Parse repositories and packages files for git repositories

17 files changed, 340 insertions, 120 deletions

diff --git a/bpkg/archive.cxx b/bpkg/archive.cxx
index 03728a4..cc96cd1 100644
--- a/bpkg/archive.cxx
+++ b/bpkg/archive.cxx
@@ -5,7 +5,6 @@
 #include <bpkg/archive.hxx>
 
 #include <libbutl/process.mxx>
-#include <libbutl/fdstream.mxx>
 
 #include <bpkg/diagnostics.hxx>
 
diff --git a/bpkg/auth.cxx b/bpkg/auth.cxx
index df9a259..df31a60 100644
--- a/bpkg/auth.cxx
+++ b/bpkg/auth.cxx
@@ -13,7 +13,6 @@
 #include <libbutl/base64.mxx>
 #include <libbutl/process.mxx>
 #include <libbutl/openssl.mxx>
-#include <libbutl/fdstream.mxx>
 #include <libbutl/timestamp.mxx>
 #include <libbutl/filesystem.mxx>
 
diff --git a/bpkg/cfg-create.cxx b/bpkg/cfg-create.cxx
index 1a21cfa..70d8848 100644
--- a/bpkg/cfg-create.cxx
+++ b/bpkg/cfg-create.cxx
@@ -4,15 +4,12 @@
 
 #include <bpkg/cfg-create.hxx>
 
-#include <libbutl/fdstream.mxx>
-
 #include <bpkg/package.hxx>
 #include <bpkg/package-odb.hxx>
 #include <bpkg/database.hxx>
 #include <bpkg/diagnostics.hxx>
 
 using namespace std;
-using namespace butl;
 
 namespace bpkg
 {
diff --git a/bpkg/checksum.cxx b/bpkg/checksum.cxx
index 0ada207..14c0bf7 100644
--- a/bpkg/checksum.cxx
+++ b/bpkg/checksum.cxx
@@ -13,7 +13,6 @@
 
 #include <libbutl/sha256.mxx>
 #include <libbutl/process.mxx>
-#include <libbutl/fdstream.mxx>
 #include <libbutl/filesystem.mxx>
 
 #include <bpkg/diagnostics.hxx>
diff --git a/bpkg/diagnostics.cxx b/bpkg/diagnostics.cxx
index 9672926..bb175d8 100644
--- a/bpkg/diagnostics.cxx
+++ b/bpkg/diagnostics.cxx
@@ -10,6 +10,7 @@
 #include <odb/statement.hxx>
 
 #include <libbutl/process.mxx>
+#include <libbutl/process-io.mxx> // operator<<(ostream, process_arg)
 
 using namespace std;
 using namespace butl;
@@ -25,19 +26,6 @@ namespace bpkg
     print_process (r, args, n);
   }
 
-  struct process_args
-  {
-    const char* const* a;
-    size_t n;
-  };
-
-  inline static ostream&
-  operator<< (ostream& o, const process_args& p)
-  {
-    process::print (o, p.a, p.n);
-    return o;
-  }
-
   void
   print_process (diag_record& r, const char* const args[], size_t n)
   {
@@ -104,7 +92,7 @@ namespace bpkg
     if (verb >= 3)
     {
       diag_record dr (*this);
-      process::print (dr.os, args, n);
+      print_process (dr, args, n);
     }
   }
 
diff --git a/bpkg/fetch-bpkg.cxx b/bpkg/fetch-bpkg.cxx
index 4fe0bfc..606843f 100644
--- a/bpkg/fetch-bpkg.cxx
+++ b/bpkg/fetch-bpkg.cxx
@@ -6,7 +6,6 @@
 
 #include <sstream>
 
-#include <libbutl/fdstream.mxx>
 #include <libbutl/filesystem.mxx>      // cpfile ()
 #include <libbutl/manifest-parser.mxx>
 
diff --git a/bpkg/fetch-git.cxx b/bpkg/fetch-git.cxx
index fa9723c..7ffaaaf 100644
--- a/bpkg/fetch-git.cxx
+++ b/bpkg/fetch-git.cxx
@@ -10,7 +10,6 @@
 
 #include <libbutl/utility.mxx>          // digit(), xdigit()
 #include <libbutl/process.mxx>
-#include <libbutl/fdstream.mxx>
 #include <libbutl/standard-version.mxx>
 
 #include <bpkg/diagnostics.hxx>
@@ -34,32 +33,6 @@ namespace bpkg
 
   static const diag_noreturn_end<fail_git> endg;
 
-  static fdpipe
-  open_pipe ()
-  {
-    try
-    {
-      return fdopen_pipe ();
-    }
-    catch (const io_error& e)
-    {
-      fail << "unable to open pipe: " << e << endf;
-    }
-  }
-
-  static auto_fd
-  open_dev_null ()
-  {
-    try
-    {
-      return fdnull ();
-    }
-    catch (const io_error& e)
-    {
-      fail << "unable to open null device: " << e << endf;
-    }
-  }
-
   using opt = optional<const char*>; // Program option.
 
   static strings
@@ -167,7 +140,9 @@ namespace bpkg
           }
 
           if (v.empty ())
-            fail << "unable to obtain git version from '" << s << "'" << endg;
+            fail << "'" << s << "' doesn't appear to contain a git version" <<
+              info << "produced by '" << co.git () << "'; "
+                 << "use --git to override" << endg;
 
           if (v.version < 20120000000)
             fail << "unsupported git version " << v.string () <<
@@ -191,15 +166,14 @@ namespace bpkg
 
           try
           {
-            ifdstream is (move (pipe.in), fdstream_mode::skip);
+            ifdstream is (move (pipe.in),
+                          fdstream_mode::skip,
+                          ifdstream::badbit);
 
-            while (is.peek () != ifdstream::traits_type::eof ())
+            for (string l; !eof (getline (is, l)); )
             {
-              string v;
-              getline (is, v);
-
-              if (v != "GIT_CONFIG_PARAMETERS")
-                unset_vars->push_back (move (v));
+              if (l != "GIT_CONFIG_PARAMETERS")
+                unset_vars->push_back (move (l));
             }
 
             is.close ();
@@ -246,7 +220,9 @@ namespace bpkg
   static process_exit
   run_git (const common_options& co, A&&... args)
   {
-    process pr (start_git (co, 1, 2, forward<A> (args)...));
+    process pr (start_git (co,
+                           1 /* stdout */, 2 /* stderr */,
+                           forward<A> (args)...));
     pr.wait ();
     return *pr.exit;
   }
@@ -508,16 +484,13 @@ namespace bpkg
     try
     {
       bool r (false);
-      ifdstream is (move (pipe.in), fdstream_mode::skip);
+      ifdstream is (move (pipe.in), fdstream_mode::skip, ifdstream::badbit);
 
-      while (is.peek () != ifdstream::traits_type::eof ())
+      for (string l; !eof (getline (is, l)); )
       {
-        string s;
-        getline (is, s);
-
-        l4 ([&]{trace << "ref: " << s;});
+        l4 ([&]{trace << "ref: " << l;});
 
-        if (s.compare (0, commit.size (), commit) == 0)
+        if (l.compare (0, commit.size (), commit) == 0)
         {
           r = true;
           break;
@@ -787,9 +760,9 @@ namespace bpkg
 
     try
     {
-      ifdstream is (move (pipe.in), fdstream_mode::skip);
+      ifdstream is (move (pipe.in), fdstream_mode::skip, ifdstream::badbit);
 
-      while (is.peek () != ifdstream::traits_type::eof ())
+      for (string l; !eof (getline (is, l)); )
       {
         // The line describing a submodule has the following form:
         //
@@ -799,19 +772,16 @@ namespace bpkg
         //
         // 160000 658436a9522b5a0d016c3da0253708093607f95d 0	doc/style
         //
-        string s;
-        getline (is, s);
-
-        l4 ([&]{trace << "submodule: " << s;});
+        l4 ([&]{trace << "submodule: " << l;});
 
-        if (!(s.size () > 50 && s[48] == '0' && s[49] == '\t'))
+        if (!(l.size () > 50 && l[48] == '0' && l[49] == '\t'))
           failure ("invalid submodule description");
 
-        string commit (s.substr (7, 40));
+        string commit (l.substr (7, 40));
 
         // Submodule directory path, relative to the containing project.
         //
-        dir_path sdir  (s.substr (50));
+        dir_path sdir  (l.substr (50));
 
         // Submodule directory path, relative to the top project.
         //
@@ -955,7 +925,22 @@ namespace bpkg
     }
   }
 
-  void
+  // Produce a repository directory name for the specified git reference.
+  //
+  // Truncate commit id-based directory names to shorten absolute directory
+  // paths, lowering the probability of hitting the limit on Windows.
+  //
+  // Note that we can't truncate them for branches/tags as chances to clash
+  // would be way higher than for commit ids. Though such names are normally
+  // short anyway.
+  //
+  static inline dir_path
+  repository_dir (const git_reference& ref)
+  {
+    return dir_path (ref.commit ? ref.commit->substr (0, 16) : *ref.branch);
+  }
+
+  dir_path
   git_clone (const common_options& co,
              const repository_location& rl,
              const dir_path& destdir)
@@ -975,14 +960,8 @@ namespace bpkg
     else
       fetch_warn (cap, single_branch ? "branch" : "repository");
 
-    dir_path d (destdir);
-
-    // Truncate commit id-based directory names to shorten the absolute
-    // directory path to lower probability of hitting the limit on Windows.
-    // Note that we can't do the same for branch/tag names as chances to clash
-    // would be way higher. Though such names are normally short anyway.
-    //
-    d /= dir_path (ref.branch ? *ref.branch : ref.commit->substr (0, 16));
+    dir_path r (repository_dir (ref));
+    dir_path d (destdir / r);
 
     strings to (timeout_opts (co, url.scheme));
 
@@ -1007,9 +986,10 @@ namespace bpkg
       update_tree (co, d, dir_path (), ref, cap, shallow, to);
 
     update_submodules (co, d, dir_path ());
+    return r;
   }
 
-  void
+  dir_path
   git_fetch (const common_options& co,
              const repository_location& rl,
              const dir_path& destdir)
@@ -1017,6 +997,8 @@ namespace bpkg
     repository_url url (rl.url ());
     git_reference  ref (parse_reference (url, "fetch"));
 
+    dir_path r (repository_dir (ref));
+
     // Fetch is noop if the specific commit is checked out.
     //
     // What if the user replaces the repository URL with a one with a new
@@ -1026,7 +1008,7 @@ namespace bpkg
     // this should work correctly automatically.
     //
     if (ref.commit)
-      return;
+      return r;
 
     assert (ref.branch);
 
@@ -1045,5 +1027,6 @@ namespace bpkg
                  timeout_opts (co, url.scheme));
 
     update_submodules (co, d, dir_path ());
+    return r;
   }
 }
diff --git a/bpkg/fetch.cxx b/bpkg/fetch.cxx
index c5366e3..680ab9e 100644
--- a/bpkg/fetch.cxx
+++ b/bpkg/fetch.cxx
@@ -4,7 +4,7 @@
 
 #include <bpkg/fetch.hxx>
 
-#include <libbutl/fdstream.mxx>
+#include <libbutl/process.mxx>
 
 #include <bpkg/diagnostics.hxx>
 
diff --git a/bpkg/fetch.hxx b/bpkg/fetch.hxx
index f243e09..659e019 100644
--- a/bpkg/fetch.hxx
+++ b/bpkg/fetch.hxx
@@ -49,16 +49,18 @@ namespace bpkg
   // Repository type git (fetch-git.cxx).
   //
 
-  // Clone git repository into destdir/<fragment>/.
+  // Clone git repository into destdir/<name>/. Return the cloned repository
+  // directory name that was deduced from the repository URL fragment.
   //
-  void
+  dir_path
   git_clone (const common_options&,
              const repository_location&,
              const dir_path& destdir);
 
-  // Fetch git repository in destdir/<fragment>/.
+  // Fetch git repository in destdir/<name>/. Return the fetched repository
+  // directory name that was deduced from the repository URL fragment.
   //
-  void
+  dir_path
   git_fetch (const common_options&,
              const repository_location&,
              const dir_path& destdir);
diff --git a/bpkg/package.hxx b/bpkg/package.hxx
index 95b1bb3..67b1753 100644
--- a/bpkg/package.hxx
+++ b/bpkg/package.hxx
@@ -354,7 +354,8 @@ namespace bpkg
 
     dependencies_type dependencies;
 
-    // Present for non-transient objects only.
+    // Present for non-transient objects only (and only for certain repository
+    // types).
     //
     optional<string> sha256sum;
 
diff --git a/bpkg/pkg-verify.cxx b/bpkg/pkg-verify.cxx
index d46e5b6..2f01f94 100644
--- a/bpkg/pkg-verify.cxx
+++ b/bpkg/pkg-verify.cxx
@@ -5,7 +5,6 @@
 #include <bpkg/pkg-verify.hxx>
 
 #include <libbutl/process.mxx>
-#include <libbutl/fdstream.mxx>
 #include <libbutl/manifest-parser.mxx>
 
 #include <bpkg/archive.hxx>
diff --git a/bpkg/rep-create.cxx b/bpkg/rep-create.cxx
index 228b7f6..e9619ca 100644
--- a/bpkg/rep-create.cxx
+++ b/bpkg/rep-create.cxx
@@ -6,7 +6,6 @@
 
 #include <map>
 
-#include <libbutl/fdstream.mxx>
 #include <libbutl/filesystem.mxx>          // dir_iterator
 #include <libbutl/manifest-serializer.mxx>
 
diff --git a/bpkg/rep-fetch.cxx b/bpkg/rep-fetch.cxx
index d7f0386..029db1d 100644
--- a/bpkg/rep-fetch.cxx
+++ b/bpkg/rep-fetch.cxx
@@ -5,6 +5,9 @@
 #include <bpkg/rep-fetch.hxx>
 
 #include <libbutl/sha256.mxx>
+#include <libbutl/process.mxx>
+#include <libbutl/process-io.mxx>      // operator<<(ostream, process_path)
+#include <libbutl/manifest-parser.mxx>
 
 #include <bpkg/auth.hxx>
 #include <bpkg/fetch.hxx>
@@ -74,30 +77,64 @@ namespace bpkg
     return rep_fetch_data {move (rms), move (pms), move (cert)};
   }
 
+  template <typename M>
+  static M
+  parse_manifest (const path& f, bool iu, const repository_location& rl)
+  {
+    try
+    {
+      ifdstream ifs (f);
+      manifest_parser mp (ifs, f.string ());
+      return M (mp, iu);
+    }
+    catch (const manifest_parsing& e)
+    {
+      fail (e.name, e.line, e.column) << e.description <<
+        info << "repository " << rl << endf;
+    }
+    catch (const io_error& e)
+    {
+      fail << "unable to read from " << f << ": " << e <<
+        info << "repository " << rl << endf;
+    }
+  }
+
   static rep_fetch_data
   rep_fetch_git (const common_options& co,
                  const dir_path* conf,
                  const repository_location& rl,
-                 bool /* ignore_unknown */)
+                 bool ignore_unknown)
   {
     // Plan:
     //
     // 1. Check repos_dir/<hash>/:
     //
-    // 1.a If does not exist, git-clone into temp_dir/<hash>/.
+    // 1.a If does not exist, git-clone into temp_dir/<hash>/<fragment>/.
     //
     // 1.a Otherwise, move as temp_dir/<hash>/ and git-fetch.
     //
-    // 2. Move from temp_dir/<hash>/ to repos_dir/<hash>/
+    // 2. Move from temp_dir/<hash>/ to repos_dir/<hash>/<fragment>/
     //
-    // 3. Load manifest from repos_dir/<hash>/<fragment>/
+    // 3. Check if repos_dir/<hash>/<fragment>/repositories exists:
     //
-    // 4. Run 'b info' in repos_dir/<hash>/<fragment>/ and fix-up
-    //    package version.
+    // 3.a If exists, load.
     //
-    // 5. Synthesize repository manifest.
+    // 3.b Otherwise, synthesize repository list with base repository.
     //
-    // 6. Return repository and package manifest (certificate is NULL).
+    // 4. Check if repos_dir/<hash>/<fragment>/packages exists:
+    //
+    // 4.a If exists, load. (into "skeleton" packages list to be filled?)
+    //
+    // 4.b Otherwise, synthesize as if single 'location: ./'.
+    //
+    // 5. For each package location obtained on step 4:
+    //
+    // 5.a Load repos_dir/<hash>/<fragment>/<location>/manifest.
+    //
+    // 5.b Run 'b info: repos_dir/<hash>/<fragment>/<location>/' and fix-up
+    //     package version.
+    //
+    // 6. Return repository and package manifests (certificate is NULL).
     //
 
     if (conf != nullptr && conf->empty ())
@@ -105,6 +142,8 @@ namespace bpkg
 
     assert (conf == nullptr || !conf->empty ());
 
+    // Clone or fetch the repository.
+    //
     dir_path h (sha256 (rl.canonical_name ()).abbreviated_string (16));
 
     auto_rmdir rm (temp_dir / h);
@@ -129,10 +168,7 @@ namespace bpkg
       }
     }
 
-    if (fetch)
-      git_fetch (co, rl, td);
-    else
-      git_clone (co, rl, td);
+    dir_path nm (fetch ? git_fetch (co, rl, td) : git_clone (co, rl, td));
 
     if (!rd.empty ())
       mv (td, rd);
@@ -144,9 +180,179 @@ namespace bpkg
 
     rm.cancel ();
 
-    // @@ TODO
+    rd /= nm;
+
+    // Produce repository manifest list.
     //
-    return rep_fetch_data ();
+    git_repository_manifests rms;
+    {
+      path f (rd / path ("repositories"));
+
+      if (exists (f))
+        rms = parse_manifest<git_repository_manifests> (f, ignore_unknown, rl);
+      else
+        rms.emplace_back (repository_manifest ()); // Add the base repository.
+    }
+
+    // Produce the "skeleton" package manifest list.
+    //
+    git_package_manifests pms;
+    {
+      path f (rd / path ("packages"));
+
+      if (exists (f))
+        pms = parse_manifest<git_package_manifests> (f, ignore_unknown, rl);
+      else
+      {
+        pms.push_back (package_manifest ());
+        pms.back ().location = current_dir;
+      }
+    }
+
+    // Fill "skeleton" package manifests.
+    //
+    for (package_manifest& sm: pms)
+    {
+      assert (sm.location);
+
+      auto package_info = [&sm, &rl] (diag_record& dr)
+      {
+        dr << "package ";
+
+        if (!sm.location->current ())
+          dr << "'" << sm.location->string () << "' "; // Strip trailing '/'.
+
+        dr << "in repository " << rl;
+      };
+
+      auto failure = [&package_info] (const char* desc)
+      {
+        diag_record dr (fail);
+        dr << desc << " for ";
+        package_info (dr);
+      };
+
+      dir_path d (rd / path_cast<dir_path> (*sm.location));
+      path f (d / path ("manifest"));
+
+      if (!exists (f))
+        failure ("no manifest file");
+
+      try
+      {
+        ifdstream ifs (f);
+        manifest_parser mp (ifs, f.string ());
+        package_manifest m (bpkg_package_manifest (mp, ignore_unknown));
+
+        // Save the package manifest, preserving its location.
+        //
+        m.location = move (sm.location);
+        sm = move (m);
+      }
+      catch (const manifest_parsing& e)
+      {
+        diag_record dr (fail (e.name, e.line, e.column));
+        dr << e.description << info;
+        package_info (dr);
+      }
+      catch (const io_error& e)
+      {
+        diag_record dr (fail);
+        dr << "unable to read from " << f << ": " << e << info;
+        package_info (dr);
+      }
+
+      // Fix-up the package version.
+      //
+      const char* b (name_b (co));
+
+      try
+      {
+        process_path pp (process::path_search (b, exec_dir));
+
+        fdpipe pipe (open_pipe ());
+
+        process pr (
+          process_start_callback (
+            [] (const char* const args[], size_t n)
+            {
+              if (verb >= 2)
+                print_process (args, n);
+            },
+            0 /* stdin */, pipe /* stdout */, 2 /* stderr */,
+            pp,
+
+            verb < 2
+            ? strings ({"-q"})
+            : verb == 2
+              ? strings ({"-v"})
+              : strings ({"--verbose", to_string (verb)}),
+
+            co.build_option (),
+            "info:",
+            d.representation ()));
+
+        // Shouldn't throw, unless something is severely damaged.
+        //
+        pipe.out.close ();
+
+        try
+        {
+          ifdstream is (move (pipe.in),
+                        fdstream_mode::skip,
+                        ifdstream::badbit);
+
+          for (string l; !eof (getline (is, l)); )
+          {
+            if (l.compare (0, 9, "version: ") == 0)
+            try
+            {
+              string v (l, 9);
+
+              // An empty version indicates that the version module is not
+              // enabled for the project, and so we don't amend the package
+              // version.
+              //
+              if (!v.empty ())
+                sm.version = version (v);
+
+              break;
+            }
+            catch (const invalid_argument&)
+            {
+              fail << "no package version in '" << l << "'" <<
+                info << "produced by '" << pp << "'; use --build to override";
+            }
+          }
+
+          is.close ();
+
+          if (pr.wait ())
+            continue; // Go to the next package.
+
+          // Fall through.
+        }
+        catch (const io_error&)
+        {
+          if (pr.wait ())
+            failure ("unable to read information");
+
+          // Fall through.
+        }
+
+        // We should only get here if the child exited with an error status.
+        //
+        assert (!pr.wait ());
+
+        failure ("unable to obtain information");
+      }
+      catch (const process_error& e)
+      {
+        fail << "unable to execute " << b << ": " << e;
+      }
+    }
+
+    return rep_fetch_data {move (rms), move (pms), nullptr};
   }
 
   rep_fetch_data
@@ -319,21 +525,28 @@ namespace bpkg
       {
         // Make sure this is the same package.
         //
-        assert (p->sha256sum && !p->locations.empty ()); // Can't be transient.
+        assert (!p->locations.empty ()); // Can't be transient.
 
-        if (*pm.sha256sum != *p->sha256sum)
+        // Note that sha256sum may not present for some repository types.
+        //
+        if (pm.sha256sum)
         {
-          // All the previous repositories that contain this package have the
-          // same checksum (since they passed this test), so we can pick any
-          // to show to the user.
-          //
-          const string& r1 (rl.canonical_name ());
-          const string& r2 (p->locations[0].repository.object_id ());
-
-          fail << "checksum mismatch for " << pm.name << " " << pm.version <<
-            info << r1 << " has " << *pm.sha256sum <<
-            info << r2 << " has " << *p->sha256sum <<
-            info << "consider reporting this to the repository maintainers";
+          if (!p->sha256sum)
+            p->sha256sum = move (pm.sha256sum);
+          else if (*pm.sha256sum != *p->sha256sum)
+          {
+            // All the previous repositories that have checksum for this
+            // package have it the same (since they passed this test), so we
+            // can pick any to show to the user.
+            //
+            const string& r1 (rl.canonical_name ());
+            const string& r2 (p->locations[0].repository.object_id ());
+
+            fail << "checksum mismatch for " << pm.name << " " << pm.version <<
+              info << r1 << " has " << *pm.sha256sum <<
+              info << r2 << " has " << *p->sha256sum <<
+              info << "consider reporting this to the repository maintainers";
+          }
         }
       }
 
diff --git a/bpkg/satisfaction.cxx b/bpkg/satisfaction.cxx
index 9aaca23..9211ac0 100644
--- a/bpkg/satisfaction.cxx
+++ b/bpkg/satisfaction.cxx
@@ -5,7 +5,6 @@
 #include <bpkg/satisfaction.hxx>
 
 #include <libbutl/process.mxx>
-#include <libbutl/fdstream.mxx>
 
 #include <bpkg/utility.hxx>
 #include <bpkg/package-odb.hxx>
diff --git a/bpkg/types.hxx b/bpkg/types.hxx
index 505d468..3133696 100644
--- a/bpkg/types.hxx
+++ b/bpkg/types.hxx
@@ -24,6 +24,7 @@
 
 #include <libbutl/path.mxx>
 #include <libbutl/optional.mxx>
+#include <libbutl/fdstream.mxx>
 
 namespace bpkg
 {
@@ -82,6 +83,14 @@ namespace bpkg
 
   using paths = std::vector<path>;
   using dir_paths = std::vector<dir_path>;
+
+  // <libbutl/fdstream.mxx>
+  //
+  using butl::auto_fd;
+  using butl::fdpipe;
+  using butl::ifdstream;
+  using butl::ofdstream;
+  using butl::fdstream_mode;
 }
 
 // In order to be found (via ADL) these have to be either in std:: or in
diff --git a/bpkg/utility.cxx b/bpkg/utility.cxx
index 26716e8..252bdef 100644
--- a/bpkg/utility.cxx
+++ b/bpkg/utility.cxx
@@ -234,6 +234,32 @@ namespace bpkg
     }
   }
 
+  fdpipe
+  open_pipe ()
+  {
+    try
+    {
+      return fdopen_pipe ();
+    }
+    catch (const io_error& e)
+    {
+      fail << "unable to open pipe: " << e << endf;
+    }
+  }
+
+  auto_fd
+  open_dev_null ()
+  {
+    try
+    {
+      return fdnull ();
+    }
+    catch (const io_error& e)
+    {
+      fail << "unable to open null device: " << e << endf;
+    }
+  }
+
   dir_path exec_dir;
 
   void
diff --git a/bpkg/utility.hxx b/bpkg/utility.hxx
index 05835b0..b05f668 100644
--- a/bpkg/utility.hxx
+++ b/bpkg/utility.hxx
@@ -116,6 +116,14 @@ namespace bpkg
   void
   mv (const dir_path& from, const dir_path& to);
 
+  // File descriptor streams.
+  //
+  fdpipe
+  open_pipe ();
+
+  auto_fd
+  open_dev_null ();
+
   // Process.
   //
   // By default the process command line is printed for verbosity >= 2