lib: Add mlibc

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 116 insertions, 0 deletions

diff --git a/lib/mlibc/options/linux/generic/utmp-stubs.cpp b/lib/mlibc/options/linux/generic/utmp-stubs.cpp
new file mode 100644
index 0000000..658dfd3
--- /dev/null
+++ b/lib/mlibc/options/linux/generic/utmp-stubs.cpp
@@ -0,0 +1,116 @@
+#include <utmp.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+
+/*
+ * The code in this file is largely based on glibc.
+ * This includes:
+ * - setutent
+ * - read_last_entry
+ * - getutent
+ * - getutent_r
+ * - endutent
+ */
+static int fd = -1;
+static off_t offset;
+
+static struct utmp last_entry;
+
+void setutent(void) {
+	if(fd < 0) {
+		fd = open("/run/utmp", O_RDONLY | O_LARGEFILE | O_CLOEXEC);
+		if(fd == -1) {
+			return;
+		}
+	}
+
+	lseek(fd, 0, SEEK_SET);
+	offset = 0;
+}
+
+static ssize_t read_last_entry(void) {
+	struct utmp buf;
+	ssize_t bytes_read = pread(fd, &buf, sizeof(buf), offset);
+
+	if(bytes_read < 0) {
+		return -1;
+	} else if(bytes_read != sizeof(buf)) {
+		// EOF
+		return 0;
+	} else {
+		last_entry = buf;
+		offset += sizeof(buf);
+		return 1;
+	}
+}
+
+struct utmp *getutent(void) {
+	struct utmp *result;
+	static struct utmp *buf;
+	if(buf == NULL) {
+		buf = (struct utmp *)malloc(sizeof(struct utmp));
+		if(buf == NULL) {
+			return NULL;
+		}
+	}
+
+	if(getutent_r(buf, &result) < 0) {
+		return NULL;
+	}
+	return result;
+}
+
+int getutent_r(struct utmp *buf, struct utmp **res) {
+	int saved_errno = errno;
+
+	if(fd < 0) {
+		setutent();
+	}
+
+	ssize_t bytes_read = read_last_entry();
+
+	if(bytes_read <= 0) {
+		if(bytes_read == 0) {
+			errno = saved_errno;
+			*res = NULL;
+			return -1;
+		}
+	}
+
+	memcpy(buf, &last_entry, sizeof(struct utmp));
+	*res = buf;
+
+	return 0;
+}
+
+void endutent(void) {
+	if(fd >= 0) {
+		close(fd);
+		fd = -1;
+	}
+}
+
+struct utmp *pututline(const struct utmp *) {
+	mlibc::infoLogger() << "\e[31mmlibc: pututline() is a stub!\e[39m" << frg::endlog;
+	return NULL;
+}
+
+struct utmp *getutline(const struct utmp *) {
+	mlibc::infoLogger() << "\e[31mmlibc: getutline() is a stub!\e[39m" << frg::endlog;
+	return NULL;
+}
+
+int utmpname(const char *) {
+	mlibc::infoLogger() << "\e[31mmlibc: utmpname() is a stub!\e[39m" << frg::endlog;
+	return -1;
+}
+
+struct utmp *getutid(const struct utmp *) {
+	mlibc::infoLogger() << "\e[31mmlibc: getutid() is a stub!\e[39m" << frg::endlog;
+	return NULL;
+}