[PATCH] runtime sysroot

[heroxbd at gentoo dot org]

Dear Guys and Gals,
(cross posting to bintuils list from bug-binutils)

When we are developing Gentoo RAP[1], a solution to run a full
independent GNU userland managed by portage in a directory prefix, we
find the feature of sysroot can be decomposed to meet a larger variaty
of needs.

The attached patch is tested against binutils-2.23 and SVN head, please
review.

Cheers,
Benda

1. http://git.heroxbd.z.tuna.tsinghua.edu.cn/?p=doc.git;a=blob;f=glep-gap.rst

===

The feature sysroot originally for cross compiling has two parts. The
first is to prepend lib path, done in configure phase, which we call
configure-time sysroot. The second is to prepend rpath in libraries
and path inside ld scripts when ld is called, which we call runtime
sysroot.

In the case of cross compilation, both are needed. While in the case
of native sysroot, which runs userland in a directory prefix natively,
only configure-time sysroot is needed.

Here we add an additional option of --enable-runtime-sysroot to fine
control such features.

2013-08-25  Benda Xu  <heroxbd@gentoo.org>

	* configure.in: add enable-runtime-sysroot to control the 
	macro ENABLE_RUNTIME_SYSROOT
	* emultempl/elf32.em: only prepend rpath with sysroot when
	ENABLE_RUNTIME_SYSROOT is defined
	* ldfile.c: only prepend lib path with sysroot when
	ENABLE_RUNTIME_SYSROOT is defined
	* ld.texinfo: document this new behavior for ld script

Index: binutils-2.23/ld/configure.in
===================================================================
--- binutils-2.23.orig/ld/configure.in
+++ binutils-2.23/ld/configure.in
@@ -70,6 +70,18 @@ AC_SUBST(use_sysroot)
 AC_SUBST(TARGET_SYSTEM_ROOT)
 AC_SUBST(TARGET_SYSTEM_ROOT_DEFINE)
 
+AC_ARG_ENABLE(runtime-sysroot,
+[AS_HELP_STRING([--enable-runtime-sysroot],
+		 [prepend sysroot to libpath in ld script and rpath,
+                 only used in addition to --with-sysroot (default is yes)])],
+[case "${enableval}" in
+  no) ;;
+  *) AC_DEFINE(ENABLE_RUNTIME_SYSROOT, [], \
+               [prepend sysroot to libpath in ld script and rpath]) ;;
+esac],
+AC_DEFINE(ENABLE_RUNTIME_SYSROOT, [], \
+          [prepend sysroot to libpath in ld script and rpath]))
+
 dnl Use --enable-gold to decide if this linker should be the default.
 dnl "install_as_default" is set to false if gold is the default linker.
 dnl "installed_linker" is the installed BFD linker name.
Index: binutils-2.23/ld/emultempl/elf32.em
===================================================================
--- binutils-2.23.orig/ld/emultempl/elf32.em
+++ binutils-2.23/ld/emultempl/elf32.em
@@ -525,7 +525,10 @@ static char *
 gld${EMULATION_NAME}_add_sysroot (const char *path)
 {
   int len, colons, i;
-  char *ret, *p;
+  char *ret;
+
+#ifdef ENABLE_RUNTIME_SYSROOT
+  char *p;
 
   len = strlen (path);
   colons = 0;
@@ -553,6 +556,11 @@ gld${EMULATION_NAME}_add_sysroot (const
       *p++ = path[i++];
 
   *p = 0;
+#else
+  ret = xmalloc (strlen (path) + 1);
+  strcpy (ret, path);
+#endif
+
   return ret;
 }
 
Index: binutils-2.23/ld/ldfile.c
===================================================================
--- binutils-2.23.orig/ld/ldfile.c
+++ binutils-2.23/ld/ldfile.c
@@ -463,7 +463,11 @@ try_open (const char *name, bfd_boolean
   result = fopen (name, "r");
 
   if (result != NULL)
+#ifdef ENABLE_RUNTIME_SYSROOT
     *sysrooted = is_sysrooted_pathname (name);
+#else
+    *sysrooted = 0;
+#endif
 
   if (verbose)
     {
Index: binutils-2.23/ld/ld.texinfo
===================================================================
--- binutils-2.23.orig/ld/ld.texinfo
+++ binutils-2.23/ld/ld.texinfo
@@ -3026,13 +3026,14 @@ then you can put @samp{INPUT (subr.o)} i
 In fact, if you like, you can list all of your input files in the linker
 script, and then invoke the linker with nothing but a @samp{-T} option.
 
-In case a @dfn{sysroot prefix} is configured, and the filename starts
-with the @samp{/} character, and the script being processed was
-located inside the @dfn{sysroot prefix}, the filename will be looked
-for in the @dfn{sysroot prefix}.  Otherwise, the linker will try to
-open the file in the current directory.  If it is not found, the
-linker will search through the archive library search path.  See the
-description of @samp{-L} in @ref{Options,,Command Line Options}.
+In case a @dfn{sysroot prefix} is configured without explict
+--disable-runtime-sysroot, and the filename starts with the @samp{/}
+character, and the script being processed was located inside the
+@dfn{sysroot prefix}, the filename will be looked for in the
+@dfn{sysroot prefix}.  Otherwise, the linker will try to open the file
+in the current directory.  If it is not found, the linker will search
+through the archive library search path.  See the description of
+@samp{-L} in @ref{Options,,Command Line Options}.
 
 If you use @samp{INPUT (-l@var{file})}, @command{ld} will transform the
 name to @code{lib@var{file}.a}, as with the command line argument