search_binfmt_handler(9)

💅 search_binfmt_handler(9) — like, the kernel API manual, bestie 💅

okay so real talk, this one's from the Kernel API Manual and it's genuinely such a cute lil function. It's called search_binfmt_handler and it does exactly what it says on the tin: it goes looking for a binary handler. Let's get into it ✨

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🌸 SYNOPSIS 🌸

struct binfmt_misc_entry * search_binfmt_handler (struct binfmt_misc
       *misc , struct linux_binprm *bprm );

That return type is struct binfmt_misc_entry *, no cap — she's giving pointer-to-entry realness 🎀

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🦋 ARGUMENTS 🦋

• misc — your handle to the binfmt_misc instance. Like, this is the whole world we're searching in, bestie 🫶
• bprm — the binary we're trying to find a handler for. The main character of this operation, honestly 👑

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💜 DESCRIPTION 💜

So here's the vibe: this function searches for a binary type handler for bprm in the list of registered binary type handlers. Simple enough, right?

A 'B' entry's match program is the one that decides whether the handler applies. And listen — that match program may sleep to read the binary. Not a drill, it's allowed to do that, and that's lowkey important for the locking situation below 🙈

The matched entry gets returned with a reference taken while the walk still held it. Meanwhile, a dying entry — one that's been unlinked with its last reference gone — cannot be matched, so the walk just moves on. She's gone, we're not matching her, periodt 💀

ok so this part is the actual important bit: the caller must hold the bm_entries_srcu read lock, and that's exactly what allows an entry's evaluation to sleep. Do not skip this, fr fr 😭

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⭐ RETURN ⭐

• referenced binary type list entry on success 🔥
• NULL on failure 😭

That's it. That's the whole return section. Iconic brevity, honestly 👑

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🌈 SEE ALSO 🌈

The kernel file ./fs/binfmt_misc.c — yes, that's where all the magic lives 🧚

And the whole squad of related functions, because she does not exist in a vacuum bestie:

• struct binfmt_misc_flag(9)
• get_binfmt_handler(9)
• binfmt_misc_find_interp(9)
• entry_attach_interpreter(9)
• put_binfmt_handler(9)
• current_binfmt_misc(9)
• entry_select_interpreter(9)
• entry_invocation_flags(9)
• entry_open_interpreter(9)
• build_interp_argv(9)
• i_binfmt_misc(9)
• bm_evict_inode(9)
• unlink_binfmt_handler(9)
• remove_binfmt_handler(9)
• bm_unlink(9)
• bm_entry_add_interp(9)

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aaaand that's the page!! this one's living in ./fs and it's dated October 2026, so future-core of her honestly 🦋💖 go hold that bm_entries_srcu read lock and slay, bestie 🌸✨