From 415eb17490607ac5a133ba62d0ea733393a30131 Mon Sep 17 00:00:00 2001
From: Peter Elliott <pelliott@ualberta.ca>
Date: Mon, 24 Oct 2022 22:15:58 -0600
Subject: [PATCH] LibCore: Add Core::System::readlink

---
 Userland/Libraries/LibCore/System.cpp | 21 +++++++++++++++++++++
 Userland/Libraries/LibCore/System.h   |  1 +
 2 files changed, 22 insertions(+)

diff --git a/Userland/Libraries/LibCore/System.cpp b/Userland/Libraries/LibCore/System.cpp
index 170a0c7336..f060bb87c3 100644
--- a/Userland/Libraries/LibCore/System.cpp
+++ b/Userland/Libraries/LibCore/System.cpp
@@ -1326,4 +1326,25 @@ ErrorOr<void> access(StringView pathname, int mode)
 #endif
 }
 
+ErrorOr<String> readlink(StringView pathname)
+{
+    // FIXME: Try again with a larger buffer.
+    char data[PATH_MAX];
+#ifdef AK_OS_SERENITY
+    Syscall::SC_readlink_params small_params {
+        { pathname.characters_without_null_termination(), pathname.length() },
+        { data, sizeof(data) }
+    };
+    int rc = syscall(SC_readlink, &small_params);
+    HANDLE_SYSCALL_RETURN_VALUE("readlink", rc, String(data, rc));
+#else
+    String path_string = pathname;
+    int rc = ::readlink(path_string.characters(), data, sizeof(data));
+    if (rc == -1)
+        return Error::from_syscall("readlink"sv, -errno);
+
+    return String(data, rc);
+#endif
+}
+
 }
diff --git a/Userland/Libraries/LibCore/System.h b/Userland/Libraries/LibCore/System.h
index 12edc46638..9b1b8345e0 100644
--- a/Userland/Libraries/LibCore/System.h
+++ b/Userland/Libraries/LibCore/System.h
@@ -193,5 +193,6 @@ ErrorOr<int> posix_openpt(int flags);
 ErrorOr<void> grantpt(int fildes);
 ErrorOr<void> unlockpt(int fildes);
 ErrorOr<void> access(StringView pathname, int mode);
+ErrorOr<String> readlink(StringView pathname);
 
 }