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comparison pipes.cpp @ 0:4171b2d4684b default tip

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initial commit
author Yasuri <linuxoverwindows@charliesmp.net>
date Sat, 05 Sep 2026 15:35:48 -0500
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-1:000000000000 0:4171b2d4684b
1 #include <iostream>
2 #include <unistd.h>
3 #include <spawn.h>
4 #include <cstring>
5 #include <string>
6 #include <sys/wait.h>
7 extern char** environ;
8 std::string run_piped(const char* path, char* const argv[], const std::string& input)
9 {
10 int status;
11 pid_t pid;
12 int pipeA[2];
13 int pipeB[2];
14 pipe(pipeA);
15 pipe(pipeB);
16 posix_spawn_file_actions_t actions;
17 posix_spawn_file_actions_init(&actions); // initialize actions
18 posix_spawn_file_actions_adddup2(&actions, pipeA[0], STDIN_FILENO);
19 posix_spawn_file_actions_adddup2(&actions, pipeB[1], STDOUT_FILENO);
20 posix_spawn_file_actions_addclose(&actions, pipeA[1]); // closes write end in child
21 posix_spawn_file_actions_addclose(&actions, pipeB[0]); // makes sure child doesn't read its own output pipe
22 posix_spawn_file_actions_addclose(&actions, pipeA[0]); // close read fd in child
23 posix_spawn_file_actions_addclose(&actions, pipeB[1]); // close read fd in child, part 2
24 std::cout << "Running posix_spawn()..." << std::endl;
25 status = posix_spawn(&pid, path, &actions, NULL, const_cast<char* const*>(argv), environ);
26 close(pipeA[0]);
27 close(pipeB[1]);
28 if (status != 0) {
29 posix_spawn_file_actions_destroy(&actions);
30 close(pipeA[1]);
31 close(pipeB[0]);
32 std::cerr << "posix_spawn failed: " << strerror(status) << std::endl;
33 return "error";
34 }
35 write(pipeA[1],input.c_str(), input.size());
36 close(pipeA[1]);
37 char buf[256];
38 std::string result;
39 ssize_t n;
40 while ((n = read(pipeB[0], buf, sizeof(buf))) > 0) {
41 result.append(buf, n);
42 }
43 close(pipeB[0]);
44 if (waitpid(pid, &status, 0) == -1) {
45 posix_spawn_file_actions_destroy(&actions);
46 close(pipeA[1]);
47 close(pipeB[0]);
48 perror("waitpid");
49 return "error";
50 }
51 return result;
52 }