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rev.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1992-2007 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                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);
}

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