label_cmp(9)

💅 label_cmp(9) — yes bestie, we're in the Kernel API Manual for this one

Okay so picture this: you're deep in the kernel, you've got a bunch of labels, and you need to know which one comes first. That's the whole gig. label_cmp is literally the label comparison for set ordering — it's the function that tells the sorting gods how to line aa_label structs up. ✨

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🌸 NAME 🌸

label_cmp — label comparison for set ordering

Like, that's it. That's the function. It compares labels so sets can be ordered. No cap. 🎀

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🦋 SYNOPSIS 🦋

int label_cmp (const struct aa_label *a , const struct aa_label *b );

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💖 ARGUMENTS 💖

• a — label to compare. NOT NULL, bestie, I'm serious. Do not pass NULL here, that's not the vibe. 🙈
• b — the other label to compare. Also NOT NULL. Both of them. Non-negotiable. 💀

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⭐ RETURN ⭐

The return value is giving comparison-function classic:

• <0 if a < b
• ==0 if a == b
• >0 if a > b

So basically the standard three-state thing — negative, zero, positive. Iconic behaviour, zero surprises. 👑

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🔥 SEE ALSO 🔥

Okay this list is long long, so buckle up, we're going on a tour of AppArmor label internals. 💜

• Kernel file ./security/apparmor/label.c
• ns_cmp(9)
• profile_cmp(9)
• vec_cmp(9)
• aa_vec_unique(9)
• aa_label_alloc(9)
• __aa_label_next_not_in_set(9)
• aa_label_is_subset(9)
• aa_label_is_unconfined_subset(9)
• __label_remove(9)
• __label_replace(9)
• __label_insert(9)
• __vec_find(9)
• __label_find(9)
• aa_label_remove(9)
• aa_label_replace(9)
• vec_find(9)
• aa_label_insert(9)
• aa_label_next_in_merge(9)
• label_merge_cmp(9)
• label_merge_insert(9)
• labelset_of_merge(9)
• __label_find_merge(9)
• aa_label_find_merge(9)
• aa_label_merge(9)
• label_compound_match(9)
• label_components_match(9)
• aa_label_match(9)
• aa_update_label_name(9)
• aa_profile_snxprint(9)
• aa_label_snxprint(9)
• aa_label_asxprint(9)
• aa_label_acntsxprint(9)
• aa_label_strn_parse(9)
• aa_labelset_destroy(9)
• __label_update(9)
• __labelset_update(9)
• __aa_labelset_update_subtree(9)

That's the whole squad, fr fr. 🫶

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Friendly reminder from your girl: a and b are both NOT NULL. Passing NULL is not a slay, it's a crash waiting to happen. 🙈

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✨ mwah, that's the page ✨ this little number lives in ./security/apparmor and it's dated October 2026 — so go forth, compare those labels, and stay hydrated. 💖🦋🌸