From 81c634e8d5a7af19642396fcf91c3194ee857180 Mon Sep 17 00:00:00 2001
From: Kyle Evans <kevans@FreeBSD.org>
Date: Fri, 20 Apr 2018 03:08:46 +0000
Subject: [PATCH] bsdgrep: Split match processing out of procfile

procfile is getting kind of hairy, and it's not going to get better as we
correct some more bits that assume we process one line at a time.
---
 usr.bin/grep/util.c | 152 +++++++++++++++++++++++++-------------------
 1 file changed, 87 insertions(+), 65 deletions(-)

diff --git a/usr.bin/grep/util.c b/usr.bin/grep/util.c
index 6fd841c34607..0bb6d1c71588 100644
--- a/usr.bin/grep/util.c
+++ b/usr.bin/grep/util.c
@@ -72,6 +72,18 @@ struct parsec {
 	bool		binary;				/* Binary file? */
 };
 
+/*
+ * Match printing context
+ */
+struct mprintc {
+	long long	tail;		/* Number of trailing lines to record */
+	int		last_outed;	/* Number of lines since last output */
+	bool		doctx;		/* Printing context? */
+	bool		printmatch;	/* Printing matches? */
+	bool		same_file;	/* Same file as previously printed? */
+};
+
+static bool procmatches(struct mprintc *mc, struct parsec *pc, bool matched);
 #ifdef WITH_INTERNAL_NOSPEC
 static int litexec(const struct pat *pat, const char *string,
     size_t nmatch, regmatch_t pmatch[]);
@@ -196,6 +208,71 @@ grep_tree(char **argv)
 	return (c);
 }
 
+/*
+ * Process any matches in the current parsing context, return a boolean
+ * indicating whether we should halt any further processing or not. 'true' to
+ * continue processing, 'false' to halt.
+ */
+static bool
+procmatches(struct mprintc *mc, struct parsec *pc, bool matched)
+{
+
+	/* Deal with any -B context or context separators */
+	if (matched && mc->doctx) {
+		if (!first_match && (!mc->same_file || mc->last_outed > 0))
+			printf("--\n");
+		if (Bflag > 0)
+			printqueue();
+		mc->tail = Aflag;
+	}
+
+	/* Print the matching line, but only if not quiet/binary */
+	if (matched && mc->printmatch) {
+		printline(pc, ':');
+		while (pc->matchidx >= MAX_MATCHES) {
+			/* Reset matchidx and try again */
+			pc->matchidx = 0;
+			if (procline(pc) == 0)
+				printline(pc, ':');
+			else
+				break;
+		}
+		first_match = false;
+		mc->same_file = true;
+		mc->last_outed = 0;
+	}
+
+	if (!matched && mc->doctx) {
+		/* Deal with any -A context */
+		if (mc->tail > 0) {
+			grep_printline(&pc->ln, '-');
+			mc->tail--;
+			if (Bflag > 0)
+				clearqueue();
+		} else {
+			/*
+			 * Enqueue non-matching lines for -B context.
+			 * If we're not actually doing -B context or if
+			 * the enqueue resulted in a line being rotated
+			 * out, then go ahead and increment last_outed
+			 * to signify a gap between context/match.
+			 */
+			if (Bflag == 0 || (Bflag > 0 && enqueue(&pc->ln)))
+				++mc->last_outed;
+		}
+	}
+
+	/* Count the matches if we have a match limit */
+	if (matched && mflag) {
+		/* XXX TODO: Decrement by number of matched lines */
+		mcount -= 1;
+		if (mflag && mcount <= 0)
+			return (false);
+	}
+
+	return (true);
+}
+
 /*
  * Opens a file and processes it.  Each file is processed line-by-line
  * passing the lines to procline().
@@ -204,13 +281,11 @@ int
 procfile(const char *fn)
 {
 	struct parsec pc;
-	long long tail;
+	struct mprintc mc;
 	struct file *f;
 	struct stat sb;
-	struct str *ln;
 	mode_t s;
-	int c, last_outed, t;
-	bool doctx, printmatch, same_file;
+	int c, t;
 
 	if (strcmp(fn, "-") == 0) {
 		fn = label != NULL ? label : getstr(1);
@@ -234,8 +309,6 @@ procfile(const char *fn)
 		return (0);
 	}
 
-	/* Convenience */
-	ln = &pc.ln;
 	pc.ln.file = grep_malloc(strlen(fn) + 1);
 	strcpy(pc.ln.file, fn);
 	pc.ln.line_no = 0;
@@ -243,17 +316,13 @@ procfile(const char *fn)
 	pc.ln.boff = 0;
 	pc.ln.off = -1;
 	pc.binary = f->binary;
-	pc.printed = 0;
-	tail = 0;
-	last_outed = 0;
-	same_file = false;
-	doctx = false;
-	printmatch = true;
+	memset(&mc, 0, sizeof(mc));
+	mc.printmatch = true;
 	if ((pc.binary && binbehave == BINFILE_BIN) || cflag || qflag ||
 	    lflag || Lflag)
-		printmatch = false;
-	if (printmatch && (Aflag != 0 || Bflag != 0))
-		doctx = true;
+		mc.printmatch = false;
+	if (mc.printmatch && (Aflag != 0 || Bflag != 0))
+		mc.doctx = true;
 	mcount = mlimit;
 
 	for (c = 0;  c == 0 || !(lflag || qflag); ) {
@@ -282,56 +351,9 @@ procfile(const char *fn)
 		if ((t = procline(&pc)) == 0)
 			++c;
 
-		/* Deal with any -B context or context separators */
-		if (t == 0 && doctx) {
-			if (!first_match && (!same_file || last_outed > 0))
-				printf("--\n");
-			if (Bflag > 0)
-				printqueue();
-			tail = Aflag;
-		}
-		/* Print the matching line, but only if not quiet/binary */
-		if (t == 0 && printmatch) {
-			printline(&pc, ':');
-			while (pc.matchidx >= MAX_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;
-		}
-		if (t != 0 && doctx) {
-			/* Deal with any -A context */
-			if (tail > 0) {
-				grep_printline(&pc.ln, '-');
-				tail--;
-				if (Bflag > 0)
-					clearqueue();
-			} else {
-				/*
-				 * Enqueue non-matching lines for -B context.
-				 * If we're not actually doing -B context or if
-				 * the enqueue resulted in a line being rotated
-				 * out, then go ahead and increment last_outed
-				 * to signify a gap between context/match.
-				 */
-				if (Bflag == 0 || (Bflag > 0 && enqueue(ln)))
-					++last_outed;
-			}
-		}
-
-		/* Count the matches if we have a match limit */
-		if (t == 0 && mflag) {
-			--mcount;
-			if (mflag && mcount <= 0)
-				break;
-		}
-
+		/* Halt processing if we hit our match limit */
+		if (!procmatches(&mc, &pc, t == 0))
+			break;
 	}
 	if (Bflag > 0)
 		clearqueue();