1 files changed, 252 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/profiles.cc b/third_party/nix/src/libstore/profiles.cc
new file mode 100644
index 000000000000..53e64879954b
--- /dev/null
+++ b/third_party/nix/src/libstore/profiles.cc
@@ -0,0 +1,252 @@
+#include "profiles.hh"
+
+#include <cerrno>
+#include <cstdio>
+
+#include <absl/strings/numbers.h>
+#include <absl/strings/string_view.h>
+#include <absl/strings/strip.h>
+#include <glog/logging.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "store-api.hh"
+#include "util.hh"
+
+namespace nix {
+
+static bool cmpGensByNumber(const Generation& a, const Generation& b) {
+  return a.number < b.number;
+}
+
+// Parse a generation out of the format
+// `<profilename>-<generation>-link'.
+static int parseName(absl::string_view profileName, absl::string_view name) {
+  // Consume the `<profilename>-' prefix and and `-link' suffix.
+  if (!(absl::ConsumePrefix(&name, profileName) &&
+        absl::ConsumePrefix(&name, "-") &&
+        absl::ConsumeSuffix(&name, "-link"))) {
+    return -1;
+  }
+
+  int n;
+  if (!absl::SimpleAtoi(name, &n) || n < 0) {
+    return -1;
+  }
+
+  return n;
+}
+
+Generations findGenerations(const Path& profile, int& curGen) {
+  Generations gens;
+
+  Path profileDir = dirOf(profile);
+  std::string profileName = baseNameOf(profile);
+
+  for (auto& i : readDirectory(profileDir)) {
+    int n;
+    if ((n = parseName(profileName, i.name)) != -1) {
+      Generation gen;
+      gen.path = profileDir + "/" + i.name;
+      gen.number = n;
+      struct stat st;
+      if (lstat(gen.path.c_str(), &st) != 0) {
+        throw SysError(format("statting '%1%'") % gen.path);
+      }
+      gen.creationTime = st.st_mtime;
+      gens.push_back(gen);
+    }
+  }
+
+  gens.sort(cmpGensByNumber);
+
+  curGen = pathExists(profile) ? parseName(profileName, readLink(profile)) : -1;
+
+  return gens;
+}
+
+static void makeName(const Path& profile, unsigned int num, Path& outLink) {
+  Path prefix = (format("%1%-%2%") % profile % num).str();
+  outLink = prefix + "-link";
+}
+
+Path createGeneration(const ref<LocalFSStore>& store, const Path& profile,
+                      const Path& outPath) {
+  /* The new generation number should be higher than old the
+     previous ones. */
+  int dummy;
+  Generations gens = findGenerations(profile, dummy);
+
+  unsigned int num;
+  if (!gens.empty()) {
+    Generation last = gens.back();
+
+    if (readLink(last.path) == outPath) {
+      /* We only create a new generation symlink if it differs
+         from the last one.
+
+         This helps keeping gratuitous installs/rebuilds from piling
+         up uncontrolled numbers of generations, cluttering up the
+         UI like grub. */
+      return last.path;
+    }
+
+    num = gens.back().number;
+  } else {
+    num = 0;
+  }
+
+  /* Create the new generation.  Note that addPermRoot() blocks if
+     the garbage collector is running to prevent the stuff we've
+     built from moving from the temporary roots (which the GC knows)
+     to the permanent roots (of which the GC would have a stale
+     view).  If we didn't do it this way, the GC might remove the
+     user environment etc. we've just built. */
+  Path generation;
+  makeName(profile, num + 1, generation);
+  store->addPermRoot(outPath, generation, false, true);
+
+  return generation;
+}
+
+static void removeFile(const Path& path) {
+  if (remove(path.c_str()) == -1) {
+    throw SysError(format("cannot unlink '%1%'") % path);
+  }
+}
+
+void deleteGeneration(const Path& profile, unsigned int gen) {
+  Path generation;
+  makeName(profile, gen, generation);
+  removeFile(generation);
+}
+
+static void deleteGeneration2(const Path& profile, unsigned int gen,
+                              bool dryRun) {
+  if (dryRun) {
+    LOG(INFO) << "would remove generation " << gen;
+  } else {
+    LOG(INFO) << "removing generation " << gen;
+    deleteGeneration(profile, gen);
+  }
+}
+
+void deleteGenerations(const Path& profile,
+                       const std::set<unsigned int>& gensToDelete,
+                       bool dryRun) {
+  PathLocks lock;
+  lockProfile(lock, profile);
+
+  int curGen;
+  Generations gens = findGenerations(profile, curGen);
+
+  if (gensToDelete.find(curGen) != gensToDelete.end()) {
+    throw Error(format("cannot delete current generation of profile %1%'") %
+                profile);
+  }
+
+  for (auto& i : gens) {
+    if (gensToDelete.find(i.number) == gensToDelete.end()) {
+      continue;
+    }
+    deleteGeneration2(profile, i.number, dryRun);
+  }
+}
+
+void deleteGenerationsGreaterThan(const Path& profile, int max, bool dryRun) {
+  PathLocks lock;
+  lockProfile(lock, profile);
+
+  int curGen;
+  bool fromCurGen = false;
+  Generations gens = findGenerations(profile, curGen);
+  for (auto i = gens.rbegin(); i != gens.rend(); ++i) {
+    if (i->number == curGen) {
+      fromCurGen = true;
+      max--;
+      continue;
+    }
+    if (fromCurGen) {
+      if (max != 0) {
+        max--;
+        continue;
+      }
+      deleteGeneration2(profile, i->number, dryRun);
+    }
+  }
+}
+
+void deleteOldGenerations(const Path& profile, bool dryRun) {
+  PathLocks lock;
+  lockProfile(lock, profile);
+
+  int curGen;
+  Generations gens = findGenerations(profile, curGen);
+
+  for (auto& i : gens) {
+    if (i.number != curGen) {
+      deleteGeneration2(profile, i.number, dryRun);
+    }
+  }
+}
+
+void deleteGenerationsOlderThan(const Path& profile, time_t t, bool dryRun) {
+  PathLocks lock;
+  lockProfile(lock, profile);
+
+  int curGen;
+  Generations gens = findGenerations(profile, curGen);
+
+  bool canDelete = false;
+  for (auto i = gens.rbegin(); i != gens.rend(); ++i) {
+    if (canDelete) {
+      assert(i->creationTime < t);
+      if (i->number != curGen) {
+        deleteGeneration2(profile, i->number, dryRun);
+      }
+    } else if (i->creationTime < t) {
+      /* We may now start deleting generations, but we don't
+         delete this generation yet, because this generation was
+         still the one that was active at the requested point in
+         time. */
+      canDelete = true;
+    }
+  }
+}
+
+void deleteGenerationsOlderThan(const Path& profile,
+                                const std::string& timeSpec, bool dryRun) {
+  time_t curTime = time(nullptr);
+  std::string strDays = std::string(timeSpec, 0, timeSpec.size() - 1);
+  int days;
+
+  if (!absl::SimpleAtoi(strDays, &days) || days < 1) {
+    throw Error(format("invalid number of days specifier '%1%'") % timeSpec);
+  }
+
+  time_t oldTime = curTime - days * 24 * 3600;
+
+  deleteGenerationsOlderThan(profile, oldTime, dryRun);
+}
+
+void switchLink(const Path& link, Path target) {
+  /* Hacky. */
+  if (dirOf(target) == dirOf(link)) {
+    target = baseNameOf(target);
+  }
+
+  replaceSymlink(target, link);
+}
+
+void lockProfile(PathLocks& lock, const Path& profile) {
+  lock.lockPaths({profile},
+                 (format("waiting for lock on profile '%1%'") % profile).str());
+  lock.setDeletion(true);
+}
+
+std::string optimisticLockProfile(const Path& profile) {
+  return pathExists(profile) ? readLink(profile) : "";
+}
+
+}  // namespace nix