.

wcfs/internal/wcfs_virtmem.cpp

@@ -224,12 +224,14 @@ void Conn::_pin1(SrvReq *req) {
 // at=None means unpin to head/ .   XXX -> C
 // NOTE this does not check wrt virtmem already mapped blk as RW.
 void _Mapping::_remmapblk(int64_t blk, Tid at) {
+    // XXX err context?
     _Mapping *mmap = this;
 
     ASSERT(mmap->blk_start <= blk && blk < mmap->blk_stop());
     _File *f = mmap->file;
 
     uint8_t *blkmem = mmap->mem_start + (blk - mmap->blk_start)*f->blksize;
+    osfile fsfile;
     if (at == TidHead) {
         fsfile = f->headf;
     }
@@ -239,15 +241,65 @@ void _Mapping::_remmapblk(int64_t blk, Tid at) {
         defer(fsfile.close)
     }
 
-    _ = os.fstat(fsfile.fileno());
-    ASSERT(_.st_blksize == f->blksize);  // FIXME assert
+    struct stat st;
+    err = fsfile.stat(&st);
+    if (err != nil)
+        return err;
+    ASSERT(st.st_blksize == f->blksize);  // FIXME assert
 
     // block is beyond file size - mmap with zeros   (assumes head/f size ↑=)
-    if ((blk+1)*f->blksize > _.st_size) {
-        mm.map_zero_into_ro(blkmem)
+    if ((blk+1)*f->blksize > st.st_size) {
+        mm.map_zero_into_ro(blkmem);
     }
     // block is inside file - mmap file data
     else {
-        mm.map_into_ro(blkmem, fsfile.fileno(), blk*f->blksize)
+        mm.map_into_ro(blkmem, fsfile.fileno(), blk*f->blksize);
     }
 }
+
+
+
+struct error {
+    err string;
+
+    error()             {}
+    error(nullptr_t)    {}          //  = nil
+    bool operator==(nullptr_t) {    // == nil
+        return err.is_empty();
+    }
+    bool operator!=(nullptr_t) {    // != nil
+        return !(this==nil);
+    }
+};
+
+struct osfile {
+    int    fd;
+    string path;
+
+    error close();
+    error stat(struct stat *st);
+};
+
+
+error osfile::close() {
+    osfile *f = this;
+
+    int err = close(f->fd);
+    if (err != 0)
+        return f->_errno("close");
+}
+
+error osfile::stat(struct stat *st) {
+    osfile *f = this;
+
+    int err = fstat(f->fd, st);
+    if (err != 0)
+        return f->_errno("stat");
+    return nil;
+}
+
+
+// _errno returns error corresponding to op and errno.
+error osfile::_err(const char *op) {
+    return errorf("%s %s: %s", op, f->path, strerror_r(errno));
+}