strlcat(9)

okay bestie, welcome to strlcat(9) from the Kernel API Manual — she appends strings, but pls read the warning before you get attached 💀✨

🎀 NAME 🎀

strlcat — Append a string to an existing string 💖

✨ SYNOPSIS ✨

size_t strlcat (char * const p , const char * const q , size_t avail );

🦋 ARGUMENTS 🦋

• p — pointer to the NUL-terminated string you're appending to 🫶
• q — pointer to the NUL-terminated string you're appending from 🌸
• avail — maximum bytes available in p ⭐

💅 DESCRIPTION 💅

So the vibe is: strlcat appends the NUL-terminated string q after the NUL-terminated string at p, but it will not write beyond avail bytes total — which can potentially truncate the copy from q 😭

p will stay NUL-terminated only if a NUL already existed within the avail bytes of p. If that NUL is there, the resulting number of bytes copied from q will be at most avail - strlen(p) - 1 ✨

🚨 Do not use this function. While FORTIFY_SOURCE tries to avoid read and write overflows, this is only possible when the sizes of p and q are known to the compiler. Prefer building the string with formatting, via scnprintf, seq_buf, or similar. no cap, this one's giving deprecated energy 💀

Returns the total bytes that _would_ have been contained by p regardless of truncation, similar to snprintf. If the return value is >= avail, the string has been truncated 👑🔥

🌈 SEE ALSO 🌈

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

mwah 💋 — signed off from ./include/linux, October 2026, on the strlcat(9) page. bye bestie, stay NUL-terminated 🫶🎀