Xen project Mailing List

On 16. Sep 2019, at 19:01, Ross Lagerwall <ross.lagerwall@xxxxxxxxxx> wrote:

On 9/16/19 11:59 AM, Pawel Wieczorkiewicz wrote:
snip

+/*
+ * Parse user provided action flags.
+ * This function expects to only receive an array of input parameters being flags.
+ * Expected action is specified via idx paramater (index of flag_options[]).
+ */
+static int get_flags(int argc, char *argv[], unsigned int idx, uint64_t *flags)
+{
+    int i, j;
+
+    if ( !flags || idx >= ARRAY_SIZE(flag_options) )
+        return -1;
+
+    *flags = 0;
+    for ( i = 0; i < argc; i++ )
+    {
+        for ( j = 0; j < ARRAY_SIZE(flag_options[idx]); j++ )
+        {
+            if ( !flag_options[idx][j].name )
+                goto error;
+
+            if ( !strcmp(flag_options[idx][j].name, argv[i]) )
+            {
+                *flags |= flag_options[idx][j].flag;
+                break;
+            }
+        }
+
+        if ( j == ARRAY_SIZE(flag_options[idx]) )
+            goto error;
+    }
+
+    return 0;
+error:
+    fprintf(stderr, "Unsupported flag: %s.\n", argv[i]);
+    errno = EINVAL;
+    return errno;
+}

You return -1 above but +ve errno here. Please make it consistent.

Well, I understood from the code of the file (e.g. action_func()) that the -1 value indicates a unexpected runtime error (negative val).

Whereas, positive errno values are expected error to be dealt with.

So:

<0 - fatal errors

0 - ok

>0 - errors to be handled

Could you confirm please that I should make get_flags() return only positive errors?

Also, you don't need to set errno if returning the actual error.

Honestly, I just copied the code from get_name() and wanted to the get_flags() to follow similar pattern.

(The error handling in this file looks fairly inconsistent anyway but let's not make it worse.)

+
/* The hypervisor timeout for the live patching operation is 30 msec,
  * but it could take some time for the operation to start, so wait twice
  * that period. */
@@ -291,8 +357,9 @@ int action_func(int argc, char *argv[], unsigned int idx)
     char name[XEN_LIVEPATCH_NAME_SIZE];
     int rc;
     xen_livepatch_status_t status;
+    uint64_t flags;
-    if ( argc != 1 )
+    if ( argc < 1 )
     {
         show_help();
         return -1;
@@ -301,7 +368,10 @@ int action_func(int argc, char *argv[], unsigned int idx)
     if ( idx >= ARRAY_SIZE(action_options) )
         return -1;
-    if ( get_name(argc, argv, name) )
+    if ( get_name(argc--, argv++, name) )
+        return EINVAL;
+
+    if ( get_flags(argc, argv, idx, &flags) )
         return EINVAL;
       /* Check initial status. */
@@ -332,7 +402,7 @@ int action_func(int argc, char *argv[], unsigned int idx)
     if ( action_options[idx].allow & status.state )
     {
         printf("%s %s... ", action_options[idx].verb, name);
-        rc = action_options[idx].function(xch, name, HYPERVISOR_TIMEOUT_NS);
+        rc = action_options[idx].function(xch, name, HYPERVISOR_TIMEOUT_NS, flags);
         if ( rc )
         {
             int saved_errno = errno;
@@ -394,17 +464,23 @@ int action_func(int argc, char *argv[], unsigned int idx)
   static int load_func(int argc, char *argv[])
{
-    int rc;
-    char *new_argv[2];
-    char *path, *name, *lastdot;
+    int i, rc = ENOMEM;
+    char *upload_argv[2];
+    char **apply_argv, *path, *name, *lastdot;
-    if ( argc != 1 )
+    if ( argc < 1 )
     {
         show_help();
         return -1;
     }
+
+    /* apply action has <id> [flags] input requirement, which must be constructed */
+    apply_argv = (char **) malloc(argc * sizeof(*apply_argv));
+    if ( !apply_argv )
+        return rc;
+
     /* <file> */
-    new_argv[1] = argv[0];
+    upload_argv[1] = argv[0];
       /* Synthesize the <id> */
     path = strdup(argv[0]);
@@ -413,16 +489,23 @@ static int load_func(int argc, char *argv[])
     lastdot = strrchr(name, '.');
     if ( lastdot != NULL )
         *lastdot = '\0';
-    new_argv[0] = name;
+    upload_argv[0] = name;
+    apply_argv[0] = name;
-    rc = upload_func(2 /* <id> <file> */, new_argv);
+    /* Fill in all user provided flags */
+    for ( i = 0; i < argc - 1; i++ )
+        apply_argv[i + 1] = argv[i + 1];

Wouldn't this make the loop body simpler? i = 1; i < argc;

ACK. It would indeed.

Or alternatively, just a straight memcpy().

--
Ross Lagerwall

Re: [Xen-devel] [PATCH v3 02/12] livepatch: Allow to override inter-modules buildid dependency