Re: Sendkey patch

[phcoder <phcoder@gmail.com>]

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Sorry, forgot to attach
phcoder wrote:
> Hello, again
> I had a look at your patch. In some mail it was suggested that kernel
> patch should be split from module that uses it. So I resend the kernel
> part of my patch. Another question is whether we need some kind of
> abortion procedure (like in your patch) if a preboot hook fails.
> Javier Martín wrote:
>> An interface like this is implemented in another patch in "discussion",
>> my drivemap patch (see the August list archives). As yours, it is
>> linked-list based and very similar in the prototypes. I haven't checked
>> if your code has any kind of errors/corner cases,
> 
> I checked and found that I didn't check if grub_malloc succeeded
> 
>> but it seems terser
>> than mine even though it's a bit more difficult to understand because
>> you use double pointers to avoid my handling of the head case. I don't
>> understand the purpose of doubly-linking the list though...
>>
> The goal is to avoid walking through list when deleting an entry from it.
>>> Whether we need also interface for adding "postboot" commands? (in case
>>> boot_function returns)
>> I don't think it would offer a lot of functionality because most loaders
>> don't return on failure, they just get stuck or their payload
>> triple-faults and reboots.
> 
> It's the case for i386-pc loaders but not the case of some other targets
> (e.g. EFI). So the question remains.
> 
> Vladimir Serbinenko


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Index: kern/loader.c
===================================================================
--- kern/loader.c	(revision 1845)
+++ kern/loader.c	(working copy)
@@ -22,12 +22,46 @@
 #include <grub/err.h>
 #include <grub/kernel.h>
 
+
 static grub_err_t (*grub_loader_boot_func) (void);
 static grub_err_t (*grub_loader_unload_func) (void);
 static int grub_loader_noreturn;
 
 static int grub_loader_loaded;
 
+static struct grub_preboot_t *grub_loader_preboots=0;
+
+struct grub_preboot_t *
+grub_loader_add_preboot (grub_err_t (*preboot_func) (int))
+{
+  struct grub_preboot_t **cur=&grub_loader_preboots;
+  if (!preboot_func)
+    return 0;
+  while (*cur)    
+    cur=&((*cur)->next);
+  *cur=(struct grub_preboot_t *)grub_malloc (sizeof (struct grub_preboot_t));
+  if (!*cur)
+    {
+      grub_error (GRUB_ERR_OUT_OF_MEMORY, "hook not added");
+      return 0;
+    }
+  (*cur)->prev_pointer=cur;
+  (*cur)->next=0;
+  (*cur)->preboot_func=preboot_func;
+  return *cur;
+}
+
+void
+grub_loader_remove_preboot (struct grub_preboot_t *p)
+{
+  if (!p)
+    return;
+  *(p->prev_pointer)=p->next;
+  if (p->next)
+    (p->next)->prev_pointer=p->prev_pointer;
+  grub_free (p);
+}
+
 int
 grub_loader_is_loaded (void)
 {
@@ -64,11 +98,19 @@
 grub_err_t
 grub_loader_boot (void)
 {
+  struct grub_preboot_t *iter=grub_loader_preboots;
   if (! grub_loader_loaded)
     return grub_error (GRUB_ERR_NO_KERNEL, "no loaded kernel");
 
   if (grub_loader_noreturn)
     grub_machine_fini ();
+
+  while (iter)
+    {
+      if (iter->preboot_func)
+	iter->preboot_func (grub_loader_noreturn);
+      iter=iter->next;
+    }
   
   return (grub_loader_boot_func) ();
 }
Index: include/grub/loader.h
===================================================================
--- include/grub/loader.h	(revision 1845)
+++ include/grub/loader.h	(working copy)
@@ -25,6 +25,14 @@
 #include <grub/err.h>
 #include <grub/types.h>
 
+struct grub_preboot_t
+{
+  grub_err_t (*preboot_func) (int);  
+  struct grub_preboot_t *next;
+  struct grub_preboot_t **prev_pointer;
+};
+
+
 /* Check if a loader is loaded.  */
 int EXPORT_FUNC(grub_loader_is_loaded) (void);
 
@@ -37,6 +45,12 @@
 /* Unset current loader, if any.  */
 void EXPORT_FUNC(grub_loader_unset) (void);
 
+/*Add a preboot function*/
+struct grub_preboot_t *EXPORT_FUNC(grub_loader_add_preboot) (grub_err_t (*preboot_func) (int noreturn));
+
+/*Remove given preboot function*/
+void EXPORT_FUNC(grub_loader_remove_preboot) (struct grub_preboot_t *p);
+
 /* Call the boot hook in current loader. This may or may not return,
    depending on the setting by grub_loader_set.  */
 grub_err_t EXPORT_FUNC(grub_loader_boot) (void);