From f4be51104a8e353795716a63268d0d32aa97de7a Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Sat, 16 Aug 2003 17:28:33 +0000 Subject: An invalid initial value for *read_pos would result in `tail -n0 -f FILE' and `tail -c0 -f FILE' doing what amounted to a busy-wait rather than sleeping between iterations. The bug manifests itself only when tailing regular files that are initially nonempty. (tail_bytes): Set *read_pos to new file offset after each xlseek call. (tail_lines): Likewise, after lseek calls. --- src/tail.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'src/tail.c') diff --git a/src/tail.c b/src/tail.c index 1e551c5c9..7d8378707 100644 --- a/src/tail.c +++ b/src/tail.c @@ -1138,13 +1138,13 @@ tail_bytes (const char *pretty_filename, int fd, uintmax_t n_bytes, more bytes than have been requested. So reposition the file pointer to the incoming current position and print everything after that. */ - xlseek (fd, current_pos, SEEK_SET, pretty_filename); + *read_pos = xlseek (fd, current_pos, SEEK_SET, pretty_filename); } else { /* There are more bytes remaining than were requested. Back up. */ - xlseek (fd, -nb, SEEK_END, pretty_filename); + *read_pos = xlseek (fd, -nb, SEEK_END, pretty_filename); } *read_pos += dump_remainder (pretty_filename, fd, n_bytes); } @@ -1194,12 +1194,15 @@ tail_lines (const char *pretty_filename, int fd, uintmax_t n_lines, && (start_pos = lseek (fd, (off_t) 0, SEEK_CUR)) != -1 && start_pos < (end_pos = lseek (fd, (off_t) 0, SEEK_END))) { + *read_pos = end_pos; if (end_pos != 0 && file_lines (pretty_filename, fd, n_lines, start_pos, end_pos, read_pos)) return 1; } else - return pipe_lines (pretty_filename, fd, n_lines, read_pos); + { + return pipe_lines (pretty_filename, fd, n_lines, read_pos); + } } return 0; } -- cgit v1.2.3-54-g00ecf