From b27f36b7af5186ad66fd1afa6e7fdc742f2aa1bd Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 21 May 2020 22:47:10 +0300
Subject: Make build script to create special files in temporary directory

---
 libbuild2/build/script/runner.cxx | 97 ++++++++++++++++++++++++++++++++++++++-
 libbuild2/build/script/script.cxx |  4 +-
 libbuild2/build/script/script.hxx | 14 ++++--
 3 files changed, 108 insertions(+), 7 deletions(-)

(limited to 'libbuild2/build/script')

diff --git a/libbuild2/build/script/runner.cxx b/libbuild2/build/script/runner.cxx
index 5535bbb..c4a93fd 100644
--- a/libbuild2/build/script/runner.cxx
+++ b/libbuild2/build/script/runner.cxx
@@ -3,8 +3,12 @@
 
 #include <libbuild2/build/script/runner.hxx>
 
+#include <libbutl/filesystem.mxx>
+
 #include <libbuild2/script/run.hxx>
 
+using namespace butl;
+
 namespace build2
 {
   namespace build
@@ -12,15 +16,104 @@ namespace build2
     namespace script
     {
       void default_runner::
-      enter (environment&, const location&)
+      enter (environment& env, const location& ll)
       {
-        // Noop.
+        // Create the temporary directory for this run regardless of the
+        // dry-run mode, since some commands still can be executed (see run()
+        // for details). This also a reason for not using the build2
+        // filesystem API that considers the dry-run mode.
+        //
+        // Note that the directory auto-removal is active.
+        //
+        dir_path& td (env.temp_dir.path);
+
+        try
+        {
+          td = dir_path::temp_path ("build2-build-script");
+        }
+        catch (const system_error& e)
+        {
+          // While there can be no fault of the script being currently
+          // executed let's add the location anyway to ease the
+          // troubleshooting. And let's stick to that principle down the road.
+          //
+          fail (ll) << "unable to obtain temporary directory for buildscript "
+                    << "execution" << e;
+        }
+
+        mkdir_status r;
+
+        try
+        {
+          r = try_mkdir (td);
+        }
+        catch (const system_error& e)
+        {
+          fail(ll) << "unable to create temporary directory '" << td << "': "
+                   << e << endf;
+        }
+
+        // Note that the temporary directory can potentially stay after some
+        // abnormally terminated script run. Clean it up and reuse if that's
+        // the case.
+        //
+        if (r == mkdir_status::already_exists)
+        try
+        {
+          butl::rmdir_r (td, false /* dir */);
+        }
+        catch (const system_error& e)
+        {
+          fail (ll) << "unable to cleanup temporary directory '" << td
+                    << "': " << e;
+        }
+
+        if (verb >= 3)
+          text << "mkdir " << td;
       }
 
       void default_runner::
       leave (environment& env, const location& ll)
       {
         clean (env, ll);
+
+        // Note that since the temporary directory may only contain special
+        // files that are created and registered for cleanup by the script
+        // running machinery and should all be removed by the above clean()
+        // function call, its removal failure may not be the script fault but
+        // potentially a bug or a filesystem problem. Thus, we don't ignore
+        // the errors and report them.
+        //
+        env.temp_dir.cancel ();
+
+        const dir_path& td (env.temp_dir.path);
+
+        try
+        {
+          // Note that the temporary directory must be empty to date.
+          //
+          rmdir_status r (try_rmdir (td));
+
+          if (r != rmdir_status::success)
+          {
+            diag_record dr (fail (ll));
+            dr << "temporary directory '" << td
+               << (r == rmdir_status::not_exist
+                   ? "' does not exist"
+                   : "' is not empty");
+
+            if (r == rmdir_status::not_empty)
+              build2::script::print_dir (dr, td, ll);
+          }
+        }
+        catch (const system_error& e)
+        {
+          fail (ll) << "unable to remove temporary directory '" << td << "': "
+                    << e;
+        }
+
+        if (verb >= 3)
+          text << "rmdir " << td;
       }
 
       void default_runner::
diff --git a/libbuild2/build/script/script.cxx b/libbuild2/build/script/script.cxx
index cbd41c7..b43203c 100644
--- a/libbuild2/build/script/script.cxx
+++ b/libbuild2/build/script/script.cxx
@@ -24,8 +24,8 @@ namespace build2
           : build2::script::environment (
               pt.ctx,
               cast<target_triplet> (pt.ctx.global_scope["build.host"]),
-              work,
-              wd_name,
+              work, wd_name,
+              temp_dir.path, false /* temp_dir_keep */,
               redirect (redirect_type::none),
               redirect (redirect_type::merge, 2),
               redirect (redirect_type::pass)),
diff --git a/libbuild2/build/script/script.hxx b/libbuild2/build/script/script.hxx
index 29d62aa..f8306e1 100644
--- a/libbuild2/build/script/script.hxx
+++ b/libbuild2/build/script/script.hxx
@@ -9,6 +9,7 @@
 #include <libbuild2/utility.hxx>
 
 #include <libbuild2/variable.hxx>
+#include <libbuild2/filesystem.hxx> // auto_rmdir
 
 #include <libbuild2/script/script.hxx>
 
@@ -58,9 +59,6 @@ namespace build2
         location end_loc;
       };
 
-      //@@ Does environment need script? Can't we just pass it to parser along
-      //   with environment.
-      //
       class environment: public build2::script::environment
       {
       public:
@@ -83,6 +81,16 @@ namespace build2
         //
         variable_map vars;
 
+        // Temporary directory for the script run (see build2::script::
+        // environment::temp_dir for details).
+        //
+        // Currently this directory is removed regardless of the script
+        // execution success or failure. Later, to ease the troubleshooting,
+        // we may invent the build2 option suppressing the directory removal
+        // on failure.
+        //
+        auto_rmdir temp_dir;
+
         virtual void
         set_variable (string&& name, names&&, const string& attrs) override;
 
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