94 lines
3.1 KiB
Go
94 lines
3.1 KiB
Go
// SPDX-License-Identifier: Apache-2.0
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// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
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//go:build darwin || freebsd || linux
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package purego
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import (
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"unsafe"
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)
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// Unix Specification for dlfcn.h: https://pubs.opengroup.org/onlinepubs/7908799/xsh/dlfcn.h.html
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var (
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fnDlopen func(path string, mode int) uintptr
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fnDlsym func(handle uintptr, name string) uintptr
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fnDlerror func() string
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fnDlclose func(handle uintptr) bool
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)
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func init() {
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RegisterFunc(&fnDlopen, dlopenABI0)
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RegisterFunc(&fnDlsym, dlsymABI0)
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RegisterFunc(&fnDlerror, dlerrorABI0)
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RegisterFunc(&fnDlclose, dlcloseABI0)
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}
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// Dlopen examines the dynamic library or bundle file specified by path. If the file is compatible
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// with the current process and has not already been loaded into the
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// current process, it is loaded and linked. After being linked, if it contains
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// any initializer functions, they are called, before Dlopen
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// returns. It returns a handle that can be used with Dlsym and Dlclose.
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// A second call to Dlopen with the same path will return the same handle, but the internal
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// reference count for the handle will be incremented. Therefore, all
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// Dlopen calls should be balanced with a Dlclose call.
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func Dlopen(path string, mode int) (uintptr, error) {
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u := fnDlopen(path, mode)
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if u == 0 {
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return 0, Dlerror{fnDlerror()}
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}
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return u, nil
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}
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// Dlsym takes a "handle" of a dynamic library returned by Dlopen and the symbol name.
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// It returns the address where that symbol is loaded into memory. If the symbol is not found,
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// in the specified library or any of the libraries that were automatically loaded by Dlopen
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// when that library was loaded, Dlsym returns zero.
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func Dlsym(handle uintptr, name string) (uintptr, error) {
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u := fnDlsym(handle, name)
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if u == 0 {
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return 0, Dlerror{fnDlerror()}
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}
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return u, nil
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}
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// Dlclose decrements the reference count on the dynamic library handle.
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// If the reference count drops to zero and no other loaded libraries
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// use symbols in it, then the dynamic library is unloaded.
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func Dlclose(handle uintptr) error {
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if fnDlclose(handle) {
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return Dlerror{fnDlerror()}
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}
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return nil
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}
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//go:linkname openLibrary openLibrary
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func openLibrary(name string) (uintptr, error) {
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return Dlopen(name, RTLD_NOW|RTLD_GLOBAL)
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}
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func loadSymbol(handle uintptr, name string) (uintptr, error) {
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return Dlsym(handle, name)
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}
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// these functions exist in dlfcn_stubs.s and are calling C functions linked to in dlfcn_GOOS.go
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// the indirection is necessary because a function is actually a pointer to the pointer to the code.
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// sadly, I do not know of anyway to remove the assembly stubs entirely because //go:linkname doesn't
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// appear to work if you link directly to the C function on darwin arm64.
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//go:linkname dlopen dlopen
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var dlopen uintptr
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var dlopenABI0 = uintptr(unsafe.Pointer(&dlopen))
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//go:linkname dlsym dlsym
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var dlsym uintptr
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var dlsymABI0 = uintptr(unsafe.Pointer(&dlsym))
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//go:linkname dlclose dlclose
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var dlclose uintptr
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var dlcloseABI0 = uintptr(unsafe.Pointer(&dlclose))
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//go:linkname dlerror dlerror
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var dlerror uintptr
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var dlerrorABI0 = uintptr(unsafe.Pointer(&dlerror))
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