libc: Add pseudoterminal-related functions

libc/include/stdlib.h

@@ -148,6 +148,18 @@ extern "C"
     /* Create a unique file from a template string whose last 6 bytes must be XXXXXX. */
     int mkstemp(char* _template);
 
+    /* Create a new pseudoterminal pair. */
+    int posix_openpt(int flags);
+
+    /* Set the credentials of a pseudoterminal master. */
+    int grantpt(int fd);
+
+    /* Unlock a pseudoterminal master. */
+    int unlockpt(int fd);
+
+    /* Return the name of the slave associated with a pseudoterminal master. */
+    char* ptsname(int fd);
+
 #ifdef __cplusplus
 }
 #endif

libc/src/stdlib.cpp

@@ -1,4 +1,5 @@
 #include <bits/errno-return.h>
+#include <bits/termios.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
@@ -7,8 +8,10 @@
 #include <luna/Sort.h>
 #include <luna/Utf8.h>
 #include <signal.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/wait.h>
@@ -300,4 +303,31 @@ extern "C"
     {
         return strtod(str, nullptr);
     }
+
+    int posix_openpt(int flags)
+    {
+        return open("/dev/ptmx", flags);
+    }
+
+    int grantpt(int)
+    {
+        return 0;
+    }
+
+    int unlockpt(int)
+    {
+        return 0;
+    }
+
+    char* ptsname(int fd)
+    {
+        static char buffer[4096];
+
+        int index;
+        if (ioctl(fd, TIOCGPTN, &index) < 0) return nullptr;
+
+        snprintf(buffer, sizeof(buffer), "/dev/pts/%d", index);
+
+        return buffer;
+    }
 }