user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/options/linux/generic/utmp.cpp

@@ -0,0 +1,181 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <utmp.h>
+
+#include <bits/ensure.h>
+#include <frg/mutex.hpp>
+#include <frg/spinlock.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/utmp.hpp>
+#include <mlibc/posix-sysdeps.hpp>
+
+namespace {
+
+constexpr const char *defaultUtmpPath = UTMP_FILE;
+
+const char *utmpPath = defaultUtmpPath;
+frg::ticket_spinlock utmpMutex;
+
+frg::optional<int> utmpFd = frg::null_opt;
+
+utmp returned;
+
+} // namespace
+
+void setutent(void) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd) {
+		int fd;
+		int err = mlibc::sys_open(utmpPath, O_RDWR | O_CREAT | O_CLOEXEC, 0644, &fd);
+		if(err) {
+			mlibc::infoLogger() << "\e[31mmlibc: setutent() failed to open " << utmpPath << ": "
+			                    << strerror(err) << "\e[39m" << frg::endlog;
+			utmpFd = frg::null_opt;
+		} else {
+			utmpFd = fd;
+		}
+	} else {
+		off_t discard;
+		mlibc::sys_seek(utmpFd.value(), 0, SEEK_SET, &discard);
+	}
+}
+
+struct utmp *getutent(void) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd)
+		setutent();
+	if(!utmpFd) {
+		errno = ENOENT;
+		return nullptr;
+	}
+
+	if(int e = mlibc::getUtmpEntry(*utmpFd, &returned); e) {
+		errno = e;
+		return nullptr;
+	}
+
+	return &returned;
+}
+
+int getutent_r(struct utmp *buf, struct utmp **res) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd)
+		setutent();
+	if(!utmpFd) {
+		*res = nullptr;
+		errno = ENOENT;
+		return -1;
+	}
+
+	if(int e = mlibc::getUtmpEntry(*utmpFd, buf); e) {
+		*res = nullptr;
+		errno = e;
+		return -1;
+	}
+
+	*res = buf;
+	return 0;
+}
+
+void endutent(void) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(utmpFd) {
+		mlibc::sys_close(utmpFd.value());
+		utmpFd = frg::null_opt;
+	}
+}
+
+struct utmp *pututline(const struct utmp *ut) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd)
+		setutent();
+	if(!utmpFd) {
+		errno = ENOENT;
+		return nullptr;
+	}
+
+	if(int e = mlibc::putUtmpEntry(*utmpFd, ut); e) {
+		errno = e;
+		return nullptr;
+	}
+
+	return (utmp *) ut;
+}
+
+struct utmp *getutline(const struct utmp *ut) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd)
+		setutent();
+	if(!utmpFd) {
+		errno = ENOENT;
+		return nullptr;
+	}
+
+	if(int e = mlibc::getUtmpEntryByType(*utmpFd, ut, &returned); e) {
+		errno = e;
+		return nullptr;
+	}
+
+	return &returned;
+}
+
+int utmpname(const char *file) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(strcmp(file, utmpPath)) {
+		if(!strcmp(file, defaultUtmpPath)) {
+			free((void *) utmpPath);
+			utmpPath = defaultUtmpPath;
+		} else {
+			char *name = strdup(file);
+			if(!name)
+				return -1;
+
+			if(utmpPath != defaultUtmpPath)
+				free((void *) utmpPath);
+
+			utmpPath = name;
+		}
+	}
+
+	return 0;
+}
+
+struct utmp *getutid(const struct utmp *ut) {
+	frg::unique_lock lock{utmpMutex};
+
+	if(!utmpFd)
+		setutent();
+	if(!utmpFd) {
+		errno = ENOENT;
+		return nullptr;
+	}
+
+	if(int e = mlibc::getUtmpEntryById(*utmpFd, ut, &returned); e) {
+		errno = e;
+		return nullptr;
+	}
+
+	return &returned;
+}
+
+void updwtmp(const char *file, const struct utmp *ut) {
+	int fd;
+	int err = mlibc::sys_open(file, O_RDWR | O_CREAT | O_CLOEXEC | O_APPEND, 0644, &fd);
+	if(err) {
+		mlibc::infoLogger() << "\e[31mmlibc: updwtmp() failed to open " << file << ": "
+							<< strerror(err) << "\e[39m" << frg::endlog;
+		return;
+	}
+
+	mlibc::putUtmpEntry(fd, ut);
+	mlibc::sys_close(fd);
+}