LibCore: Add a Core::System wrapper around unsetenv

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/6655de189f
Pull-request: https://github.com/SerenityOS/serenity/pull/21833

Userland/Libraries/LibCore/System.cpp

@@ -1639,6 +1639,19 @@ ErrorOr<void> setenv(StringView name, StringView value, bool overwrite)
     return {};
 }
 
+ErrorOr<void> unsetenv(StringView name)
+{
+    auto builder = TRY(StringBuilder::create());
+    TRY(builder.try_append(name));
+    TRY(builder.try_append('\0'));
+
+    // Note the explicit null terminator above.
+    auto rc = ::unsetenv(builder.string_view().characters_without_null_termination());
+    if (rc < 0)
+        return Error::from_errno(errno);
+    return {};
+}
+
 ErrorOr<void> putenv(StringView env)
 {
 #ifdef AK_OS_SERENITY

Userland/Libraries/LibCore/System.h

@@ -229,6 +229,7 @@ ErrorOr<void> setgroups(ReadonlySpan<gid_t>);
 ErrorOr<void> mknod(StringView pathname, mode_t mode, dev_t dev);
 ErrorOr<void> mkfifo(StringView pathname, mode_t mode);
 ErrorOr<void> setenv(StringView, StringView, bool);
+ErrorOr<void> unsetenv(StringView);
 ErrorOr<void> putenv(StringView);
 ErrorOr<int> posix_openpt(int flags);
 ErrorOr<void> grantpt(int fildes);