pipes: Add dump_one_pipe_data helpers

Will need it for fifo data dumping. At moment
the helper is pushed out of compilation procedure
for easier review, and will be real used in next
patch.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

pipes.c

@@ -304,6 +304,98 @@ static int open_pipe(struct file_desc *d)
 static u32 *pipes_with_data;	/* pipes for which data already dumped */
 static int nr_pipes = 0;
 
+#if 0
+static int dump_one_pipe_data(int lfd, u32 id, const struct fd_parms *p)
+{
+	int pipe_size, i, bytes;
+	int steal_pipe[2];
+	int ret = -1;
+
+	if (p->flags & O_WRONLY)
+		return 0;
+
+	/* Maybe we've dumped it already */
+	for (i = 0; i < nr_pipes; i++) {
+		if (pipes_with_data[i] == p->id)
+			return 0;
+	}
+
+	pr_info("Dumping data from pipe %#x fd %d\n", id, lfd);
+
+	if (PIPES_SIZE < nr_pipes + 1) {
+		pr_err("OOM storing pipe\n");
+		return -1;
+	}
+
+	pipes_with_data[nr_pipes] = p->id;
+	nr_pipes++;
+
+	pipe_size = fcntl(lfd, F_GETPIPE_SZ);
+	if (pipe_size < 0) {
+		pr_err("Can't obtain piped data size\n");
+		goto err;
+	}
+
+	if (pipe(steal_pipe) < 0) {
+		pr_perror("Can't create pipe for stealing data");
+		goto err;
+	}
+
+	bytes = tee(lfd, steal_pipe[1], pipe_size, SPLICE_F_NONBLOCK);
+	if (bytes > 0) {
+		int fd_pipes_data = fdset_fd(glob_fdset, CR_FD_PIPES_DATA);
+		struct pipe_data_entry pde;
+		int wrote;
+
+		pde.pipe_id	= p->id;
+		pde.bytes	= bytes;
+		pde.off		= 0;
+
+		if (bytes > PIPE_MAX_NONALIG_SIZE) {
+			off_t off;
+
+			off  = lseek(fd_pipes_data, 0, SEEK_CUR);
+			off += sizeof(pde);
+			off &= ~PAGE_MASK;
+
+			if (off)
+				pde.off = PAGE_SIZE - off;
+
+			pr_info("\toff %#lx %#x bytes %#x\n", off, pde.off, bytes);
+		}
+
+		if (write_img(fd_pipes_data, &pde))
+			goto err_close;
+
+		/* Don't forget to advance position if a hole needed */
+		if (pde.off)
+			lseek(fd_pipes_data, pde.off, SEEK_CUR);
+
+		wrote = splice(steal_pipe[0], NULL, fd_pipes_data, NULL, bytes, 0);
+		if (wrote < 0) {
+			pr_perror("Can't push pipe data");
+			goto err_close;
+		} else if (wrote != bytes) {
+			pr_err("%#x: Wanted to write %d bytes, but wrote %d\n", id, bytes, wrote);
+			goto err_close;
+		}
+	} else if (bytes < 0) {
+		if (errno != EAGAIN) {
+			pr_perror("Can't pick pipe data");
+			goto err_close;
+		}
+	}
+
+	ret = 0;
+
+err_close:
+	close(steal_pipe[0]);
+	close(steal_pipe[1]);
+err:
+	return ret;
+}
+#endif
+
 static int dump_one_pipe(int lfd, u32 id, const struct fd_parms *p)
 {
 	struct pipe_entry pe;