Use /data/local/tmp as temp directory on android

[tberghammer]

Summary

Use /data/local/tmp as temp directory on android

If no temp directory specified by the user on android then fall back
to /data/local/tmp what is always present on the device. It removes
the dependency of specifying TMPDIR for executing platform commands
on android.

[tberghammer]

Overwrite the ComputeGlobalTempFileDirectory function instead of ComputeProcessTempFileDirectory

[ovyalov]

Please see my comment.

source/Host/android/HostInfoAndroid.cpp

99

What do you think about adding lldb sub directory - i.e. /data/local/tmp/lldb?
In this case it will be consistent with default implementation (https://github.com/llvm-mirror/lldb/blob/789afe8e6565a1370b2f34e075e9ca5289d362f8/source/Host/common/HostInfoBase.cpp#L360) .

[tberghammer]

Changing the default temp directory to include /lldb suffix

[labath]

LGTM.

include/lldb/Host/android/HostInfoAndroid.h

class HostInfoAndroid : public HostInfoLinux
     friend class HostInfoBase;
 
   public:
     static FileSpec GetDefaultShell();
     static FileSpec ResolveLibraryPath (const std::string& path, const ArchSpec& arch);
 
   protected:
     static void ComputeHostArchitectureSupport(ArchSpec &arch_32, ArchSpec &arch_64);
+    static bool ComputeGlobalTempFileDirectory(FileSpec &file_spec);
 };
 
 } // end of namespace lldb_private
 
 #endif // #ifndef lldb_Host_android_HostInfoAndroid_h_

source/Host/android/HostInfoAndroid.cpp

for (const StringRef& path : ld_paths)
         file_candidate.AppendPathComponent(module_path.c_str());
 
         if (file_candidate.Exists())
             return file_candidate;
     }
 
     return FileSpec();
 }
+
+bool
+HostInfoAndroid::ComputeGlobalTempFileDirectory(FileSpec &file_spec)
+{
+    if (HostInfoLinux::ComputeGlobalTempFileDirectory(file_spec))
+        return true;
+
+    // If the default mechanism for computing the temp directory failed then
+    // fall back to /data/local/tmp
+    file_spec = FileSpec("/data/local/tmp", false);
+    return true;
+}