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/*
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 * Attempt at emulation of Unix tar by calling Plan 9 tar.
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 *
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 * The differences from Plan 9 tar are:
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 *	In the absence of an "f" flag, the file /dev/tape is used.
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 *	An "f" flag with argument "-" causes use of stdin/stdout
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 *		by passing no "f" flag (nor argument) to Plan 9 tar.
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 *	By default, the "T" flag is passed to Plan 9 tar.
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 *		The "m" flag to this tar inhibits this behavior.
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 */
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#include <u.h>
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#include <libc.h>
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void
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usage(void)
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{
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	fprint(2, "usage: ape/tar [crtx][vfm] [args...] [file...]\n");
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	exits("usage");
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}
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void
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main(int argc, char **argv)
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{
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	int i, j, verb, vflag, fflag, Tflag, nargc;
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	char *p, *file, **nargv, *cpu, flagbuf[10], execbuf[128];
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	Waitmsg *w;
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	argv++, argc--;
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	if(argc < 1)
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		usage();
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	p = argv[0];
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	argv++, argc--;
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	if(*p == '-')
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		p++;
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	if(strchr("crtx", *p) == nil)
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		usage();
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	verb = *p++;
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	/* unix defaults */
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	fflag = 1;
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	file = "/dev/tape";
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	Tflag = 1;
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	vflag = 0;
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	for(; *p; p++) {
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		switch(*p) {
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		default:
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			usage();
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		case 'v':
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			vflag = 1;
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			break;
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		case 'f':
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			if(argc <= 0)
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				usage();
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			fflag = 1;
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			file = argv[0];
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			argv++, argc--;
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			if(strcmp(file, "-") == 0) {
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				/*
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				 * plan9 doesn't know about "-" meaning stdin/stdout,
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				 * but it's the default,
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				 * so rewrite to not use f flag at all.
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				 */
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				file = nil;
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				fflag = 0;
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			}
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			break;
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		case 'm':
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			Tflag = 0;
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			break;
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		case 'p':		/* pretend nothing's wrong */
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			break;
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		}
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	}
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	nargc = 1 + 1 + fflag + argc + 1;
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	nargv = malloc(sizeof(char*) * nargc);
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	if(nargv == nil) {
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		fprint(2, "ape/tar: out of memory\n");
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		exits("memory");
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	}
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	cpu = getenv("cputype");
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	if(cpu == nil) {
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		fprint(2, "ape/tar: need cputype environment variable set\n");
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		exits("cputype");
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	}
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	snprint(execbuf, sizeof execbuf, "/%s/bin/tar", cpu);
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	nargv[0] = "tar";
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	sprint(flagbuf, "%c%s%s%s", verb, vflag ? "v" : "", Tflag ? "T" : "", fflag ? "f" : "");
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	nargv[1] = flagbuf;
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	i = 2;
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	if(fflag)
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		nargv[i++] = file;
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	for(j=0; j<argc; j++, i++)
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		nargv[i] = argv[j];
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	nargv[i++] = nil;
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	assert(i == nargc);
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	switch(fork()){
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	case -1:
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		fprint(2, "ape/tar: fork failed: %r\n");
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		exits("fork");
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	case 0:
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		exec(execbuf, nargv);
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		fprint(2, "exec %s fails: %r\n", execbuf);
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		_exits("exec");
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	default:
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		w = wait();
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		if(w == nil)
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			exits("wait failed");
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		if(w->msg[0] == '\0')
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			exits(nil);
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		else
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			exits(w->msg);
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	}
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	assert(0);
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}