From 6e8a1782ab7ed52c623038821b335fd25578dea5 Mon Sep 17 00:00:00 2001 From: Wayne Davison Date: Tue, 3 Aug 2004 08:05:29 +0000 Subject: [PATCH] - Changed the calling syntax for map_file() so that it takes both a (possibly approximate) window size and an optional block size (which is used to round-up the window size if it is non-zero). - Don't set window_start behind the supplied offset in map_ptr(). --- fileio.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/fileio.c b/fileio.c index f1d06329..2b86a5ef 100644 --- a/fileio.c +++ b/fileio.c @@ -139,21 +139,25 @@ int write_file(int f,char *buf,size_t len) } -/* this provides functionality somewhat similar to mmap() but using - read(). It gives sliding window access to a file. mmap() is not - used because of the possibility of another program (such as a - mailer) truncating the file thus giving us a SIGBUS */ -struct map_struct *map_file(int fd, OFF_T len, size_t block_size) +/* This provides functionality somewhat similar to mmap() but using read(). + * It gives sliding window access to a file. mmap() is not used because of + * the possibility of another program (such as a mailer) truncating the + * file thus giving us a SIGBUS. */ +struct map_struct *map_file(int fd, OFF_T len, OFF_T map_size, + size_t block_size) { struct map_struct *map; if (!(map = new(struct map_struct))) out_of_memory("map_file"); + if (block_size && (map_size % block_size)) + map_size += block_size - (map_size % block_size); + memset(map, 0, sizeof map[0]); map->fd = fd; map->file_size = len; - map->def_window_size = MAX(MAX_MAP_SIZE, block_size * 32); + map->def_window_size = map_size; return map; } @@ -181,12 +185,7 @@ char *map_ptr(struct map_struct *map,OFF_T offset,int len) } /* nope, we are going to have to do a read. Work out our desired window */ - if (offset > 2*CHUNK_SIZE) { - window_start = offset - 2*CHUNK_SIZE; - window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */ - } else { - window_start = 0; - } + window_start = offset; window_size = map->def_window_size; if (window_start + window_size > map->file_size) { window_size = map->file_size - window_start; -- 2.34.1