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ft_strlcpy.c
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ft_strlcpy.c
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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* ft_strlcpy.c :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: pvaladar <pvaladar@student.42lisboa.com> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2022/01/22 10:53:14 by pvaladar #+# #+# */
/* Updated: 2022/03/10 16:10:16 by pvaladar ### ########.fr */
/* */
/* ************************************************************************** */
// STRLCPY(3) BSD Library Functions Manual STRLCPY(3)
//
// NAME
// strlcpy, strlcat -- size-bounded string copying and concatenation
//
// LIBRARY
// Standard C Library (libc, -lc)
//
// SYNOPSIS
// #include <string.h>
//
// size_t
// strlcpy(char * restrict dst, const char * restrict src, size_t dstsize);
//
// size_t
// strlcat(char * restrict dst, const char * restrict src, size_t dstsize);
//
// DESCRIPTION
// The strlcpy() and strlcat() functions copy and concatenate strings with
// the same input parameters and output result as snprintf(3).
// They are designed to be safer, more consistent, and less error prone
// replacements for the easily misused functions strncpy(3) and strncat(3).
//
// strlcpy() and strlcat() take the full size of the destination buffer and
// guarantee NUL-termination if there is room.
// Note that room for the NUL should be included in dstsize.
//
// strlcpy() copies up to dstsize - 1 characters from the string
// src to dst, NUL-terminating the result if dstsize is not 0.
//
// strlcat() appends string src to the end of dst. It will append at most
// dstsize - strlen(dst) - 1 characters. It will then NUL-terminate,
// unless dstsize is 0 or the original dst string was longer than dstsize
// (in practice this should not happen as it means that either dstsize is
// incorrect or that dst is not a proper string).
//
// If the src and dst strings overlap, the behavior is undefined.
//
// RETURN VALUES
// Besides quibbles over the return type (size_t versus int) and signal
// handler safety (snprintf(3) is not entirely safe on some systems),
// the following two are equivalent:
//
// n = strlcpy(dst, src, len);
// n = snprintf(dst, len, "%s", src);
//
// Like snprintf(3), the strlcpy() and strlcat() functions return the
// total length of the string they tried to create.
// For strlcpy() that means the length of src.
// For strlcat() that means the initial length of dst plus the length
// of src.
//
// If the return value is >= dstsize, the output string has been
// truncated. It is the caller's responsibility to handle this.
//
// EXAMPLES
// The following code fragment illustrates the simple case:
//
// char *s, *p, buf[BUFSIZ];
//
// ...
//
// (void)strlcpy(buf, s, sizeof(buf));
// (void)strlcat(buf, p, sizeof(buf));
//
// To detect truncation, perhaps while building a pathname, something
// like the following might be used:
//
// char *dir, *file, pname[MAXPATHLEN];
//
// ...
//
// if (strlcpy(pname, dir, sizeof(pname)) >= sizeof(pname))
// goto toolong;
// if (strlcat(pname, file, sizeof(pname)) >= sizeof(pname))
// goto toolong;
//
// Since it is known how many characters were copied the first time,
// things can be sped up a bit by using a copy instead of an append:
//
// char *dir, *file, pname[MAXPATHLEN];
// size_t n;
//
// ...
//
// n = strlcpy(pname, dir, sizeof(pname));
// if (n >= sizeof(pname))
// goto toolong;
// if (strlcpy(pname + n, file, sizeof(pname) - n)
// >= sizeof(pname) - n)
// goto toolong;
//
// However, one may question the validity of such optimizations, as they
// defeat the whole purpose of strlcpy() and strlcat().
// As a matter of fact, the first version of this manual page got it wrong.
#include "libft.h" // size_t is defined in header <stdlib.h>
// "Some of the functions’ prototypes you have to redo use the ’restrict’
// qualifier."
size_t ft_strlcpy(char *dst, const char *src, size_t dstsize)
{
size_t i;
i = 0;
if (dstsize != 0)
{
while (src[i] && i < dstsize - 1)
{
dst[i] = src[i];
i++;
}
dst[i] = 0;
}
return (ft_strlen(src));
}