From 459c17bc350f93e7da9dd3f57345fbda75e20290 Mon Sep 17 00:00:00 2001
From: Jason Hiser <jdhiser@gmail.com>
Date: Tue, 17 Dec 2019 20:25:59 -0500
Subject: [PATCH] fixed deadlock in pipe code
---
src/cmdstr.hpp | 60 ++++++++++++++++++++++++++++++++++----------------
1 file changed, 41 insertions(+), 19 deletions(-)
diff --git a/src/cmdstr.hpp b/src/cmdstr.hpp
index 48d67c5e5..eeccc1bb0 100644
--- a/src/cmdstr.hpp
+++ b/src/cmdstr.hpp
@@ -1,10 +1,7 @@
#ifndef cmdstr_hpp
#define cmdstr_hpp
-/*BINFMTCXX: -std=c++11 -Wall -Werror
-*/
-
-#include <spawn.h> // see manpages-posix-dev
+#include <spawn.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
@@ -14,19 +11,45 @@
#include <iostream>
#include <string>
#include <vector>
-using namespace std;
+#include <array>
+using namespace std;
static inline pair<string,int> command_to_string( const string& command)
{
auto ret=string();
int exit_code=0;
- int cout_pipe[2];
- int cerr_pipe[2];
posix_spawn_file_actions_t action;
- if(pipe(cout_pipe) || pipe(cerr_pipe))
- cout << "pipe returned an error.\n";
+
+ const auto pipe_closer = function<void(int*)>([](int *p_pipefd) -> void
+ {
+ const auto pipe = *p_pipefd;
+ close(pipe);
+ delete p_pipefd;
+ });
+ using PipeFD_t = unique_ptr<int,decltype(pipe_closer)>;
+
+ const auto pipe_opener = [&]() -> vector<PipeFD_t>
+ {
+ auto pipe_fds = array<int,2>();
+ if(pipe( pipe_fds.data()))
+ {
+ const auto err_str = string(strerror(errno));
+ throw runtime_error("Cannot open pipe: " + err_str);
+ }
+ auto ret = vector<PipeFD_t>();
+// PipeFD_t p(new int(pipe_fds[0]), pipe_closer);
+// ret.push_back(move(p));
+ ret.push_back({new int(pipe_fds[0]), pipe_closer});
+ ret.push_back({new int(pipe_fds[1]), pipe_closer});
+ return ret;
+ };
+
+ auto cout_pipe_vec = pipe_opener();
+ auto cerr_pipe_vec = pipe_opener();
+ const auto cout_pipe = vector<int>{*(cout_pipe_vec[0]), *(cout_pipe_vec[1])};
+ const auto cerr_pipe = vector<int>{*(cerr_pipe_vec[0]), *(cerr_pipe_vec[1])};
posix_spawn_file_actions_init(&action);
posix_spawn_file_actions_addclose(&action, cout_pipe[0]);
@@ -37,8 +60,6 @@ static inline pair<string,int> command_to_string( const string& command)
posix_spawn_file_actions_addclose(&action, cout_pipe[1]);
posix_spawn_file_actions_addclose(&action, cerr_pipe[1]);
- // string command = "echo bla"; // example #1
- // string command = "pgmcrater -width 64 -height 9 |pgmtopbm |pnmtoplainpnm";
vector<char> argsmem[] = {{'s', 'h', '\0'}, {'-', 'c', '\0'}}; // allows non-const access to literals
char *args[] = {&argsmem[0][0], &argsmem[1][0],const_cast<char*>(command.c_str()),nullptr};
@@ -46,23 +67,23 @@ static inline pair<string,int> command_to_string( const string& command)
if(posix_spawnp(&pid, args[0], &action, NULL, args, environ) != 0)
cout << "posix_spawnp failed with error: " << strerror(errno) << "\n";
- close(cout_pipe[1]), close(cerr_pipe[1]); // close child-side of pipes
+ cout_pipe_vec[1].reset();
+ cerr_pipe_vec[1].reset(); // close child-side of pipes
+
// Read from pipes
string buffer(1024,' ');
- std::vector<pollfd> plist = { {cout_pipe[0],POLLIN}, {cerr_pipe[0],POLLIN} };
+ vector<pollfd> plist = { {cout_pipe[0],POLLIN}, {cerr_pipe[0],POLLIN} };
for ( int rval; (rval=poll(&plist[0],plist.size(),/*timeout*/-1))>0; )
{
- if ( plist[0].revents&POLLIN) {
+ if ( plist[0].revents&POLLIN)
+ {
const auto bytes_read = read(cout_pipe[0], &buffer[0], buffer.length());
- // cout << "read " << bytes_read << " bytes from stdout.\n";
- // cout << buffer.substr(0, static_cast<size_t>(bytes_read)) << "\n";
ret += buffer.substr(0, static_cast<size_t>(bytes_read));
}
- else if ( plist[1].revents&POLLIN ) {
+ else if ( plist[1].revents&POLLIN )
+ {
const auto bytes_read = read(cerr_pipe[0], &buffer[0], buffer.length());
- // cout << "read " << bytes_read << " bytes from stderr.\n";
- // cout << buffer.substr(0, static_cast<size_t>(bytes_read)) << "\n";
ret += buffer.substr(0, static_cast<size_t>(bytes_read));
}
else
@@ -85,4 +106,5 @@ static inline int command_to_stream(const string& command, ostream& stream)
return res.second;
}
+
#endif
--
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