LibC: Add posix_openpt(), grantpt() and unlockpt()

This makes getting a pseudoterminal pair a little bit more portable.
Note that grantpt() and unlockpt() are currently no-ops, since we've
already granted the pseudoterminal slave to the calling user.

We also accept O_CLOEXEC to posix_openpt(), unlike some systems. :^)

Applications/Terminal/main.cpp

@@ -202,9 +202,17 @@ int main(int argc, char** argv)
     if (chdir(get_current_user_home_path().characters()) < 0)
         perror("chdir");
 
-    int ptm_fd = open("/dev/ptmx", O_RDWR | O_CLOEXEC);
+    int ptm_fd = posix_openpt(O_RDWR | O_CLOEXEC);
     if (ptm_fd < 0) {
-        perror("open(ptmx)");
+        perror("posix_openpt");
+        return 1;
+    }
+    if (grantpt(ptm_fd) < 0) {
+        perror("grantpt");
+        return 1;
+    }
+    if (unlockpt(ptm_fd) < 0) {
+        perror("unlockpt");
         return 1;
     }
 

DevTools/HackStudio/TerminalWrapper.cpp

@@ -52,9 +52,17 @@ void TerminalWrapper::run_command(const String& command)
         return;
     }
 
-    int ptm_fd = open("/dev/ptmx", O_RDWR | O_CLOEXEC);
+    int ptm_fd = posix_openpt(O_RDWR | O_CLOEXEC);
     if (ptm_fd < 0) {
-        perror("open(ptmx)");
+        perror("posix_openpt");
+        ASSERT_NOT_REACHED();
+    }
+    if (grantpt(ptm_fd) < 0) {
+        perror("grantpt");
+        ASSERT_NOT_REACHED();
+    }
+    if (unlockpt(ptm_fd) < 0) {
+        perror("unlockpt");
         ASSERT_NOT_REACHED();
     }
 

Libraries/LibC/stdlib.cpp

@@ -746,4 +746,26 @@ char* realpath(const char* pathname, char* buffer)
     errno = 0;
     return buffer;
 }
+
+int posix_openpt(int flags)
+{
+    if (flags & ~(O_RDWR | O_NOCTTY | O_CLOEXEC)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    return open("/dev/ptmx", flags);
+}
+
+int grantpt(int fd)
+{
+    (void)fd;
+    return 0;
+}
+
+int unlockpt(int fd)
+{
+    (void)fd;
+    return 0;
+}
 }

Libraries/LibC/stdlib.h

@@ -100,4 +100,8 @@ typedef struct {
 } ldiv_t;
 ldiv_t ldiv(long, long);
 
+int posix_openpt(int flags);
+int grantpt(int fd);
+int unlockpt(int fd);
+
 __END_DECLS

Servers/TelnetServer/main.cpp

@@ -143,9 +143,19 @@ int main(int argc, char** argv)
             return;
         }
 
-        int ptm_fd = open("/dev/ptmx", O_RDWR);
+        int ptm_fd = posix_openpt(O_RDWR);
         if (ptm_fd < 0) {
-            perror("open(ptmx)");
+            perror("posix_openpt");
+            client_socket->close();
+            return;
+        }
+        if (grantpt(ptm_fd) < 0) {
+            perror("grantpt");
+            client_socket->close();
+            return;
+        }
+        if (unlockpt(ptm_fd) < 0) {
+            perror("unlockpt");
             client_socket->close();
             return;
         }