golang doesn't work with ccache. In the current state, a lot of parsing
happens where it'll grab the first string in CC or LD and uses that for
its builds. When ccache is enabled, it results in trying to do builds
with just ccache. 

The brokeness is seen when building with apps that uses cgo, like docker.
To enable ccache to work, some string comparisons and changes to parsing
had to be made.

Signed-off-by: Amy Fong <amy.fong@windriver.com>

Index: go/src/cmd/cgo/gcc.go
===================================================================
--- go.orig/src/cmd/cgo/gcc.go	2014-06-18 17:26:26.000000000 -0700
+++ go/src/cmd/cgo/gcc.go	2015-06-18 13:19:08.908877160 -0700
@@ -712,6 +712,12 @@
 func (p *Package) gccBaseCmd() []string {
 	// Use $CC if set, since that's what the build uses.
 	if ret := strings.Fields(os.Getenv("CC")); len(ret) > 0 {
+		if strings.Contains(ret[0], "ccache") {
+			base_cc := ret[0] + " " + ret[1]
+			os.Setenv("CCACHE_CC", ret[1])
+			ret[1] = base_cc
+			return ret[1:]
+		}
 		return ret
 	}
 	// Try $GCC if set, since that's what we used to use.
Index: go/src/pkg/os/exec/lp_unix.go
===================================================================
--- go.orig/src/pkg/os/exec/lp_unix.go	2014-06-18 17:26:25.000000000 -0700
+++ go/src/pkg/os/exec/lp_unix.go	2015-06-18 13:19:29.464876331 -0700
@@ -35,8 +35,14 @@
 	// (only bypass the path if file begins with / or ./ or ../)
 	// but that would not match all the Unix shells.
 
-	if strings.Contains(file, "/") {
-		err := findExecutable(file)
+	tmp := file
+	if strings.Contains(file, " ") {
+		exec_part := strings.Split(file, " ")[0]
+		tmp = exec_part
+	}
+
+	if strings.Contains(tmp, "/") {
+		err := findExecutable(tmp)
 		if err == nil {
 			return file, nil
 		}
@@ -51,7 +57,7 @@
 			// Unix shell semantics: path element "" means "."
 			dir = "."
 		}
-		path := dir + "/" + file
+		path := dir + "/" + tmp
 		if err := findExecutable(path); err == nil {
 			return path, nil
 		}
Index: go/src/cmd/go/build.go
===================================================================
--- go.orig/src/cmd/go/build.go	2014-06-18 17:26:26.000000000 -0700
+++ go/src/cmd/go/build.go	2015-06-18 13:20:08.724874749 -0700
@@ -2005,8 +2005,15 @@
 	// strings returned are "gcc", "-I", objdir (and cuts them off).
 
 	compiler := envList(envvar, defcmd)
-	a := []string{compiler[0], "-I", objdir}
-	a = append(a, compiler[1:]...)
+
+	a := []string{compiler[0]}
+	if strings.Contains(compiler[0], "ccache") {
+		a = append(a, compiler[1], "-I", objdir)
+		a = append(a, compiler[2:]...)
+	} else {
+		a = append(a, "-I", objdir)
+		a = append(a, compiler[1:]...)
+	}
 
 	// Definitely want -fPIC but on Windows gcc complains
 	// "-fPIC ignored for target (all code is position independent)"
Index: go/src/cmd/ld/lib.c
===================================================================
--- go.orig/src/cmd/ld/lib.c	2014-06-18 17:26:27.000000000 -0700
+++ go/src/cmd/ld/lib.c	2015-06-18 13:18:39.564878343 -0700
@@ -552,7 +552,7 @@
 void
 hostlink(void)
 {
-	char *p, **argv;
+	char *p, *q, **argv;
 	int c, i, w, n, argc, len;
 	Hostobj *h;
 	Biobuf *f;
@@ -577,6 +577,19 @@
 	if(extld == nil)
 		extld = "gcc";
 	argv[argc++] = extld;
+
+	p = extldflags;
+	if (strstr(argv[0], "ccache") != NULL) {
+		while(p != nil) {
+			while(*p == ' ')
+				*p++ = '\0';
+			if(*p == '\0')
+				break;
+			argv[argc++] = p;
+			p = strchr(p + 1, ' ');
+			break;
+		}
+	}
 	switch(thechar){
 	case '8':
 		argv[argc++] = "-m32";
@@ -629,12 +642,12 @@
 			errorexit();
 		}
 		Bseek(f, h->off, 0);
-		p = smprint("%s/%06d.o", tmpdir, i);
-		argv[argc++] = p;
-		w = create(p, 1, 0775);
+		q = smprint("%s/%06d.o", tmpdir, i);
+		argv[argc++] = q;
+		w = create(q, 1, 0775);
 		if(w < 0) {
 			ctxt->cursym = S;
-			diag("cannot create %s: %r", p);
+			diag("cannot create %s: %r", q);
 			errorexit();
 		}
 		len = h->len;
@@ -646,7 +659,7 @@
 		}
 		if(close(w) < 0) {
 			ctxt->cursym = S;
-			diag("cannot write %s: %r", p);
+			diag("cannot write %s: %r", q);
 			errorexit();
 		}
 		Bterm(f);
@@ -656,7 +669,6 @@
 	for(i=0; i<nldflag; i++)
 		argv[argc++] = ldflag[i];
 
-	p = extldflags;
 	while(p != nil) {
 		while(*p == ' ')
 			*p++ = '\0';