test: add example to show usage of vprintf override

core/shared/platform/cosmopolitan/platform_init.c

@@ -25,7 +25,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/darwin/platform_init.c

@@ -25,7 +25,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/freebsd/platform_init.c

@@ -25,7 +25,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/include/platform_common.h

@@ -54,10 +54,11 @@ BH_FREE(void *ptr);
 
 #if defined(BH_VPRINTF)
 #if defined(MSVC)
-__declspec(dllimport) int BH_VPRINTF(const char *format, va_list ap);
+__declspec(dllimport) int BH_VPRINTF(uint32_t log_level, const char *format,
+                                     va_list ap);
 #else
 int
-BH_VPRINTF(LogLevel log_level, const char *format, va_list ap);
+BH_VPRINTF(uint32_t log_level, const char *format, va_list ap);
 #endif
 #endif
 

core/shared/platform/linux/platform_init.c

@@ -25,7 +25,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/vxworks/platform_init.c

@@ -25,7 +25,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/windows/platform_init.c

@@ -45,7 +45,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

core/shared/platform/zephyr/zephyr_platform.c

@@ -130,7 +130,7 @@ os_printf(const char *format, ...)
 #ifndef BH_VPRINTF
     ret += vprintf(format, ap);
 #else
-    ret += BH_VPRINTF(format, ap);
+    ret += BH_VPRINTF(BH_LOG_LEVEL_DEBUG, format, ap);
 #endif
     va_end(ap);
 

doc/build_wamr.md

@@ -164,7 +164,7 @@ Currently we only profile the memory consumption of module, module_instance and
 > Note: if the vprintf_callback function is provided by developer, the os_printf() and os_vprintf() in Linux, Darwin, Windows and VxWorks platforms, besides WASI Libc output will call the callback function instead of libc vprintf() function to redirect the stdout output. For example, developer can define the callback function like below outside runtime lib:
 >
 > ```C
-> int my_vprintf(LogLevel log_level, const char *format, va_list ap)
+> int my_vprintf(log_level_t log_level, const char *format, va_list ap)
 > {
 >     /* output to pre-opened file stream */
 >     FILE *my_file = ...;
@@ -179,7 +179,7 @@ Currently we only profile the memory consumption of module, module_instance and
 > }
 > ```
 >
-> and then use `cmake -DWAMR_BH_VPRINTF=my_vprintf ..` to pass the callback function, or add `BH_VPRINTF=my_vprintf` macro for the compiler, e.g. add line `add_defintions(-DBH_VPRINTF=my_vprintf)` in CMakeListst.txt.
+> and then use `cmake -DWAMR_BH_VPRINTF=my_vprintf ..` to pass the callback function, or add `BH_VPRINTF=my_vprintf` macro for the compiler, e.g. add line `add_defintions(-DBH_VPRINTF=my_vprintf)` in CMakeListst.txt. See [basic sample](../samples/basic/src/main.c) for a usage example.
 
 #### **Enable reference types feature**
 - **WAMR_BUILD_REF_TYPES**=1/0, default to disable if not set

samples/basic/build.sh

@@ -21,7 +21,7 @@ echo "#####################build basic project"
 cd ${CURR_DIR}
 mkdir -p cmake_build
 cd cmake_build
-cmake .. -DCMAKE_BUILD_TYPE=Debug
+cmake .. -DCMAKE_BUILD_TYPE=Debug -DWAMR_BH_VPRINTF=my_vprintf
 make -j ${nproc}
 if [ $? != 0 ];then
     echo "BUILD_FAIL basic exit as $?\n"

samples/basic/src/main.c

@@ -15,6 +15,23 @@ get_pow(int x, int y);
 int32_t
 calculate_native(int32_t n, int32_t func1, int32_t func2);
 
+int
+my_vprintf(log_level_t log_level, const char *format, va_list ap)
+{
+    if (log_level == WASM_LOG_LEVEL_DEBUG) {
+        /* Print in blue */
+        char buf[200];
+        snprintf(buf, 200,
+                 "\x1b[34m"
+                 "%s"
+                 "\x1b[0m",
+                 format);
+        return vprintf(buf, ap);
+    }
+
+    return vprintf(format, ap);
+}
+
 void
 print_usage(void)
 {