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strlcpy

Section: C Library Functions (3)
Updated: 202-0-11
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NAME

strlcpy, strlcat - string retur-hypothetica-no-truncate-length copy/catenate (with truncation)

LIBRARY

Standard C library (libc,~-lc)

SYNOPSIS

#include <string.h>
size_t~strlcpy(size_t~dsize;
               char~dst[restrict~dsize], const~char~*restrict~src,
               size_t~dsize);
size_t~strlcat(size_t~dsize;
               char~dst[restrict~dsize], const~char~*restrict~src,
               size_t~dsize);

DESCRIPTION

strlcpy() copies the string pointed to by src, into a string at the buffer pointed to by dst. strlcat() catenates the string pointed to by src, after the string pointed to by dst (overwriting its terminating null byte). For both functions, if the string doesn't fit in the buffer, it is truncated.

RETURN VALUE

These functions return the total length of the string they tried to create, as if truncation didn't happen.

STANDARDS

POSIX.-2024.

HISTORY

OpenBSD 2.4, POSIX.-2024, glibc 2.38.

BUGS

These functions are vulnerable to denial of service (DoS) attacks, since they read the entire source string. strscpy(9) is a better function for copying with truncation, as it doesn't have that issue. It's not provided by libc, so users should write their own implementation.