`This is not LINUX!  This is Plan 9.  There are rules.'  -boyd/walter

See also `cat -v Considered Harmful'

Reference: /n/sources/patch/sorry/tard
Date: Fri Apr 22 21:31:15 CES 2005

--- /rc/bin/tard	Thu Jan  1 00:00:00 1970
+++ /rc/bin/tard	Fri Apr 22 21:27:19 2005
@@ -0,0 +1,22 @@
+#!/bin/rc
+
+opts=$1;shift
+f=$1;shift
+
+switch ($f) {
+case (~ $f  '(\.tar\.gz|\.tgz)$')
+	c='gzip'
+	uc='gunzip'
+case (~ $f  '(\.tar\.bz|\.tbz|\.tar\.bz2|\.tbz2)$')
+	c='bzip2'
+	uc='bunzip2'
+case (~ $f  '(\.tar\.Z|\.tz)$')
+	c='compress'
+	uc='uncompress'
+}
+
+if(~ $opts 'x')
+	cat $f | $uc | tar $opts 
+if not {
+	tar $opts $* | $c > $f
+}
--- /sys/man/1/tard	Thu Jan  1 00:00:00 1970
+++ /sys/man/1/tard	Fri Apr 22 21:27:36 2005
@@ -0,0 +1,18 @@
+.TH TARD 1
+.SH NAME
+tard \- tar with file compression detection
+.SH SYNOPSIS
+.B tard 
+.I opts
+.I  file 
+[
+.I files ...
+]
+.SH DESCRIPTION
+.I Tard 
+Calls tar and does (de)compression depending on the extension of the third parameter.
+
+.SH SOURCE
+.B /rc/bin/tard
+.SH "SEE ALSO"
+.IR tar (1)
--- /sys/man/1/tar	Fri Apr 22 21:27:55 2005
+++ /sys/man/1/tar	Fri Apr 22 21:27:52 2005
@@ -108,40 +108,7 @@
 .BR t ,
 give more details about the
 archive entries.
-.TP
-.B z
-Operate on compressed tar archives.
-The type of compression is inferred from the file name extension:
-.IR gzip (1)
-for
-.B .tar.gz
-and
-.BR .tgz ;
-.I bzip2
-(see
-.IR gzip (1))
-for
-.BR .tar.bz ,
-.BR .tbz ,
-.BR .tar.bz2 ,
-and
-.BR .tbz2 ;
-.I compress
-(not distributed)
-for
-.B .tar.Z
-and
-.BR .tz .
-If no extension matches,
-.I gzip
-is used.
-The
-.B z
-flag is unnecessary (but allowed) when using the
-.B t
-and
-.B x
-verbs on archives with recognized extensions.
+
 .SH EXAMPLES
 .I Tar
 can be used to copy hierarchies thus:
@@ -155,6 +122,7 @@
 .IR ar (1),
 .IR bundle (1),
 .IR tapefs (1)
+.IR tard (1)
 .SH BUGS
 There is no way to ask for any but the last
 occurrence of a file.
--- /sys/src/cmd/tar.c	Fri Apr 22 21:28:24 2005
+++ /sys/src/cmd/tar.c	Fri Apr 22 21:28:16 2005
@@ -93,18 +93,6 @@
 	};
 } Hdr;
 
-typedef struct {
-	char	*comp;
-	char	*decomp;
-	char	*sfx[4];
-} Compress;
-
-static Compress comps[] = {
-	"gzip",		"gunzip",	{ ".tar.gz", ".tgz" },	/* default */
-	"compress",	"uncompress",	{ ".tar.Z",  ".tz" },
-	"bzip2",	"bunzip2",	{ ".tar.bz", ".tbz",
-					  ".tar.bz2",".tbz2" },
-};
 
 typedef struct {
 	int	kid;
@@ -125,7 +113,6 @@
 static int relative = 1;
 static int settime;
 static int verbose;
-static int docompress;
 static int keepexisting;
 static Off nexthdr;
 
@@ -143,80 +130,6 @@
 	exits("usage");
 }
 
-/* compression */
-
-static Compress *
-compmethod(char *name)
-{
-	int i, nmlen = strlen(name), sfxlen;
-	Compress *cp;
-
-	for (cp = comps; cp < comps + nelem(comps); cp++)
-		for (i = 0; i < nelem(cp->sfx) && cp->sfx[i]; i++) {
-			sfxlen = strlen(cp->sfx[i]);
-			if (nmlen > sfxlen &&
-			    strcmp(cp->sfx[i], name + nmlen - sfxlen) == 0)
-				return cp;
-		}
-	return docompress? comps: nil;
-}
-
-/*
- * push a filter, cmd, onto fd.  if input, it's an input descriptor.
- * returns a descriptor to replace fd, or -1 on error.
- */
-static int
-push(int fd, char *cmd, int input, Pushstate *ps)
-{
-	int nfd, pifds[2];
-	String *s;
-
-	ps->open = 0;
-	ps->fd = fd;
-	ps->input = input;
-	if (fd < 0 || pipe(pifds) < 0)
-		return -1;
-	ps->kid = fork();
-	switch (ps->kid) {
-	case -1:
-		return -1;
-	case 0:
-		if (input)
-			dup(pifds[Wr], Stdout);
-		else
-			dup(pifds[Rd], Stdin);
-		close(pifds[input? Rd: Wr]);
-		dup(fd, (input? Stdin: Stdout));
-		s = s_new();
-		if (cmd[0] != '/')
-			s_append(s, "/bin/");
-		s_append(s, cmd);
-		execl(s_to_c(s), cmd, nil);
-		sysfatal("can't exec %s: %r", cmd);
-	default:
-		nfd = pifds[input? Rd: Wr];
-		close(pifds[input? Wr: Rd]);
-		break;
-	}
-	ps->rfd = nfd;
-	ps->open = 1;
-	return nfd;
-}
-
-static char *
-pushclose(Pushstate *ps)
-{
-	Waitmsg *wm;
-
-	if (ps->fd < 0 || ps->rfd < 0 || !ps->open)
-		return "not open";
-	close(ps->rfd);
-	ps->rfd = -1;
-	ps->open = 0;
-	while ((wm = wait()) != nil && wm->pid != ps->kid)
-		continue;
-	return wm? wm->msg: nil;
-}
 
 /*
  * block-buffer management
@@ -674,19 +587,13 @@
 	ulong blksleft, blksread;
 	Off bytes;
 	Hdr *hp;
-	Compress *comp = nil;
-	Pushstate ps;
 
 	if (usefile && docreate) {
 		ar = create(usefile, OWRITE, 0666);
-		if (docompress)
-			comp = compmethod(usefile);
 	} else if (usefile)
 		ar = open(usefile, ORDWR);
 	else
 		ar = Stdout;
-	if (comp)
-		ar = push(ar, comp->comp, Output, &ps);
 	if (ar < 0)
 		sysfatal("can't open archive %s: %r", usefile);
 
@@ -720,8 +627,6 @@
 	getblkz(ar);
 	putlastblk(ar);
 
-	if (comp)
-		return pushclose(&ps);
 	if (ar > Stderr)
 		close(ar);
 	return nil;
@@ -913,16 +818,11 @@
 	int ar;
 	char *longname;
 	Hdr *hp;
-	Compress *comp = nil;
-	Pushstate ps;
 
 	if (usefile) {
 		ar = open(usefile, OREAD);
-		comp = compmethod(usefile);
 	} else
 		ar = Stdin;
-	if (comp)
-		ar = push(ar, comp->decomp, Input, &ps);
 	if (ar < 0)
 		sysfatal("can't open archive %s: %r", usefile);
 
@@ -934,8 +834,6 @@
 			skip(ar, hp, longname);
 	}
 
-	if (comp)
-		return pushclose(&ps);
 	if (ar > Stderr)
 		close(ar);
 	return nil;
@@ -993,9 +891,6 @@
 		break;
 	case 'x':
 		verb = Xtract;
-		break;
-	case 'z':
-		docompress++;
 		break;
 	case '-':
 		break;