From 49a5aa9d0aecb47b9456d5141c14fba723f7eb74 Mon Sep 17 00:00:00 2001
From: kevans <kevans@FreeBSD.org>
Date: Thu, 17 Aug 2017 04:26:04 +0000
Subject: MFC r318571: bsdgrep: emit more than MAX_LINE_MATCHES per line

We should not set an arbitrary cap on the number of matches on a line,
and in any case MAX_LINE_MATCHES of 32 is much too low.  Instead, if we
match more than MAX_LINE_MATCHES, keep processing and matching from the
last match until all are found.

For the regression test, we produce 4096 matches (larger than we expect
we'll ever set MAX_LINE_MATCHES) and make sure we actually get 4096
lines of output with the -o flag.

We'll also make sure that every distinct line is getting its own line
number to detect line metadata not being printed as appropriate along
the way.

PR:		218811
Approved by:	emaste (mentor, blanket MFC)
---
 usr.bin/grep/util.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

(limited to 'usr.bin/grep')

diff --git a/usr.bin/grep/util.c b/usr.bin/grep/util.c
index e4d99c7..0101c06 100644
--- a/usr.bin/grep/util.c
+++ b/usr.bin/grep/util.c
@@ -63,6 +63,7 @@ static bool	 first_match = true;
 struct parsec {
 	regmatch_t matches[MAX_LINE_MATCHES];	/* Matches made */
 	struct str ln;				/* Current line */
+	size_t lnstart;				/* Start of line processing */
 	size_t matchidx;			/* Latest used match index */
 	bool binary;				/* Binary file? */
 };
@@ -247,8 +248,9 @@ procfile(const char *fn)
 	mcount = mlimit;
 
 	for (c = 0;  c == 0 || !(lflag || qflag); ) {
-		/* Reset match count for every line processed */
+		/* Reset match count and line start for every line processed */
 		pc.matchidx = 0;
+		pc.lnstart = 0;
 		pc.ln.off += pc.ln.len + 1;
 		if ((pc.ln.dat = grep_fgetln(f, &pc.ln.len)) == NULL ||
 		    pc.ln.len == 0) {
@@ -288,6 +290,14 @@ procfile(const char *fn)
 		/* Print the matching line, but only if not quiet/binary */
 		if (t == 0 && printmatch) {
 			printline(&pc, ':');
+			while (pc.matchidx >= MAX_LINE_MATCHES) {
+				/* Reset matchidx and try again */
+				pc.matchidx = 0;
+				if (procline(&pc) == 0)
+					printline(&pc, ':');
+				else
+					break;
+			}
 			first_match = false;
 			same_file = true;
 			last_outed = 0;
@@ -356,11 +366,11 @@ procline(struct parsec *pc)
 {
 	regmatch_t pmatch, lastmatch, chkmatch;
 	wchar_t wbegin, wend;
-	size_t st = 0, nst = 0;
+	size_t st, nst;
 	unsigned int i;
 	int c = 0, r = 0, lastmatches = 0, leflags = eflags;
 	size_t startm = 0, matchidx;
-	int retry;
+	unsigned int retry;
 
 	matchidx = pc->matchidx;
 
@@ -376,6 +386,8 @@ procline(struct parsec *pc)
 	} else if (matchall)
 		return (0);
 
+	st = pc->lnstart;
+	nst = 0;
 	/* Initialize to avoid a false positive warning from GCC. */
 	lastmatch.rm_so = lastmatch.rm_eo = 0;
 
@@ -432,12 +444,12 @@ procline(struct parsec *pc)
 				 * still match a whole word.
 				 */
 				if (r == REG_NOMATCH &&
-				    (retry == 0 || pmatch.rm_so + 1 < retry))
+				    (retry == pc->lnstart ||
+				    pmatch.rm_so + 1 < retry))
 					retry = pmatch.rm_so + 1;
 				if (r == REG_NOMATCH)
 					continue;
 			}
-
 			lastmatches++;
 			lastmatch = pmatch;
 
@@ -466,8 +478,11 @@ procline(struct parsec *pc)
 			}
 			/* avoid excessive matching - skip further patterns */
 			if ((color == NULL && !oflag) || qflag || lflag ||
-			    matchidx >= MAX_LINE_MATCHES)
+			    matchidx >= MAX_LINE_MATCHES) {
+				pc->lnstart = nst;
+				lastmatches = 0;
 				break;
+			}
 		}
 
 		/*
@@ -475,7 +490,7 @@ procline(struct parsec *pc)
 		 * again just in case we still have a chance to match later in
 		 * the string.
 		 */
-		if (lastmatches == 0 && retry > 0) {
+		if (lastmatches == 0 && retry > pc->lnstart) {
 			st = retry;
 			continue;
 		}
@@ -497,6 +512,7 @@ procline(struct parsec *pc)
 
 		/* Advance st based on previous matches */
 		st = nst;
+		pc->lnstart = st;
 	}
 
 	/* Reflect the new matchidx in the context */
-- 
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