Revert "Merge bitcoin/bitcoin#32343: common: Close non-std fds before exec in RunCommandJSON"

This reverts commit 31d3eeb, reversing
changes made to 4b26ca0.

Author: MarcoFalke

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}, sp::close_fds{true});
+    auto c = sp::Popen(str_command, sp::input{sp::PIPE}, sp::output{sp::PIPE}, sp::error{sp::PIPE});
     if (!str_std_in.empty()) {
         c.send(str_std_in);
     }

src/util/subprocess.h

@@ -36,8 +36,6 @@ 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>
@@ -538,20 +536,6 @@ 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.
  */
@@ -749,7 +733,6 @@ 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;
@@ -1043,8 +1026,6 @@ class Popen
   std::future<void> cleanup_future_;
 #endif
 
-  bool close_fds_ = false;
-
   std::string exe_name_;
 
   // Command in string format
@@ -1288,10 +1269,6 @@ 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__
@@ -1338,41 +1315,6 @@ namespace detail {
       if (stream.err_write_ != -1 && stream.err_write_ > 2)
         subprocess_close(stream.err_write_);
 
-      // Close all the inherited fd's except the error write pipe
-      if (parent_->close_fds_) {
-        // If possible, try to get the list of open file descriptors from the
-        // operating system. This is more efficient, but not guaranteed to be
-        // available.
-#ifdef __linux__
-        // For Linux, enumerate /proc/<pid>/fd.
-        try {
-          std::vector<int> fds_to_close;
-          for (const auto& it : fs::directory_iterator(strprintf("/proc/%d/fd", getpid()))) {
-            auto fd{ToIntegral<uint64_t>(it.path().filename().native())};
-            if (!fd || *fd > std::numeric_limits<int>::max()) continue;
-            if (*fd <= 2) continue;  // leave std{in,out,err} alone
-            if (*fd == static_cast<uint64_t>(err_wr_pipe_)) continue;
-            fds_to_close.push_back(*fd);
-          }
-          for (const int fd : fds_to_close) {
-            close(fd);
-          }
-        } catch (const fs::filesystem_error &e) {
-          throw OSError("/proc/<pid>/fd iteration failed", e.code().value());
-        }
-#else
-        // On other operating systems, iterate over all file descriptor slots
-        // and try to close them all.
-        int max_fd = sysconf(_SC_OPEN_MAX);
-        if (max_fd == -1) throw OSError("sysconf failed", errno);
-
-        for (int i = 3; i < max_fd; i++) {
-          if (i == err_wr_pipe_) continue;
-          close(i);
-        }
-#endif
-      }
-
       // Replace the current image with the executable
       sys_ret = execvp(parent_->exe_name_.c_str(), parent_->cargv_.data());