From 195d1526cc67f7b7d20dd3fe32b97840a4193223 Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Tue, 26 Nov 2024 14:02:24 +0000
Subject: ok

---
 run.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 run.c

diff --git a/run.c b/run.c
new file mode 100644
index 0000000..ff2565c
--- /dev/null
+++ b/run.c
@@ -0,0 +1,101 @@
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <string.h>
+#include <lua.h>
+
+#define CKE(val, name) do { if (val == -1) { perror(name); exit(1); } } while (0)
+
+#ifdef DEBUG
+#define DP(...) fprintf(stderr, __VA_ARGS__);
+#else
+#define DP(...)
+#endif
+
+int filefork(char *argv[], int input, int output) {
+	int pid = fork();
+	switch (pid) {
+	case -1: perror("fork"); exit(1); break;
+	case 0:
+		if (input != -1) {
+			CKE(close(STDIN_FILENO),"close stdin");
+			CKE(dup2(input, STDIN_FILENO),"dup2 stdin");
+		}
+		if (output != -1) {
+			CKE(close(STDOUT_FILENO),"close stdout");
+			CKE(dup2(output, STDOUT_FILENO),"dup2 stdout");
+		}
+		CKE(execvp(argv[0], argv), "exec");
+		exit(1);
+		break;
+	default: return pid;
+	}
+}
+
+int echofork(char *str, size_t len, int fd) {
+	int pid = fork();
+	switch (pid) { 
+	case -1: perror("fork"), exit(1); break;
+	case 0:
+		size_t remaining = len;
+		char *cur = str;
+		do {
+			ssize_t res = write(fd, cur, remaining);
+			if (res == -1) { perror("write"); exit(1); }
+			cur += res;
+			remaining -= res;
+		} while (remaining > 0);
+		exit(0);
+	default: return pid;
+	}
+}
+
+char *p1[] = {"sed","-e","s/a/b/g",NULL};
+char *p2[] = {"tac",NULL};
+char *p3[] = {"sed","-e","s/fish/PIG/",NULL};
+char *p4[] = {"rev",NULL};
+
+void empipe(int pipefd[2]) {
+	CKE(pipe(pipefd), "pipe");
+	fcntl(pipefd[0], F_SETFD, FD_CLOEXEC);
+	fcntl(pipefd[1], F_SETFD, FD_CLOEXEC);
+}
+
+void run(int count, char **progs[], char *inputstr, size_t inputlen) {
+	if (inputstr) count++;
+	int (*pipefds)[2] = malloc((count-1) * sizeof(int[2]));
+	pid_t *pids = malloc(count * sizeof(pid_t));
+	for (int i = 0; i < count-1; i++) empipe(pipefds[i]);
+	for (int i = 0; i < count; i++) {
+		int input =        (i == 0) ? -1 : pipefds[i-1][0];
+		int output = (i == count-1) ? -1 : pipefds[i  ][1];
+		if (!inputstr) pids[i] = filefork(progs[i  ], input, output);
+		else if (i==0) pids[i] = echofork(inputstr, inputlen, output);
+		     else      pids[i] = filefork(progs[i-1], input, output);
+
+		DP("[%d] %d\n",i,pids[i]);
+	}
+	// pipes need to be closed everywhere they aren't being used.
+	// close them in the parent process here; CLOEXEC will take care of them everwhere else
+	// (duped fds won't have CLOEXEC set so those ones, ie the ones being used, won't be closed)
+	for (int i = 0; i < count-1; i++) {
+		CKE(close(pipefds[i][0]), "close");
+		CKE(close(pipefds[i][1]), "close");
+	}
+
+	for (int i = 0; i < count; i++) {
+		int status;
+		pid_t rpid = waitpid(pids[i], &status, 0);
+		DP("-> %d %d\n",rpid,WEXITSTATUS(status));
+	}
+
+	free(pipefds);
+	free(pids);
+}
+
+int luaopen_run(lua_State *L) {
+	lua_pushliteral(L, "fuck");
+	return 1;
+}
-- 
cgit v1.2.3