#pragma prototyped
/*
* pack [-] [-f] file ...
*
* pack files using Huffman coding
*
* David Korn
* AT&T Research
*
*/
static const char usage[] =
"[-?\n@(#)$Id: pack (AT&T Research) 2003-04-28 $\n]"
USAGE_LICENSE
"[+NAME?pack - pack files using Huffman coding]"
"[+DESCRIPTION?\bpack\b attempts to store the specified files in a compressed "
"form using static Huffman coding. Wherever possible each \afile\a "
"is replaced by a packed file named \afile\a\b.z\b with the same "
"access modes, access and modified dates, and owner as those of "
"\afile\a. The \b-f\b option forces packing of \afile\a even when "
"there is no space benefit for packing the file.]"
"[+?If \bpack\b is successful, \afile\a will be removed. Packed files "
"can be restored to their original form using \bunpack\b or \bpcat\b.]"
"[+?\bpack\b uses Huffman (minimum redundancy) codes on a byte-by-byte basis. "
"Ordinarily, for each file that is packed, a line is written to "
"standard output containing \afile\a\b.z\b and the percent "
"compression. If the \b-v\b options is specified, or if the \b-\b "
"argument is specified, an internal flag is set that causes the "
"number of times each byte is used, its relative frequency, and the "
"code for the byte to be written to the standard output. Additional "
"occurrences of \b-\b in place of name cause the internal flag to be "
"set and reset.]"
"[+?No packing occurs if:]{"
"[+-?\afile\a appears to be already packed.]"
"[+-?\afile\a has links.]"
"[+-?\afile\a is a directory.]"
"[+-?\afile\a cannot be opened.]"
"[+-?No disk storage blocks will be saved by packing unless \b-f\b "
"is specified.]"
"[+-?A file called \afile\a\b.z\b already exists.]"
"[+-?The \b.z\b file cannot be created.]"
"[+-?An I/O error occurred during processing.]"
"}"
"[f:force?Pack the file even if the packed size is larger than the original.]"
"[v:verbose?Causes additional information to be written to standard ouput.]"
"\n"
"\nfile ...\n"
"\n"
"[+EXIT STATUS]{"
"[+0?All files packed successfully.]"
"[+\an\a?\an\a files failed to pack, where \an\a is less than 125.]"
"[+125?125 or more files failed to pack.]"
"}"
"[+SEE ALSO?\bunpack\b(1), \bpcat\b(1), \bcompress\b(1), \bgzip\b(1)]"
;
#include "huffman.h"
#include <error.h>
#include <ls.h>
#define BLKSIZE 512
#define block(size) (((size) + BLKSIZE-1) & ~(BLKSIZE-1))
#define PERM(m) ((m)&(S_IRWXU|S_IRWXG|S_IRWXO))
static void vprint(Huff_t*, int);
static char *outname(char*);
static const char suffix[] = ".z";
int
main(int argc, register char *argv[])
{
static char command[] = "pack";
register Huff_t *hp;
register char *infile,*outfile;
Sfio_t *fpin,*fpout;
int nfile=0, npack=0, force=0, verbose=0;
int out, deleted, dsize, n;
struct stat statb;
NOT_USED(argc);
error_info.id = command;
while(n = optget(argv,usage)) switch(n)
{
case 'f':
force++;
break;
case 'v':
verbose = !verbose;
break;
case ':':
error(2, opt_info.arg);
break;
case '?':
error(ERROR_usage(2), "%s", opt_info.arg);
break;
}
argv += opt_info.index;
if(error_info.errors || !*argv)
error(ERROR_usage(2), "%s", optusage((char*)0));
while (infile = *argv++)
{
if(*infile == '-')
{
/* awful way to handle options, but preserves SVID */
switch(infile[1])
{
case 'f':
force++;
continue;
case 0:
verbose = !verbose;
continue;
}
}
nfile++;
fpin = fpout = (Sfio_t*)0;
hp = (Huff_t*)0;
deleted = 0;
if(!(outfile = outname(infile)))
continue;
if (!(fpin=sfopen((Sfio_t*)0,infile,"r")))
error(ERROR_system(0), "%s: cannot open", infile);
else if(fstat(sffileno(fpin),&statb) < 0)
error(ERROR_system(0), "%s: cannot stat", infile);
else if(S_ISDIR(statb.st_mode))
error(2, "%s: cannot pack a directory", infile);
else if(statb.st_nlink > 1)
error(2, "%s: has links", infile);
else if(statb.st_size ==0)
error(2, "%s: cannot pack a zero length file", infile);
else if(access(outfile,F_OK) ==0)
error(ERROR_system(0), "%s: already exists", outfile);
else if(((out=open(outfile,O_WRONLY|O_CREAT|O_TRUNC|O_BINARY,PERM(statb.st_mode))) < 0) ||
!(fpout = sfnew((Sfio_t*)0,(char*)0,SF_UNBOUND,out,SF_WRITE)))
error(ERROR_system(0), "%s: cannot create", outfile);
else if((deleted++,chmod(outfile,statb.st_mode)) < 0)
error(ERROR_system(0), "%s: cannot change mode to %o",outfile,statb.st_mode);
else
{
chown(outfile,statb.st_uid,statb.st_gid);
if(!(hp = huffinit(fpin,(Sfoff_t)-1)))
error(2, "%s: read error", infile);
else if(sfseek(fpin,(Sfoff_t)0,0) < 0)
error(ERROR_system(0),"%s: seek error", infile);
else if((dsize = huffputhdr(hp,fpout)) < 0)
error(2, "%s: write error", infile);
else if(!force && block(huffisize(hp)) <= block(huffosize(hp)+dsize))
error(2, "%s:no savings - file unchanged", infile);
else if(huffencode(hp,fpin,fpout,SF_UNBOUND)<0)
error(2, "%s: read error", infile);
else
{
double diff;
if(remove(infile) < 0)
error(ERROR_system(0), "%s: cannot remove", infile);
diff = huffisize(hp) - (dsize+huffosize(hp));
sfprintf(sfstdout,"%s: %s : %.1f%% Compression\n",command,
infile,(100*diff)/((double)huffisize(hp)));
if(verbose)
vprint(hp,dsize);
npack++;
deleted = 0;
}
}
if(hp)
huffend(hp);
if(fpin)
sfclose(fpin);
if(fpout)
sfclose(fpout);
if(deleted)
remove(outfile);
if(outfile)
free(outfile);
}
nfile -= npack;
if(nfile > 125)
nfile = 125;
exit(nfile);
}
static char *outname(char *infile)
{
register int n = strlen(infile);
register int sufflen = strlen(suffix);
register char *cp;
if(streq(suffix,infile+n-sufflen))
{
error(ERROR_exit(1), "%s: already packed", infile);
return((char*)0);
}
if(cp = (char*)malloc(n+sufflen+1))
{
strcpy(cp,infile);
strcat(cp+n,suffix);
}
return(cp);
}
static void vprint(Huff_t *hp,int dsize)
{
sfprintf(sfstdout," from %lld to %lld bytes\n", huffisize(hp), huffosize(hp));
sfprintf(sfstdout," Huffman tree has %d levels below root\n", hp->maxlev);
sfprintf(sfstdout," %d distinct bytes in input\n", hp->nchars);
sfprintf(sfstdout," dictionary overhead = %ld bytes\n", dsize);
sfprintf(sfstdout," effective entropy = %.2f bits/byte\n",
((double)(huffosize(hp))/(double)huffisize(hp))*CHAR_BIT);
sfprintf(sfstdout," asymptotic entropy = %.2f bits/byte\n",
((double)(huffosize(hp)-dsize)/(double)huffisize(hp))*CHAR_BIT);
}
