(maint) Merge up 170e094 to master

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* commit '170e0941cbbe6251a02ba15fa1f25e891c5f579d':
  (LTH-162) Don't check for /proc when running CMake
  (LTH-162) Use /proc to close file descriptors
  (LTH-160) Use closefrom(2) when available (#291)

execution/src/posix/execution.cc

@@ -317,10 +317,26 @@ namespace leatherman { namespace execution {
 #ifdef HAS_CLOSEFROM
         closefrom(STDERR_FILENO + 1);
 #else
-        for (uint64_t i = (STDERR_FILENO + 1); i < max_fd; ++i) {
-            close(i);
+        uint64_t fd;
+        const char* fdpath = "/proc/self/fd";
+        std::list<uint64_t> fd_list;
+
+        if (is_directory(fdpath)) {
+            for (const directory_entry& dent : directory_iterator(fdpath)) {
+                fd = atol(dent.path().filename().c_str());
+                if (fd >= (STDERR_FILENO + 1)) {
+                    fd_list.push_back(fd);
+                }
+            }
+            for (auto fd : fd_list) {
+                close(fd);
+            }
+        } else {
+            for (uint64_t i = (STDERR_FILENO + 1); i < max_fd; ++i) {
+                close(i);
+            }
         }
-#endif
+#endif  // HAS_CLOSEFROM
 
         // Execute the given program; this should not return if successful
         execve(program, const_cast<char* const*>(argv), const_cast<char* const*>(envp));