From 70b84be9e85969491e542cecc3ae28fa7558a7ec Mon Sep 17 00:00:00 2001 From: Ron Yorston Date: Fri, 24 Jul 2015 14:28:08 +0100 Subject: [PATCH] less: rearrange detection of non-regular files Move the code to detect non-regular files to the point where the file is being opened. If num_lines == READING_FILE guarantees that the file is regular. Detect when a file becomes unreadable between it first being opened and the call to update_num_lines. Mark the file as being non-regular so we don't try that again. function old new delta reinitialize 197 245 +48 update_num_lines 159 127 -32 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 48/-32) Total: 16 bytes Signed-off-by: Ron Yorston Signed-off-by: Denys Vlasenko --- miscutils/less.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/miscutils/less.c b/miscutils/less.c index 8fd0874e2..91a933a3a 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 { @@ -615,15 +616,16 @@ static void update_num_lines(void) int count, fd; ssize_t len, i; char buf[4096]; - struct stat stbuf; + /* only do this for regular files */ if (num_lines == READING_FILE) { count = 0; fd = open(filename, O_RDONLY); - if (fd < 0) - goto skip; - if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode)) - goto do_close; + if (fd < 0) { + /* somebody stole my file! */ + num_lines = READING_NONREG; + return; + } while ((len = safe_read(fd, buf, sizeof(buf))) > 0) { for (i = 0; i < len; ++i) { if (buf[i] == '\n' && ++count == MAXLINES) @@ -632,9 +634,7 @@ static void update_num_lines(void) } done: num_lines = count; - do_close: close(fd); - skip: ; } } @@ -943,6 +943,13 @@ 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[] */ -- 2.25.1