first_non_ff(9)

💅 first_non_ff(9) — like, the Kernel API Manual entry, bestie ✨

Okay so picture this: you're deep in the Kernel API Manual (yes, that one, the first_non_ff(9) page), and you just need to know where the first non-0xff byte is hiding. That's it. That's the whole plot. 🎀

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🌸 NAME 🌸

first_non_ff — find the offset of the first non-0xff byte. literally its whole job, no notes 👑

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✨ SYNOPSIS ✨

int first_non_ff (void *buf , int len );

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🦋 ARGUMENTS 🦋

• buf — the buffer you're searching in, bestie. hand it over 💜
• len — how long that buffer is. gotta know where to stop looking fr fr

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💖 DESCRIPTION 💖

So this function returns the offset of the first non-0xff byte inside buf 🫶

And if the buffer is literally all 0xff bytes — like every single one, no survivors — it comes back with -1 instead. that's the vibe check failing, basically 💀

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🌈 SEE ALSO 🌈

Kernel file ./fs/ubifs/recovery.c is, like, the whole friend group here — every single one of these icons:

• is_empty(9)
• get_master_node(9)
• write_rcvrd_mst_node(9)
• ubifs_recover_master_node(9)
• ubifs_write_rcvrd_mst_node(9)
• is_last_write(9)
• clean_buf(9)
• no_more_nodes(9)
• fix_unclean_leb(9)
• drop_last_group(9)
• drop_last_node(9)
• ubifs_recover_leb(9)
• get_cs_sqnum(9)
• ubifs_recover_log_leb(9)
• recover_head(9)
• ubifs_recover_inl_heads(9)
• clean_an_unclean_leb(9)
• ubifs_clean_lebs(9)
• grab_empty_leb(9)
• ubifs_rcvry_gc_commit(9)
• struct size_entry(9)
• add_ino(9)
• find_ino(9)
• remove_ino(9)
• ubifs_destroy_size_tree(9)
• ubifs_recover_size_accum(9)
• fix_size_in_place(9)
• inode_fix_size(9)
• ubifs_recover_size(9)

like go read them?? they're right there?? 😭💅

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okay that's the page, ily, go forth and scan your buffers 🧚

sign-off szn: this lil masterpiece lives in ./fs/ubifs, and it's dated October 2026 — yes, that October 2026 🌸 periodt.