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estrlcat(3) [netbsd man page]

EFUN(3) 						   BSD Library Functions Manual 						   EFUN(3)

esetfunc, easprintf, efopen, emalloc, ecalloc, erealloc, estrdup, estrndup, estrlcat, estrlcpy, evasprintf -- error-checked utility functions LIBRARY
System Utilities Library (libutil, -lutil) SYNOPSIS
#include <util.h> void (*)(int, const char *, ...) esetfunc(void (*)(int, const char *, ...)); int easprintf(char ** restrict str, const char * restrict fmt, ...); FILE * efopen(const char *p, const char *m); void * ecalloc(size_t n, size_t c); void * emalloc(size_t n); void * erealloc(void *p, size_t n); char * estrdup(const char *s); char * estrndup(const char *s, size_t len); size_t estrlcat(char *dst, const char *src, size_t len); size_t estrlcpy(char *dst, const char *src, size_t len); int evasprintf(char ** restrict str, const char * restrict fmt, ...); DESCRIPTION
The easprintf(), efopen(), ecalloc(), emalloc(), erealloc(), estrdup(), estrndup(), estrlcat(), estrlcpy(), and evasprintf() functions oper- ate exactly as the corresponding functions that do not start with an 'e' except that in case of an error, they call the installed error han- dler that can be configured with esetfunc(). For the string handling functions, it is an error when the destination buffer is not large enough to hold the complete string. For functions that allocate memory or open a file, it is an error when they would return a null pointer. The default error handler is err(3). The func- tion esetfunc() returns the previous error handler function. A NULL error handler will just call exit(3). SEE ALSO
asprintf(3), calloc(3), err(3), exit(3), fopen(3), malloc(3), realloc(3), strdup(3), strlcat(3), strlcpy(3), strndup(3), vasprintf(3) BSD
May 3, 2010 BSD

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STRLCPY(3)						   BSD Library Functions Manual 						STRLCPY(3)

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. 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
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