svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
strcat(3c)
strcat(3C) Standard C Library Functions strcat(3C)
NAME
strcat, strncat, strlcat, strcpy, strncpy, strlcpy, stpcpy, stpncpy,
strcpy_s, strncpy_s, strcat_s, strncat_s - string copying and concate‐
nation operations
SYNOPSIS
#include <string.h>
char *strcat(char *restrict s1, const char *restrict s2);
char *strncat(char *restrict s1, const char *restrict s2, size_t n);
size_t strlcat(char *dst, const char *src, size_t dstsize);
char *strcpy(char *restrict s1, const char *restrict s2);
char *strncpy(char *restrict s1, const char *restrict s2, size_t n);
size_t strlcpy(char *dst, const char *src, size_t dstsize);
char *stpcpy(char *restrict s1, const char *restrict s2);
char *stpncpy(char *restrict s1, const char *restrict s2, size_t n);
C11 Bounds Checking Interfaces
#define __STDC_WANT_LIB_EXT1__ 1
#include <string.h>
errno_t strcpy_s(char *restrict s1, rsize_t s1max,
const char *restrict s2);
errno_t strncpy_s(char *restrict s1, rsize_t s1max,
const char *restrict s2, rsize_t n);
errno_t strcat_s(char *restrict s1, rsize_t s1max,
const char *restrict s2);
errno_t strncat_s(char *restrict s1, rsize_t s1max,
const char *restrict s2, rsize_t n);
DESCRIPTION
These functions copy data from one string (array of characters) to an‐
other. Depending on the function, strings may be either terminated by a
null character or consist of a length of n bytes. All character counts
are measured in individual bytes, even if a string with multibyte char‐
acters is used, which may result in copying only part of a multibyte
character if the full character does not fit within the byte count
specified. They do not check for null pointers, and programs may crash
if passing null or otherwise invalid pointers to these functions, or
specifying sizes larger than the memory allocation in use for the
string. Use of adi(7) may help in detecting buffer overflows or invalid
pointer usage in code.
The strcat(), stpcpy(), and strcpy() functions do not check for over‐
flow of the array. Use of one of the bounds-checking variants is recom‐
mended instead of those functions.
strcat(), strncat(), strlcat()
The strcat() function appends a copy of string s2, including the termi‐
nating null character, to the end of string s1. The strncat() function
appends at most n bytes. Each returns a pointer to the null-terminated
result. The initial character of s2 is written over the null character
at the end of s1. If copying takes place between objects that overlap,
the behavior of strcat(), strncat(), and strlcat() is undefined.
The strlcat() function appends at most (dstsize-strlen(dst)-1) charac‐
ters of src to dst (dstsize being the size of the string buffer dst).
If the string pointed to by dst contains a null-terminated string that
fits into dstsize bytes when strlcat() is called, the string pointed to
by dst will be a null-terminated string that fits in dstsize bytes (in‐
cluding the terminating null character) when it completes, and the ini‐
tial character of src will override the null character at the end of
dst. If the string pointed to by dst is longer than dstsize bytes when
strlcat() is called, the string pointed to by dst will not be changed.
The function returns min{dstsize, strlen(dst)} + strlen(src). Insuffi‐
cient space can be checked for as follows:
if (strlcat(dst, src, dstsize) >= dstsize)
return −1;
strcpy(), stpcpy(), strncpy(), stpncpy(), strlcpy()
The strcpy() and stpcpy() functions copy string s2 to s1, including the
terminating null character, stopping after the null character has been
copied. The strcpy() function returns s1. The stpcpy() function returns
a pointer to the terminating null character copied into the s1 array.
The strncpy() and stpncpy() functions copy not more than n bytes (bytes
that follow a null byte are not copied) from the array pointed to by s2
to the array pointed to by s1. If the array pointed to by s2 is a
string that is shorter than n bytes, null bytes are appended to the
copy in the array pointed to by s1, until n bytes in all are written.
If the array pointed to by s2 is a string that is n bytes or longer,
the resulting s1 will not be null terminated. The strncpy() function
returns s1. If s1 contains null bytes, stpncpy() returns a pointer to
the first such null byte. Otherwise, it returns &s1[n].
The strlcpy() function copies at most dstsize−1 characters (dstsize be‐
ing the size of the string buffer dst) from src to dst, truncating src
if necessary. The result is always null-terminated. The function re‐
turns strlen(src). Insufficient space can be checked for as follows:
if (strlcpy(dst, src, dstsize) >= dstsize)
return −1;
If copying takes place between objects that overlap, the behavior of
these functions is undefined.
C11 Bounds Checking Interfaces
The strcpy_s(), strncpy_s(), strcat_s(), strncat_s(), and strlen_s()
functions are part of the C11 bounds checking interfaces specified in
the C11 standard, Annex K. Each of these functions provides similar
functionality to their respective non-bounds checking counterpart func‐
tions, but with additional safety checks in the form of explicit run‐
time constraints as defined in the C11 standard. See runtime_con‐
straint_handler(3C) and INCITS/ISO/IEC 9899:2011.
If no runtime constraint violation is detected, the strcpy_s(),
strncpy_s(), strcat_s() and strncat_s() functions return zero. If a
runtime constraint violation is detected and the handler returns, they
return a non-zero value.
ERRORS
The C11 bounds checking interface functions will fail if:
EINVAL Null pointer is passed or source and destination overlap
ERANGE A size argument is not a valid value
EOVERFLOW Destination array is too small
The other functions described in this page do not check if a null
pointer is passed, and programs passing null pointers to them may
crash.
USAGE
Usage of the strlcat() and strlcpy() functions is recommended over the
other variants to avoid buffer overflows and make code easier to review
and maintain.
It is not possible to limit the strcat() and strcpy() functions to a
maximum buffer size. Although one can calculate the amount of space
needed before calling strcat or strcpy, the use of these functions will
always force reviewers to follow the logic, and hinder automated scan‐
ning of source code for vulnerabilities.
strncpy() is not guaranteed to null-terminate the destination buffer.
This fact, together with the side effect that it will add null bytes if
there is space left make it a useful function for updating fixed-length
structures that reside on disk, for example, wtmpx(5).
strncat() is hard to use safely as it requires the remaining size of
the destination buffer to be calculated by the caller.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelSee below _
StandardSee below
MT-Level
The strcat(), strncat(), strlcat(), strcpy(), strncpy(), strlcpy(),
stpcpy(), and stpncpy() functions are Async-Signal-Safe.
The strcpy_s(), strncpy_s(), strcat_s(), and strncat_s() functions can‐
not be used safely in a multithreaded application due to the runtime
constraint handler. For more information, see the runtime_con‐
straint_handler(3C) man page.
Standard
See standards(7) for descriptions of the following standards:
tab() box; cw(2.44i) |cw(3.06i) lw(2.44i) |lw(3.06i) INTERFACESAPPLICA‐
BLE STANDARDS _ T{ strcat(), strcpy(), strncat(), strncpy() T}T{
C89 through C11,
POSIX.1-1990 through 2008,
SUS through SUSv4,
XPG1 through XPG7
T} _ stpcpy(), stpncpy()T{
POSIX.1-2008,
SUSv4,
XPG7
T} _ T{ strcat_s(), strcpy_s(), strncat_s(), strncpy_s() T}C11 Annex K
_ strlcat(), strlcpy()None
SEE ALSO
strdup(3C), string(3C), wcscat(3C), wcscpy(3C), attributes(7), stan‐
dards(7), runtime_constraint_handler(3C)
Appendix E, Security Considerations When Using C Functions, in Devel‐
oper's Guide to Oracle Solaris 11.4 Security
HISTORY
Support for the following functions is available in Oracle Solaris
starting with the listed release:
tab() box; cw(4.71i) |cw(0.79i) lw(4.71i) |lw(0.79i) FUNCTIONRELEASE _
T{ strcat_s(), strcpy_s(), strncat_s(), strncpy_s() T}11.4.0 _
stpcpy(), stpncpy()11.0.0 _ strlcat(), strlcpy()8 _ T{ strcat(),
strcpy(), strncat(), strncpy() T}1.0
Oracle Solaris 11.4 28 Feb 2022 strcat(3C)