bpf_strncasestr(9)

💅 bpf_strncasestr — the kernel API manual, but make it make sense

okay so real talk, this page is from the Kernel API Manual, section 9, and it's all about bpf_strncasestr(9). Bestie, it's a string-search girlie and she does NOT care about your capitals. Let's get into it 🎀

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✨ NAME ✨

bpf_strncasestr — find the first substring in a length-limited string, ignoring the case of the characters 🦋

like, she's strnstr but she's case-blind and she's thriving, no cap.

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🌸 SYNOPSIS 🌸

__bpf_kfunc int bpf_strncasestr (const char *s1__ign , const char
* s2__ign , size_t len );

so it's __bpf_kfunc, it hands you back an int, and it takes three args. the __ign suffix on the pointers is just the kernel's little annotation moment — do not come for her 💅

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👑 ARGUMENTS 👑

• s1__ign — the string to be searched. the main character. the one we're snooping around in 🔍
• s2__ign — the string to search for. the little icon we're hunting for inside s1__ign.
• len — the maximum number of characters to search. think of it as the vibe check boundary — she stops looking past this many characters, periodt.

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💖 RETURN 💖

bestie, here's what she can give you back:

• >=0 — index of the first character of the first occurrence of s2__ign within the first len characters of s1__ign. found her! 🎉
• -ENOENT — s2__ign not found in the first len characters of s1__ign. she's not there, move on 😭
• -EFAULT — cannot read one of the strings. ouch, invalid memory moment 🙈
• -E2BIG — one of the strings is too large. too much, even for us 💀
• -ERANGE — one of the strings is outside of kernel address space. wrong neighborhood entirely 🚫

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🔥 SEE ALSO 🔥

okay this list is LONG and honestly iconic — it's the whole Kernel file ./kernel/bpf/helpers.c friend group. buckle up 🫶

• bpf_obj_new(9)
• bpf_percpu_obj_new(9)
• bpf_obj_drop(9)
• bpf_percpu_obj_drop(9)
• bpf_refcount_acquire(9)
• bpf_list_push_front(9)
• bpf_list_push_back(9)
• bpf_rbtree_add(9)
• bpf_task_acquire(9)
• bpf_task_release(9)
• bpf_cgroup_acquire(9)
• bpf_cgroup_release(9)
• bpf_cgroup_ancestor(9)
• bpf_cgroup_from_id(9)
• bpf_task_under_cgroup(9)
• bpf_task_get_cgroup1(9)
• bpf_task_from_pid(9)
• bpf_task_from_vpid(9)
• bpf_dynptr_slice(9)
• bpf_dynptr_slice_rdwr(9)
• bpf_dynptr_copy(9)
• bpf_dynptr_memset(9)
• bpf_iter_bits_new(9)
• bpf_iter_bits_next(9)
• bpf_iter_bits_destroy(9)
• bpf_copy_from_user_str(9)
• bpf_copy_from_user_task_str(9)
• bpf_strcmp(9)
• bpf_strcasecmp(9)
• bpf_strnchr(9)
• bpf_strchr(9)
• bpf_strchrnul(9)
• bpf_strrchr(9)
• bpf_strnlen(9)
• bpf_strlen(9)
• bpf_strspn(9)
• bpf_strcspn(9)
• bpf_strstr(9)
• bpf_strcasestr(9)
• bpf_strnstr(9)
• bpf_lookup_user_key(9)
• bpf_lookup_system_key(9)
• bpf_key_put(9)
• bpf_verify_pkcs7_signature(9)
• bpf_task_work_schedule_signal(9)
• bpf_task_work_schedule_resume(9)
• bpf_timer_cancel_async(9)

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ngl the whole "case-insensitive but only for len characters" thing is the entire personality of this function. respect it. 🧚

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and that's the page, bestie! this little baddie lives at the path ./kernel/bpf, the version stamp on her birth certificate says October 2026, and she's filed under bpf_strncasestr(9) in the Kernel API Manual — slay, bye! ⭐💜