+
+/* Memory-map the given log object into memory (read-only) and return a pointer
+ * to it. FIXME: Use some type of cache, map entire log segments, and use
+ * reference counting? */
+static int page_size = 0;
+
+BlueSkyRCStr *bluesky_log_map_object(BlueSkyLog *log,
+ int log_seq, int log_offset, int log_size)
+{
+ if (page_size == 0) {
+ page_size = getpagesize();
+ }
+
+ int dirfd = open(log->log_directory, O_DIRECTORY);
+ if (dirfd < 0) {
+ fprintf(stderr, "Unable to open logging directory: %m\n");
+ return NULL;
+ }
+
+ char logfile[64];
+ g_snprintf(logfile, sizeof(logfile), "log-%08d", log_seq);
+ int fd = openat(dirfd, logfile, O_RDONLY);
+ close(dirfd);
+
+ if (fd < 0) {
+ fprintf(stderr, "Error opening logfile %s: %m\n", logfile);
+ return NULL;
+ }
+
+ off_t off_start, off_end;
+ off_start = log_offset;
+ off_end = off_start + log_size;
+ off_start &= ~(page_size - 1);
+ off_end = (off_end + (page_size - 1)) & (page_size - 1);
+
+ const char *ptr = (const char *)mmap(NULL, off_end - off_start, PROT_READ,
+ MAP_SHARED, fd, off_start);
+
+ if (ptr == NULL) {
+ fprintf(stderr, "Error mapping logfile: %m\n");
+ close(fd);
+ return NULL;
+ }
+
+ close(fd);
+
+ BlueSkyMmap *mmap = g_new0(BlueSkyMmap, 1);
+ mmap->addr = ptr;
+ mmap->len = off_end - off_start;
+ g_atomic_int_set(&mmap->refcount, 1);
+
+ return bluesky_string_new_from_mmap(mmap,
+ log_offset - off_start, log_size);
+}