ecryptfs_wri...acket_length(9)

💅 ecryptfs_wri...acket_length(9) — Kernel API Manual

okay bestie, so this one is a kernel API manpage, the ecryptfs_wri...acket_length one (yes the name is literally abbreviated with ... in the header, that's just how it's printed, don't come for me 🫶). It lives in the Kernel API Manual, and we're gonna walk through it together, no cap.

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✨ NAME ✨

ecryptfs_write_packet_length -

and that's it. that's the whole NAME line. just the function and a little dash with nothing after it 🙈 no one-liner description, no teaser, nothing. lowkey iconic of it to give us zero context, but okay.

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🌸 SYNOPSIS 🌸

int ecryptfs_write_packet_length (char *dest , size_t size , size_t
*packet_size_length );

there she is. returns an int, takes three args, and yes the spacing is a little chaotic but we copy it exactly, character for character, periodt 💅

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🎀 ARGUMENTS 🎀

• dest — the byte array target where the length gets written. it must have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated. like, not "probably", not "eh, close enough" — at least that many. respect the buffer, bestie 😭
• size — the actual length you're writing. that's the number going in.
• packet_size_length — the number of bytes used to encode the packet length gets written to this address. so it's like, the length of the length. very meta of it ✨

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🦋 DESCRIPTION 🦋

Returns zero on success; non-zero on error. short and sweet, fr fr. zero = we ate. non-zero = something went sideways 💀

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🌈 SEE ALSO 🌈

the kernel file ./fs/ecryptfs/keystore.c — that's the source of truth, go look if you're curious 👀 and then the whole friend group of related functions:

• ecryptfs_parse_packet_length(9)
• ecryptfs_verify_version(9)
• ecryptfs_verify_auth_tok_from_key(9)
• ecryptfs_find_auth_tok_for_sig(9)
• ecryptfs_parse_tag_70_packet(9)
• decrypt_pki_encrypted_session_key(9)
• parse_tag_1_packet(9)
• parse_tag_3_packet(9)
• parse_tag_11_packet(9)
• decrypt_passphrase_encrypted_session_key(9)
• ecryptfs_parse_packet_set(9)
• write_tag_1_packet(9)
• write_tag_11_packet(9)
• write_tag_3_packet(9)
• ecryptfs_generate_key_packet_set(9)

like a whole group chat of packet functions, and this one is absolutely a main character in it 👑

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ngl the vibe check here is simple: give dest enough room (ECRYPTFS_MAX_PKT_LEN_SIZE minimum, no negotiations), pass the size, and let it tell you how many bytes it used via packet_size_length. zero means slay, anything else means go debug 🧚

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and that's the page, bestie 💖 cute lil sign-off: this one comes from ./fs/ecryptfs, dated October 2026, and the manual name is ecryptfs_wri...acket_length(9). go forth and write those packet lengths 🌸🎀