Merge ff198b5ce5 into 85f96b01b7

src/common/run_command.cpp

@@ -24,7 +24,7 @@ UniValue RunCommandParseJSON(const std::string& str_command, const std::string&
 
     if (str_command.empty()) return UniValue::VNULL;
 
-    auto c = sp::Popen(str_command, sp::input{sp::PIPE}, sp::output{sp::PIPE}, sp::error{sp::PIPE});
+    auto c = sp::Popen(str_command, sp::input{sp::PIPE}, sp::output{sp::PIPE}, sp::error{sp::PIPE}, sp::close_fds{true});
     if (!str_std_in.empty()) {
         c.send(str_std_in);
     }

src/util/subprocess.h

@@ -36,6 +36,8 @@ Documentation for C++ subprocessing library.
 #ifndef BITCOIN_UTIL_SUBPROCESS_H
 #define BITCOIN_UTIL_SUBPROCESS_H
 
+#include <util/fs.h>
+#include <util/strencodings.h>
 #include <util/syserror.h>
 
 #include <algorithm>
@@ -520,6 +522,20 @@ namespace util
  * -------------------------------
  */
 
+/*!
+ * Option to close all file descriptors
+ * when the child process is spawned.
+ * The close fd list does not include
+ * input/output/error if they are explicitly
+ * set as part of the Popen arguments.
+ *
+ * Default value is false.
+ */
+struct close_fds {
+  explicit close_fds(bool c): close_all(c) {}
+  bool close_all = false;
+};
+
 /*!
  * Base class for all arguments involving string value.
  */
@@ -717,6 +733,7 @@ struct ArgumentDeducer
   void set_option(input&& inp);
   void set_option(output&& out);
   void set_option(error&& err);
+  void set_option(close_fds&& cfds);
 
 private:
   Popen* popen_ = nullptr;
@@ -1004,6 +1021,8 @@ private:
   std::future<void> cleanup_future_;
 #endif
 
+  bool close_fds_ = false;
+
   std::string exe_name_;
 
   // Command in string format
@@ -1233,6 +1252,10 @@ namespace detail {
     if (err.rd_ch_ != -1) popen_->stream_.err_read_ = err.rd_ch_;
   }
 
+  inline void ArgumentDeducer::set_option(close_fds&& cfds) {
+    popen_->close_fds_ = cfds.close_all;
+  }
+
 
   inline void Child::execute_child() {
 #ifndef __USING_WINDOWS__
@@ -1279,6 +1302,25 @@ namespace detail {
       if (stream.err_write_ != -1 && stream.err_write_ > 2)
         close(stream.err_write_);
 
+      // Close all the inherited fd's except the error write pipe
+      if (parent_->close_fds_) {
+        try {
+            std::vector<int> fds_to_close;
+            for (const auto& it : fs::directory_iterator("/proc/self/fd")) {
+                int64_t fd;
+                if (!ParseInt64(it.path().filename().native(), &fd)) continue;
+                if (fd <= 2) continue;  // leave std{in,out,err} alone
+                if (fd == err_wr_pipe_) continue;
+                fds_to_close.push_back(fd);
+            }
+            for (const int fd : fds_to_close) {
+                close(fd);
+            }
+        } catch (...) {
+            // TODO: maybe log this - but we're in a child process, so maybe non-trivial!
+        }
+      }
+
       // Replace the current image with the executable
       sys_ret = execvp(parent_->exe_name_.c_str(), parent_->cargv_.data());