From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 9 Jul 2012 16:18:48 +0000 (+0300)
Subject: Defer the retrieval of owner/group names until they are needed
X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=commitdiff_plain;h=df74f89b175c1579f9383e6dec8ddb821e606642

Defer the retrieval of owner/group names until they are needed
---

diff --git a/source/fs/stat.cpp b/source/fs/stat.cpp
index 77564f0..85fead5 100644
--- a/source/fs/stat.cpp
+++ b/source/fs/stat.cpp
@@ -20,6 +20,21 @@ using namespace std;
 namespace {
 
 #ifdef WIN32
+PSID copy_sid(PSID sid)
+{
+	if(!sid || !IsValidSid(sid))
+		return 0;
+	DWORD len = GetLengthSid(sid);
+	PSID copy = reinterpret_cast<PSID>(HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, len));
+	if(!CopySid(len, copy, sid))
+	{
+		DWORD err = GetLastError();
+		HeapFree(GetProcessHeap(), 0, copy);
+		throw Msp::system_error("CopySid", err);
+	}
+	return copy;
+}
+
 string get_account_name(PSID sid)
 {
 	char name[1024];
@@ -39,12 +54,55 @@ string get_account_name(PSID sid)
 namespace Msp {
 namespace FS {
 
-#ifndef WIN32
 struct Stat::Private
 {
+#ifdef WIN32
+	PSID owner_id;
+	PSID group_id;
+#else
+	uid_t owner_id;
+	gid_t group_id;
+#endif
+
+	Private();
+	Private(const Private &);
+	~Private();
+
+#ifndef WIN32
+	/* This is here because it needs access to private members of Stat, but we
+	can't expose the system stat struct in the public header */
 	static Stat from_struct_stat(const struct stat &);
+#endif
+
+	void fill_owner_info(Stat::OwnerInfo &);
 };
 
+Stat::Private::Private():
+	owner_id(0),
+	group_id(0)
+{ }
+
+Stat::Private::Private(const Private &other):
+#ifdef WIN32
+	owner_id(copy_sid(other.owner_id)),
+	group_id(copy_sid(other.group_id))
+#else
+	owner_id(other.owner_id),
+	group_id(other.group_id)
+#endif
+{ }
+
+Stat::Private::~Private()
+{
+#ifdef WIN32
+	if(owner_id)
+		HeapFree(GetProcessHeap(), 0, owner_id);
+	if(group_id)
+		HeapFree(GetProcessHeap(), 0, group_id);
+#endif
+}
+
+#ifndef WIN32
 Stat Stat::Private::from_struct_stat(const struct stat &st)
 {
 	Stat result;
@@ -61,33 +119,83 @@ Stat Stat::Private::from_struct_stat(const struct stat &st)
 	result.alloc_size = st.st_blocks*512;
 	result.mtime = Time::TimeStamp::from_unixtime(st.st_mtime);
 
+	result.priv = new Private;
+	result.priv->owner_id = st.st_uid;
+	result.priv->group_id = st.st_gid;
+
+	return result;
+}
+#endif
+
+void Stat::Private::fill_owner_info(Stat::OwnerInfo &result)
+{
+#ifdef WIN32
+	if(owner_id)
+		result.owner = get_account_name(owner_id);
+	else
+		result.owner = "None";
+
+	if(group_id)
+		result.group = get_account_name(group_id);
+	else
+		result.group = "None";
+#else
 	char buf[1024];
 
 	struct passwd pw;
 	struct passwd *owner;
-	if(!getpwuid_r(st.st_uid, &pw, buf, sizeof(buf), &owner) && owner)
+	if(!getpwuid_r(owner_id, &pw, buf, sizeof(buf), &owner) && owner)
 		result.owner = owner->pw_name;
 	else
-		result.owner = format("%d", st.st_uid);
+		result.owner = format("%d", owner_id);
 
 	struct group gr;
 	struct group *group;
-	if(!getgrgid_r(st.st_gid, &gr, buf, sizeof(buf), &group) && group)
+	if(!getgrgid_r(group_id, &gr, buf, sizeof(buf), &group) && group)
 		result.group = group->gr_name;
 	else
-		result.group = format("%d", st.st_gid);
-
-	return result;
-}
+		result.group = format("%d", group_id);
 #endif
+}
+
 
 Stat::Stat():
 	exists(false),
 	type(UNKNOWN),
 	size(0),
-	alloc_size(0)
+	alloc_size(0),
+	priv(0)
 { }
 
+Stat::Stat(const Stat &other):
+	exists(other.exists),
+	type(other.type),
+	size(other.type),
+	alloc_size(other.alloc_size),
+	mtime(other.mtime),
+	owner_info(other.owner_info),
+	priv(other.priv ? new Private(*other.priv) : 0)
+{ }
+
+Stat &Stat::operator=(const Stat &other)
+{
+	exists = other.exists;
+	type = other.type;
+	size = other.size;
+	alloc_size = other.alloc_size;
+	mtime = other.mtime;
+	owner_info = other.owner_info;
+	delete priv;
+	priv = (other.priv ? new Private(*other.priv) : 0);
+
+	return *this;
+}
+
+Stat::~Stat()
+{
+	delete priv;
+}
+
 Stat Stat::stat(const Path &path)
 {
 #ifdef WIN32
@@ -130,10 +238,9 @@ Stat Stat::stat(const Path &path)
 		throw system_error("GetSecurityInfo", err);
 	}
 
-	if(owner)
-		result.owner = get_account_name(owner);
-	if(group)
-		result.group = get_account_name(group);
+	result.priv = new Private;
+	result.priv->owner_id = copy_sid(owner);
+	result.priv->group_id = copy_sid(group);
 
 	LocalFree(sec_desc);
 
@@ -155,6 +262,20 @@ Stat Stat::stat(const Path &path)
 #endif
 }
 
+const std::string &Stat::get_owner() const
+{
+	if(priv && owner_info.owner.empty())
+		priv->fill_owner_info(owner_info);
+	return owner_info.owner;
+}
+
+const std::string &Stat::get_group() const
+{
+	if(priv && owner_info.group.empty())
+		priv->fill_owner_info(owner_info);
+	return owner_info.group;
+}
+
 Stat Stat::lstat(const Path &path)
 {
 #ifdef WIN32
diff --git a/source/fs/stat.h b/source/fs/stat.h
index 6ae551f..8c05771 100644
--- a/source/fs/stat.h
+++ b/source/fs/stat.h
@@ -30,16 +30,25 @@ class Stat
 private:
 	struct Private;
 
+	struct OwnerInfo
+	{
+		std::string owner;
+		std::string group;
+	};
+
 	bool exists;
 	FileType type;
 	FileSize size;
 	FileSize alloc_size;
 	Time::TimeStamp mtime;
-	std::string owner;
-	std::string group;
+	mutable OwnerInfo owner_info;
+	Private *priv;
 
 public:
 	Stat();
+	Stat(const Stat &);
+	Stat &operator=(const Stat &);
+	~Stat();
 
 	FileType get_type() const { return type; }
 	bool is_regular() const { return type==REGULAR; }
@@ -48,8 +57,8 @@ public:
 	FileSize get_size() const { return size; }
 	FileSize get_alloc_size() const { return alloc_size; }
 	const Time::TimeStamp &get_modify_time() const { return mtime; }
-	const std::string &get_owner() const { return owner; }
-	const std::string &get_group() const { return group; }
+	const std::string &get_owner() const;
+	const std::string &get_group() const;
 
 	operator bool() const { return exists; }