5l, 6l, 8l: implement -X flag

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/5643050

3 files changed, 64 insertions, 2 deletions

diff --git a/src/cmd/ld/data.c b/src/cmd/ld/data.c
index d34d23c770..b5f1b99312 100644
--- a/src/cmd/ld/data.c
+++ b/src/cmd/ld/data.c
@@ -589,6 +589,25 @@ strnput(char *s, int n)
 	}
 }
 
+void
+addstrdata(char *name, char *value)
+{
+	Sym *s, *sp;
+	char *p;
+	
+	p = smprint("%s.str", name);
+	sp = lookup(p, 0);
+	free(p);
+	addstring(sp, value);
+
+	s = lookup(name, 0);
+	s->dupok = 1;
+	addaddr(s, sp);
+	adduint32(s, strlen(value));
+	if(PtrSize == 8)
+		adduint32(s, 0);  // round struct to pointer width
+}
+
 vlong
 addstring(Sym *s, char *str)
 {
diff --git a/src/cmd/ld/doc.go b/src/cmd/ld/doc.go
index 972e2a32c9..4728fccb8b 100644
--- a/src/cmd/ld/doc.go
+++ b/src/cmd/ld/doc.go
@@ -4,8 +4,50 @@
 
 /*
 
-This directory contains the portable section of the Plan 9 C linkers.
-See ../6l, ../8l, and ../5l for more information.
+Ld is the portable code for a modified version of the Plan 9 linker.  The original is documented at
+
+	http://plan9.bell-labs.com/magic/man2html/1/2l
+
+It reads object files (.5, .6, or .8 files) and writes a binary named for the
+architecture (5.out, 6.out, 8.out) by default.
+
+Major changes include:
+	- support for ELF and Mach-O binary files
+	- support for segmented stacks (this feature is implemented here, not in the compilers).
+
+Original options are listed on the manual page linked above.
+
+Options new in this version:
+
+-d
+	Elide the dynamic linking header.  With this option, the binary
+	is statically linked and does not refer to dynld.  Without this option
+	(the default), the binary's contents are identical but it is loaded with dynld.
+-Hdarwin
+	Write Apple Mach-O binaries (default when $GOOS is darwin)
+-Hlinux
+	Write Linux ELF binaries (default when $GOOS is linux)
+-Hfreebsd
+	Write FreeBSD ELF binaries (default when $GOOS is freebsd)
+-Hnetbsd
+	Write NetBSD ELF binaries (default when $GOOS is netbsd)
+-Hopenbsd
+	Write OpenBSD ELF binaries (default when $GOOS is openbsd)
+-Hwindows
+	Write Windows PE32+ binaries (default when $GOOS is windows)
+-I interpreter
+	Set the ELF dynamic linker to use.
+-L dir1 -L dir2
+	Search for libraries (package files) in dir1, dir2, etc.
+	The default is the single location $GOROOT/pkg/$GOOS_amd64.
+-r dir1:dir2:...
+	Set the dynamic linker search path when using ELF.
+-V
+	Print the linker version.
+-X symbol value
+	Set the value of an otherwise uninitialized string variable.
+	The symbol name should be of the form importpath.name,
+	as displayed in the symbol table printed by "go tool nm".
 
 */
 package documentation
diff --git a/src/cmd/ld/lib.h b/src/cmd/ld/lib.h
index bbaa52d43c..188ff9f928 100644
--- a/src/cmd/ld/lib.h
+++ b/src/cmd/ld/lib.h
@@ -179,6 +179,7 @@ void	reloc(void);
 void	relocsym(Sym*);
 void	savedata(Sym*, Prog*, char*);
 void	symgrow(Sym*, int32);
+void	addstrdata(char*, char*);
 vlong	addstring(Sym*, char*);
 vlong	adduint32(Sym*, uint32);
 vlong	adduint64(Sym*, uint64);