Support Static Linking (#1261)

* [C] Add aeron_symbol_table and use it to resovle internal symbols.  Encapsulate dlsym lookups.  Separate object and function pointers and correctly deal generic versions of each.  Remove multiple instances of warning ignores for -Wpendantic.

* [C] Fix windows compilation error.

* [C] Add unit test.  Break early on object resolution.

* [C] Switch to specifying length on symbol tables instead of using a NULL terminator.

* [C] Use struct to hold function pointer to avoid ignoring -Wpendantic.

* [C] Move function definition out of header.  Add missing prototype.

* [C] Use length when scanning function symbol tables.

* [C] Use strncmp to perform a bounded comparison.  Add additional bounded length check function.  Use typedef for generic function pointer.

* [C] Newline at end of file.

aeron-client/src/main/c/CMakeLists.txt

@@ -81,6 +81,7 @@ set(SOURCE
     util/aeron_parse_util.c
     util/aeron_properties_util.c
     util/aeron_strutil.c
+    util/aeron_symbol_table.c
     uri/aeron_uri.c
     aeron_agent.c
     aeron_alloc.c
@@ -152,6 +153,7 @@ set(HEADERS
     util/aeron_platform.h
     util/aeron_properties_util.h
     util/aeron_strutil.h
+    util/aeron_symbol_table.h
     uri/aeron_uri.h
     aeron_agent.h
     aeron_alloc.h

aeron-client/src/main/c/aeron_agent.c

@@ -28,6 +28,7 @@
 #include "util/aeron_error.h"
 #include "util/aeron_dlopen.h"
 #include "util/aeron_parse_util.h"
+#include "util/aeron_symbol_table.h"
 #include "aeron_agent.h"
 #include "aeron_alloc.h"
 
@@ -282,6 +283,19 @@ aeron_idle_strategy_t aeron_idle_strategy_backoff =
         aeron_idle_strategy_backoff_state_init_args
     };
 
+static const aeron_symbol_table_obj_t aeron_idle_strategy_table[] =
+    {
+        { "sleeping", "aeron_idle_strategy_sleeping", &aeron_idle_strategy_sleeping },
+        { "sleep-ns", "aeron_idle_strategy_sleeping", &aeron_idle_strategy_sleeping },
+        { "yield", "aeron_idle_strategy_yielding", &aeron_idle_strategy_yielding },
+        { "spin", "aeron_idle_strategy_busy_spinning", &aeron_idle_strategy_busy_spinning },
+        { "noop", "aeron_idle_strategy_noop", &aeron_idle_strategy_noop },
+        { "backoff", "aeron_idle_strategy_backoff", &aeron_idle_strategy_backoff },
+    };
+
+static const size_t aeron_idle_strategy_table_length =
+    sizeof(aeron_idle_strategy_table) / sizeof (aeron_symbol_table_obj_t);
+
 aeron_idle_strategy_func_t aeron_idle_strategy_load(
     const char *idle_strategy_name,
     void **idle_strategy_state,
@@ -292,74 +306,43 @@ aeron_idle_strategy_func_t aeron_idle_strategy_load(
 
     if (NULL == idle_strategy_name || NULL == idle_strategy_state)
     {
-        AERON_SET_ERR(EINVAL, "%s", "invalid idle strategy name or state");
+        AERON_SET_ERR(EINVAL, "%s", "invalid idle object name or state");
         return NULL;
     }
 
-    *idle_strategy_state = NULL;
+    aeron_idle_strategy_t *idle_strategy = aeron_symbol_table_obj_load(
+        aeron_idle_strategy_table, aeron_idle_strategy_table_length, idle_strategy_name, "idle strategy");
 
-    if (strncmp(idle_strategy_name, "sleep-ns", strlen("sleep-ns")) == 0 ||
-        strncmp(idle_strategy_name, "sleeping", strlen("sleeping")) == 0)
-    {
-        return aeron_idle_strategy_load("aeron_idle_strategy_sleeping", idle_strategy_state, env_var, init_args);
-    }
-    else if (strncmp(idle_strategy_name, "yield", strlen("yield")) == 0)
+    if (NULL == idle_strategy)
     {
-        return aeron_idle_strategy_load("aeron_idle_strategy_yielding", idle_strategy_state, env_var, init_args);
-    }
-    else if (strncmp(idle_strategy_name, "spin", strlen("spin")) == 0)
-    {
-        return aeron_idle_strategy_load("aeron_idle_strategy_busy_spinning", idle_strategy_state, env_var, init_args);
-    }
-    else if (strncmp(idle_strategy_name, "noop", strlen("noop")) == 0)
-    {
-        return aeron_idle_strategy_load("aeron_idle_strategy_noop", idle_strategy_state, env_var, init_args);
-    }
-    else if (strncmp(idle_strategy_name, "backoff", strlen("backoff")) == 0)
-    {
-        return aeron_idle_strategy_load("aeron_idle_strategy_backoff", idle_strategy_state, env_var, init_args);
+        AERON_APPEND_ERR("%s", "");
+        return NULL;
     }
-    else
-    {
-        char idle_func_name[AERON_MAX_PATH] = { 0 };
-        aeron_idle_strategy_t *idle_strategy = NULL;
 
-        snprintf(idle_func_name, sizeof(idle_func_name) - 1, "%s", idle_strategy_name);
-        if ((idle_strategy = (aeron_idle_strategy_t *)aeron_dlsym(RTLD_DEFAULT, idle_func_name)) == NULL)
-        {
-            AERON_SET_ERR(EINVAL, "could not find idle strategy %s: dlsym - %s", idle_func_name, aeron_dlerror());
-            return NULL;
-        }
-        idle_func = idle_strategy->idle;
-        aeron_idle_strategy_init_func_t idle_init_func = idle_strategy->init;
-
-        void *idle_state = NULL;
-        if (idle_init_func(&idle_state, env_var, init_args) < 0)
-        {
-            return NULL;
-        }
+    *idle_strategy_state = NULL;
+    idle_func = idle_strategy->idle;
+    aeron_idle_strategy_init_func_t idle_init_func = idle_strategy->init;
 
-        *idle_strategy_state = idle_state;
+    void *idle_state = NULL;
+    if (idle_init_func(&idle_state, env_var, init_args) < 0)
+    {
+        return NULL;
     }
 
+    *idle_strategy_state = idle_state;
+
     return idle_func;
 }
 
 aeron_agent_on_start_func_t aeron_agent_on_start_load(const char *name)
 {
     aeron_agent_on_start_func_t func = NULL;
-#if defined(AERON_COMPILER_GCC)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
-#endif
-    if ((func = (aeron_agent_on_start_func_t)aeron_dlsym(RTLD_DEFAULT, name)) == NULL)
+
+    if ((*(void **)(&func) = aeron_dlsym(RTLD_DEFAULT, name)) == NULL)
     {
         AERON_SET_ERR(EINVAL, "could not find agent on_start func %s: dlsym - %s", name, aeron_dlerror());
         return NULL;
     }
-#if defined(AERON_COMPILER_GCC)
-#pragma GCC diagnostic pop
-#endif
 
     return func;
 }

aeron-client/src/main/c/aeron_common.h

@@ -33,4 +33,6 @@ uint8_t aeron_semantic_version_minor(int32_t version);
 
 uint8_t aeron_semantic_version_patch(int32_t version);
 
+typedef void (*aeron_fptr_t)(void);
+
 #endif //AERON_COMMON_H

aeron-client/src/main/c/util/aeron_dlopen.c

@@ -45,6 +45,19 @@ const char *aeron_dlinfo(const void *addr, char *buffer, size_t max_buffer_lengt
     return buffer;
 }
 
+const char *aeron_dlinfo_func(void (*func)(void), char *buffer, size_t max_buffer_length)
+{
+#if defined(AERON_COMPILER_GCC)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpedantic"
+#endif
+    void *addr = (void *)func;
+#if defined(AERON_COMPILER_GCC)
+#pragma GCC diagnostic pop
+#endif
+    return aeron_dlinfo(addr, buffer, max_buffer_length);
+}
+
 #elif defined(AERON_COMPILER_MSVC)
 
 #include "concurrent/aeron_counters_manager.h"
@@ -158,6 +171,12 @@ char *aeron_dlerror()
     return messageBuffer;
 }
 
+const char *aeron_dlinfo_func(void (*func)(void), char *buffer, size_t max_buffer_length)
+{
+    buffer[0] = '\0';
+    return buffer;
+}
+
 const char *aeron_dlinfo(const void *addr, char *buffer, size_t max_buffer_length)
 {
     buffer[0] = '\0';

aeron-client/src/main/c/util/aeron_dlopen.h

@@ -28,7 +28,8 @@
 #define aeron_dlopen(x) dlopen(x, RTLD_LAZY | RTLD_GLOBAL)
 #define aeron_dlerror dlerror
 
-const char *aeron_dlinfo(const void *addr, char *buffer, size_t max_buffer_length);
+const char *aeron_dlinfo(const void *, char *buffer, size_t max_buffer_length);
+const char *aeron_dlinfo_func(void (*func)(void), char *buffer, size_t max_buffer_length);
 
 #elif defined(AERON_COMPILER_MSVC)
 
@@ -39,6 +40,7 @@ void *aeron_dlsym(void *module, const char *name);
 void *aeron_dlopen(const char *filename);
 char *aeron_dlerror();
 const char *aeron_dlinfo(const void *addr, char *buffer, size_t max_buffer_length);
+const char *aeron_dlinfo_func(void (*func)(void), char *buffer, size_t max_buffer_length);
 
 #else
 #error Unsupported platform!

aeron-client/src/main/c/util/aeron_strutil.c

@@ -263,3 +263,4 @@ int getopt(int argc, char *const argv[], const char *opt_string)
 #endif
 
 extern uint64_t aeron_fnv_64a_buf(uint8_t *buf, size_t len);
+extern bool aeron_str_length(const char *str, size_t length_bound, size_t *length);

aeron-client/src/main/c/util/aeron_strutil.h

@@ -19,6 +19,7 @@
 
 #include <stdint.h>
 #include <stddef.h>
+#include <stdbool.h>
 
 void aeron_format_date(char *str, size_t count, int64_t timestamp);
 
@@ -78,4 +79,40 @@ AERON_EXPORT extern int optind;
 int getopt(int argc, char *const argv[], const char *opt_string);
 #endif
 
+/**
+ * Checks that the string length is strictly less than the specified bound.
+ *
+ * @param str           String to be compared.
+ * @param length_bound  Limit to the length of the string being checked.
+ * @param length        Out parameter for the actual length of the string (if non-null and less than length_bound).
+ *                      NULL values for this parameter are permitted.  If str is NULL this value is unmodified.  If
+ *                      the function returns false, the value is also unmodified.
+ * @return              true if less than the specified bound, NULL is always true.
+ */
+inline bool aeron_str_length(const char *str, size_t length_bound, size_t *length)
+{
+    if (NULL == str)
+    {
+        return true;
+    }
+
+    size_t i = 0;
+    bool result = false;
+    for (; i < length_bound; i++)
+    {
+        if ('\0' == str[i])
+        {
+            result = true;
+            break;
+        }
+    }
+
+    if (result && NULL != length)
+    {
+        *length = i;
+    }
+
+    return result;
+}
+
 #endif //AERON_STRUTIL_H