1 files changed, 83 insertions, 21 deletions

diff --git a/absl/time/internal/cctz/src/time_zone_info.cc b/absl/time/internal/cctz/src/time_zone_info.cc
index 8039353e..4f175d95 100644
--- a/absl/time/internal/cctz/src/time_zone_info.cc
+++ b/absl/time/internal/cctz/src/time_zone_info.cc
@@ -39,10 +39,12 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <fstream>
 #include <functional>
 #include <memory>
 #include <sstream>
 #include <string>
+#include <utility>
 
 #include "absl/base/config.h"
 #include "absl/time/internal/cctz/include/cctz/civil_time.h"
@@ -576,14 +578,17 @@ bool TimeZoneInfo::Load(ZoneInfoSource* zip) {
 
 namespace {
 
+using FilePtr = std::unique_ptr<FILE, int (*)(FILE*)>;
+
 // fopen(3) adaptor.
-inline FILE* FOpen(const char* path, const char* mode) {
+inline FilePtr FOpen(const char* path, const char* mode) {
 #if defined(_MSC_VER)
   FILE* fp;
   if (fopen_s(&fp, path, mode) != 0) fp = nullptr;
-  return fp;
+  return FilePtr(fp, fclose);
 #else
-  return fopen(path, mode);  // TODO: Enable the close-on-exec flag.
+  // TODO: Enable the close-on-exec flag.
+  return FilePtr(fopen(path, mode), fclose);
 #endif
 }
 
@@ -611,11 +616,11 @@ class FileZoneInfoSource : public ZoneInfoSource {
 
  protected:
   explicit FileZoneInfoSource(
-      FILE* fp, std::size_t len = std::numeric_limits<std::size_t>::max())
-      : fp_(fp, fclose), len_(len) {}
+      FilePtr fp, std::size_t len = std::numeric_limits<std::size_t>::max())
+      : fp_(std::move(fp)), len_(len) {}
 
  private:
-  std::unique_ptr<FILE, int (*)(FILE*)> fp_;
+  FilePtr fp_;
   std::size_t len_;
 };
 
@@ -644,17 +649,9 @@ std::unique_ptr<ZoneInfoSource> FileZoneInfoSource::Open(
   path.append(name, pos, std::string::npos);
 
   // Open the zoneinfo file.
-  FILE* fp = FOpen(path.c_str(), "rb");
+  auto fp = FOpen(path.c_str(), "rb");
   if (fp == nullptr) return nullptr;
-  std::size_t length = 0;
-  if (fseek(fp, 0, SEEK_END) == 0) {
-    long offset = ftell(fp);
-    if (offset >= 0) {
-      length = static_cast<std::size_t>(offset);
-    }
-    rewind(fp);
-  }
-  return std::unique_ptr<ZoneInfoSource>(new FileZoneInfoSource(fp, length));
+  return std::unique_ptr<ZoneInfoSource>(new FileZoneInfoSource(std::move(fp)));
 }
 
 class AndroidZoneInfoSource : public FileZoneInfoSource {
@@ -663,8 +660,9 @@ class AndroidZoneInfoSource : public FileZoneInfoSource {
   std::string Version() const override { return version_; }
 
  private:
-  explicit AndroidZoneInfoSource(FILE* fp, std::size_t len, const char* vers)
-      : FileZoneInfoSource(fp, len), version_(vers) {}
+  explicit AndroidZoneInfoSource(FilePtr fp, std::size_t len,
+                                 std::string version)
+      : FileZoneInfoSource(std::move(fp), len), version_(std::move(version)) {}
   std::string version_;
 };
 
@@ -676,8 +674,8 @@ std::unique_ptr<ZoneInfoSource> AndroidZoneInfoSource::Open(
   // See Android's libc/tzcode/bionic.cpp for additional information.
   for (const char* tzdata : {"/data/misc/zoneinfo/current/tzdata",
                              "/system/usr/share/zoneinfo/tzdata"}) {
-    std::unique_ptr<FILE, int (*)(FILE*)> fp(FOpen(tzdata, "rb"), fclose);
-    if (fp.get() == nullptr) continue;
+    auto fp = FOpen(tzdata, "rb");
+    if (fp == nullptr) continue;
 
     char hbuf[24];  // covers header.zonetab_offset too
     if (fread(hbuf, 1, sizeof(hbuf), fp.get()) != sizeof(hbuf)) continue;
@@ -703,7 +701,7 @@ std::unique_ptr<ZoneInfoSource> AndroidZoneInfoSource::Open(
       if (strcmp(name.c_str() + pos, ebuf) == 0) {
         if (fseek(fp.get(), static_cast<long>(start), SEEK_SET) != 0) break;
         return std::unique_ptr<ZoneInfoSource>(new AndroidZoneInfoSource(
-            fp.release(), static_cast<std::size_t>(length), vers));
+            std::move(fp), static_cast<std::size_t>(length), vers));
       }
     }
   }
@@ -711,6 +709,69 @@ std::unique_ptr<ZoneInfoSource> AndroidZoneInfoSource::Open(
   return nullptr;
 }
 
+// A zoneinfo source for use inside Fuchsia components. This attempts to
+// read zoneinfo files from one of several known paths in a component's
+// incoming namespace. [Config data][1] is preferred, but package-specific
+// resources are also supported.
+//
+// Fuchsia's implementation supports `FileZoneInfoSource::Version()`.
+//
+// [1]:
+// https://fuchsia.dev/fuchsia-src/development/components/data#using_config_data_in_your_component
+class FuchsiaZoneInfoSource : public FileZoneInfoSource {
+ public:
+  static std::unique_ptr<ZoneInfoSource> Open(const std::string& name);
+  std::string Version() const override { return version_; }
+
+ private:
+  explicit FuchsiaZoneInfoSource(FilePtr fp, std::string version)
+      : FileZoneInfoSource(std::move(fp)), version_(std::move(version)) {}
+  std::string version_;
+};
+
+std::unique_ptr<ZoneInfoSource> FuchsiaZoneInfoSource::Open(
+    const std::string& name) {
+  // Use of the "file:" prefix is intended for testing purposes only.
+  const std::size_t pos = (name.compare(0, 5, "file:") == 0) ? 5 : 0;
+
+  // Prefixes where a Fuchsia component might find zoneinfo files,
+  // in descending order of preference.
+  const auto kTzdataPrefixes = {
+      "/config/data/tzdata/",
+      "/pkg/data/tzdata/",
+      "/data/tzdata/",
+  };
+  const auto kEmptyPrefix = {""};
+  const bool name_absolute = (pos != name.size() && name[pos] == '/');
+  const auto prefixes = name_absolute ? kEmptyPrefix : kTzdataPrefixes;
+
+  // Fuchsia builds place zoneinfo files at "<prefix><format><name>".
+  for (const std::string prefix : prefixes) {
+    std::string path = prefix;
+    if (!prefix.empty()) path += "zoneinfo/tzif2/";  // format
+    path.append(name, pos, std::string::npos);
+
+    auto fp = FOpen(path.c_str(), "rb");
+    if (fp == nullptr) continue;
+
+    std::string version;
+    if (!prefix.empty()) {
+      // Fuchsia builds place the version in "<prefix>revision.txt".
+      std::ifstream version_stream(prefix + "revision.txt");
+      if (version_stream.is_open()) {
+        // revision.txt should contain no newlines, but to be
+        // defensive we read just the first line.
+        std::getline(version_stream, version);
+      }
+    }
+
+    return std::unique_ptr<ZoneInfoSource>(
+        new FuchsiaZoneInfoSource(std::move(fp), std::move(version)));
+  }
+
+  return nullptr;
+}
+
 }  // namespace
 
 bool TimeZoneInfo::Load(const std::string& name) {
@@ -728,6 +789,7 @@ bool TimeZoneInfo::Load(const std::string& name) {
       name, [](const std::string& n) -> std::unique_ptr<ZoneInfoSource> {
         if (auto z = FileZoneInfoSource::Open(n)) return z;
         if (auto z = AndroidZoneInfoSource::Open(n)) return z;
+        if (auto z = FuchsiaZoneInfoSource::Open(n)) return z;
         return nullptr;
       });
   return zip != nullptr && Load(zip.get());