github.com/ebitengine/purego@v0.8.0-alpha.2.0.20240512170805-6cd12240d332/dlfcn.go (about) 1 // SPDX-License-Identifier: Apache-2.0 2 // SPDX-FileCopyrightText: 2022 The Ebitengine Authors 3 4 //go:build darwin || freebsd || linux 5 6 package purego 7 8 import ( 9 "unsafe" 10 ) 11 12 // Unix Specification for dlfcn.h: https://pubs.opengroup.org/onlinepubs/7908799/xsh/dlfcn.h.html 13 14 var ( 15 fnDlopen func(path string, mode int) uintptr 16 fnDlsym func(handle uintptr, name string) uintptr 17 fnDlerror func() string 18 fnDlclose func(handle uintptr) bool 19 ) 20 21 func init() { 22 RegisterFunc(&fnDlopen, dlopenABI0) 23 RegisterFunc(&fnDlsym, dlsymABI0) 24 RegisterFunc(&fnDlerror, dlerrorABI0) 25 RegisterFunc(&fnDlclose, dlcloseABI0) 26 } 27 28 // Dlopen examines the dynamic library or bundle file specified by path. If the file is compatible 29 // with the current process and has not already been loaded into the 30 // current process, it is loaded and linked. After being linked, if it contains 31 // any initializer functions, they are called, before Dlopen 32 // returns. It returns a handle that can be used with Dlsym and Dlclose. 33 // A second call to Dlopen with the same path will return the same handle, but the internal 34 // reference count for the handle will be incremented. Therefore, all 35 // Dlopen calls should be balanced with a Dlclose call. 36 func Dlopen(path string, mode int) (uintptr, error) { 37 u := fnDlopen(path, mode) 38 if u == 0 { 39 return 0, Dlerror{fnDlerror()} 40 } 41 return u, nil 42 } 43 44 // Dlsym takes a "handle" of a dynamic library returned by Dlopen and the symbol name. 45 // It returns the address where that symbol is loaded into memory. If the symbol is not found, 46 // in the specified library or any of the libraries that were automatically loaded by Dlopen 47 // when that library was loaded, Dlsym returns zero. 48 func Dlsym(handle uintptr, name string) (uintptr, error) { 49 u := fnDlsym(handle, name) 50 if u == 0 { 51 return 0, Dlerror{fnDlerror()} 52 } 53 return u, nil 54 } 55 56 // Dlclose decrements the reference count on the dynamic library handle. 57 // If the reference count drops to zero and no other loaded libraries 58 // use symbols in it, then the dynamic library is unloaded. 59 func Dlclose(handle uintptr) error { 60 if fnDlclose(handle) { 61 return Dlerror{fnDlerror()} 62 } 63 return nil 64 } 65 66 func loadSymbol(handle uintptr, name string) (uintptr, error) { 67 return Dlsym(handle, name) 68 } 69 70 // these functions exist in dlfcn_stubs.s and are calling C functions linked to in dlfcn_GOOS.go 71 // the indirection is necessary because a function is actually a pointer to the pointer to the code. 72 // sadly, I do not know of anyway to remove the assembly stubs entirely because //go:linkname doesn't 73 // appear to work if you link directly to the C function on darwin arm64. 74 75 //go:linkname dlopen dlopen 76 var dlopen uintptr 77 var dlopenABI0 = uintptr(unsafe.Pointer(&dlopen)) 78 79 //go:linkname dlsym dlsym 80 var dlsym uintptr 81 var dlsymABI0 = uintptr(unsafe.Pointer(&dlsym)) 82 83 //go:linkname dlclose dlclose 84 var dlclose uintptr 85 var dlcloseABI0 = uintptr(unsafe.Pointer(&dlclose)) 86 87 //go:linkname dlerror dlerror 88 var dlerror uintptr 89 var dlerrorABI0 = uintptr(unsafe.Pointer(&dlerror))