Add process::print()

2 files changed, 52 insertions, 1 deletions

diff --git a/butl/process b/butl/process
index 96b161f..e1eea29 100644
--- a/butl/process
+++ b/butl/process
@@ -9,8 +9,9 @@
 #  include <sys/types.h> // pid_t
 #endif
 
+#include <iosfwd>
 #include <cassert>
-#include <cstdint> // uint32_t
+#include <cstdint>      // uint32_t
 #include <system_error>
 
 #include <butl/path>
@@ -260,6 +261,18 @@ namespace butl
     static process_path
     try_path_search (const path&, bool, const dir_path& = dir_path ());
 
+    // Print process commmand line. If the number of elements is specified,
+    // then it will print the piped multi-process command line, if present.
+    // In this case, the expected format is as follows:
+    //
+    // name1 arg arg ... nullptr
+    // name2 arg arg ... nullptr
+    // ...
+    // nameN arg arg ... nullptr nullptr
+    //
+    static void
+    print (std::ostream&, const char* const args[], size_t n = 0);
+
   public:
 #ifndef _WIN32
     using handle_type = pid_t;
diff --git a/butl/process.cxx b/butl/process.cxx
index e13a8cd..38948a1 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -37,6 +37,7 @@
 #include <cassert>
 #include <cstddef> // size_t
 #include <cstring> // strlen(), strchr()
+#include <ostream>
 
 #include <butl/utility>  // casecmp()
 #include <butl/fdstream> // fdnull(), fdclose()
@@ -120,6 +121,43 @@ namespace butl
     return r;
   }
 
+  void process::
+  print (ostream& o, const char* const args[], size_t n)
+  {
+    size_t m (0);
+    const char* const* p (args);
+    do
+    {
+      if (m != 0)
+        o << " |"; // Trailing space will be added inside the loop.
+
+      for (m++; *p != nullptr; p++, m++)
+      {
+        if (p != args)
+          o << ' ';
+
+        // Quote if empty or contains spaces.
+        //
+        bool q (**p == '\0' || strchr (*p, ' ') != nullptr);
+
+        if (q)
+          o << '"';
+
+        o << *p;
+
+        if (q)
+          o << '"';
+      }
+
+      if (m < n) // Can we examine the next element?
+      {
+        p++;
+        m++;
+      }
+
+    } while (*p != nullptr);
+  }
+
 #ifndef _WIN32
 
   static process_path