[RFC]: add a logging handler callback

Just some code to guide a discussion on how to add a logging callback
routine to make applications and bindings uses the various apis easier
to integrate into different logging mechanisms. This would be nice for
the Python bindings.

Changed:
- Updated the API to call with various params over just a single string.
- Added SYS and ESYS routines.

TODO:
1. Add FAPI support
2. Test
3. Fiddle with names, style and locations in the code base

Signed-off-by: William Roberts <william.c.roberts@intel.com>

include/tss2/tss2_common.h

@@ -39,6 +39,31 @@ struct TSS2_ABI_VERSION {
 
 #define TSS2_ABI_VERSION_CURRENT {1, 2, 1, 108}
 
+/* TODO: Maybe this is better in tss2_log.h? */
+#include <stddef.h>
+#define LOGL_NONE    0
+#define LOGL_ERROR   2
+#define LOGL_WARNING 3
+#define LOGL_INFO    4
+#define LOGL_DEBUG   5
+#define LOGL_TRACE   6
+#define LOGL_UNDEF   0xFF
+
+typedef enum {
+    LOGLEVEL_NONE      = LOGL_NONE,
+    LOGLEVEL_ERROR     = LOGL_ERROR,
+    LOGLEVEL_WARNING   = LOGL_WARNING,
+    LOGLEVEL_INFO      = LOGL_INFO,
+    LOGLEVEL_DEBUG     = LOGL_DEBUG,
+    LOGLEVEL_TRACE     = LOGL_TRACE,
+    LOGLEVEL_UNDEFINED = LOGL_UNDEF
+} log_level;
+
+/* TODO ENUMs can change size based on compiler settings, so just use int or unisgned here */
+typedef void (*TSS2_LOG_HANDLER)(log_level loglevel, const char *module,
+                   const char *file, const char *func, int line,
+                   const char *msg);
+
 /*
  * Return Codes
  */

include/tss2/tss2_esys.h

@@ -3302,6 +3302,10 @@ Esys_GetSysContext(
     ESYS_CONTEXT *esys_context,
     TSS2_SYS_CONTEXT **sys_context);
 
+TSS2_LOG_HANDLER
+Esys_SetLogHandler(
+    TSS2_LOG_HANDLER new_handler);
+
 #ifdef __cplusplus
 }
 #endif

include/tss2/tss2_sys.h

@@ -2281,6 +2281,10 @@ TSS2_RC Tss2_Sys_PolicyAuthorizeNV(
     TSS2L_SYS_AUTH_COMMAND const *cmdAuthsArray,
     TSS2L_SYS_AUTH_RESPONSE *rspAuthsArray);
 
+TSS2_LOG_HANDLER
+Tss2_Sys_SetLogHandler(
+    TSS2_LOG_HANDLER new_handler);
+
 #ifdef __cplusplus
 }
 #endif

lib/tss2-esys.def

@@ -362,3 +362,4 @@ EXPORTS
     Esys_ZGen_2Phase
     Esys_ZGen_2Phase_Async
     Esys_ZGen_2Phase_Finish
+    Esys_SetLogHandler

lib/tss2-esys.map

@@ -365,6 +365,7 @@
         Esys_Initialize;
         Esys_GetPollHandles;
         Esys_Finalize;
+        Esys_SetLogHandler;
     local:
         *;
 };

lib/tss2-sys.def

@@ -366,3 +366,4 @@ EXPORTS
     Tss2_Sys_ZGen_2Phase_Prepare
     Tss2_Sys_ZGen_2Phase_Complete
     Tss2_Sys_ZGen_2Phase
+    Tss2_Sys_SetLogHandler

lib/tss2-sys.map

@@ -370,6 +370,7 @@
         Tss2_Sys_ZGen_2Phase_Prepare;
         Tss2_Sys_ZGen_2Phase_Complete;
         Tss2_Sys_ZGen_2Phase;
+        Tss2_Sys_SetLogHandler;
     local:
         *;
 };

src/tss2-esys/api/Esys_SetLogHandler.c

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "tss2_esys.h"
+#define LOGMODULE esys
+#include "util/log.h"
+
+TSS2_LOG_HANDLER
+Esys_SetLogHandler(
+    TSS2_LOG_HANDLER new_handler)
+{
+    return set_log_handler(new_handler);
+}

src/tss2-sys/api/Tss2_Sys_SetLogHandler.c

@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/***********************************************************************;
+ * Copyright (c) 2015 - 2018, Intel Corporation
+ * All rights reserved.
+ ***********************************************************************/
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "tss2_sys.h"
+#define LOGMODULE sys
+#include "util/log.h"
+
+TSS2_LOG_HANDLER
+Tss2_Sys_SetLogHandler(
+    TSS2_LOG_HANDLER new_handler)
+{
+    return set_log_handler(new_handler);
+}

src/util/log.c

@@ -106,6 +106,28 @@ getLogFile(void)
 #endif
 }
 
+static void do_default_log(log_level loglevel, const char *module,
+        const char *file, const char *func, int line,
+        const char *msg) {
+
+    char buf[4096];
+    int size = snprintf(buf, sizeof(buf), "%s:%s:%s:%d:%s() %s \n",
+                log_strings[loglevel], module, file, line, func, msg);
+
+    FILE *logfile = getLogFile();
+    fwrite (buf, size, 1, logfile);
+    fflush(logfile);
+}
+
+static TSS2_LOG_HANDLER log_handler = do_default_log;
+
+TSS2_LOG_HANDLER set_log_handler(TSS2_LOG_HANDLER new_handler) {
+    TSS2_LOG_HANDLER old = log_handler;
+    log_handler = new_handler;
+    return old;
+}
+
+/* TODO update logblob */
 void
 doLogBlob(log_level loglevel, const char *module, log_level logdefault,
            log_level *status,
@@ -188,27 +210,27 @@ doLog(log_level loglevel, const char *module, log_level logdefault,
            const char *file, const char *func, int line,
            const char *msg, ...)
 {
-    FILE *logfile;
-    if (unlikely(*status == LOGLEVEL_UNDEFINED))
-        *status = getLogLevel(module, logdefault);
-
-    if (loglevel > *status)
+    /* No log handler, skip message */
+    if (!log_handler) {
         return;
+    /* If the default is registered, short circuit if loglevel is not high enough */
+    } else if (log_handler == do_default_log) {
+        if (unlikely(*status == LOGLEVEL_UNDEFINED))
+            *status = getLogLevel(module, logdefault);
 
-    int size = snprintf(NULL, 0, "%s:%s:%s:%d:%s() %s \n",
-                log_strings[loglevel], module, file, line, func, msg);
-    char fmt[size+1];
-    snprintf(fmt, sizeof(fmt), "%s:%s:%s:%d:%s() %s \n",
-                log_strings[loglevel], module, file, line, func, msg);
+        if (loglevel > *status)
+            return;
+    }
+
+    /* Either the message needs to be logged or needs to defer to registered handler */
+    char usermsgbuf[1024];
 
     va_list vaargs;
     va_start(vaargs, msg);
-    logfile = getLogFile();
-    vfprintf (logfile, fmt,
-        /* log_strings[loglevel], module, file, func, line, */
-        vaargs);
-    fflush(logfile);
+    vsnprintf(usermsgbuf, sizeof(usermsgbuf), msg, vaargs);
     va_end(vaargs);
+
+    log_handler(loglevel, module, file, func, line, usermsgbuf);
 }
 
 static log_level

src/util/log.h

@@ -13,24 +13,6 @@
 #define LOGDEFAULT LOGLEVEL_WARNING
 #endif
 
-#define LOGL_NONE    0
-#define LOGL_ERROR   2
-#define LOGL_WARNING 3
-#define LOGL_INFO    4
-#define LOGL_DEBUG   5
-#define LOGL_TRACE   6
-#define LOGL_UNDEF   0xFF
-
-typedef enum {
-    LOGLEVEL_NONE      = LOGL_NONE,
-    LOGLEVEL_ERROR     = LOGL_ERROR,
-    LOGLEVEL_WARNING   = LOGL_WARNING,
-    LOGLEVEL_INFO      = LOGL_INFO,
-    LOGLEVEL_DEBUG     = LOGL_DEBUG,
-    LOGLEVEL_TRACE     = LOGL_TRACE,
-    LOGLEVEL_UNDEFINED = LOGL_UNDEF
-} log_level;
-
 static const char *log_strings[] COMPILER_ATTR(unused) = {
     "none",
     "(unused)",
@@ -146,6 +128,8 @@ static log_level LOGMODULE_status COMPILER_ATTR(unused) = LOGLEVEL_UNDEFINED;
 #define LOGBLOB_TRACE(FORMAT, ...) {}
 #endif
 
+TSS2_LOG_HANDLER set_log_handler(TSS2_LOG_HANDLER new_handler);
+
 void
 doLog(log_level loglevel, const char *module, log_level logdefault,
        log_level *status,