1 files changed, 112 insertions, 0 deletions
diff --git a/usr/src/lib/libcmd/common/revlib.c b/usr/src/lib/libcmd/common/revlib.c
new file mode 100644
index 0000000000..3693d15b2d
--- /dev/null
+++ b/usr/src/lib/libcmd/common/revlib.c
@@ -0,0 +1,112 @@
+/***********************************************************************
+*                                                                      *
+*               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
+/*
+ * common support for tail and rev
+ */
+
+#include	<cmd.h>
+#include	<rev.h>
+
+#define BUFSIZE			SF_BUFSIZE
+#define rounddown(n,size)	(((n)-1)&~((size)-1))
+
+/*
+ * copy the lines starting at offset <start> from in <in> to <out>
+ * in reverse order
+ */
+int rev_line(Sfio_t *in, Sfio_t *out, off_t start)
+{
+	register char *cp, *cpold;
+	register int n, nleft=0;
+	char buff[BUFSIZE];
+	off_t offset;
+	if(sfseek(in,(off_t)0,SEEK_CUR) < 0)
+	{
+		Sfio_t *tmp = sftmp(4*SF_BUFSIZE);
+		if(!tmp)
+			return(-1);
+		if(start>0 && sfmove(in, (Sfio_t*)0, start, -1) != start)
+			return(-1);
+		if(sfmove(in, tmp, SF_UNBOUND, -1) < 0 || !sfeof(in) || sferror(tmp))
+			return(-1);
+		in = tmp;
+		start=0;
+	}
+	if((offset = sfseek(in,(off_t)0,SEEK_END)) <= start)
+		return(0);
+	offset = rounddown(offset,BUFSIZE);
+	while(1)
+	{
+		n = BUFSIZE;
+		if(offset < start)
+		{
+			n -= (start-offset);
+			offset = start;
+		}
+		sfseek(in, offset, SEEK_SET);
+		if((n=sfread(in, buff, n)) <=0)
+			break;
+		cp = buff+n;
+		n = *buff;
+		*buff = '\n';
+		while(1)
+		{
+			cpold = cp;
+			if(nleft==0)
+				cp--;
+			if(cp==buff)
+			{
+				nleft= 1;
+				break;
+			}
+			while(*--cp != '\n');
+			if(cp==buff && n!='\n')
+			{
+				*cp = n;
+				nleft += cpold-cp;
+				break;
+			}
+			else
+				cp++;
+			if(sfwrite(out,cp,cpold-cp) < 0)
+				return(-1);
+			if(nleft)
+			{
+				if(nleft==1)
+					sfputc(out,'\n');
+				else if(sfmove(in,out,nleft,-1) != nleft)
+					return(-1);
+				nleft = 0;
+			}
+		}
+		if(offset <= start)
+			break;
+		offset -= BUFSIZE;
+	}
+	if(nleft)
+	{
+		sfseek(in, start, SEEK_SET);
+		if(sfmove(in,out,nleft,-1) != nleft)
+			return(-1);
+	}
+	return(0);
+}