[llvm] r298513 - Make home_directory look in the password database in addition to $HOME.

[Stephan Bergmann via llvm-commits]

On 03/22/2017 05:12 PM, Zachary Turner wrote:
> I wasn't aware people do this.  If that's the case, then perhaps I could
> simply change the test to get the value from the password database
> inside the test, then unset HOME, then confirm that it returns the same
> thing that it says in the password database?
>
> It sounds like you don't disagree with the functionality change in
> home_directory(), but just the way the test is implemented, right?

Right.  (And I myself don't routinely build with such a distorted 
environment, just wondered whether this is a breaking point waiting to 
happen eventually.)

> On Wed, Mar 22, 2017 at 9:02 AM Stephan Bergmann <sbergman at redhat.com
> <mailto:sbergman at redhat.com>> wrote:
>
>     On 03/22/2017 04:24 PM, Zachary Turner via llvm-commits wrote:
>     > Author: zturner
>     > Date: Wed Mar 22 10:24:59 2017
>     > New Revision: 298513
>     >
>     > URL: http://llvm.org/viewvc/llvm-project?rev=298513&view=rev
>     > Log:
>     > Make home_directory look in the password database in addition to
>     $HOME.
>     >
>     > This is something of an edge case, but when the $HOME environment
>     > variable is not set, we can still look in the password database
>     > to get the current user's home directory.
>     >
>     > Added a test for this by getting the value of $HOME, then unsetting
>     > it, then calling home_directory() and verifying that it succeeds
>     > and that the value is the same as what we originally read from
>     > the environment.
>
>     Why should builds not be supported which are done in an environment
>     where HOME deliberately points somewhere other than the user's home
>     directory?
>
>     > Modified:
>     >     llvm/trunk/lib/Support/Unix/Path.inc
>     >     llvm/trunk/unittests/Support/Path.cpp
>     >
>     > Modified: llvm/trunk/lib/Support/Unix/Path.inc
>     > URL:
>     http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/Path.inc?rev=298513&r1=298512&r2=298513&view=diff
>     >
>     ==============================================================================
>     > --- llvm/trunk/lib/Support/Unix/Path.inc (original)
>     > +++ llvm/trunk/lib/Support/Unix/Path.inc Wed Mar 22 10:24:59 2017
>     > @@ -920,12 +920,18 @@ std::error_code real_path(const Twine &p
>     >  namespace path {
>     >
>     >  bool home_directory(SmallVectorImpl<char> &result) {
>     > -  if (char *RequestedDir = getenv("HOME")) {
>     > -    result.clear();
>     > -    result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
>     > -    return true;
>     > +  char *RequestedDir = getenv("HOME");
>     > +  if (!RequestedDir) {
>     > +    struct passwd *pw = getpwuid(getuid());
>     > +    if (pw && pw->pw_dir)
>     > +      RequestedDir = pw->pw_dir;
>     >    }
>     > -  return false;
>     > +  if (!RequestedDir)
>     > +    return false;
>     > +
>     > +  result.clear();
>     > +  result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
>     > +  return true;
>     >  }
>     >
>     >  static bool getDarwinConfDir(bool TempDir, SmallVectorImpl<char>
>     &Result) {
>     >
>     > Modified: llvm/trunk/unittests/Support/Path.cpp
>     > URL:
>     http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/Path.cpp?rev=298513&r1=298512&r2=298513&view=diff
>     >
>     ==============================================================================
>     > --- llvm/trunk/unittests/Support/Path.cpp (original)
>     > +++ llvm/trunk/unittests/Support/Path.cpp Wed Mar 22 10:24:59 2017
>     > @@ -328,6 +328,26 @@ TEST(Support, HomeDirectory) {
>     >    }
>     >  }
>     >
>     > +#ifndef LLVM_ON_WIN32
>     > +TEST(Support, HomeDirectoryWithNoEnv) {
>     > +  std::string Original;
>     > +  char const *path = ::getenv("HOME");
>     > +  // Don't try to test if we don't have something to compare against.
>     > +  if (!path)
>     > +    return;
>     > +  Original = path;
>     > +  ::unsetenv("HOME");
>     > +
>     > +  SmallString<128> HomeDir;
>     > +  auto status = path::home_directory(HomeDir);
>     > +  EXPECT_TRUE(status);
>     > +  EXPECT_EQ(Original, HomeDir);
>     > +
>     > +  // Now put the original environment variable back
>     > +  ::setenv("HOME", Original.c_str(), 1);
>     > +}
>     > +#endif
>     > +
>     >  TEST(Support, UserCacheDirectory) {
>     >    SmallString<13> CacheDir;
>     >    SmallString<20> CacheDir2;