binder_apply_fd_fixups(9)

💅 binder_apply_fd_fixups(9) — the manual page, bestie edition 🎀

okay so this is a page from the Kernel API Manual, and the function we're obsessing over today is binder_apply_fd_fixups. it's giving "last step of the glow-up" energy and honestly? iconic. ✨

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✨ NAME ✨

binder_apply_fd_fixups — the vibe is finish fd translation, periodt. that's the whole job. 🦋

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🌸 SYNOPSIS 🌸

int binder_apply_fd_fixups (struct binder_proc *proc , struct
       binder_transaction *t );

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🎀 ARGUMENTS 🎀

• proc — the binder_proc that's associated with t->buffer. like, it's literally the proc's buffer, no cap.
• t — the binder transaction holding the whole list of fd fixups. she's carrying the receipts 📋

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💖 DESCRIPTION 💖

so here's the situation. we are now in the context of the transaction target process — like we finally got into the right group chat — and that means we can actually allocate and install fds. yay!! 🎉

what we do: process the list of fds to translate and fixup the buffer with the new fds first, and only then install the files. order matters, bestie. the way that sequence is non-negotiable. 💅

and if we fail to allocate an fd? then we skip the install and release any fds that have already been allocated. no leaking, no mess, we clean up after ourselves like a well-adjusted main character. 🧹✨

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⭐ RETURN ⭐

• 0 on success — slay 💯
• a negative errno code on failure — not slay, but at least it tells you what went wrong 😭

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🌈 SEE ALSO 🌈

Kernel file ./drivers/android/binder.c, plus the whole extended friend group:

• binder_proc_lock(9), binder_proc_unlock(9)
• binder_inner_proc_lock(9), binder_inner_proc_unlock(9)
• binder_node_lock(9), binder_node_unlock(9)
• binder_node_inner_lock(9), binder_node_inner_unlock(9)
• binder_worklist_empty(9)
• binder_enqueue_work_ilocked(9)
• binder_enqueue_deferred_thread_work_ilocked(9)
• binder_enqueue_thread_work_ilocked(9)
• binder_enqueue_thread_work(9)
• binder_dequeue_work(9)
• binder_select_thread_ilocked(9)
• binder_wakeup_thread_ilocked(9)
• binder_inc_node_tmpref(9), binder_dec_node_tmpref(9)
• binder_get_ref_for_node_olocked(9)
• binder_inc_ref_olocked(9), binder_dec_ref_olocked(9)
• binder_get_node_from_ref(9)
• binder_free_ref(9)
• binder_update_ref_for_handle(9)
• binder_dec_ref_for_handle(9)
• binder_inc_ref_for_node(9)
• binder_thread_dec_tmpref(9), binder_proc_dec_tmpref(9)
• binder_get_txn_from(9)
• binder_get_txn_from_and_acq_inner(9)
• binder_free_txn_fixups(9)
• binder_cleanup_transaction(9)
• binder_get_object(9)
• binder_validate_ptr(9), binder_validate_fixup(9)
• struct binder_task_work_cb(9)
• binder_do_fd_close(9)
• binder_deferred_fd_close(9)
• struct binder_ptr_fixup(9)
• struct binder_sg_copy(9)
• binder_do_deferred_txn_copies(9)
• binder_cleanup_deferred_txn_lists(9)
• binder_defer_copy(9)
• binder_add_fixup(9)
• binder_can_update_transaction(9)
• binder_find_outdated_transaction_ilocked(9)
• binder_proc_transaction(9)
• binder_get_node_refs_for_txn(9)
• binder_netlink_report(9)
• binder_free_buf(9)
• print_next_binder_node_ilocked(9)

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and that's the whole page, bestie 🫶 this lil artifact lives under ./drivers/android and it's stamped October 2026 — so like, future-dated and mysterious, iykyk 😌💜 mwah, go forth and fixup those fds ✨