LibCore: Add a wrapper for endgrent()

Author: https://github.com/LucasChollet
Commit: https://github.com/SerenityOS/serenity/commit/d288c700c7
Pull-request: https://github.com/SerenityOS/serenity/pull/14222
Reviewed-by: https://github.com/petelliott ✅

Userland/Libraries/LibCore/System.cpp

@@ -687,6 +687,17 @@ ErrorOr<off_t> lseek(int fd, off_t offset, int whence)
     return rc;
 }
 
+ErrorOr<void> endgrent()
+{
+    int old_errno = 0;
+    swap(old_errno, errno);
+    ::endgrent();
+    if (errno != 0)
+        return Error::from_syscall("endgrent", -errno);
+    errno = old_errno;
+    return {};
+}
+
 ErrorOr<WaitPidResult> waitpid(pid_t waitee, int options)
 {
     int wstatus;

Userland/Libraries/LibCore/System.h

@@ -100,6 +100,7 @@ ErrorOr<void> clock_settime(clockid_t clock_id, struct timespec* ts);
 ErrorOr<pid_t> posix_spawn(StringView path, posix_spawn_file_actions_t const* file_actions, posix_spawnattr_t const* attr, char* const arguments[], char* const envp[]);
 ErrorOr<pid_t> posix_spawnp(StringView path, posix_spawn_file_actions_t* const file_actions, posix_spawnattr_t* const attr, char* const arguments[], char* const envp[]);
 ErrorOr<off_t> lseek(int fd, off_t, int whence);
+ErrorOr<void> endgrent();
 
 struct WaitPidResult {
     pid_t pid;