".Z", 3);
namesize += 2;
has_z_suffix = 1;
errno = 0;
if (lstat(tempname,&infstat) == -1)
{
perror(tempname);
goto error;
}
if ((infstat.st_mode & S_IFMT) != S_IFREG)
{
fprintf(stderr, "%s: Not a regular file.\n", tempname);
goto error;
}
}
else
{
perror(tempname);
goto error;
}
break;
default:
perror(tempname);
goto error;
}
}
else
{
perror(tempname);
goto error;
}
}
switch (infstat.st_mode & S_IFMT)
{
case S_IFDIR: /* directory */
#ifdef RECURSIVE
if (recursive)
compdir(tempname);
else
#endif
if (!quiet)
fprintf(stderr,"%s is a directory -- ignored\n", tempname);
break;
case S_IFREG: /* regular file */
if (do_decomp != 0)
{/* DECOMPRESSION */
if (!zcat_flg)
{
if (!has_z_suffix)
{
/* Ignore this scenario in recursive mode: while we
* decompress files in this dir, our readdir scan
* might turn up those new files. There is no way
* to efficiently handle this on very large dirs,
* so we ignore it. This also allows the user to
* easily resume partial decompressions.
*/
if (recursive) {
free(tempname);
return;
}
if (!quiet)
fprintf(stderr,"%s - no .Z suffix\n",tempname);
goto error;
}
}
free(ofname);
ofname = strdup(tempname);
if (ofname == NULL)
{
perror("strdup");
goto error;
}
/* Strip of .Z suffix */
if (has_z_suffix)
ofname[namesize - 2] = '\0';
}
else
{/* COMPRESSION */
if (!zcat_flg)
{
if (has_z_suffix)
{
/* Ignore this scenario in recursive mode.
* See comment above in the decompress path.
*/
if (!recursive)
fprintf(stderr, "%s: already has .Z suffix -- no change\n", tempname);
free(tempname);
return;
}
if (infstat.st_nlink > 1 && (!force))
{
fprintf(stderr, "%s has %jd other links: unchanged\n",
tempname, (intmax_t)(infstat.st_nlink - 1));
goto error;
}
}
ofname = malloc(namesize + 3);
if (ofname == NULL)
{
perror("malloc");
goto error;
}
memcpy(ofname, tempname, namesize);
strcpy(&ofname[namesize], ".Z");
}
if ((fdin = open(ifname = tempname, O_RDONLY|O_BINARY)) == -1)
{
perror(tempname);
goto error;
}
if (zcat_flg == 0)
{
if (access(ofname, F_OK) == 0)
{
if (!force)
{
inbuf[0] = 'n';
fprintf(stderr, "%s already exists.\n", ofname);
if (fgnd_flag && isatty(0))
{
fprintf(stderr, "Do you wish to overwrite %s (y or n)? ", ofname);
fflush(stderr);
if (read(0, inbuf, 1) > 0)
{
if (inbuf[0] != '\n')
{
do
{
if (read(0, inbuf+1, 1) <= 0)
{
perror("stdin");
break;
}
}
while (inbuf[1] != '\n');
}
}
else
perror("stdin");
}
if (inbuf[0] != 'y')
{
fprintf(stderr, "%s not overwritten\n", ofname);
goto error;
}
}
if (unlink(ofname))
{
fprintf(stderr, "Can't remove old output file\n");
perror(ofname);
goto error;
}
}
if ((fdout = open(ofname, O_WRONLY|O_CREAT|O_EXCL|O_BINARY,0600)) == -1)
{
perror(tempname);
goto error;
}
if (!quiet)
fprintf(stderr, "%s: ", tempname);
remove_ofname = 1;
}
else
{
fdout = 1;
setmode(fdout, O_BINARY);
remove_ofname = 0;
}
if (do_decomp == 0)
compress(fdin, fdout);
else
decompress(fdin, fdout);
close(fdin);
if (fdout != 1 && close(fdout))
write_error();
if ( (bytes_in == 0) && (force == 0 ) )
{
if (remove_ofname)
{
if (!quiet)
fprintf(stderr, "No compression -- %s unchanged\n", ifname);
if (unlink(ofname)) /* Remove input file */
{
fprintf(stderr, "\nunlink error (ignored) ");
perror(ofname);
}
remove_ofname = 0;
exit_code = 2;
}
}
else
if (zcat_flg == 0)
{
struct utimbuf timep;
if (!do_decomp && bytes_out >= bytes_in && (!force))
{/* No compression: remove file.Z */
if (!quiet)
fprintf(stderr, "No compression -- %s unchanged\n", ifname);
if (unlink(ofname))
{
fprintf(stderr, "unlink error (ignored) ");
perror(ofname);
}
remove_ofname = 0;
exit_code = 2;
}
else
{/* ***** Successful Compression ***** */
if (!quiet)
{
fprintf(stderr, " -- replaced with %s",ofname);
if (!do_decomp)
{
fprintf(stderr, " Compression: ");
prratio(stderr, bytes_in-bytes_out, bytes_in);
}
fprintf(stderr, "\n");
}
timep.actime = infstat.st_atime;
timep.modtime = infstat.st_mtime;
if (utime(ofname, &timep))
{
fprintf(stderr, "\nutime error (ignored) ");
perror(ofname);
}
if (chmod(ofname, infstat.st_mode & 07777)) /* Copy modes */
{
fprintf(stderr, "\nchmod error (ignored) ");
perror(ofname);
}
if (chown(ofname, infstat.st_uid, infstat.st_gid)) /* Copy ownership */
{
fprintf(stderr, "\nchown error (ignored) ");
perror(ofname);
}
remove_ofname = 0;
if (!keep && unlink(ifname)) /* Remove input file */
{
fprintf(stderr, "\nunlink error (ignored) ");
perror(ifname);
}
}
}
if (exit_code == -1)
exit_code = 0;
break;
default:
fprintf(stderr,"%s is not a directory or a regular file - ignored\n",
tempname);
break;
}
free(tempname);
if (!remove_ofname)
{
free(ofname);
ofname = NULL;
}
return;
error:
free(ofname);
ofname = NULL;
free(tempname);
exit_code = 1;
if (fdin != -1)
close(fdin);
if (fdout != -1)
close(fdout);
}
#ifdef RECURSIVE
void
compdir(char *dir)
{
struct dirent *dp;
DIR *dirp;
char *nptr;
char *fptr;
unsigned long dir_size = strlen(dir);
/* The +256 is a lazy optimization. We'll resize on demand. */
unsigned long size = dir_size + 256;
nptr = malloc(size);
if (nptr == NULL)
{
perror("malloc");
exit_code = 1;
return;
}
memcpy(nptr, dir, dir_size);
nptr[dir_size] = '/';
fptr = &nptr[dir_size + 1];
dirp = opendir(dir);
if (dirp == NULL)
{
free(nptr);
printf("%s unreadable\n", dir); /* not stderr! */
return ;
}
while ((dp = readdir(dirp)) != NULL)
{
if (dp->d_ino == 0)
continue;
if (strcmp(dp->d_name,".") == 0 || strcmp(dp->d_name,"..") == 0)
continue;
if (size < dir_size + strlen(dp->d_name) + 2)
{
size = dir_size + strlen(dp->d_name) + 2;
nptr = realloc(nptr, size);
if (nptr == NULL)
{
perror("realloc");
exit_code = 1;
break;
}
fptr = &nptr[dir_size + 1];
}
strcpy(fptr, dp->d_name);
comprexx(nptr);
}
closedir(dirp);
free(nptr);
}
#endif
/*
* compress fdin to fdout
*
* Algorithm: use open addressing double hashing (no chaining) on the
* prefix code / next character combination. We do a variant of Knuth's
* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime