Libft(10) - strlcat

Libft(10) - strlcat

 

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 consis-
     tent, 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 origi-
     nal 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.

SEE ALSO
     snprintf(3), strncat(3), strncpy(3), wcslcpy(3)

HISTORY
     The strlcpy() and strlcat() functions first appeared in OpenBSD 2.4, and FreeBSD 3.3.

BSD                            February 26, 2016                           BSD

 

 

기존 정리 노션

ex05 참고

https://www.notion.so/C03-dc2976b1f6e947e7a2ddd52798333aa6