processes

1 files changed, 119 insertions, 0 deletions

diff --git a/process-posix.c b/process-posix.c
new file mode 100644
index 0000000..53363b6
--- /dev/null
+++ b/process-posix.c
@@ -0,0 +1,119 @@
+#include "process.h"
+
+#include <fcntl.h>
+#include <sys/wait.h>
+
+struct Process {
+	pid_t pid;
+	int pipe;
+	bool stopped;
+	int exit_status; // INT_MAX if process was terminated
+};
+
+static char process_error[64];
+static Process *processes;
+
+static void process_sigaction_sigchld(int signal, siginfo_t *info, void *context) {
+	(void)context;
+	if (signal == SIGCHLD) {
+		pid_t pid = info->si_pid;
+		arr_foreach_ptr(processes, Process, process) {
+			if (process->pid == pid) {
+				process->stopped = true;
+				if (info->si_code == CLD_EXITED)
+					process->exit_status = info->si_status;
+				else
+					process->exit_status = INT_MAX;
+			}
+		}
+	}
+}
+
+void process_init(void) {
+	struct sigaction act = {0};
+	act.sa_sigaction = process_sigaction_sigchld;
+	act.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
+	sigaction(SIGCHLD, &act, NULL);
+}
+
+
+
+Process *process_exec(char const *program, char **argv) {
+	Process *proc = NULL;
+
+	int pipefd[2];
+	if (pipe(pipefd) == 0) {
+		pid_t pid = fork();
+		if (pid == 0) {
+			// child process
+			// send stdout and stderr to pipe
+			dup2(pipefd[1], STDOUT_FILENO);
+			dup2(pipefd[1], STDERR_FILENO);
+			close(pipefd[0]);
+			close(pipefd[1]);
+			if (execv(program, argv) == -1) {
+				dprintf(STDERR_FILENO, "%s: %s\n", program, strerror(errno));
+				exit(127);
+			}
+		} else if (pid > 0) {
+			proc = arr_addp(processes);
+			// parent process
+			close(pipefd[1]);
+			fcntl(pipefd[0], F_SETFL, fcntl(pipefd[0], F_GETFL) | O_NONBLOCK); // set pipe to non-blocking
+			proc->pid = pid;
+			proc->pipe = pipefd[0];
+		}
+	} else {
+		strbuf_printf(process_error, "%s", strerror(errno));
+	}
+	return proc;
+}
+
+char const *process_geterr(void) {
+	return *process_error ? process_error : NULL;
+}
+
+long long process_read(Process *proc, char *data, size_t size) {
+	assert(proc->pipe);
+	ssize_t bytes_read = read(proc->pipe, data, size);
+	if (bytes_read >= 0) {
+		return (long long)bytes_read;
+	} else if (errno == EAGAIN) {
+		return -1;
+	} else {
+		strbuf_printf(process_error, "%s", strerror(errno));
+		return -2;
+	}
+
+}
+
+void process_stop(Process *proc) {
+	kill(proc->pid, SIGKILL);
+	// get rid of zombie process
+	waitpid(proc->pid, NULL, 0);
+	close(proc->pipe);
+	for (u32 i = 0; i < arr_len(processes); ++i)
+		if (processes[i].pid == proc->pid)
+			arr_remove(processes, i);
+}
+#include <sys/resource.h>
+int process_check_status(Process *proc, char *message, size_t message_size) {
+	if (proc->stopped) {
+		int status = proc->exit_status;
+		process_stop(proc);
+
+		switch (status) {
+		case 0:
+			if (message) str_printf(message, message_size, "exited successfully");
+			return +1;
+		case INT_MAX:
+			if (message) str_printf(message, message_size, "terminated by a signal");
+			return -1;
+		default:
+			if (message) str_printf(message, message_size, "exited with code %d", status);
+			return -1;
+		}
+	} else {
+		return 0;
+	}
+}