Add getwd().

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/e5e0bffd769

LibC/limits.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#define PATH_MAX 4096

LibC/sys/param.h

@@ -1,4 +1,4 @@
 #pragma once
 
 #include <endian.h>
-
+#include <limits.h>

LibC/unistd.cpp

@@ -156,6 +156,11 @@ char* getcwd(char* buffer, size_t size)
     __RETURN_WITH_ERRNO(rc, buffer, nullptr);
 }
 
+char* getwd(char* buf)
+{
+    return getcwd(buf, PATH_MAX);
+}
+
 int sleep(unsigned seconds)
 {
     return Syscall::invoke(Syscall::SC_sleep, (dword)seconds);

LibC/unistd.h

@@ -2,6 +2,7 @@
 
 #include <sys/cdefs.h>
 #include <sys/types.h>
+#include <limits.h>
 
 __BEGIN_DECLS
 
@@ -29,6 +30,7 @@ int close(int fd);
 pid_t waitpid(pid_t, int* wstatus, int options);
 int chdir(const char* path);
 char* getcwd(char* buffer, size_t size);
+char* getwd(char* buffer);
 int lstat(const char* path, struct stat* statbuf);
 int stat(const char* path, struct stat* statbuf);
 int sleep(unsigned seconds);