Refactor user/group name resolving code

Summary:
This creates an abstract base class called "UserIDResolver", which can
be implemented to provide user/group ID resolution capabilities for
various objects. Posix host implement a PosixUserIDResolver, which does
that using posix apis (getpwuid and friends).  PlatformGDBRemote
forwards queries over the gdb-remote link, etc. ProcessInstanceInfo
class is refactored to make use of this interface instead of taking a
platform pointer as an argument. The base resolver class already
implements caching and thread-safety, so implementations don't have to
worry about that.

The main motivating factor for this was to remove external dependencies
from the ProcessInstanceInfo class (so it can be put next to
ProcessLaunchInfo and friends), but it has other benefits too:
- ability to test the user name caching code
- ability to test ProcessInstanceInfo dumping code
- consistent interface for user/group resolution between Platform and
  Host classes.

Reviewers: zturner, clayborg, jingham

Subscribers: mgorny, lldb-commits

Differential Revision: https://reviews.llvm.org/D58167

llvm-svn: 355323

1 files changed, 7 insertions, 19 deletions

diff --git a/lldb/source/Target/RemoteAwarePlatform.cpp b/lldb/source/Target/RemoteAwarePlatform.cpp
index 04cb6cedccf..1704e1533e9 100644
--- a/lldb/source/Target/RemoteAwarePlatform.cpp
+++ b/lldb/source/Target/RemoteAwarePlatform.cpp
@@ -10,6 +10,7 @@
 #include "lldb/Host/FileCache.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/Host.h"
+#include "lldb/Host/HostInfo.h"
 
 using namespace lldb_private;
 
@@ -204,25 +205,12 @@ const char *RemoteAwarePlatform::GetHostname() {
   return nullptr;
 }
 
-const char *RemoteAwarePlatform::GetUserName(uint32_t uid) {
-  // Check the cache in Platform in case we have already looked this uid up
-  const char *user_name = Platform::GetUserName(uid);
-  if (user_name)
-    return user_name;
-
-  if (IsRemote() && m_remote_platform_sp)
-    return m_remote_platform_sp->GetUserName(uid);
-  return nullptr;
-}
-
-const char *RemoteAwarePlatform::GetGroupName(uint32_t gid) {
-  const char *group_name = Platform::GetGroupName(gid);
-  if (group_name)
-    return group_name;
-
-  if (IsRemote() && m_remote_platform_sp)
-    return m_remote_platform_sp->GetGroupName(gid);
-  return nullptr;
+UserIDResolver &RemoteAwarePlatform::GetUserIDResolver() {
+  if (IsHost())
+    return HostInfo::GetUserIDResolver();
+  if (m_remote_platform_sp)
+    return m_remote_platform_sp->GetUserIDResolver();
+  return UserIDResolver::GetNoopResolver();
 }
 
 Environment RemoteAwarePlatform::GetEnvironment() {