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-rw-r--r--dl/dl_gnu.go58
-rw-r--r--dl/dlfcn.go74
2 files changed, 132 insertions, 0 deletions
diff --git a/dl/dl_gnu.go b/dl/dl_gnu.go
new file mode 100644
index 0000000..c7c409b
--- /dev/null
+++ b/dl/dl_gnu.go
@@ -0,0 +1,58 @@
+package dl
+
+import "unsafe"
+
+//#define _GNU_SOURCE
+//#include <stdlib.h>
+//#include <stdint.h>
+//#include <dlfcn.h>
+//const uintptr_t rtld_next = (uintptr_t)RTLD_NEXT;
+//const uintptr_t rtld_default = (uintptr_t)RTLD_DEFAULT;
+import "C"
+
+const (
+ RTLD_NOLOAD Flag = C.RTLD_NOLOAD
+ RTLD_NODELETE Flag = C.RTLD_NODELETE
+ RTLD_DEEPBIND Flag = C.RTLD_DEEPBIND
+)
+
+// These are kinda weird in that they aren't required by the standard,
+// but they are reserved by the standard (see the documentation for
+// `dlsym(3)`). On glibc, it takes _GNU_SOURCE to get them.
+//
+// There are two special pseudo-handles that may be specified
+// in handle:
+var (
+ RTLD_DEFAULT Handle = Handle{unsafe.Pointer(uintptr(C.rtld_default))}
+ // Find the first occurrence of the desired symbol using
+ // the default shared object search order. The search will
+ // include global symbols in the executable and its
+ // dependencies, as well as symbols in shared objects that
+ // were dynamically loaded with the RTLD_GLOBAL flag.
+ RTLD_NEXT Handle = Handle{unsafe.Pointer(uintptr(C.rtld_next))}
+ // Find the next occurrence of the desired symbol in the
+ // search order after the current object. This allows one
+ // to provide a wrapper around a function in another shared
+ // object, so that, for example, the definition of a
+ // function in a preloaded shared object (see LD_PRELOAD in
+ // ld.so(8)) can find and invoke the "real" function
+ // provided in another shared object (or for that matter,
+ // the "next" definition of the function in cases where
+ // there are multiple layers of preloading).
+)
+
+// TODO: dlmopen
+// TODO: dlvsym
+// TODO: dladdr
+// - dladdr1
+// TODO: dlinfo
+// - RTLD_DI_LMID
+// - RTLD_DI_LINKMAP
+// - RTLD_DI_ORIGIN
+// - RTLD_DI_SERINFO
+// - RTLD_DI_SERINFOSIZE
+// - RTLD_DI_MODID
+// - RTLD_DI_DATA
+// TODO: dl_iterate_phdr
+// TODO: rtld-audit(7)
+
diff --git a/dl/dlfcn.go b/dl/dlfcn.go
new file mode 100644
index 0000000..d5467f3
--- /dev/null
+++ b/dl/dlfcn.go
@@ -0,0 +1,74 @@
+package dl
+
+import (
+ "errors"
+ "unsafe"
+)
+
+//#cgo LDFLAGS: -ldl
+//#include <stdlib.h>
+//#include <dlfcn.h>
+import "C"
+
+type Flag int
+
+const (
+ RTLD_LAZY Flag = C.RTLD_LAZY // Relocations are performed at an
+ // implementation-defined time.
+ RTLD_NOW Flag = C.RTLD_NOW // Relocations are performed when the
+ // object is loaded.
+ RTLD_GLOBAL Flag = C.RTLD_GLOBAL // All symbols are available for
+ // relocation processing of other
+ // modules.
+ RTLD_LOCAL Flag = C.RTLD_LOCAL // All symbols are not made available
+ // for relocation processing by other
+ // modules.
+)
+
+type Handle struct {
+ c unsafe.Pointer
+}
+
+func Open(name string, flags Flag) (Handle, error) {
+ nameC := C.CString(name)
+ defer C.free(unsafe.Pointer(nameC))
+
+ dlerror()
+ ptr := C.dlopen(nameC, C.int(flags))
+ if ptr == nil {
+ return Handle{}, dlerror()
+ }
+ return Handle{ptr}, nil
+}
+
+// This returns uintptr instead of unsafe.Pointer so that code using
+// reflect cannot obtain unsafe.Pointers without importing the unsafe
+// package explicitly.
+func (h Handle) Sym(symbol string) (uintptr, error) {
+ symbolC := C.CString(symbol)
+ defer C.free(unsafe.Pointer(symbolC))
+
+ dlerror()
+ ptr := C.dlsym(h.c, symbolC)
+ if ptr == nil {
+ return 0, dlerror()
+ }
+ return uintptr(ptr), nil
+}
+
+func (h Handle) Close() error {
+ dlerror()
+ r := C.dlclose(h.c)
+ if r != 0 {
+ return dlerror()
+ }
+ return nil
+}
+
+func dlerror() error {
+ strC := C.dlerror()
+ if strC == nil {
+ return nil
+ }
+ return errors.New(C.GoString(strC))
+}