Move pager to libbutl

1 files changed, 19 insertions, 189 deletions

diff --git a/bpkg/help.cxx b/bpkg/help.cxx
index 9b0fcea..587a7c7 100644
--- a/bpkg/help.cxx
+++ b/bpkg/help.cxx
@@ -4,23 +4,9 @@
 
 #include <bpkg/help>
 
-#ifndef _WIN32
-#  include <unistd.h>    // close(), STDOUT_FILENO
-#  include <sys/ioctl.h> // ioctl()
-#else
-#  ifndef WIN32_LEAN_AND_MEAN
-#    define WIN32_LEAN_AND_MEAN
-#  endif
-#  include <windows.h>   // GetConsoleScreenBufferInfo(), GetStdHandle()
-#  include <io.h>        // _close()
-#endif
+#include <system_error>
 
-#include <chrono>
-#include <thread>    // this_thread::sleep_for()
-#include <iostream>
-
-#include <butl/process>
-#include <butl/fdstream>
+#include <butl/pager>
 
 #include <bpkg/types>
 #include <bpkg/utility>
@@ -33,174 +19,6 @@ using namespace butl;
 
 namespace bpkg
 {
-  struct pager: protected streambuf
-  {
-    pager (const common_options& co, const string& name)
-    {
-      bool up (co.pager_specified ()); // User's pager.
-
-      // If we are using the default pager, try to get the terminal width
-      // so that we can center the output.
-      //
-      if (!up)
-      {
-        size_t col (0);
-
-#ifndef _WIN32
-#  ifdef TIOCGWINSZ
-        struct winsize w;
-        if (ioctl (STDOUT_FILENO, TIOCGWINSZ, &w) == 0)
-          col = static_cast<size_t> (w.ws_col);
-#  endif
-#else
-#error  TODO: needs testing
-        CONSOLE_SCREEN_BUFFER_INFO w;
-        if (GetConsoleScreenBufferInfo (GetStdHandle (STD_OUTPUT_HANDLE), &w))
-          col = static_cast<size_t> (w.srWindow.Right - w.srWindow.Left + 1);
-#endif
-        if (col > 80)
-          indent_.assign ((col - 80) / 2, ' ');
-      }
-
-      cstrings args;
-      string prompt;
-
-      if (up)
-      {
-        if (co.pager ().empty ())
-          return; // No pager should be used.
-
-        args.push_back (co.pager ().c_str ());
-      }
-      else
-      {
-        // By default try less.
-        //
-        prompt = "-Ps" + name + " (press q to quit, h for help)";
-
-        args.push_back ("less");
-        args.push_back ("-R");            // Handle ANSI color.
-        args.push_back (prompt.c_str ());
-      }
-
-      // Add extra pager options.
-      //
-      for (const string& o: co.pager_option ())
-        args.push_back (o.c_str ());
-
-      args.push_back (nullptr);
-
-      if (verb >= 2)
-        print_process (args);
-
-      // Ignore errors and go without a pager unless the pager was specified
-      // by the user.
-      //
-      try
-      {
-        p_ = process (args.data (), -1); // Redirect child's stdin to a pipe.
-
-        // Wait a bit and see if the pager has exited before reading
-        // anything (e.g., because exec() couldn't find the program).
-        // If you know a cleaner way to handle this, let me know (no,
-        // a select()-based approach doesn't work; the pipe is buffered
-        // and therefore is always ready for writing).
-        //
-        this_thread::sleep_for (chrono::milliseconds (50));
-
-        bool r;
-        if (p_.try_wait (r))
-        {
-#ifndef _WIN32
-          ::close (p_.out_fd);
-#else
-          _close (p_.out_fd);
-#endif
-          if (up)
-            fail << "pager " << args[0] << " exited unexpectedly";
-        }
-        else
-          os_.open (p_.out_fd);
-      }
-      catch (const process_error& e)
-      {
-        // Ignore unless it was a user-specified pager.
-        //
-        if (up)
-          error << "unable to execute " << args[0] << ": " << e.what ();
-
-        if (e.child ())
-          exit (1);
-
-        if (up)
-          throw failed ();
-      }
-
-      // Setup the indentation machinery.
-      //
-      if (!indent_.empty ())
-        buf_ = stream ().rdbuf (this);
-    }
-
-    ostream&
-    stream ()
-    {
-      return os_.is_open () ? os_ : cout;
-    }
-
-    bool
-    wait ()
-    {
-      // Teardown the indentation machinery.
-      //
-      if (buf_ != nullptr)
-      {
-        stream ().rdbuf (buf_);
-        buf_ = nullptr;
-      }
-
-      os_.close ();
-      return p_.wait ();
-    }
-
-    ~pager () {wait ();}
-
-    // streambuf output interface.
-    //
-  protected:
-    using int_type = streambuf::int_type;
-    using traits_type = streambuf::traits_type;
-
-    virtual int_type
-    overflow (int_type c)
-    {
-      if (prev_ == '\n' && c != '\n') // Don't indent blanks.
-      {
-        auto n (static_cast<streamsize> (indent_.size ()));
-
-        if (buf_->sputn (indent_.c_str (), n) != n)
-          return traits_type::eof ();
-      }
-
-      prev_ = c;
-      return buf_->sputc (c);
-    }
-
-    virtual int
-    sync ()
-    {
-      return buf_->pubsync ();
-    }
-
-  private:
-    process p_;
-    ofdstream os_;
-
-    string indent_;
-    int_type prev_ = '\n'; // Previous character.
-    streambuf* buf_ = nullptr;
-  };
-
   int
   help (const help_options& o, const string& t, usage_function* usage)
   {
@@ -215,11 +33,23 @@ namespace bpkg
           info << "run 'bpkg help' for more information";
     }
 
-    pager p (o, "bpkg " + (t.empty () ? "help" : t));
-    usage (p.stream (), cli::usage_para::none);
+    try
+    {
+      pager p ("bpkg " + (t.empty () ? "help" : t),
+               verb >= 2,
+               o.pager_specified () ? &o.pager () : nullptr,
+               &o.pager_option ());
+
+      usage (p.stream (), cli::usage_para::none);
 
-    // If the pager failed, assume it has issued some diagnostics.
-    //
-    return p.wait () ? 0 : 1;
+      // If the pager failed, assume it has issued some diagnostics.
+      //
+      return p.wait () ? 0 : 1;
+    }
+    catch (const system_error& e)
+    {
+      error << "pager failed: " << e.what ();
+      throw failed ();
+    }
   }
 }