0001-libc-gpu-ftell-uses-LIBC_FTELL.patch

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[libc][GPU] ftell: use the LIBC_FTELL opcode instead of LIBC_FSEEK

The GPU ftell() opened the RPC port with LIBC_FSEEK and only filled data[0].

The host server then called fseek(stream, data[1], data[2]) with whatever was

left in the buffer from a previous message. glibc just returns EINVAL, so the

bug is silent on Linux; the MSVC CRT treats an invalid 'origin' as an invalid

parameter and terminates the process (0xC0000409, FAST_FAIL_INVALID_ARG).

Still present in llvm-project main as of 2026-10.

--- a/libc/src/stdio/gpu/ftell.cpp

+++ b/libc/src/stdio/gpu/ftell.cpp

@@ -16,7 +16,7 @@

 LLVM_LIBC_FUNCTION(long, ftell, (::FILE * stream)) {

   long ret;

-  rpc::Client::Port port = rpc::client.open<LIBC_FSEEK>();

+  rpc::Client::Port port = rpc::client.open<LIBC_FTELL>();

   port.send_and_recv(

       [=](rpc::Buffer *buffer, uint32_t) {

         buffer->data[0] = file::from_stream(stream);