Linux: dev: glibc: GL 定义

今天找到了这个GL的定义，记录一下，费了一些劲才找到的。（没有想到的是#和define之间还有空格，导致一直搜不到想要的结果。）是在sysdeps/generic/ldsodefs.h文件中。依赖于SHARED和rtld的定义。

#ifndef SHARED
# define EXTERN extern
# define GL(name) _##name
#else
# define EXTERN
# if IS_IN (rtld)
#  define GL(name) _rtld_local._##name
# else
#  define GL(name) _rtld_global._##name
# endif

从当前RHEL8上的dump，可用看到如下的定义：

(gdb) ptype _rtld_local
type = struct rtld_global {struct link_namespaces _dl_ns[16];size_t _dl_nns;__rtld_lock_recursive_t _dl_load_lock;__rtld_lock_recursive_t _dl_load_write_lock;__rtld_lock_recursive_t _dl_load_tls_lock;unsigned long long _dl_load_adds;struct link_map *_dl_initfirst;struct link_map *_dl_profile_map;unsigned long _dl_num_relocations;unsigned long _dl_num_cache_relocations;struct r_search_path_elem *_dl_all_dirs;struct link_map _dl_rtld_map;struct auditstate audit_data[16];void (*_dl_rtld_lock_recursive)(void *);void (*_dl_rtld_unlock_recursive)(void *);unsigned int _dl_x86_feature_1;struct dl_x86_feature_control _dl_x86_feature_control;int (*_dl_make_stack_executable_hook)(void **);Elf64_Word _dl_stack_flags;_Bool _dl_tls_dtv_gaps;size_t _dl_tls_max_dtv_idx;struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;size_t _dl_tls_static_nelem;size_t _dl_tls_static_size;size_t _dl_tls_static_used;size_t _dl_tls_static_align;size_t _dl_tls_static_optional;void *_dl_initial_dtv;size_t _dl_tls_generation;void (*_dl_init_static_tls)(struct link_map *);void (*_dl_wait_lookup_done)(void);struct dl_scope_free_list *_dl_scope_free_list;
}(gdb) ptyp _rtld_local._dl_rtld_map.l_info
type = struct {Elf64_Sxword d_tag;union {Elf64_Xword d_val;Elf64_Addr d_ptr;} d_un;
} *[77]
(gdb) p _rtld_local
$4 = {_dl_ns = {{_ns_loaded = 0x0,_ns_nloaded = 0,_ns_main_searchlist = 0x0,