libstore: Add FreeBSD findPlatformRoots

Use libprocstat to find garbage collector roots on FreeBSD.
Tested working on a FreeBSD machine, although there is no CI yet

Change-Id: Id36bac8c3de6cc4de94e2d76e9663dd4b76068a9

5 files changed, 225 insertions, 13 deletions

diff --git a/meson.build b/meson.build
index 0e74520ca..56f447501 100644
--- a/meson.build
+++ b/meson.build
@@ -314,6 +314,10 @@ nlohmann_json = dependency('nlohmann_json', required : true)
 # *absolutely* are not going to make it work)
 lix_doc = declare_dependency(link_args : [ '-llix_doc' ])
 
+if is_freebsd
+  libprocstat = declare_dependency(link_args : [ '-lprocstat' ])
+endif
+
 #
 # Build-time tools
 #
diff --git a/src/libstore/meson.build b/src/libstore/meson.build
index fa363bd19..5416bd2b5 100644
--- a/src/libstore/meson.build
+++ b/src/libstore/meson.build
@@ -167,6 +167,9 @@ if host_machine.system() == 'linux'
 elif host_machine.system() == 'darwin'
   libstore_sources += files('platform/darwin.cc')
   libstore_headers += files('platform/darwin.hh')
+elif host_machine.system() == 'freebsd'
+  libstore_sources += files('platform/freebsd.cc')
+  libstore_headers += files('platform/freebsd.hh')
 else
   libstore_sources += files('platform/fallback.cc')
   libstore_headers += files('platform/fallback.hh')
@@ -202,23 +205,29 @@ foreach name, value : cpp_str_defines
   ]
 endforeach
 
+dependencies = [
+  libarchive,
+  liblixutil, # Internal.
+  seccomp,
+  sqlite,
+  sodium,
+  curl,
+  openssl,
+  aws_sdk,
+  aws_s3,
+  aws_sdk_transfer,
+  nlohmann_json,
+]
+
+if host_machine.system() == 'freebsd'
+  dependencies += [ libprocstat ]
+endif
+
 libstore = library(
   'lixstore',
   libstore_generated_headers,
   libstore_sources,
-  dependencies : [
-    libarchive,
-    liblixutil, # Internal.
-    seccomp,
-    sqlite,
-    sodium,
-    curl,
-    openssl,
-    aws_sdk,
-    aws_s3,
-    aws_sdk_transfer,
-    nlohmann_json,
-  ],
+  dependencies : dependencies,
   cpp_args : cpp_args,
   cpp_pch : cpp_pch,
   install : true,
diff --git a/src/libstore/platform.cc b/src/libstore/platform.cc
index d10d33f0e..72757e39b 100644
--- a/src/libstore/platform.cc
+++ b/src/libstore/platform.cc
@@ -5,6 +5,8 @@
 #include "platform/linux.hh"
 #elif __APPLE__
 #include "platform/darwin.hh"
+#elif __FreeBSD__
+#include "platform/freebsd.hh"
 #else
 #include "platform/fallback.hh"
 #endif
@@ -16,6 +18,8 @@ std::shared_ptr<LocalStore> LocalStore::makeLocalStore(const Params & params)
     return std::shared_ptr<LocalStore>(new LinuxLocalStore(params));
 #elif __APPLE__
     return std::shared_ptr<LocalStore>(new DarwinLocalStore(params));
+#elif __FreeBSD__
+    return std::shared_ptr<LocalStore>(new FreeBSDLocalStore(params));
 #else
     return std::shared_ptr<LocalStore>(new FallbackLocalStore(params));
 #endif
@@ -32,6 +36,8 @@ std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
     return std::make_shared<LinuxLocalDerivationGoal>(drvPath, wantedOutputs, worker, buildMode);
 #elif __APPLE__
     return std::make_shared<DarwinLocalDerivationGoal>(drvPath, wantedOutputs, worker, buildMode);
+#elif __FreeBSD__
+    return std::make_shared<FreeBSDLocalDerivationGoal>(drvPath, wantedOutputs, worker, buildMode);
 #else
     return std::make_shared<FallbackLocalDerivationGoal>(drvPath, wantedOutputs, worker, buildMode);
 #endif
@@ -53,6 +59,10 @@ std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
     return std::make_shared<DarwinLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, buildMode
     );
+#elif __FreeBSD__
+    return std::make_shared<FreeBSDLocalDerivationGoal>(
+        drvPath, drv, wantedOutputs, worker, buildMode
+    );
 #else
     return std::make_shared<FallbackLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, buildMode
diff --git a/src/libstore/platform/freebsd.cc b/src/libstore/platform/freebsd.cc
new file mode 100644
index 000000000..bdba1abf5
--- /dev/null
+++ b/src/libstore/platform/freebsd.cc
@@ -0,0 +1,142 @@
+#include "platform/freebsd.hh"
+#include "regex.hh"
+#include <sys/param.h>
+#include <sys/queue.h>
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#include <libprocstat.h>
+
+namespace nix {
+
+static void readSysctlRoots(const char * name, UncheckedRoots & unchecked)
+{
+    size_t len = 0;
+    std::string value;
+    if (int err = sysctlbyname(name, nullptr, &len, nullptr, 0) < 0) {
+        if (err == ENOENT || err == EACCES) {
+            return;
+        } else {
+            throw SysError(err, "sysctlbyname %1%", name);
+        }
+    }
+
+    value.resize(len, ' ');
+    if (int err = sysctlbyname(name, value.data(), &len, nullptr, 0) < 0) {
+        if (err == ENOENT || err == EACCES) {
+            return;
+        } else {
+            throw SysError(err, "sysctlbyname %1%", name);
+        }
+    }
+
+    for (auto & path : tokenizeString<Strings>(value, ";")) {
+        unchecked[path].emplace(fmt("{{sysctl:%1%}}", name));
+    }
+}
+
+struct ProcstatDeleter
+{
+    void operator()(struct procstat * ps)
+    {
+        procstat_close(ps);
+    }
+};
+
+template<auto del>
+struct ProcstatReferredDeleter
+{
+    struct procstat * ps;
+
+    ProcstatReferredDeleter(struct procstat * ps) : ps(ps) {}
+
+    template<typename T>
+    void operator()(T * p)
+    {
+        del(ps, p);
+    }
+};
+
+void FreeBSDLocalStore::findPlatformRoots(UncheckedRoots & unchecked)
+{
+    readSysctlRoots("kern.module_path", unchecked);
+
+    auto storePathRegex = regex::storePathRegex(storeDir);
+
+    auto ps = std::unique_ptr<struct procstat, ProcstatDeleter>(procstat_open_sysctl());
+    if (!ps) {
+        throw SysError("procstat_open_sysctl");
+    }
+
+    auto procs = std::unique_ptr<struct kinfo_proc[], ProcstatReferredDeleter<procstat_freeprocs>>(
+        nullptr, ps.get()
+    );
+    auto files = std::unique_ptr<struct filestat_list, ProcstatReferredDeleter<procstat_freefiles>>(
+        nullptr, ps.get()
+    );
+
+    unsigned int numprocs = 0;
+    procs.reset(procstat_getprocs(ps.get(), KERN_PROC_PROC, 0, &numprocs));
+    if (!procs || numprocs == 0) {
+        throw SysError("procstat_getprocs");
+    };
+
+    for (unsigned int procidx = 0; procidx < numprocs; procidx++) {
+        // Includes file descriptors, executable, cwd,
+        // and mmapped files (including dynamic libraries)
+        files.reset(procstat_getfiles(ps.get(), &procs[procidx], 1));
+        // We only have permission if we're root so just skip it if we fail
+        if (!files) {
+            continue;
+        }
+
+        for (struct filestat * file = files->stqh_first; file; file = file->next.stqe_next) {
+            if (!file->fs_path) {
+                continue;
+            }
+
+            std::string role;
+            if (file->fs_uflags & PS_FST_UFLAG_CTTY) {
+                role = "ctty";
+            } else if (file->fs_uflags & PS_FST_UFLAG_CDIR) {
+                role = "cwd";
+            } else if (file->fs_uflags & PS_FST_UFLAG_JAIL) {
+                role = "jail";
+            } else if (file->fs_uflags & PS_FST_UFLAG_RDIR) {
+                role = "root";
+            } else if (file->fs_uflags & PS_FST_UFLAG_TEXT) {
+                role = "text";
+            } else if (file->fs_uflags & PS_FST_UFLAG_TRACE) {
+                role = "trace";
+            } else if (file->fs_uflags & PS_FST_UFLAG_MMAP) {
+                role = "mmap";
+            } else {
+                role = fmt("fd/%1%", file->fs_fd);
+            }
+
+            unchecked[file->fs_path].emplace(fmt("{procstat:%1%/%2%}", procs[procidx].ki_pid, role)
+            );
+        }
+
+        auto env_name = fmt("{procstat:%1%/env}", procs[procidx].ki_pid);
+        // No need to free, the buffer is reused on next call and deallocated in procstat_close
+        char ** env = procstat_getenvv(ps.get(), &procs[procidx], 0);
+        if (env == nullptr) {
+            continue;
+        }
+
+        for (size_t i = 0; env[i]; i++) {
+            auto envString = std::string(env[i]);
+
+            auto envEnd = std::sregex_iterator{};
+            for (auto match =
+                     std::sregex_iterator{envString.begin(), envString.end(), storePathRegex};
+                 match != envEnd;
+                 match++)
+            {
+                unchecked[match->str()].emplace(env_name);
+            }
+        }
+    }
+}
+}
diff --git a/src/libstore/platform/freebsd.hh b/src/libstore/platform/freebsd.hh
new file mode 100644
index 000000000..99aff3c10
--- /dev/null
+++ b/src/libstore/platform/freebsd.hh
@@ -0,0 +1,47 @@
+#pragma once
+///@file
+
+#include "build/local-derivation-goal.hh"
+#include "gc-store.hh"
+#include "local-store.hh"
+
+namespace nix {
+
+/**
+ * FreeBSD-specific implementation of LocalStore
+ */
+class FreeBSDLocalStore : public LocalStore
+{
+public:
+    FreeBSDLocalStore(const Params & params)
+        : StoreConfig(params)
+        , LocalFSStoreConfig(params)
+        , LocalStoreConfig(params)
+        , Store(params)
+        , LocalFSStore(params)
+        , LocalStore(params)
+    {
+    }
+    FreeBSDLocalStore(const std::string scheme, std::string path, const Params & params)
+        : FreeBSDLocalStore(params)
+    {
+        throw UnimplementedError("FreeBSDLocalStore");
+    }
+
+private:
+
+    void findPlatformRoots(UncheckedRoots & unchecked) override;
+};
+
+/**
+ * FreeBSD-specific implementation of LocalDerivationGoal
+ */
+class FreeBSDLocalDerivationGoal : public LocalDerivationGoal
+{
+public:
+    using LocalDerivationGoal::LocalDerivationGoal;
+
+private:
+};
+
+}