Last change
on this file since 471 was
444,
checked in by satin@…, 6 years ago
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add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
|
File size:
1.1 KB
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Line | |
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1 | /* |
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2 | FUNCTION |
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3 | <<strnstr>>---find string segment |
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4 | |
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5 | INDEX |
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6 | strnstr |
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7 | |
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8 | SYNOPSIS |
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9 | #include <string.h> |
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10 | size_t strnstr(const char *<[s1]>, const char *<[s2]>, size_t <[n]>); |
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11 | |
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12 | DESCRIPTION |
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13 | Locates the first occurrence in the string pointed to by <[s1]> of |
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14 | the sequence of limited to the <[n]> characters in the string |
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15 | pointed to by <[s2]> |
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16 | |
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17 | RETURNS |
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18 | Returns a pointer to the located string segment, or a null |
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19 | pointer if the string <[s2]> is not found. If <[s2]> points to |
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20 | a string with zero length, <[s1]> is returned. |
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21 | |
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22 | |
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23 | PORTABILITY |
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24 | <<strnstr>> is a BSD extension. |
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25 | |
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26 | <<strnstr>> requires no supporting OS subroutines. |
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27 | |
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28 | QUICKREF |
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29 | strnstr pure |
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30 | |
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31 | */ |
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32 | |
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33 | #define _GNU_SOURCE |
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34 | #include <string.h> |
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35 | |
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36 | /* |
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37 | * Find the first occurrence of find in s, where the search is limited to the |
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38 | * first slen characters of s. |
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39 | */ |
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40 | char * |
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41 | strnstr(const char *haystack, const char *needle, size_t haystack_len) |
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42 | { |
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43 | size_t needle_len = strnlen(needle, haystack_len); |
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44 | |
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45 | if (needle_len < haystack_len || !needle[needle_len]) { |
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46 | char *x = memmem(haystack, haystack_len, needle, needle_len); |
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47 | if (x && !memchr(haystack, 0, x - haystack)) |
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48 | return x; |
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49 | } |
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50 | return NULL; |
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51 | } |
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