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/* $OpenBSD: inet_ntop.c,v 1.13 2016/09/21 04:38:56 guenther Exp $ */ |
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/* Copyright (c) 1996 by Internet Software Consortium. |
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* |
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* Permission to use, copy, modify, and distribute this software for any |
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* purpose with or without fee is hereby granted, provided that the above |
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* copyright notice and this permission notice appear in all copies. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS |
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE |
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
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* SOFTWARE. |
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*/ |
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#include <sys/types.h> |
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#include <sys/socket.h> |
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#include <netinet/in.h> |
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#include <arpa/inet.h> |
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#include <arpa/nameser.h> |
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#include <string.h> |
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#include <errno.h> |
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#include <stdio.h> |
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/* |
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* WARNING: Don't even consider trying to compile this on a system where |
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* sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. |
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*/ |
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static const char *inet_ntop4(const u_char *src, char *dst, size_t size); |
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static const char *inet_ntop6(const u_char *src, char *dst, size_t size); |
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/* const char * |
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* inet_ntop(af, src, dst, size) |
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* convert a network format address to presentation format. |
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* return: |
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* pointer to presentation format address (`dst'), or NULL (see errno). |
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* author: |
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* Paul Vixie, 1996. |
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*/ |
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const char * |
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inet_ntop(int af, const void *src, char *dst, socklen_t size) |
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{ |
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switch (af) { |
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case AF_INET: |
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return (inet_ntop4(src, dst, size)); |
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case AF_INET6: |
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return (inet_ntop6(src, dst, size)); |
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default: |
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errno = EAFNOSUPPORT; |
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return (NULL); |
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} |
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/* NOTREACHED */ |
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} |
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DEF_WEAK(inet_ntop); |
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/* const char * |
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* inet_ntop4(src, dst, size) |
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* format an IPv4 address, more or less like inet_ntoa() |
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* return: |
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* `dst' (as a const) |
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* notes: |
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* (1) uses no statics |
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* (2) takes a u_char* not an in_addr as input |
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* author: |
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* Paul Vixie, 1996. |
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*/ |
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static const char * |
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inet_ntop4(const u_char *src, char *dst, size_t size) |
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{ |
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char tmp[sizeof "255.255.255.255"]; |
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int l; |
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l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", |
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src[0], src[1], src[2], src[3]); |
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if (l <= 0 || l >= size) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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strlcpy(dst, tmp, size); |
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return (dst); |
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} |
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/* const char * |
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* inet_ntop6(src, dst, size) |
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* convert IPv6 binary address into presentation (printable) format |
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* author: |
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* Paul Vixie, 1996. |
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*/ |
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static const char * |
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inet_ntop6(const u_char *src, char *dst, size_t size) |
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{ |
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/* |
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* Note that int32_t and int16_t need only be "at least" large enough |
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* to contain a value of the specified size. On some systems, like |
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* Crays, there is no such thing as an integer variable with 16 bits. |
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* Keep this in mind if you think this function should have been coded |
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* to use pointer overlays. All the world's not a VAX. |
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*/ |
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char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; |
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char *tp, *ep; |
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struct { int base, len; } best, cur; |
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u_int words[IN6ADDRSZ / INT16SZ]; |
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int i; |
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int advance; |
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/* |
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* Preprocess: |
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* Copy the input (bytewise) array into a wordwise array. |
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* Find the longest run of 0x00's in src[] for :: shorthanding. |
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*/ |
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memset(words, '\0', sizeof words); |
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for (i = 0; i < IN6ADDRSZ; i++) |
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words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); |
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best.base = -1; |
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cur.base = -1; |
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for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { |
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if (words[i] == 0) { |
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if (cur.base == -1) |
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cur.base = i, cur.len = 1; |
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else |
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cur.len++; |
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} else { |
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if (cur.base != -1) { |
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if (best.base == -1 || cur.len > best.len) |
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best = cur; |
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cur.base = -1; |
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} |
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} |
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} |
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if (cur.base != -1) { |
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if (best.base == -1 || cur.len > best.len) |
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best = cur; |
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} |
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if (best.base != -1 && best.len < 2) |
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best.base = -1; |
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/* |
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* Format the result. |
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*/ |
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tp = tmp; |
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ep = tmp + sizeof(tmp); |
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for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { |
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/* Are we inside the best run of 0x00's? */ |
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if (best.base != -1 && i >= best.base && |
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i < (best.base + best.len)) { |
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if (i == best.base) { |
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if (tp + 1 >= ep) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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*tp++ = ':'; |
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} |
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continue; |
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} |
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/* Are we following an initial run of 0x00s or any real hex? */ |
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if (i != 0) { |
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if (tp + 1 >= ep) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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*tp++ = ':'; |
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} |
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/* Is this address an encapsulated IPv4? */ |
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if (i == 6 && best.base == 0 && |
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(best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { |
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if (!inet_ntop4(src+12, tp, ep - tp)) |
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return (NULL); |
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tp += strlen(tp); |
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break; |
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} |
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advance = snprintf(tp, ep - tp, "%x", words[i]); |
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if (advance <= 0 || advance >= ep - tp) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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tp += advance; |
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} |
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/* Was it a trailing run of 0x00's? */ |
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if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { |
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if (tp + 1 >= ep) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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*tp++ = ':'; |
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} |
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if (tp + 1 >= ep) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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*tp++ = '\0'; |
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/* |
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* Check for overflow, copy, and we're done. |
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*/ |
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if ((size_t)(tp - tmp) > size) { |
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errno = ENOSPC; |
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return (NULL); |
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} |
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strlcpy(dst, tmp, size); |
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return (dst); |
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} |