fix: 用可移植的 dlopen 方案替换内部 _dl_sym 符号

将 _dl_sym（GLIBC_PRIVATE 符号）替换为 dlopen("libc.so.6") + dlsym()，
修复在 glibc 版本不兼容的容器环境中出现的
"undefined symbol: _dl_sym, version GLIBC_PRIVATE" 运行时错误。

涉及文件：
- src/libvgpu.c
- src/nvml/hook.c
- src/include/libvgpu.h

Signed-off-by: weipeng <weip3@chinatelecom.cn>

Author: weipeng

src/include/libvgpu.h

@@ -29,8 +29,6 @@ extern void load_cuda_libraries();
 
 #define FUNC_OVERRIDE_NAME(fname) overrided_##fname
 
-extern void* _dl_sym(void*, const char*, void*);
-
 #if defined(DLSYM_HOOK_DEBUG)
 #define DLSYM_HOOK_FUNC(f)                                       \
     if (0 == strcmp(symbol, #f)) {                               \

src/libvgpu.c

@@ -99,9 +99,12 @@ FUNC_ATTR_VISIBLE void* dlsym(void* handle, const char* symbol) {
         }
         if (real_dlsym == NULL) {
             LOG_ERROR("real dlsym not found");
-            real_dlsym = _dl_sym(RTLD_NEXT, "dlsym", dlsym);
+            void *libc_handle = dlopen("libc.so.6", RTLD_LAZY);
+            if (libc_handle) {
+                real_dlsym = dlsym(libc_handle, "dlsym");
+            }
             if (real_dlsym == NULL)
-                LOG_ERROR("real dlsym not found");
+                LOG_ERROR("real dlsym not found after trying libc.so.6");
         }
     }
     if (handle == RTLD_NEXT) {
@@ -858,9 +861,12 @@ void preInit(){
         real_dlsym = dlvsym(RTLD_NEXT,"dlsym","GLIBC_2.2.5");
         if (real_dlsym == NULL) {
             LOG_ERROR("real dlsym not found");
-            real_dlsym = _dl_sym(RTLD_NEXT, "dlsym", dlsym);
-            if (real_dlsym == NULL)
+            void *libc_handle = dlopen("libc.so.6", RTLD_LAZY);
+            if (libc_handle) {
+                real_dlsym = dlsym(libc_handle, "dlsym");
+            } else {
                 LOG_ERROR("real dlsym not found");
+            }
         }
     }
     real_realpath = NULL;

src/nvml/hook.c

@@ -267,16 +267,17 @@ nvmlReturn_t nvmlDeviceGetIndex(nvmlDevice_t device, unsigned int *index) {
 }
 
 
-extern void* _dl_sym(void*, const char*, void*);
-
 void load_nvml_libraries() {
     void *table = NULL;
     char driver_filename[FILENAME_MAX];
 
     if (real_dlsym == NULL) {
         real_dlsym = dlvsym(RTLD_NEXT,"dlsym","GLIBC_2.2.5");
         if (real_dlsym == NULL) {
-            real_dlsym = _dl_sym(RTLD_NEXT, "dlsym", dlsym);
+            void *libc_handle = dlopen("libc.so.6", RTLD_LAZY);
+            if (libc_handle) {
+                real_dlsym = dlsym(libc_handle, "dlsym");
+            }
             if (real_dlsym == NULL)
                 LOG_ERROR("real dlsym not found");
         }