Add missing file for 1.2.0.

Signed-off-by: Daniel Starke <daniel-email@gmx.net>

src/pcf/UtilityLinux.cpp

@@ -0,0 +1,136 @@
+/**
+ * @file UtilityLinux.cpp
+ * @author Daniel Starke
+ * @date 2024-02-15
+ * @version 2024-02-15
+ */
+#include <pcf/Utility.hpp>
+
+
+#ifdef PCF_IS_LINUX
+#include <FL/fl_ask.H>
+#include <pcf/ScopeExit.hpp>
+extern "C" {
+#include <errno.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+}
+
+
+#ifndef NSIG
+#define NSIG 32
+#endif
+#undef READ_PIPE
+#define READ_PIPE 0
+#undef WRITE_PIPE
+#define WRITE_PIPE 1
+
+
+/**
+ * Ensures that the current process is running with root permissions.
+ * This may open a password prompt and uses `sudo` as backend.
+ *
+ * @param[in] argc - number of command-line arguments
+ * @param[in] argv - command-line arguments
+ * @return true on success, else false
+ */
+bool requestRootPermission(int argc, char * argv[]) {
+	const int euid = geteuid();
+	if (euid == 0) return true;
+	int pStandardInput[2] = {-1, -1};
+	sigset_t oldMask, newMask;
+	struct sigaction sigAction;
+	bool hasOldMask = false;
+	char arg0[] = "sudo";
+	char arg1[] = "-S";
+	char ** newArgv = NULL;
+	const char * constPassword = NULL;
+	char * password = NULL;
+	const auto closePipe = [](int & fd) {
+		if (fd != -1) {
+			close(fd);
+			fd = -1;
+		}
+	};
+	const auto cleanup = makeScopeExit([&]() {
+		closePipe(pStandardInput[READ_PIPE]);
+		closePipe(pStandardInput[WRITE_PIPE]);
+		if (newArgv != NULL) free(newArgv);
+		if (password != NULL) free(password);
+	});
+
+	fl_message_title("sudo vkvm");
+	const struct passwd * pw = getpwuid(euid);
+	if (pw != NULL) {
+		constPassword = fl_password("Root permission is required. Enter password for \"%s\":", "", pw->pw_name);
+	} else {
+		constPassword = fl_password("Root permission is required. Please authenticate.", "");
+	}
+	if (constPassword == NULL) return false;
+	password = strdup(constPassword);
+	if (password == NULL) return false;
+
+	/* build command-line for `sudo` call */
+	newArgv = static_cast<char **>(calloc(1, sizeof(char *) * (argc + 3)));
+	if (newArgv == NULL) return false;
+	newArgv[0] = arg0;
+	newArgv[1] = arg1;
+	for (int i = 0; i < argc; i++) {
+		newArgv[i + 2] = argv[i];
+	}
+
+	if (pipe(pStandardInput) != 0) goto onError;
+
+	/* Temporary disable signal handling for calling thread to avoid unexpected signals
+	 * between `fork()` and `execvp()`. */
+	sigfillset(&newMask);
+	if (pthread_sigmask(SIG_SETMASK, &newMask, &oldMask) != 0) goto onError;
+	hasOldMask = true;
+
+	switch (fork()) {
+	case -1: /* fork failed */
+		break;
+	case 0: /* child */
+		/* clear out signal handlers to avoid unexpected events */
+		memset(&sigAction, 0, sizeof(sigAction));
+		sigAction.sa_handler = SIG_DFL;
+		sigemptyset(&sigAction.sa_mask);
+		for (int i = 1; i < NSIG; i++) sigaction(i, &sigAction, NULL);
+		if (pthread_sigmask(SIG_SETMASK, &oldMask, NULL) < 0) goto onError;
+
+		/* forward password to parent process' standard input */
+		closePipe(pStandardInput[READ_PIPE]);
+		if (write(pStandardInput[WRITE_PIPE], password, strlen(password)) < 0) {
+			closePipe(pStandardInput[WRITE_PIPE]);
+		} else {
+			closePipe(pStandardInput[WRITE_PIPE]);
+			exit(EXIT_SUCCESS);
+		}
+
+		exit(EXIT_FAILURE);
+		break;
+	default: /* parent */
+		/* restore original signal handler */
+		if ( hasOldMask ) pthread_sigmask(SIG_SETMASK, &oldMask, NULL);
+
+		/* set standard input accordingly */
+		dup2(pStandardInput[READ_PIPE], STDIN_FILENO);
+
+		/* close other pipe fd */
+		closePipe(pStandardInput[WRITE_PIPE]);
+
+		execvp(newArgv[0], newArgv);
+		/* something went wrong */
+		break;
+	}
+onError:
+	/* restore original signal handler */
+	if ( hasOldMask ) pthread_sigmask(SIG_SETMASK, &oldMask, NULL);
+	return false;
+}
+
+
+#endif /* PCF_IS_LINUX */