1 files changed, 133 insertions, 0 deletions
diff --git a/usr.bin/doas/persist.c b/usr.bin/doas/persist.c
new file mode 100644
index 0000000..4ad1bf1
--- /dev/null
+++ b/usr.bin/doas/persist.c
@@ -0,0 +1,133 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "doas.h"
+
+#define PERSIST_DIR "/run/doas"
+#define PERSIST_TIMEOUT 5 * 60
+
+static int
+ttyid(dev_t *tty)
+{
+	int fd, i;
+	char buf[BUFSIZ], *p;
+	ssize_t n;
+
+	fd = open("/proc/self/stat", O_RDONLY);
+	if (fd == -1)
+		return -1;
+	n = read(fd, buf, sizeof(buf) - 1);
+	if (n >= 0)
+		buf[n] = '\0';
+	/* check that we read the whole file */
+	n = read(fd, buf, 1);
+	close(fd);
+	if (n != 0)
+		return -1;
+	p = strrchr(buf, ')');
+	if (!p)
+		return -1;
+	++p;
+	/* ttr_nr is the 5th field after executable name, so skip the next 4 */
+	for (i = 0; i < 4; ++i) {
+		p = strchr(++p, ' ');
+		if (!p)
+			return -1;
+	}
+	*tty = strtol(p, &p, 10);
+	if (*p != ' ')
+		return -1;
+	return 0;
+}
+
+static int
+persistpath(char *buf, size_t len)
+{
+	dev_t tty;
+	int n;
+
+	if (ttyid(&tty) < 0)
+		return -1;
+	n = snprintf(buf, len, PERSIST_DIR "/%ju-%ju", (uintmax_t)getuid(), (uintmax_t)tty);
+	if (n < 0 || n >= (int)len)
+		return -1;
+	return 0;
+}
+
+int
+openpersist(int *valid)
+{
+	char path[256];
+	struct stat st;
+	struct timespec ts;
+	int fd;
+
+	if (stat(PERSIST_DIR, &st) < 0) {
+		if (errno != ENOENT)
+			return -1;
+		if (mkdir(PERSIST_DIR, 0700) < 0)
+			return -1;
+	} else if (st.st_uid != 0 || st.st_mode != (S_IFDIR | 0700)) {
+		return -1;
+	}
+	if (persistpath(path, sizeof(path)) < 0)
+		return -1;
+	fd = open(path, O_RDONLY);
+	if (fd == -1) {
+		char tmp[256];
+		struct timespec ts[2] = { { .tv_nsec = UTIME_OMIT }, { 0 } };
+		int n;
+
+		n = snprintf(tmp, sizeof(tmp), PERSIST_DIR "/.tmp-%d", getpid());
+		if (n < 0 || n >= (int)sizeof(tmp))
+			return -1;
+		fd = open(tmp, O_RDONLY | O_CREAT | O_EXCL, 0);
+		if (fd == -1)
+			return -1;
+		if (futimens(fd, ts) < 0 || rename(tmp, path) < 0) {
+			close(fd);
+			unlink(tmp);
+			return -1;
+		}
+		*valid = 0;
+	} else {
+		*valid = clock_gettime(CLOCK_BOOTTIME, &ts) == 0 &&
+		         fstat(fd, &st) == 0 &&
+		         (ts.tv_sec < st.st_mtim.tv_sec ||
+		          (ts.tv_sec == st.st_mtim.tv_sec && ts.tv_nsec < st.st_mtim.tv_nsec)) &&
+		         st.st_mtime - ts.tv_sec <= PERSIST_TIMEOUT;
+	}
+	return fd;
+}
+
+int
+setpersist(int fd)
+{
+	struct timespec times[2];
+
+	if (clock_gettime(CLOCK_BOOTTIME, &times[1]) < 0)
+		return -1;
+	times[0].tv_nsec = UTIME_OMIT;
+	times[1].tv_sec += PERSIST_TIMEOUT;
+	return futimens(fd, times);
+}
+
+int
+clearpersist(void)
+{
+	char path[256];
+
+	if (persistpath(path, sizeof(path)) < 0)
+		return -1;
+	if (unlink(path) < 0 && errno != ENOENT)
+		return -1;
+	return 0;
+}