From 1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Sat, 11 Jan 2020 23:36:56 +0000 Subject: Squashed 'third_party/git/' content from commit cb71568594 git-subtree-dir: third_party/git git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7 --- compat/win32/lazyload.h | 57 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 compat/win32/lazyload.h (limited to 'compat/win32/lazyload.h') diff --git a/compat/win32/lazyload.h b/compat/win32/lazyload.h new file mode 100644 index 000000000000..9e631c8593ff --- /dev/null +++ b/compat/win32/lazyload.h @@ -0,0 +1,57 @@ +#ifndef LAZYLOAD_H +#define LAZYLOAD_H + +/* + * A pair of macros to simplify loading of DLL functions. Example: + * + * DECLARE_PROC_ADDR(kernel32.dll, BOOL, CreateHardLinkW, + * LPCWSTR, LPCWSTR, LPSECURITY_ATTRIBUTES); + * + * if (!INIT_PROC_ADDR(CreateHardLinkW)) + * return error("Could not find CreateHardLinkW() function"; + * + * if (!CreateHardLinkW(source, target, NULL)) + * return error("could not create hardlink from %S to %S", + * source, target); + */ + +struct proc_addr { + const char *const dll; + const char *const function; + FARPROC pfunction; + unsigned initialized : 1; +}; + +/* Declares a function to be loaded dynamically from a DLL. */ +#define DECLARE_PROC_ADDR(dll, rettype, function, ...) \ + static struct proc_addr proc_addr_##function = \ + { #dll, #function, NULL, 0 }; \ + static rettype (WINAPI *function)(__VA_ARGS__) + +/* + * Loads a function from a DLL (once-only). + * Returns non-NULL function pointer on success. + * Returns NULL + errno == ENOSYS on failure. + * This function is not thread-safe. + */ +#define INIT_PROC_ADDR(function) \ + (function = get_proc_addr(&proc_addr_##function)) + +static inline void *get_proc_addr(struct proc_addr *proc) +{ + /* only do this once */ + if (!proc->initialized) { + HANDLE hnd; + proc->initialized = 1; + hnd = LoadLibraryExA(proc->dll, NULL, + LOAD_LIBRARY_SEARCH_SYSTEM32); + if (hnd) + proc->pfunction = GetProcAddress(hnd, proc->function); + } + /* set ENOSYS if DLL or function was not found */ + if (!proc->pfunction) + errno = ENOSYS; + return proc->pfunction; +} + +#endif -- cgit 1.4.1