cmd/ld: add tmpdir flag to preserve temp files

R=ken2
CC=golang-dev
https://golang.org/cl/7497044

src/cmd/5l/obj.c

@@ -123,6 +123,7 @@ main(int argc, char *argv[])
 	flagstr("r", "dir1:dir2:...: set ELF dynamic linker search path", &rpath);
 	flagcount("race", "enable race detector", &flag_race);
 	flagcount("s", "disable symbol table", &debug['s']);
+	flagstr("tmpdir", "leave temporary files in this directory", &tmpdir);
 	flagcount("u", "reject unsafe packages", &debug['u']);
 	flagcount("v", "print link trace", &debug['v']);
 	flagcount("w", "disable DWARF generation", &debug['w']);

src/cmd/6l/obj.c

@@ -117,10 +117,11 @@ main(int argc, char *argv[])
 	flagstr("r", "dir1:dir2:...: set ELF dynamic linker search path", &rpath);
 	flagcount("race", "enable race detector", &flag_race);
 	flagcount("s", "disable symbol table", &debug['s']);
+	flagcount("shared", "generate shared object", &flag_shared);
+	flagstr("tmpdir", "leave temporary files in this directory", &tmpdir);
 	flagcount("u", "reject unsafe packages", &debug['u']);
 	flagcount("v", "print link trace", &debug['v']);
 	flagcount("w", "disable DWARF generation", &debug['w']);
-	flagcount("shared", "generate shared object", &flag_shared);
 	
 	flagparse(&argc, &argv, usage);
 	

src/cmd/8l/obj.c

@@ -123,6 +123,7 @@ main(int argc, char *argv[])
 	flagcount("race", "enable race detector", &flag_race);
 	flagcount("s", "disable symbol table", &debug['s']);
 	flagcount("n", "dump symbol table", &debug['n']);
+	flagstr("tmpdir", "leave temporary files in this directory", &tmpdir);
 	flagcount("u", "reject unsafe packages", &debug['u']);
 	flagcount("v", "print link trace", &debug['v']);
 	flagcount("w", "disable DWARF generation", &debug['w']);

src/cmd/ld/lib.c

@@ -557,8 +557,6 @@ hostobjs(void)
 	}
 }
 
-static char *tmpdir;
-
 static void
 rmtemp(void)
 {
@@ -574,10 +572,11 @@ hostlinksetup(void)
 		return;
 
 	// create temporary directory and arrange cleanup
-	// TODO: Add flag to specify tempdir, which is then not cleaned up.
-	tmpdir = mktempdir();
-	atexit(rmtemp);
-	
+	if(tmpdir == nil) {
+		tmpdir = mktempdir();
+		atexit(rmtemp);
+	}
+
 	// change our output to temporary object file
 	close(cout);
 	p = smprint("%s/go.o", tmpdir);

src/cmd/ld/lib.h

@@ -148,6 +148,7 @@ EXTERN	int	flag_race;
 EXTERN	int flag_shared;
 EXTERN	char*	tracksym;
 EXTERN	char*	interpreter;
+EXTERN	char*	tmpdir;
 
 enum
 {
@@ -166,8 +167,7 @@ enum
 
 EXTERN	Segment	segtext;
 EXTERN	Segment	segdata;
-EXTERN	Segment	segsym;
-EXTERN	Segment segdwarf;
+EXTERN	Segment	segdwarf;
 
 void	addlib(char *src, char *obj);
 void	addlibpath(char *srcref, char *objref, char *file, char *pkg);