strlen(9)

💖 strlen(9) — Kernel API Manual 💖

okay bestie, welcome to the strlen(9) page from the Kernel API Manual. it's short, it's iconic, and it has one huge safety warning. let's get into it 🫶

🌸 NAME 🌸

strlen — Return count of characters in a NUL-terminated string

✨ SYNOPSIS ✨

strlen (p );

🎀 ARGUMENTS 🎀

• p — pointer to NUL-terminated string to count.

🦋 DESCRIPTION 🦋

🚨 Do not use this function unless the string length is known at compile-time. When p is unterminated, this function may crash or return unexpected counts that could lead to memory content exposures. Prefer strnlen.

Returns number of characters in p (NOT including the final NUL). periodt. 💅

👑 SEE ALSO 👑

cross-refs, go look 👀:

• Kernel file ./include/linux/fortify-string.h unsafe_memcpy(9), strnlen(9), strlcat(9), strcat(9), strncat(9), strcpy(9)

mwah 💋 okay that's the whole page! source/version: ./include/linux; date: October 2026; and the page is strlen(9). bye bestie, stay NUL-terminated 🫶✨