wc(1): Extend non-controversial optimizations to '-c' mode

wc(1)'s slow path for counting words or multibyte characters requires
conversion of the 8-bit input stream to wide characters.  However, a faster
path can be used for counting only lines ('-l' -- newlines have the same
representation in all supported encodings) or bytes ('-c').

The existing line count optimization was not used if the input was the
implicit stdin.  Additionally, it wasn't used if only byte counting was
requested.  This change expands the fast path to both of these scenarios.

Expanding the buffer size from 64 kB helps reduce the number of read(2)
calls needed, but exactly what impact that change has and what size to
expand the buffer to are still under discussion.

PR:		224160
Tested by:	wosch (earlier version)
Sponsored by:	Dell EMC Isilon

1 files changed, 51 insertions, 50 deletions

diff --git a/usr.bin/wc/wc.c b/usr.bin/wc/wc.c
index d403433e50427..c0c6810fd4dfd 100644
--- a/usr.bin/wc/wc.c
+++ b/usr.bin/wc/wc.c
@@ -206,30 +206,30 @@ cnt(const char *file)
 	linect = wordct = charct = llct = tmpll = 0;
 	if (file == NULL)
 		fd = STDIN_FILENO;
-	else {
-		if ((fd = open(file, O_RDONLY, 0)) < 0) {
-			xo_warn("%s: open", file);
-			return (1);
-		}
-		if (doword || (domulti && MB_CUR_MAX != 1))
-			goto word;
-		/*
-		 * Line counting is split out because it's a lot faster to get
-		 * lines than to get words, since the word count requires some
-		 * logic.
-		 */
-		if (doline) {
-			while ((len = read(fd, buf, MAXBSIZE))) {
-				if (len == -1) {
-					xo_warn("%s: read", file);
-					(void)close(fd);
-					return (1);
-				}
-				if (siginfo) {
-					show_cnt(file, linect, wordct, charct,
-					    llct);
-				}
-				charct += len;
+	else if ((fd = open(file, O_RDONLY, 0)) < 0) {
+		xo_warn("%s: open", file);
+		return (1);
+	}
+	if (doword || (domulti && MB_CUR_MAX != 1))
+		goto word;
+	/*
+	 * Line counting is split out because it's a lot faster to get
+	 * lines than to get words, since the word count requires some
+	 * logic.
+	 */
+	if (doline || dochar) {
+		while ((len = read(fd, buf, MAXBSIZE))) {
+			if (len == -1) {
+				xo_warn("%s: read", file);
+				(void)close(fd);
+				return (1);
+			}
+			if (siginfo) {
+				show_cnt(file, linect, wordct, charct,
+				    llct);
+			}
+			charct += len;
+			if (doline) {
 				for (p = buf; len--; ++p)
 					if (*p == '\n') {
 						if (tmpll > llct)
@@ -239,37 +239,38 @@ cnt(const char *file)
 					} else
 						tmpll++;
 			}
-			reset_siginfo();
+		}
+		reset_siginfo();
+		if (doline)
 			tlinect += linect;
-			if (dochar)
-				tcharct += charct;
-			if (dolongline) {
-				if (llct > tlongline)
-					tlongline = llct;
-			}
+		if (dochar)
+			tcharct += charct;
+		if (dolongline) {
+			if (llct > tlongline)
+				tlongline = llct;
+		}
+		show_cnt(file, linect, wordct, charct, llct);
+		(void)close(fd);
+		return (0);
+	}
+	/*
+	 * If all we need is the number of characters and it's a
+	 * regular file, just stat the puppy.
+	 */
+	if (dochar || domulti) {
+		if (fstat(fd, &sb)) {
+			xo_warn("%s: fstat", file);
+			(void)close(fd);
+			return (1);
+		}
+		if (S_ISREG(sb.st_mode)) {
+			reset_siginfo();
+			charct = sb.st_size;
 			show_cnt(file, linect, wordct, charct, llct);
+			tcharct += charct;
 			(void)close(fd);
 			return (0);
 		}
-		/*
-		 * If all we need is the number of characters and it's a
-		 * regular file, just stat the puppy.
-		 */
-		if (dochar || domulti) {
-			if (fstat(fd, &sb)) {
-				xo_warn("%s: fstat", file);
-				(void)close(fd);
-				return (1);
-			}
-			if (S_ISREG(sb.st_mode)) {
-				reset_siginfo();
-				charct = sb.st_size;
-				show_cnt(file, linect, wordct, charct, llct);
-				tcharct += charct;
-				(void)close(fd);
-				return (0);
-			}
-		}
 	}
 
 	/* Do it the hard way... */