cmd/dist: avoid use of 'go tool pack'

All packages now use the -pack option to the compiler.
For a pure Go package, that's enough.
For a package with additional C and assembly files, the extra
archive entries can be added directly (by concatenation)
instead of by invoking go tool pack.

These changes make it possible to rewrite cmd/pack in Go.

R=iant, r
CC=golang-dev
https://golang.org/cl/42890043

diff --git a/src/cmd/dist/build.c b/src/cmd/dist/build.c
index e7d1900a014293cde6b4f7ee34d0e8a9434b2044..26d546af520e9e875de108d5fc4a18c2bb182d57 100644 (file)
--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -33,6 +33,7 @@ bool defaultclang;
 
 static bool shouldbuild(char*, char*);
 static void copy(char*, char*, int);
+static void dopack(char*, char*, char**, int);
 static char *findgoversion(void);
 
 // The known architecture letters.
@@ -622,7 +623,7 @@ static void
 install(char *dir)
 {
        char *name, *p, *elem, *prefix, *exe;
-       bool islib, ispkg, isgo, stale;
+       bool islib, ispkg, isgo, stale, ispackcmd;
        Buf b, b1, path;
        Vec compile, files, link, go, missing, clean, lib, extra;
        Time ttarg, t;
@@ -696,6 +697,7 @@ install(char *dir)
 
        // Start final link command line.
        // Note: code below knows that link.p[targ] is the target.
+       ispackcmd = 0;
        if(islib) {
                // C library.
                vadd(&link, "ar");
@@ -710,8 +712,8 @@ install(char *dir)
                vadd(&link, bpathf(&b, "%s/pkg/obj/%s_%s/%s%s.a", goroot, gohostos, gohostarch, prefix, name));
        } else if(ispkg) {
                // Go library (package).
-               vadd(&link, bpathf(&b, "%s/pack", tooldir));
-               vadd(&link, "grc");
+               ispackcmd = 1;
+               vadd(&link, "pack"); // program name - unused here, but all the other cases record one
                p = bprintf(&b, "%s/pkg/%s_%s/%s", goroot, goos, goarch, dir+4);
                *xstrrchr(p, '/') = '\0';
                xmkdirall(p);
@@ -1048,11 +1050,13 @@ install(char *dir)
                vreset(&compile);
                vadd(&compile, bpathf(&b, "%s/%sg", tooldir, gochar));
 
-               bpathf(&b, "%s/_go_.%s", workdir, gochar);
+               bpathf(&b, "%s/_go_.a", workdir);
+               vadd(&compile, "-pack");
                vadd(&compile, "-o");
                vadd(&compile, bstr(&b));
                vadd(&clean, bstr(&b));
-               vadd(&link, bstr(&b));
+               if(!ispackcmd)
+                       vadd(&link, bstr(&b));
 
                vadd(&compile, "-p");
                if(hasprefix(dir, "pkg/"))
@@ -1066,6 +1070,12 @@ install(char *dir)
                vcopy(&compile, go.p, go.len);
 
                runv(nil, bstr(&path), CheckExit, &compile);
+
+               if(ispackcmd) {
+                       xremove(link.p[targ]);
+                       dopack(link.p[targ], bstr(&b), &link.p[targ+1], link.len - (targ+1));
+                       goto nobuild;
+               }
        }
 
        if(!islib && !isgo) {
@@ -1236,6 +1246,48 @@ copy(char *dst, char *src, int exec)
        bfree(&b);
 }
 
+// dopack copies the package src to dst,
+// appending the files listed in extra.
+// The archive format is the traditional Unix ar format.
+static void
+dopack(char *dst, char *src, char **extra, int nextra)
+{
+       int i;
+       char c, *p, *q;
+       Buf b, bdst;
+       
+       binit(&b);
+       binit(&bdst);
+
+       readfile(&bdst, src);
+       for(i=0; i<nextra; i++) {
+               readfile(&b, extra[i]);
+               // find last path element for archive member name
+               p = xstrrchr(extra[i], '/');
+               if(p)
+                       p++;
+               q = xstrrchr(extra[i], '\\');
+               if(q) {
+                       q++;
+                       if(p == nil || q > p)
+                               p = q;
+               }
+               if(p == nil)
+                       p = extra[i];
+               bwritef(&bdst, "%-16.16s%-12d%-6d%-6d%-8o%-10d`\n", p, 0, 0, 0, 0644, b.len);
+               bwriteb(&bdst, &b);
+               if(b.len&1) {
+                       c = 0;
+                       bwrite(&bdst, &c, 1);
+               }
+       }
+
+       writefile(&bdst, dst, 0);
+
+       bfree(&b);
+       bfree(&bdst);
+}
+
 // buildorder records the order of builds for the 'go bootstrap' command.
 static char *buildorder[] = {
        "lib9",