gc: Find roots using libproc on Darwin

Previously, the garbage collector found runtime roots on Darwin by
shelling out to `lsof -n -w -F n` then parsing the result.
However, this requires an lsof binary and can be extremely slow.

The official Apple lsof returns in a reasonable amount of time,
about 250ms in my tests, but the lsof packaged in nixpkgs is quite slow,
taking about 40 seconds to run the command.

Using libproc directly is about the same speed as Apple lsof,
and allows us to reënable several tests that were disabled on Darwin.

Change-Id: Ifa0adda7984e13c15535693baba835aae79a3577

1 files changed, 2 insertions, 8 deletions

diff --git a/src/libstore/platform/linux.cc b/src/libstore/platform/linux.cc
index 9be3e47da..a34608894 100644
--- a/src/libstore/platform/linux.cc
+++ b/src/libstore/platform/linux.cc
@@ -1,6 +1,7 @@
 #include "gc-store.hh"
 #include "signals.hh"
 #include "platform/linux.hh"
+#include "regex.hh"
 
 #include <regex>
 
@@ -26,12 +27,6 @@ static void readProcLink(const std::string & file, UncheckedRoots & roots)
     }
 }
 
-static std::string quoteRegexChars(const std::string & raw)
-{
-    static auto specialRegex = std::regex(R"([.^$\\*+?()\[\]{}|])");
-    return std::regex_replace(raw, specialRegex, R"(\$&)");
-}
-
 static void readFileRoots(const char * path, UncheckedRoots & roots)
 {
     try {
@@ -50,8 +45,7 @@ void LinuxLocalStore::findPlatformRoots(UncheckedRoots & unchecked)
         struct dirent * ent;
         auto digitsRegex = std::regex(R"(^\d+$)");
         auto mapRegex = std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
-        auto storePathRegex =
-            std::regex(quoteRegexChars(storeDir) + R"(/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*)");
+        auto storePathRegex = regex::storePathRegex(storeDir);
         while (errno = 0, ent = readdir(procDir.get())) {
             checkInterrupt();
             if (std::regex_match(ent->d_name, digitsRegex)) {