From 5fc53bd74c7635a292cef041180da4cd32b7fb12 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 24 Feb 2015 06:09:23 +0200
Subject: Add fsdir{} for creating directories

---
 build/b.cxx      |  6 +++++-
 build/rule       | 13 +++++++++++++
 build/rule.cxx   | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 build/target     | 17 ++++++++++++++++
 build/target.cxx |  9 +++++++++
 5 files changed, 103 insertions(+), 1 deletion(-)

diff --git a/build/b.cxx b/build/b.cxx
index 1edce6b..05dac4c 100644
--- a/build/b.cxx
+++ b/build/b.cxx
@@ -84,6 +84,7 @@ main (int argc, char* argv[])
     //
     target_types.insert (file::static_type);
     target_types.insert (dir::static_type);
+    target_types.insert (fsdir::static_type);
 
     target_types.insert (exe::static_type);
     target_types.insert (obj::static_type);
@@ -164,7 +165,7 @@ main (int argc, char* argv[])
 
     try
     {
-      p.parse (ifs, bf, scopes[path::current ()]);
+      p.parse (ifs, bf, scopes[out_base]);
     }
     catch (const std::ios_base::failure&)
     {
@@ -184,6 +185,9 @@ main (int argc, char* argv[])
     dir_rule dir_r;
     rules[typeid (dir)].emplace ("dir", dir_r);
 
+    fsdir_rule fsdir_r;
+    rules[typeid (fsdir)].emplace ("fsdir", fsdir_r);
+
     path_rule path_r;
     rules[typeid (path_target)].emplace ("path", path_r);
 
diff --git a/build/rule b/build/rule
index cbaac04..4336c8f 100644
--- a/build/rule
+++ b/build/rule
@@ -58,6 +58,19 @@ namespace build
     static target_state
     update (target&);
   };
+
+  class fsdir_rule: public rule
+  {
+  public:
+    virtual void*
+    match (target&, const std::string& hint) const;
+
+    virtual recipe
+    apply (target&, void*) const;
+
+    static target_state
+    update (target&);
+  };
 }
 
 #endif // BUILD_RULE
diff --git a/build/rule.cxx b/build/rule.cxx
index dcb6df1..e57feca 100644
--- a/build/rule.cxx
+++ b/build/rule.cxx
@@ -4,10 +4,15 @@
 
 #include <build/rule>
 
+#include <string.h>    // strerror_r()
+#include <sys/stat.h>  // mkdir()
+#include <sys/types.h> // mkdir()
+
 #include <utility>  // move()
 
 #include <build/algorithm>
 #include <build/diagnostics>
+#include <build/timestamp>
 
 using namespace std;
 
@@ -121,4 +126,58 @@ namespace build
     //
     return update_prerequisites (t);
   }
+
+  // fsdir_rule
+  //
+  void* fsdir_rule::
+  match (target& t, const string&) const
+  {
+    return &t;
+  }
+
+  recipe fsdir_rule::
+  apply (target& t, void*) const
+  {
+    // Let's not allow any prerequisites for this target since it
+    // doesn't make much sense. The sole purpose of this target type
+    // is to create a directory.
+    //
+    if (!t.prerequisites.empty ())
+      fail << "no prerequisites allowed for target " << t;
+
+    return &update;
+  }
+
+  target_state fsdir_rule::
+  update (target& t)
+  {
+    path d (t.dir / path (t.name));
+
+    // Add the extension back if it was specified.
+    //
+    if (t.ext != nullptr)
+    {
+      d += '.';
+      d += *t.ext;
+    }
+
+    if (path_mtime (d) != timestamp_nonexistent)
+      return target_state::uptodate;
+
+    if (verb >= 1)
+      text << "mkdir " << d.string ();
+    else
+      text << "mkdir " << t; //@@ Probably only show if [show]?
+
+    if (mkdir (d.string ().c_str (), 0777) != 0)
+    {
+      char b[512];
+      const char* m (strerror_r (errno, b, sizeof (b)) == 0
+                     ? b
+                     : "error message too long");
+      fail << "mkdir: unable to create directory " << d.string () << ": " << m;
+    }
+
+    return target_state::updated;
+  }
 }
diff --git a/build/target b/build/target
index da5cf71..881bfb7 100644
--- a/build/target
+++ b/build/target
@@ -255,6 +255,23 @@ namespace build
     virtual const target_type& type () const {return static_type;}
     static const target_type static_type;
   };
+
+  // While a filesystem directory is mtime-based, the semantics is
+  // not very useful in our case. In particular, if another target
+  // depends on fsdir{}, then all that's desired is the creation of
+  // the directory if it doesn't already exist. In particular, we
+  // don't want to update the target just because some unrelated
+  // entry was created in that directory.
+  //
+  class fsdir: public target
+  {
+  public:
+    using target::target;
+
+  public:
+    virtual const target_type& type () const {return static_type;}
+    static const target_type static_type;
+  };
 }
 
 #endif // BUILD_TARGET
diff --git a/build/target.cxx b/build/target.cxx
index 50a7cc6..235ceef 100644
--- a/build/target.cxx
+++ b/build/target.cxx
@@ -212,4 +212,13 @@ namespace build
     &target_factory<dir>,
     &search_alias
   };
+
+  const target_type fsdir::static_type
+  {
+    typeid (fsdir),
+    "fsdir",
+    &target::static_type,
+    &target_factory<fsdir>,
+    target::static_type.search
+  };
 }
-- 
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