machined: introduce a ptsname_namespace() call and make use of it

The call is like ptsname() but does not assume the pty path was
accessible in the local namespace. It uses the same internal ioctl
though.

3 files changed, 25 insertions, 3 deletions

diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c
index cf55263bbf..c5ef5ab0d1 100644
--- a/src/basic/terminal-util.c
+++ b/src/basic/terminal-util.c
@@ -1074,3 +1074,22 @@ int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
 
         return 0;
 }
+
+int ptsname_namespace(int pty, char **ret) {
+        int no = -1, r;
+
+        /* Like ptsname(), but doesn't assume that the path is
+         * accessible in the local namespace. */
+
+        r = ioctl(pty, TIOCGPTN, &no);
+        if (r < 0)
+                return -errno;
+
+        if (no < 0)
+                return -EIO;
+
+        if (asprintf(ret, "/dev/pts/%i", no) < 0)
+                return -ENOMEM;
+
+        return 0;
+}
diff --git a/src/basic/terminal-util.h b/src/basic/terminal-util.h
index 188714f228..b9a3809a6c 100644
--- a/src/basic/terminal-util.h
+++ b/src/basic/terminal-util.h
@@ -107,3 +107,5 @@ int get_ctty(pid_t, dev_t *_devnr, char **r);
 
 int getttyname_malloc(int fd, char **r);
 int getttyname_harder(int fd, char **r);
+
+int ptsname_namespace(int pty, char **ret);
diff --git a/src/machine/machine-dbus.c b/src/machine/machine-dbus.c
index f27b58b893..a63b9785af 100644
--- a/src/machine/machine-dbus.c
+++ b/src/machine/machine-dbus.c
@@ -45,6 +45,7 @@
 #include "formats-util.h"
 #include "process-util.h"
 #include "env-util.h"
+#include "terminal-util.h"
 
 static int property_get_id(
                 sd_bus *bus,
@@ -500,7 +501,7 @@ int bus_machine_method_open_pty(sd_bus_message *message, void *userdata, sd_bus_
         if (master < 0)
                 return master;
 
-        r = ptsname_malloc(master, &pty_name);
+        r = ptsname_namespace(master, &pty_name);
         if (r < 0)
                 return r;
 
@@ -589,7 +590,7 @@ int bus_machine_method_open_login(sd_bus_message *message, void *userdata, sd_bu
         if (master < 0)
                 return master;
 
-        r = ptsname_malloc(master, &pty_name);
+        r = ptsname_namespace(master, &pty_name);
         if (r < 0)
                 return r;
 
@@ -687,7 +688,7 @@ int bus_machine_method_open_shell(sd_bus_message *message, void *userdata, sd_bu
         if (master < 0)
                 return master;
 
-        r = ptsname_malloc(master, &pty_name);
+        r = ptsname_namespace(master, &pty_name);
         if (r < 0)
                 return r;