sslobodr | d046be8 | 2019-01-16 10:02:22 -0500 | [diff] [blame] | 1 | // Copyright 2016 CoreOS, Inc. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | // Package dlopen provides some convenience functions to dlopen a library and |
| 16 | // get its symbols. |
| 17 | package dlopen |
| 18 | |
| 19 | // #cgo LDFLAGS: -ldl |
| 20 | // #include <stdlib.h> |
| 21 | // #include <dlfcn.h> |
| 22 | import "C" |
| 23 | import ( |
| 24 | "errors" |
| 25 | "fmt" |
| 26 | "unsafe" |
| 27 | ) |
| 28 | |
| 29 | var ErrSoNotFound = errors.New("unable to open a handle to the library") |
| 30 | |
| 31 | // LibHandle represents an open handle to a library (.so) |
| 32 | type LibHandle struct { |
| 33 | Handle unsafe.Pointer |
| 34 | Libname string |
| 35 | } |
| 36 | |
| 37 | // GetHandle tries to get a handle to a library (.so), attempting to access it |
| 38 | // by the names specified in libs and returning the first that is successfully |
| 39 | // opened. Callers are responsible for closing the handler. If no library can |
| 40 | // be successfully opened, an error is returned. |
| 41 | func GetHandle(libs []string) (*LibHandle, error) { |
| 42 | for _, name := range libs { |
| 43 | libname := C.CString(name) |
| 44 | defer C.free(unsafe.Pointer(libname)) |
| 45 | handle := C.dlopen(libname, C.RTLD_LAZY) |
| 46 | if handle != nil { |
| 47 | h := &LibHandle{ |
| 48 | Handle: handle, |
| 49 | Libname: name, |
| 50 | } |
| 51 | return h, nil |
| 52 | } |
| 53 | } |
| 54 | return nil, ErrSoNotFound |
| 55 | } |
| 56 | |
| 57 | // GetSymbolPointer takes a symbol name and returns a pointer to the symbol. |
| 58 | func (l *LibHandle) GetSymbolPointer(symbol string) (unsafe.Pointer, error) { |
| 59 | sym := C.CString(symbol) |
| 60 | defer C.free(unsafe.Pointer(sym)) |
| 61 | |
| 62 | C.dlerror() |
| 63 | p := C.dlsym(l.Handle, sym) |
| 64 | e := C.dlerror() |
| 65 | if e != nil { |
| 66 | return nil, fmt.Errorf("error resolving symbol %q: %v", symbol, errors.New(C.GoString(e))) |
| 67 | } |
| 68 | |
| 69 | return p, nil |
| 70 | } |
| 71 | |
| 72 | // Close closes a LibHandle. |
| 73 | func (l *LibHandle) Close() error { |
| 74 | C.dlerror() |
| 75 | C.dlclose(l.Handle) |
| 76 | e := C.dlerror() |
| 77 | if e != nil { |
| 78 | return fmt.Errorf("error closing %v: %v", l.Libname, errors.New(C.GoString(e))) |
| 79 | } |
| 80 | |
| 81 | return nil |
| 82 | } |