Implement "addr1,+N" ranges - not dissimilar to grep's -A switch.

PR:		134856
Submitted by:	Jeremie Le Hen - jeremie at le-hen dot org

4 files changed, 39 insertions, 18 deletions

diff --git a/usr.bin/sed/compile.c b/usr.bin/sed/compile.c
index 39250a3..53e2af7 100644
--- a/usr.bin/sed/compile.c
+++ b/usr.bin/sed/compile.c
@@ -181,7 +181,7 @@ semicolon:	EATSPACE();
 		if ((*link = cmd = malloc(sizeof(struct s_command))) == NULL)
 			err(1, "malloc");
 		link = &cmd->next;
-		cmd->nonsel = cmd->inrange = 0;
+		cmd->startline = cmd->nonsel = 0;
 		/* First parse the addresses */
 		naddr = 0;
 
@@ -775,6 +775,7 @@ compile_addr(char *p, struct s_addr *a)
 
 	icase = 0;
 
+	a->type = 0;
 	switch (*p) {
 	case '\\':				/* Context address */
 		++p;
@@ -798,10 +799,16 @@ compile_addr(char *p, struct s_addr *a)
 	case '$':				/* Last line */
 		a->type = AT_LAST;
 		return (p + 1);
+
+	case '+':				/* Relative line number */
+		a->type = AT_RELLINE;
+		p++;
+		/* FALLTHROUGH */
 						/* Line number */
 	case '0': case '1': case '2': case '3': case '4':
 	case '5': case '6': case '7': case '8': case '9':
-		a->type = AT_LINE;
+		if (a->type == 0)
+			a->type = AT_LINE;
 		a->u.l = strtol(p, &end, 10);
 		return (end);
 	default:
diff --git a/usr.bin/sed/defs.h b/usr.bin/sed/defs.h
index 895e719..d4f434e 100644
--- a/usr.bin/sed/defs.h
+++ b/usr.bin/sed/defs.h
@@ -38,8 +38,9 @@
  * Types of address specifications
  */
 enum e_atype {
-	AT_RE,					/* Line that match RE */
+	AT_RE	    = 1,			/* Line that match RE */
 	AT_LINE,				/* Specific line */
+	AT_RELLINE,				/* Relative line */
 	AT_LAST,				/* Last line */
 };
 
@@ -91,6 +92,7 @@ struct s_tr {
 struct s_command {
 	struct s_command *next;			/* Pointer to next command */
 	struct s_addr *a1, *a2;			/* Start and end address */
+	u_long startline;			/* Start line number or zero */
 	char *t;				/* Text for : a c i r w */
 	union {
 		struct s_command *c;		/* Command(s) for b t { */
@@ -100,7 +102,6 @@ struct s_command {
 	} u;
 	char code;				/* Command code */
 	u_int nonsel:1;				/* True if ! */
-	u_int inrange:1;			/* True if in range */
 };
 
 /*
diff --git a/usr.bin/sed/process.c b/usr.bin/sed/process.c
index a29fe0e..5e2618a 100644
--- a/usr.bin/sed/process.c
+++ b/usr.bin/sed/process.c
@@ -275,8 +275,8 @@ new:		if (!nflag && !pd)
 	    (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())
 
 /*
- * Return TRUE if the command applies to the current line.  Sets the inrange
- * flag to process ranges.  Interprets the non-select (``!'') flag.
+ * Return TRUE if the command applies to the current line.  Sets the start
+ * line for process ranges.  Interprets the non-select (``!'') flag.
  */
 static __inline int
 applies(struct s_command *cp)
@@ -287,18 +287,22 @@ applies(struct s_command *cp)
 	if (cp->a1 == NULL && cp->a2 == NULL)
 		r = 1;
 	else if (cp->a2)
-		if (cp->inrange) {
+		if (cp->startline > 0) {
 			if (MATCH(cp->a2)) {
-				cp->inrange = 0;
+				cp->startline = 0;
 				lastaddr = 1;
 				r = 1;
-			} else if (cp->a2->type == AT_LINE &&
-				   linenum > cp->a2->u.l) {
+			} else if (linenum - cp->startline <= cp->a2->u.l)
+				r = 1;
+			else if ((cp->a2->type == AT_LINE &&
+				   linenum > cp->a2->u.l) ||
+				   (cp->a2->type == AT_RELLINE &&
+				   linenum - cp->startline > cp->a2->u.l)) {
 				/*
 				 * We missed the 2nd address due to a branch,
 				 * so just close the range and return false.
 				 */
-				cp->inrange = 0;
+				cp->startline = 0;
 				r = 0;
 			} else
 				r = 1;
@@ -308,12 +312,15 @@ applies(struct s_command *cp)
 			 * equal to the line number first selected, only
 			 * one line shall be selected.
 			 *	-- POSIX 1003.2
+			 * Likewise if the relative second line address is zero.
 			 */
-			if (cp->a2->type == AT_LINE &&
-			    linenum >= cp->a2->u.l)
+			if ((cp->a2->type == AT_LINE &&
+			    linenum >= cp->a2->u.l) ||
+			    (cp->a2->type == AT_RELLINE && cp->a2->u.l == 0))
 				lastaddr = 1;
-			else
-				cp->inrange = 1;
+			else {
+				cp->startline = linenum;
+			}
 			r = 1;
 		} else
 			r = 0;
@@ -331,11 +338,11 @@ resetstate(void)
 	struct s_command *cp;
 
 	/*
-	 * Reset all inrange markers.
+	 * Reset all in-range markers.
 	 */
 	for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
 		if (cp->a2)
-			cp->inrange = 0;
+			cp->startline = 0;
 
 	/*
 	 * Clear out the hold space.
diff --git a/usr.bin/sed/sed.1 b/usr.bin/sed/sed.1
index f694f40..2481ac2 100644
--- a/usr.bin/sed/sed.1
+++ b/usr.bin/sed/sed.1
@@ -211,6 +211,9 @@ that matches the second address.
 If the second address is a number
 less than or equal to the line number first selected, only that
 line is selected.
+The number in the second address may be prefixed with a
+.Pq Dq \&+
+to specify the number of lines to match after the first pattern.
 In the case when the second address is a context
 address,
 .Nm
@@ -594,7 +597,10 @@ The
 .Fl E , I , a
 and
 .Fl i
-options, as well as the
+options, the prefixing
+.Dq \&+
+in the second member of an address range,
+as well as the
 .Dq I
 flag to the address regular expression and substitution command are
 non-standard