[PATCH] less: rearrange detection of non-regular files

[Ron Yorston]

Move the code to detect non-regular files to the point where the
file is being opened.  The line-counting code in m_status_print
now only has to handle regular files.

Still check the error return from the open call in m_status_print.
This permits detection of the case where a file becomes unreadable
between it first being opened and the call to m_status_print.  But
mark the file as being non-regular so we don't try that again.

function                                             old     new   delta
reinitialize                                         197     245     +48
m_status_print                                       409     379     -30
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 48/-30)             Total: 18 bytes

Signed-off-by: Ron Yorston <rmy at pobox.com>
---
 miscutils/less.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/miscutils/less.c b/miscutils/less.c
index dd932c5..6a59a00 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -167,7 +167,8 @@ enum { pattern_valid = 0 };
 
 enum {
 	READING_FILE = -1,
-	READING_STDIN = -2
+	READING_STDIN = -2,
+	READING_NONREG = -3
 };
 
 struct globals {
@@ -633,15 +634,15 @@ static void m_status_print(void)
 		int count, fd;
 		ssize_t len, i;
 		char buf[4096];
-		struct stat stbuf;
 
-		/* count number of lines in file */
+		/* count number of lines in (regular) file */
 		count = 0;
 		fd = open(filename, O_RDONLY);
-		if (fd < 0)
+		if (fd < 0) {
+			/* somebody stole my file! */
+			num_lines = READING_NONREG;
 			goto skip;
-		if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode))
-			goto do_close;
+		}
 		while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
 			for (i = 0; i < len; ++i) {
 				if (buf[i] == '\n' && ++count == MAXLINES)
@@ -650,7 +651,6 @@ static void m_status_print(void)
 		}
  done:
 		num_lines = count;
- do_close:
 		close(fd);
  skip: ;
 	}
@@ -939,6 +939,13 @@ static void buffer_line(int linenum)
 static void open_file_and_read_lines(void)
 {
 	if (filename) {
+#if ENABLE_FEATURE_LESS_FLAGS
+		struct stat stbuf;
+
+		xstat(filename, &stbuf);
+		if (!S_ISREG(stbuf.st_mode))
+			num_lines = READING_NONREG;
+#endif
 		xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
 	} else {
 		/* "less" with no arguments in argv[] */
-- 
2.4.3