rev.c   [plain text]

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*           Copyright (c) 1992-2007 AT&T Knowledge Ventures            *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                      by AT&T Knowledge Ventures                      *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * rev [-l] [file ...]
 *
 * reverse the characters or lines of one or more files
 *
 *   David Korn
 *   AT&T Laboratories
 *   dgk@research.att.com
 *
 */

static const char usage[] =
"[-?\n@(#)$Id: rev (AT&T Research) 1999-04-10 $\n]"
USAGE_LICENSE
"[+NAME?rev - reverse the characters or lines of one or more files]"
"[+DESCRIPTION?\brev\b copies one or more files to standard output "
	"reversing the order of characters on every line of the file "
	"or reversing the order of lines of the file if \b-l\b is specified.]"
"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \brev\b "
        "copies from standard input starting at the current offset.]"
"[l:line?Reverse the lines of the file.]"

"\n"
"\n[file ...]\n"
"\n"
"[+EXIT STATUS?]{"
        "[+0?All files copied successfully.]"
        "[+>0?One or more files did not copy.]"
"}"
"[+SEE ALSO?\bcat\b(1), \btail\b(1)]"
;

#include	<cmd.h>
#include	<rev.h>

/*
 * reverse the characters within a line
 */
static int rev_char(Sfio_t *in, Sfio_t *out)
{
	register int c;
	register char *ep, *bp, *cp;
	register int n;
	while(cp = bp = sfgetr(in,'\n',0))
	{
		ep = bp + (n=sfvalue(in)) -1;
		while(ep > bp)
		{
			c = *--ep;
			*ep = *bp;
			*bp++ = c;
		}
		if(sfwrite(out,cp,n)<0)
			return(-1);
	}
	return(0);
}

int
b_rev(int argc, register char** argv, void* context)
{
	register Sfio_t *fp;
	register char *cp;
	register int n, line=0;
	NOT_USED(argc);

	cmdinit(argc, argv, context, ERROR_CATALOG, 0);
	while (n = optget(argv, usage)) switch (n)
	{
	    case 'l':
		line=1;
		break;
	    case ':':
		error(2, "%s", opt_info.arg);
		break;
	    case '?':
		error(ERROR_usage(2), "%s", opt_info.arg);
		break;
	}
	argv += opt_info.index;
	if(error_info.errors)
		error(ERROR_usage(2),"%s",optusage((char*)0));
	n=0;
	if(cp = *argv)
		argv++;
	do
	{
		if(!cp || streq(cp,"-"))
			fp = sfstdin;
		else if(!(fp = sfopen((Sfio_t*)0,cp,"r")))
		{
			error(ERROR_system(0),"%s: cannot open",cp);
			n=1;
			continue;
		}
		if(line)
			line = rev_line(fp,sfstdout,sftell(fp));
		else
			line = rev_char(fp,sfstdout);
		if(fp!=sfstdin)
			sfclose(fp);
		if(line < 0)
			error(ERROR_system(1),"write failed");
	}
	while(cp= *argv++);
	return(n);
}