1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build darwin || freebsd || linux
5
6package purego
7
8import (
9 "unsafe"
10)
11
12// Unix Specification for dlfcn.h: https://pubs.opengroup.org/onlinepubs/7908799/xsh/dlfcn.h.html
13
14var (
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
21func 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.
36func 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.
48func 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.
59func Dlclose(handle uintptr) error {
60 if fnDlclose(handle) {
61 return Dlerror{fnDlerror()}
62 }
63 return nil
64}
65
66//go:linkname openLibrary openLibrary
67func openLibrary(name string) (uintptr, error) {
68 return Dlopen(name, RTLD_NOW|RTLD_GLOBAL)
69}
70
71func loadSymbol(handle uintptr, name string) (uintptr, error) {
72 return Dlsym(handle, name)
73}
74
75// these functions exist in dlfcn_stubs.s and are calling C functions linked to in dlfcn_GOOS.go
76// the indirection is necessary because a function is actually a pointer to the pointer to the code.
77// sadly, I do not know of anyway to remove the assembly stubs entirely because //go:linkname doesn't
78// appear to work if you link directly to the C function on darwin arm64.
79
80//go:linkname dlopen dlopen
81var dlopen uintptr
82var dlopenABI0 = uintptr(unsafe.Pointer(&dlopen))
83
84//go:linkname dlsym dlsym
85var dlsym uintptr
86var dlsymABI0 = uintptr(unsafe.Pointer(&dlsym))
87
88//go:linkname dlclose dlclose
89var dlclose uintptr
90var dlcloseABI0 = uintptr(unsafe.Pointer(&dlclose))
91
92//go:linkname dlerror dlerror
93var dlerror uintptr
94var dlerrorABI0 = uintptr(unsafe.Pointer(&dlerror))