1 // SPDX-License-Identifier: Apache-2.0
2 // SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3 4 //go:build (darwin || freebsd || linux || netbsd) && !android && !faketime
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 //
37 // This function is not available on Windows.
38 // Use [golang.org/x/sys/windows.LoadLibrary], [golang.org/x/sys/windows.LoadLibraryEx],
39 // [golang.org/x/sys/windows.NewLazyDLL], or [golang.org/x/sys/windows.NewLazySystemDLL] for Windows instead.
40 func Dlopen(path string, mode int) (uintptr, error) {
41 u := fnDlopen(path, mode)
42 if u == 0 {
43 return 0, Dlerror{fnDlerror()}
44 }
45 return u, nil
46 }
47 48 // Dlsym takes a "handle" of a dynamic library returned by Dlopen and the symbol name.
49 // It returns the address where that symbol is loaded into memory. If the symbol is not found,
50 // in the specified library or any of the libraries that were automatically loaded by Dlopen
51 // when that library was loaded, Dlsym returns zero.
52 //
53 // This function is not available on Windows.
54 // Use [golang.org/x/sys/windows.GetProcAddress] for Windows instead.
55 func Dlsym(handle uintptr, name string) (uintptr, error) {
56 u := fnDlsym(handle, name)
57 if u == 0 {
58 return 0, Dlerror{fnDlerror()}
59 }
60 return u, nil
61 }
62 63 // Dlclose decrements the reference count on the dynamic library handle.
64 // If the reference count drops to zero and no other loaded libraries
65 // use symbols in it, then the dynamic library is unloaded.
66 //
67 // This function is not available on Windows.
68 // Use [golang.org/x/sys/windows.FreeLibrary] for Windows instead.
69 func Dlclose(handle uintptr) error {
70 if fnDlclose(handle) {
71 return Dlerror{fnDlerror()}
72 }
73 return nil
74 }
75 76 func loadSymbol(handle uintptr, name string) (uintptr, error) {
77 return Dlsym(handle, name)
78 }
79 80 // these functions exist in dlfcn_stubs.s and are calling C functions linked to in dlfcn_GOOS.go
81 // the indirection is necessary because a function is actually a pointer to the pointer to the code.
82 // sadly, I do not know of anyway to remove the assembly stubs entirely because //go:linkname doesn't
83 // appear to work if you link directly to the C function on darwin arm64.
84 85 //go:linkname dlopen dlopen
86 var dlopen uint8
87 var dlopenABI0 = uintptr(unsafe.Pointer(&dlopen))
88 89 //go:linkname dlsym dlsym
90 var dlsym uint8
91 var dlsymABI0 = uintptr(unsafe.Pointer(&dlsym))
92 93 //go:linkname dlclose dlclose
94 var dlclose uint8
95 var dlcloseABI0 = uintptr(unsafe.Pointer(&dlclose))
96 97 //go:linkname dlerror dlerror
98 var dlerror uint8
99 var dlerrorABI0 = uintptr(unsafe.Pointer(&dlerror))
100