From d87fcd48886f26373ca12bcfcff9cea44ce9fae4 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Mon, 8 Jul 2013 02:39:51 +0200 Subject: [PATCH] tail: code shrink function old new delta tail_main 1548 1613 +65 tail_read 136 34 -102 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 65/-102) Total: -37 bytes Signed-off-by: Denys Vlasenko --- coreutils/tail.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/coreutils/tail.c b/coreutils/tail.c index fb07ca27b..c9f9d00f6 100644 --- a/coreutils/tail.c +++ b/coreutils/tail.c @@ -66,23 +66,10 @@ static void tail_xprint_header(const char *fmt, const char *filename) bb_perror_nomsg_and_die(); } -static ssize_t tail_read(int fd, char *buf, size_t count, int follow) +static ssize_t tail_read(int fd, char *buf, size_t count) { ssize_t r; - if (follow) { - /* tail -f keeps following files even if they are truncated */ - off_t current; - struct stat sbuf; - - /* /proc files report zero st_size, don't lseek them */ - if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) { - current = lseek(fd, 0, SEEK_CUR); - if (sbuf.st_size < current) - xlseek(fd, 0, SEEK_SET); - } - } - r = full_read(fd, buf, count); if (r < 0) { bb_perror_msg(bb_msg_read_error); @@ -255,7 +242,7 @@ int tail_main(int argc, char **argv) * Used only by +N code ("start from Nth", 1-based): */ seen = 1; newlines_seen = 0; - while ((nread = tail_read(fd, buf, tailbufsize - taillen, /*follow:*/ 0)) > 0) { + while ((nread = tail_read(fd, buf, tailbufsize - taillen)) > 0) { if (G.from_top) { int nwrite = nread; if (seen < count) { @@ -367,7 +354,19 @@ int tail_main(int argc, char **argv) if (nfiles > header_threshhold) { fmt = header_fmt_str; } - while ((nread = tail_read(fd, tailbuf, BUFSIZ, /*follow:*/ 1)) > 0) { + for (;;) { + /* tail -f keeps following files even if they are truncated */ + struct stat sbuf; + /* /proc files report zero st_size, don't lseek them */ + if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) { + off_t current = lseek(fd, 0, SEEK_CUR); + if (sbuf.st_size < current) + xlseek(fd, 0, SEEK_SET); + } + + nread = tail_read(fd, tailbuf, BUFSIZ); + if (nread <= 0) + break; if (fmt) { tail_xprint_header(fmt, filename); fmt = NULL; -- 2.25.1