cmd/dist: make dir check in defaulttarg() more robust

1, strip last path separator from $GOROOT
   The user might define GOROOT=/path/to/go/, but then the dir
   check in defaulttarg() will always complain the current dir
   is not within $GOROOT/src/.
2, resolve symlinks in the default goroot
   Or if getcwd() returns a fully-resolved path, the check in
   defaulttarg() will always fail.

R=rsc
CC=golang-dev
https://golang.org/cl/5649073

diff --git a/src/cmd/dist/build.c b/src/cmd/dist/build.c
index f31c83ea7ad9fec4342ff49195ef146ccc004b3e..6cb33ab10fa5c40afd183c7bd522cefb81b6384d 100644 (file)
--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -77,8 +77,12 @@ init(void)
        binit(&b);
 
        xgetenv(&b, "GOROOT");
-       if(b.len > 0)
+       if(b.len > 0) {
+               // if not "/", then strip trailing path separator
+               if(b.len >= 2 && b.p[b.len - 1] == slash[0])
+                       b.len--;
                goroot = btake(&b);
+       }
 
        xgetenv(&b, "GOBIN");
        if(b.len == 0)
@@ -1373,20 +1377,30 @@ static char*
 defaulttarg(void)
 {
        char *p;
-       Buf pwd, src;
+       Buf pwd, src, real_src;
        
        binit(&pwd);
        binit(&src);
+       binit(&real_src);
 
+       // xgetwd might return a path with symlinks fully resolved, and if
+       // there happens to be symlinks in goroot, then the hasprefix test
+       // will never succeed. Instead, we use xrealwd to get a canonical
+       // goroot/src before the comparison to avoid this problem.
        xgetwd(&pwd);
        p = btake(&pwd);
        bpathf(&src, "%s/src/", goroot);
-       if(!hasprefix(p, bstr(&src)))
-               fatal("current directory %s is not under %s", p, bstr(&src));
-       p += src.len;
+       xrealwd(&real_src, bstr(&src));
+       if(!hasprefix(p, bstr(&real_src)))
+               fatal("current directory %s is not under %s", p, bstr(&real_src));
+       p += real_src.len;
+       // guard againt xrealwd return the directory without the trailing /
+       if(*p == slash[0])
+               p++;
 
        bfree(&pwd);
        bfree(&src);
+       bfree(&real_src);
        
        return p;
 }