Ticket #366: fork_completion_callback.diff

include/InnoTekLIBC/fork.h

@@ -60 +60 @@
     /** The callback is only called in the parent context. */
     __LIBC_FORK_CTX_PARENT = 1,
     /** The callback is called in both parent and child contexts. */
-    __LIBC_FORK_CTX_BOTH = 2
+    __LIBC_FORK_CTX_BOTH = 2,
+    /** The mask for the calling context values. */
+    __LIBC_FORK_CTX_MASK = 0xf,
+    /** Flag for pfnCompletionCallback to add a callback to the end of the
+     * list so that it will be called last. */
+    __LIBC_FORK_CTX_FLAGS_LAST = 0x1000
 } __LIBC_FORKCTX;
 
 /**
@@ -379 +384 @@
      *                      a non zero rc argument indicates failure.
      * @param   pvArg       Argument to pass to pfnCallback as 3rd argument.
      * @param   enmContext  __LIBC_FORK_CTX_CHILD, __LIBC_FORK_CTX_PARENT, or
-     *                      __LIBC_FORK_CTX_BOTH.
+     *                      __LIBC_FORK_CTX_BOTH. May be ORed with
+     *                      __LIBC_FORK_CTX_FLAGS_LAST to add the callback to
+     *                      the end of the list so that it will be called after
+     *                      all other registered callbacks. 
      *
      * @remark  Use with care, the memory used to remember these is taken from the
      *          fork buffer.

src/lib/sys/libcfork.c

@@ -2199 +2199 @@
  *                      a non zero rc argument indicates failure.
  * @param   pvArg       Argument to pass to pfnCallback as 3rd argument.
  * @param   enmContext  __LIBC_FORK_CTX_CHILD, __LIBC_FORK_CTX_PARENT, or
- *                      __LIBC_FORK_CTX_BOTH.
+ *                      __LIBC_FORK_CTX_BOTH. May be ORed with
+ *                      __LIBC_FORK_CTX_FLAGS_LAST to add the callback to
+ *                      the end of the list so that it will be called after
+ *                      all other registered callbacks. 
  *
  * @remark  Use with care, the memory used to remember these is taken from the
  *          fork buffer.
@@ -2219 +2222 @@
             LIBCLOG_RETURN_INT(rc);
     }
 
+    int fLast = enmContext & __LIBC_FORK_CTX_FLAGS_LAST;
+    enmContext &= __LIBC_FORK_CTX_MASK;
+
     /*
      * Add it to the completion callbacks.
      * These are eating of the buffer from the end of it.
@@ -2227 +2233 @@
     pForkHandle->cbBufLeft  -= sizeof(__LIBC_FORKCOMPLETIONCALLBACK);
     pForkHandle->cCompletionCallbacks++;
     pForkHandle->papfnCompletionCallbacks--;
-    pForkHandle->papfnCompletionCallbacks->pfnCallback  = pfnCallback;
-    pForkHandle->papfnCompletionCallbacks->enmContext   = enmContext;
-    pForkHandle->papfnCompletionCallbacks->pvArg        = pvArg;
+    if (fLast)
+    {
+        /* Add to the tail of the list to have it executed last */
+        unsigned cCallbacks = pForkHandle->cCompletionCallbacks - 1;
+        memmove(pForkHandle->papfnCompletionCallbacks, pForkHandle->papfnCompletionCallbacks + 1,
+                sizeof(__LIBC_FORKCOMPLETIONCALLBACK) * cCallbacks);
+        pForkHandle->papfnCompletionCallbacks[cCallbacks].pfnCallback  = pfnCallback;
+        pForkHandle->papfnCompletionCallbacks[cCallbacks].enmContext   = enmContext;
+        pForkHandle->papfnCompletionCallbacks[cCallbacks].pvArg        = pvArg;
+    }
+    else
+    {
+        /* Add to the head of the list to have it executed first */
+        pForkHandle->papfnCompletionCallbacks->pfnCallback  = pfnCallback;
+        pForkHandle->papfnCompletionCallbacks->enmContext   = enmContext;
+        pForkHandle->papfnCompletionCallbacks->pvArg        = pvArg;
+    }
 
     LIBCLOG_RETURN_INT(0);
 }