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Remove Lazy

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This fixes a crash during startup when compiling Nix as a single
compilation unit.
This commit is contained in:
Eelco Dolstra 2020-10-09 17:54:59 +02:00
parent 87157b2bd3
commit e845d19ae3
2 changed files with 18 additions and 64 deletions
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48
src/libutil/lazy.hh
View file

@ -1,48 +0,0 @@
#include <exception>
#include <functional>
#include <mutex>
namespace nix {
/* A helper class for lazily-initialized variables.
Lazy<T> var([]() { return value; });
declares a variable of type T that is initialized to 'value' (in a
thread-safe way) on first use, that is, when var() is first
called. If the initialiser code throws an exception, then all
subsequent calls to var() will rethrow that exception. */
template<typename T>
class Lazy
{
typedef std::function<T()> Init;
Init init;
std::once_flag done;
T value;
std::exception_ptr ex;
public:
Lazy(Init init) : init(init)
{ }
const T & operator () ()
{
std::call_once(done, [&]() {
try {
value = init();
} catch (...) {
ex = std::current_exception();
}
});
if (ex) std::rethrow_exception(ex);
return value;
}
};
}

34
src/libutil/util.cc
View file

@ -1,4 +1,3 @@
#include "lazy.hh"
#include "util.hh"
#include "affinity.hh"
#include "sync.hh"
@ -522,21 +521,24 @@ std::string getUserName()
}
static Lazy<Path> getHome2([]() {
auto homeDir = getEnv("HOME");
if (!homeDir) {
std::vector<char> buf(16384);
struct passwd pwbuf;
struct passwd * pw;
if (getpwuid_r(geteuid(), &pwbuf, buf.data(), buf.size(), &pw) != 0
|| !pw || !pw->pw_dir || !pw->pw_dir[0])
throw Error("cannot determine user's home directory");
homeDir = pw->pw_dir;
}
return *homeDir;
});
Path getHome() { return getHome2(); }
Path getHome()
{
static Path homeDir = []()
{
auto homeDir = getEnv("HOME");
if (!homeDir) {
std::vector<char> buf(16384);
struct passwd pwbuf;
struct passwd * pw;
if (getpwuid_r(geteuid(), &pwbuf, buf.data(), buf.size(), &pw) != 0
|| !pw || !pw->pw_dir || !pw->pw_dir[0])
throw Error("cannot determine user's home directory");
homeDir = pw->pw_dir;
}
return *homeDir;
}();
return homeDir;
}
Path getCacheDir()