[LibOS] Handle 0 being returned from DkStreamRead

Signed-off-by: Borys Popławski <[email protected]>
gramineproject · Feb 22, 2021 · 24b0d0c · 24b0d0c
1 parent ccb0c77
commit 24b0d0c
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Showing 6 changed files with 31 additions and 9 deletions.
diff --git a/LibOS/shim/include/shim_internal.h b/LibOS/shim/include/shim_internal.h
@@ -249,7 +249,7 @@ static inline int wait_event(AEVENTTYPE* e) {
     do {
         char byte;
         PAL_NUM ret = DkStreamRead(e->event, 0, 1, &byte, NULL, 0);
-        err = ret == PAL_STREAM_ERROR ? PAL_ERRNO() : 0;
+        err = ret == PAL_STREAM_ERROR ? PAL_ERRNO() : (ret == 0 ? ENODATA : 0);
     } while (err == EINTR || err == EAGAIN || err == EWOULDBLOCK);
 
     return -err;
@@ -273,7 +273,7 @@ static inline int clear_event(AEVENTTYPE* e) {
             int err = PAL_ERRNO();
             if (err == EINTR) {
                 continue;
-            } else if (!err || err == EAGAIN || err == EWOULDBLOCK) {
+            } else if (err == EAGAIN || err == EWOULDBLOCK) {
                 break;
             }
             return -err;
@@ -290,10 +290,13 @@ static inline int clear_event(AEVENTTYPE* e) {
             if (err == EINTR) {
                 continue;
             } else if (err == EAGAIN || err == EWOULDBLOCK) {
-                /* This should not happen, since we polled above  ... */
+                /* This should not happen, since we polled above... */
                 break;
             }
             return -err;
+        } else if (n == 0) {
+            /* This should not happen, since we polled above... */
+            return -ENODATA;
         }
     }
 

diff --git a/LibOS/shim/src/ipc/shim_ipc_helper.c b/LibOS/shim/src/ipc/shim_ipc_helper.c
@@ -567,14 +567,15 @@ static int receive_ipc_message(struct shim_ipc_port* port) {
                 DkStreamRead(port->pal_handle, /*offset=*/0, expected_size - bytes + readahead,
                              (void*)msg + bytes, NULL, 0);
 
-            if (read == PAL_STREAM_ERROR) {
-                if (PAL_ERRNO() == EINTR || PAL_ERRNO() == EAGAIN || PAL_ERRNO() == EWOULDBLOCK)
+            if (!read || read == PAL_STREAM_ERROR) {
+                int err = !read ? ENODATA : PAL_ERRNO();
+                if (err == EINTR || err == EAGAIN || err == EWOULDBLOCK)
                     continue;
 
                 debug("Port %p (handle %p) closed while receiving IPC message\n", port,
                       port->pal_handle);
                 del_ipc_port_fini(port);
-                ret = -PAL_ERRNO();
+                ret = -err;
                 goto out;
             }
 

diff --git a/LibOS/shim/src/shim_checkpoint.c b/LibOS/shim/src/shim_checkpoint.c
@@ -224,6 +224,8 @@ static int read_exact(PAL_HANDLE handle, void* buf, size_t size) {
                 continue;
             }
             return -err;
+        } else if (x == 0) {
+            return -ENODATA;
         }
 
         bytes += x;

diff --git a/LibOS/shim/src/shim_init.c b/LibOS/shim/src/shim_init.c
@@ -410,8 +410,17 @@ noreturn void* shim_init(int argc, void* args) {
         struct checkpoint_hdr hdr;
 
         PAL_NUM ret = DkStreamRead(PAL_CB(parent_process), 0, sizeof(hdr), &hdr, NULL, 0);
-        if (ret == PAL_STREAM_ERROR || ret != sizeof(hdr))
-            DkProcessExit(PAL_ERRNO());
+        int err = 0;
+        if (ret == PAL_STREAM_ERROR) {
+            /* PAL_ERRNO() == 0 should not be possible now, but old code allowed for such case.
+             * This will be removed soon anyway. */
+            err = PAL_ERRNO() ?: ENOTRECOVERABLE;
+        } else if (ret != sizeof(hdr)) {
+            err = ENODATA;
+        }
+        if (err) {
+            DkProcessExit(err);
+        }
 
         assert(hdr.size);
         RUN_INIT(receive_checkpoint_and_restore, &hdr);

diff --git a/LibOS/shim/test/regression/tcp_msg_peek.c b/LibOS/shim/test/regression/tcp_msg_peek.c
@@ -175,7 +175,13 @@ static void client(void) {
 
     /* we specify dummy MSG_DONTWAIT and MSG_WAITALL just to test these flags */
     printf("[client] receiving with MSG_PEEK: ");
-    count = client_recv(server_socket, buffer, sizeof(buffer), MSG_WAITALL | MSG_DONTWAIT | MSG_PEEK);
+    count = client_recv(server_socket, buffer, sizeof(buffer),
+                        MSG_WAITALL | MSG_DONTWAIT | MSG_PEEK);
+    fwrite(buffer, count, 1, stdout);
+
+    printf("[client] receiving with MSG_PEEK again: ");
+    count = client_recv(server_socket, buffer, sizeof(buffer),
+                        MSG_WAITALL | MSG_DONTWAIT | MSG_PEEK);
     fwrite(buffer, count, 1, stdout);
 
     printf("[client] receiving without MSG_PEEK: ");

diff --git a/LibOS/shim/test/regression/test_libos.py b/LibOS/shim/test/regression/test_libos.py
@@ -766,6 +766,7 @@ def test_200_socket_udp(self):
     def test_300_socket_tcp_msg_peek(self):
         stdout, _ = self.run_binary(['tcp_msg_peek'], timeout=50)
         self.assertIn('[client] receiving with MSG_PEEK: Hello from server!', stdout)
+        self.assertIn('[client] receiving with MSG_PEEK again: Hello from server!', stdout)
         self.assertIn('[client] receiving without MSG_PEEK: Hello from server!', stdout)
         self.assertIn('[client] checking how many bytes are left unread: 0', stdout)
         self.assertIn('[client] done', stdout)