From 5fdb50825f598035d52ea8a26be7611e1a906703 Mon Sep 17 00:00:00 2001 From: Pádraig Brady Date: Tue, 9 Jul 2013 18:45:34 +0100 Subject: head: avoid redundant allocations when reading empty files * src/head.c (elide_tail_lines_file): For seekable empty files, or seekable files where the current offset is after the end of the file, return immediately. Previously the short circuit code could not be reached due to logic error. Spotted by coverity. --- src/head.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'src') diff --git a/src/head.c b/src/head.c index 00e1be17c..5411a3c0e 100644 --- a/src/head.c +++ b/src/head.c @@ -739,18 +739,17 @@ elide_tail_lines_file (const char *filename, int fd, uintmax_t n_elide) off_t start_pos = lseek (fd, 0, SEEK_CUR); off_t end_pos = lseek (fd, 0, SEEK_END); - if (0 <= start_pos && start_pos < end_pos) + if (0 <= start_pos && 0 <= end_pos) { - /* If the file is empty, we're done. */ - if (end_pos == 0) + /* If no data to read we're done. */ + if (start_pos >= end_pos) return true; return elide_tail_lines_seekable (filename, fd, n_elide, start_pos, end_pos); } - /* lseek failed or the end offset precedes start. - Fall through. */ + /* lseek failed, Fall through... */ } return elide_tail_lines_pipe (filename, fd, n_elide); -- cgit v1.2.3-54-g00ecf