Fix a RUN_ONCE bug

We have a number of instances where there are multiple "init" functions for
a single CRYPTO_ONCE variable, e.g. to load config automatically or to not
load config automatically. Unfortunately the RUN_ONCE mechanism was not
correctly giving the right return value where an alternative init function
was being used.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7647)

1 files changed, 92 insertions, 0 deletions

diff --git a/include/internal/thread_once.h b/include/internal/thread_once.h
index c7f0ab29e8..dcb0c689f3 100644
--- a/include/internal/thread_once.h
+++ b/include/internal/thread_once.h
@@ -9,6 +9,20 @@
 
 #include <openssl/crypto.h>
 
+/*
+ * DEFINE_RUN_ONCE: Define an initialiser function that should be run exactly
+ * once. It takes no arguments and returns and int result (1 for success or
+ * 0 for failure). Typical usage might be:
+ * 
+ * DEFINE_RUN_ONCE(myinitfunc)
+ * {
+ *     do_some_initialisation();
+ *     if (init_is_successful())
+ *         return 1;
+ *
+ *     return 0;
+ * }
+ */
 #define DEFINE_RUN_ONCE(init)                   \
     static int init(void);                     \
     int init##_ossl_ret_ = 0;                   \
@@ -17,10 +31,30 @@
         init##_ossl_ret_ = init();              \
     }                                           \
     static int init(void)
+
+/*
+ * DECLARE_RUN_ONCE: Declare an initialiser function that should be run exactly
+ * once that has been defined in another file via DEFINE_RUN_ONCE().
+ */
 #define DECLARE_RUN_ONCE(init)                  \
     extern int init##_ossl_ret_;                \
     void init##_ossl_(void);
 
+/*
+ * DEFINE_RUN_ONCE_STATIC: Define an initialiser function that should be run
+ * exactly once. This function will be declared as static within the file. It
+ * takes no arguments and returns and int result (1 for success or 0 for
+ * failure). Typical usage might be:
+ * 
+ * DEFINE_RUN_ONCE_STATIC(myinitfunc)
+ * {
+ *     do_some_initialisation();
+ *     if (init_is_successful())
+ *         return 1;
+ *
+ *     return 0;
+ * }
+ */
 #define DEFINE_RUN_ONCE_STATIC(init)            \
     static int init(void);                     \
     static int init##_ossl_ret_ = 0;            \
@@ -31,6 +65,46 @@
     static int init(void)
 
 /*
+ * DEFINE_RUN_ONCE_STATIC_ALT: Define an alternative initialiser function. This
+ * function will be declared as static within the file. It takes no arguments
+ * and returns and int result (1 for success or 0 for failure). An alternative
+ * initialiser function is expected to be associated with a primary initialiser
+ * function defined via DEFINE_ONCE_STATIC where both functions use the same
+ * CRYPTO_ONCE object to synchronise. Where an alternative initialiser function
+ * is used only one of the primary or the alternative initialiser function will
+ * ever be called - and that function will be called exactly once. Definitition
+ * of an alternative initialiser function MUST occur AFTER the definition of the
+ * primiary initialiser function. 
+ * 
+ * Typical usage might be:
+ * 
+ * DEFINE_RUN_ONCE_STATIC(myinitfunc)
+ * {
+ *     do_some_initialisation();
+ *     if (init_is_successful())
+ *         return 1;
+ *
+ *     return 0;
+ * }
+ * 
+ * DEFINE_RUN_ONCE_STATIC_ALT(myaltinitfunc, myinitfunc)
+ * {
+ *     do_some_alternative_initialisation();
+ *     if (init_is_successful())
+ *         return 1;
+ *
+ *     return 0;
+ * }
+ */
+#define DEFINE_RUN_ONCE_STATIC_ALT(initalt, init) \
+    static int initalt(void);                     \
+    static void initalt##_ossl_(void)             \
+    {                                             \
+        init##_ossl_ret_ = initalt();             \
+    }                                             \
+    static int initalt(void)
+
+/*
  * RUN_ONCE - use CRYPTO_THREAD_run_once, and check if the init succeeded
  * @once: pointer to static object of type CRYPTO_ONCE
  * @init: function name that was previously given to DEFINE_RUN_ONCE,
@@ -43,3 +117,21 @@
  */
 #define RUN_ONCE(once, init)                                            \
     (CRYPTO_THREAD_run_once(once, init##_ossl_) ? init##_ossl_ret_ : 0)
+
+/*
+ * RUN_ONCE_ALT - use CRYPTO_THREAD_run_once, to run an alternative initialiser
+ *                function and check if that initialisation succeeded
+ * @once:    pointer to static object of type CRYPTO_ONCE
+ * @initalt: alternative initialiser function name that was previously given to
+ *           DEFINE_RUN_ONCE_STATIC_ALT.  This function must return 1 for
+ *           success or 0 for failure.
+ * @init:    primary initialiser function name that was previously given to
+ *           DEFINE_RUN_ONCE_STATIC.  This function must return 1 for success or
+ *           0 for failure.
+ *
+ * The return value is 1 on success (*) or 0 in case of error.
+ *
+ * (*) by convention, since the init function must return 1 on success.
+ */
+#define RUN_ONCE_ALT(once, initalt, init)                               \
+    (CRYPTO_THREAD_run_once(once, initalt##_ossl_) ? init##_ossl_ret_ : 0)