Massive documentation and copyright clean-up.

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}
+}