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-rw-r--r--dl/dl_gnu.go91
-rw-r--r--dl/dlfcn.go62
-rw-r--r--dl/dlsym_reserved.go63
3 files changed, 172 insertions, 44 deletions
diff --git a/dl/dl_gnu.go b/dl/dl_gnu.go
index c7c409b..99ec32c 100644
--- a/dl/dl_gnu.go
+++ b/dl/dl_gnu.go
@@ -1,44 +1,69 @@
-package dl
+// The code in this file is trivial, and not eligable for copyright.
+//
+// The documentation in this file is taken from the Linux Programmer's
+// Manual page for dlopen(3).
+//
+// Copyright 1995 Yggdrasil Computing, Incorporated.
+// written by Adam J. Richter (adam@yggdrasil.com),
+// with typesetting help from Daniel Quinlan (quinlan@yggdrasil.com).
+// and Copyright 2003, 2015 Michael Kerrisk (mtk.manpages@gmail.com).
+//
+// This is free documentation; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// The GNU General Public License's references to "object code"
+// and "executables" are to be interpreted as the output of any
+// document formatting or typesetting system, including
+// intermediate and printed output.
+//
+// This manual is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public
+// License along with this manual; if not, see
+// <http://www.gnu.org/licenses/>.
+//
+// Modified by David A. Wheeler <dwheeler@dwheeler.com> 2000-11-28.
+// Applied patch by Terran Melconian, aeb, 2001-12-14.
+// Modified by Hacksaw <hacksaw@hacksaw.org> 2003-03-13.
+// Modified by Matt Domsch, 2003-04-09: _init and _fini obsolete
+// Modified by Michael Kerrisk <mtk.manpages@gmail.com> 2003-05-16.
+// Modified by Walter Harms: dladdr, dlvsym
+// Modified by Petr Baudis <pasky@suse.cz>, 2008-12-04: dladdr caveat
-import "unsafe"
+package dl
//#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"
+// These flags to Open() are GNU libc extensions.
const (
- RTLD_NOLOAD Flag = C.RTLD_NOLOAD
- RTLD_NODELETE Flag = C.RTLD_NODELETE
- RTLD_DEEPBIND Flag = C.RTLD_DEEPBIND
-)
+ // Do not unload the shared object during Close().
+ // Consequently, the object's static variables are not
+ // reinitialized if the object is reloaded with Open() at a
+ // later time.
+ RTLD_NODELETE Flag = C.RTLD_NODELETE // (since glibc 2.2, also present on Solaris)
-// 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).
+ // Don't load the shared object. This can be used to test if
+ // the object is already resident (Open() returns nil if it
+ // is not, or the object's handle if it is resident). This
+ // flag can also be used to promote the flags on a shared
+ // object that is already loaded. For example, a shared
+ // object that was previously loaded with RTLD_LOCAL can be
+ // reopened with RTLD_NOLOAD | RTLD_GLOBAL.
+ RTLD_NOLOAD Flag = C.RTLD_NOLOAD // (since glibc 2.2, also present on Solaris)
+
+ // Place the lookup scope of the symbols in this shared object
+ // ahead of the global scope. This means that a
+ // self-contained object will use its own symbols in
+ // preference to global symbols with the same name contained
+ // in objects that have already been loaded.
+ RTLD_DEEPBIND Flag = C.RTLD_DEEPBIND // (since glibc 2.3.4)
)
// TODO: dlmopen
diff --git a/dl/dlfcn.go b/dl/dlfcn.go
index d5467f3..3ab5abb 100644
--- a/dl/dlfcn.go
+++ b/dl/dlfcn.go
@@ -1,3 +1,25 @@
+// Copyright 2015 Luke Shumaker <lukeshu@sbcglobal.net>.
+//
+// This is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// The GNU General Public License's references to "object code" and
+// "executables" are to be interpreted to also include the output of
+// any document formatting or typesetting system, including
+// intermediate and printed output.
+//
+// This software is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public
+// License along with this manual; if not, see
+// <http://www.gnu.org/licenses/>.
+
+// Package dl provides an interface to the POSIX runtime linker.
package dl
import (
@@ -12,26 +34,39 @@ import "C"
type Flag int
+// POSIX specifies these four flags to Open().
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.
+ // Relocations are performed at an implementation-defined
+ // time.
+ RTLD_LAZY Flag = C.RTLD_LAZY
+
+ // Relocations are performed when the object is loaded.
+ RTLD_NOW Flag = C.RTLD_NOW
+
+ // All symbols are available for relocation processing of
+ // other modules.
+ RTLD_GLOBAL Flag = C.RTLD_GLOBAL
+
+ // All symbols are not made available for relocation
+ // processing by other modules.
+ RTLD_LOCAL Flag = C.RTLD_LOCAL
)
type Handle struct {
c unsafe.Pointer
}
+// Open a shared object file, returning a Handle to it, or an error.
+// If name is an empty string, then the returned handle is the global
+// symbol table for the current process; if the name contains a slash,
+// then it is interpretted as a pathname; otherwise, it is
+// interpretted in an implementation-defined manner.
func Open(name string, flags Flag) (Handle, error) {
nameC := C.CString(name)
defer C.free(unsafe.Pointer(nameC))
+ if name == "" {
+ nameC = nil
+ }
dlerror()
ptr := C.dlopen(nameC, C.int(flags))
@@ -41,8 +76,10 @@ func Open(name string, flags Flag) (Handle, error) {
return Handle{ptr}, nil
}
+// Look up a symbol, and return a pointer to it.
+//
// This returns uintptr instead of unsafe.Pointer so that code using
-// reflect cannot obtain unsafe.Pointers without importing the unsafe
+// dl cannot obtain unsafe.Pointers without importing the unsafe
// package explicitly.
func (h Handle) Sym(symbol string) (uintptr, error) {
symbolC := C.CString(symbol)
@@ -56,6 +93,9 @@ func (h Handle) Sym(symbol string) (uintptr, error) {
return uintptr(ptr), nil
}
+// Close this handle on a shared object; decrementint the reference
+// count; if the reference count drops below 0, then the object is
+// unloaded.
func (h Handle) Close() error {
dlerror()
r := C.dlclose(h.c)
diff --git a/dl/dlsym_reserved.go b/dl/dlsym_reserved.go
new file mode 100644
index 0000000..081e012
--- /dev/null
+++ b/dl/dlsym_reserved.go
@@ -0,0 +1,63 @@
+// The documentation for RTLD_DEFAULT and RTLD_NEXT is taken from the
+// Linux Programmer's Manual page for dlsym(3).
+//
+// Copyright 1995 Yggdrasil Computing, Incorporated.
+// Copyright 2003, 2015 Michael Kerrisk <mtk.manpages@gmail.com>.
+// Copyright 2015 Luke Shumaker <lukeshu@sbcglobal.net>.
+//
+// This is free documentation; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// The GNU General Public License's references to "object code"
+// and "executables" are to be interpreted as the output of any
+// document formatting or typesetting system, including
+// intermediate and printed output.
+//
+// This manual is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public
+// License along with this manual; if not, see
+// <http://www.gnu.org/licenses/>.
+
+package dl
+
+import "unsafe"
+
+//#define _GNU_SOURCE
+//#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"
+
+// These constant values for Handles are reserved by POSIX for future
+// use with these meanings. They are available in GNU libdl if
+// _GNU_SOURCE is defined.
+var (
+ // This Handle represents the default 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_DEFAULT Handle
+
+ // This Handle represents the shared object 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).
+ RTLD_NEXT Handle
+)
+
+func init() {
+ RTLD_DEFAULT = Handle{c: unsafe.Pointer(uintptr(C.rtld_default)), o: 2}
+ RTLD_DEFAULT = Handle{c: unsafe.Pointer(uintptr(C.rtld_next)), o: 2}
+}