[MINIOS PATCH v3 2/5] reset file type in close() in one place only

[Juergen Gross <jgross@xxxxxxxx>]

Today the file type in struct file is set to FTYPE_NONE for each
file type individually. Do that at the end of close() handling for
all types.

While at it wipe the complete struct file, too, in order to avoid
old data creeping into a new allocated struct file.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- new patch
V3:
- add error handling (Andrew Cooper)
- use BUILD_BUG_ON() (Andrew Cooper)
---
 lib/sys.c | 56 ++++++++++++++++++++++++++++---------------------------
 lib/xs.c  |  1 -
 2 files changed, 29 insertions(+), 28 deletions(-)

diff --git a/lib/sys.c b/lib/sys.c
index 9a03875c..7df77cc6 100644
--- a/lib/sys.c
+++ b/lib/sys.c
@@ -265,7 +265,7 @@ int read(int fd, void *buf, size_t nbytes)
             return ret;
         }
 #ifdef HAVE_LWIP
-       case FTYPE_SOCKET:
+        case FTYPE_SOCKET:
            return lwip_read(files[fd].fd, buf, nbytes);
 #endif
 #ifdef CONFIG_NETFRONT
@@ -424,84 +424,86 @@ int fsync(int fd) {
 
 int close(int fd)
 {
+    int res = 0;
+
+    if ( fd < 0 || fd >= ARRAY_SIZE(files) )
+        goto error;
+
     printk("close(%d)\n", fd);
     switch (files[fd].type) {
         default:
-           files[fd].type = FTYPE_NONE;
-           return 0;
+            break;
 #ifdef CONFIG_XENBUS
        case FTYPE_XENBUS:
             xs_daemon_close((void*)(intptr_t) fd);
-            return 0;
+            break;
 #endif
 #ifdef HAVE_LWIP
-       case FTYPE_SOCKET: {
-           int res = lwip_close(files[fd].fd);
-           files[fd].type = FTYPE_NONE;
-           return res;
-       }
+       case FTYPE_SOCKET:
+            res = lwip_close(files[fd].fd);
+            break;
 #endif
 #ifdef CONFIG_LIBXENCTRL
        case FTYPE_XC:
            minios_interface_close_fd(fd);
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_LIBXENEVTCHN
        case FTYPE_EVTCHN:
            minios_evtchn_close_fd(fd);
-            return 0;
+            break;
 #endif
 #ifdef CONFIG_LIBXENGNTTAB
        case FTYPE_GNTMAP:
            minios_gnttab_close_fd(fd);
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_NETFRONT
        case FTYPE_TAP:
            shutdown_netfront(files[fd].dev);
-           files[fd].type = FTYPE_NONE;
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_BLKFRONT
        case FTYPE_BLK:
             shutdown_blkfront(files[fd].dev);
-           files[fd].type = FTYPE_NONE;
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_TPMFRONT
        case FTYPE_TPMFRONT:
             shutdown_tpmfront(files[fd].dev);
-           files[fd].type = FTYPE_NONE;
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_TPM_TIS
        case FTYPE_TPM_TIS:
             shutdown_tpm_tis(files[fd].dev);
-           files[fd].type = FTYPE_NONE;
-           return 0;
+            break;
 #endif
 #ifdef CONFIG_KBDFRONT
        case FTYPE_KBD:
             shutdown_kbdfront(files[fd].dev);
-            files[fd].type = FTYPE_NONE;
-            return 0;
+            break;
 #endif
 #ifdef CONFIG_FBFRONT
        case FTYPE_FB:
             shutdown_fbfront(files[fd].dev);
-            files[fd].type = FTYPE_NONE;
-            return 0;
+            break;
 #endif
 #ifdef CONFIG_CONSFRONT
         case FTYPE_SAVEFILE:
         case FTYPE_CONSOLE:
             fini_consfront(files[fd].dev);
-            files[fd].type = FTYPE_NONE;
-            return 0;
+            break;
 #endif
        case FTYPE_NONE:
-           break;
+            goto error;
     }
+
+    memset(files + fd, 0, sizeof(struct file));
+    BUILD_BUG_ON(FTYPE_NONE != 0);
+
+    return res;
+
+ error:
     printk("close(%d): Bad descriptor\n", fd);
     errno = EBADF;
     return -1;
diff --git a/lib/xs.c b/lib/xs.c
index 0459f52f..4af0f960 100644
--- a/lib/xs.c
+++ b/lib/xs.c
@@ -35,7 +35,6 @@ void xs_daemon_close(struct xs_handle *h)
         next = event->next;
         free(event);
     }
-    files[fd].type = FTYPE_NONE;
 }
 
 int xs_fileno(struct xs_handle *h)
-- 
2.26.2