From c828e2bb39f711c82c3b816f57ddde9ab29bdb20 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 18 Jun 2015 17:27:25 +0200
Subject: Move path_mtime to filesystem, rename file_mtime, follow symlinks

---
 butl/filesystem     | 11 ++++++++++-
 butl/filesystem.cxx | 44 +++++++++++++++++++++++++++++++++++++++++++-
 butl/timestamp      | 13 +++++--------
 butl/timestamp.cxx  | 44 --------------------------------------------
 4 files changed, 58 insertions(+), 54 deletions(-)

diff --git a/butl/filesystem b/butl/filesystem
index 10f61f2..18ba48e 100644
--- a/butl/filesystem
+++ b/butl/filesystem
@@ -8,9 +8,18 @@
 #include <sys/types.h> // mode_t
 
 #include <butl/path>
+#include <butl/timestamp>
 
 namespace butl
 {
+  // Return timestamp_nonexistent if the entry at the specified path
+  // does not exist or is not a path. All other errors are reported
+  // by throwing std::system_error. Note that this function resolves
+  // symlinks.
+  //
+  timestamp
+  file_mtime (const path&);
+
   // Return true if the path is to an existing directory. Note that
   // this function resolves symlinks.
   //
@@ -48,7 +57,7 @@ namespace butl
   rmdir_status
   try_rmdir (const path&);
 
-  // Try to remove the file (or symbolic link) returning not_exist if
+  // Try to remove the file (or symlinks) returning not_exist if
   // it does not exist. All other errors are reported by throwing
   // std::system_error.
   //
diff --git a/butl/filesystem.cxx b/butl/filesystem.cxx
index 230bc8e..7c8893e 100644
--- a/butl/filesystem.cxx
+++ b/butl/filesystem.cxx
@@ -4,7 +4,7 @@
 
 #include <butl/filesystem>
 
-#include <unistd.h>    // rmdir(), unlink()
+#include <unistd.h>    // stat, rmdir(), unlink()
 #include <sys/types.h> // stat
 #include <sys/stat.h>  // stat, lstat(), S_IS*, mkdir()
 
@@ -14,6 +14,48 @@ using namespace std;
 
 namespace butl
 {
+  // Figuring out whether we have the nanoseconds in some form.
+  //
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtim.tv_nsec)
+  {
+    return s->st_mtim.tv_nsec; // POSIX (GNU/Linux, Solaris).
+  }
+
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtimespec.tv_nsec)
+  {
+    return s->st_mtimespec.tv_nsec; // MacOS X.
+  }
+
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtime_n)
+  {
+    return s->st_mtime_n; // AIX 5.2 and later.
+  }
+
+  template <typename S>
+  constexpr int nsec (...) {return 0;}
+
+  timestamp
+  file_mtime (const path& p)
+  {
+    struct stat s;
+    if (::lstat (p.string ().c_str (), &s) != 0)
+    {
+      if (errno == ENOENT || errno == ENOTDIR)
+        return timestamp_nonexistent;
+      else
+        throw system_error (errno, system_category ());
+    }
+
+    return S_ISREG (s.st_mode)
+      ? system_clock::from_time_t (s.st_mtime) +
+      chrono::duration_cast<duration> (
+        chrono::nanoseconds (nsec<struct stat> (&s)))
+      : timestamp_nonexistent;
+  }
+
   bool
   dir_exists (const path& p)
   {
diff --git a/butl/timestamp b/butl/timestamp
index 76df07b..f397dc6 100644
--- a/butl/timestamp
+++ b/butl/timestamp
@@ -6,7 +6,6 @@
 #define BUTL_TIMESTAMP
 
 #include <chrono>
-#include <string>
 #include <iosfwd>
 
 #include <butl/path>
@@ -34,21 +33,19 @@ namespace butl
   using timestamp = system_clock::time_point;
   using duration = system_clock::duration;
 
+  // Generally-useful special values.
+  //
   const timestamp timestamp_unknown {duration {-1}};
   const timestamp timestamp_nonexistent {duration {0}};
 
+  // Human-readable representation. Note that these operators
+  // may throw std::system_error.
+  //
   std::ostream&
   operator<< (std::ostream&, const timestamp&);
 
   std::ostream&
   operator<< (std::ostream&, const duration&);
-
-  // Returns timestamp_nonexistent if the entry at the specified path
-  // does not exist. All other errors are reported by throwing
-  // std::system_error.
-  //
-  timestamp
-  path_mtime (const path&);
 };
 
 #endif // BUTL_TIMESTAMP
diff --git a/butl/timestamp.cxx b/butl/timestamp.cxx
index 2d02416..f9f5455 100644
--- a/butl/timestamp.cxx
+++ b/butl/timestamp.cxx
@@ -4,10 +4,6 @@
 
 #include <butl/timestamp>
 
-#include <unistd.h>    // stat
-#include <sys/types.h> // stat
-#include <sys/stat.h>  // stat
-
 #include <time.h> // localtime, gmtime, strftime
 
 #include <ostream>
@@ -17,46 +13,6 @@ using namespace std;
 
 namespace butl
 {
-  // Figuring out whether we have the nanoseconds in some form.
-  //
-  template <typename S>
-  constexpr auto nsec (const S* s) -> decltype(s->st_mtim.tv_nsec)
-  {
-    return s->st_mtim.tv_nsec; // POSIX (GNU/Linux, Solaris).
-  }
-
-  template <typename S>
-  constexpr auto nsec (const S* s) -> decltype(s->st_mtimespec.tv_nsec)
-  {
-    return s->st_mtimespec.tv_nsec; // MacOS X.
-  }
-
-  template <typename S>
-  constexpr auto nsec (const S* s) -> decltype(s->st_mtime_n)
-  {
-    return s->st_mtime_n; // AIX 5.2 and later.
-  }
-
-  template <typename S>
-  constexpr int nsec (...) {return 0;}
-
-  timestamp
-  path_mtime (const path& p)
-  {
-    struct stat s;
-    if (stat (p.string ().c_str (), &s) != 0)
-    {
-      if (errno == ENOENT || errno == ENOTDIR)
-        return timestamp_nonexistent;
-      else
-        throw system_error (errno, system_category ());
-    }
-
-    return system_clock::from_time_t (s.st_mtime) +
-      chrono::duration_cast<duration> (
-        chrono::nanoseconds (nsec<struct stat> (&s)));
-  }
-
   ostream&
   operator<< (ostream& os, const timestamp& ts)
   {
-- 
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