1 | /* GNU variant of strerror_r. */ |
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2 | /* |
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3 | FUNCTION |
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4 | <<strerror_r>>---convert error number to string and copy to buffer |
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5 | |
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6 | INDEX |
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7 | strerror_r |
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8 | |
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9 | SYNOPSIS |
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10 | #include <string.h> |
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11 | #ifdef _GNU_SOURCE |
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12 | char *strerror_r(int <[errnum]>, char *<[buffer]>, size_t <[n]>); |
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13 | #else |
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14 | int strerror_r(int <[errnum]>, char *<[buffer]>, size_t <[n]>); |
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15 | #endif |
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16 | |
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17 | DESCRIPTION |
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18 | <<strerror_r>> converts the error number <[errnum]> into a |
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19 | string and copies the result into the supplied <[buffer]> for |
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20 | a length up to <[n]>, including the NUL terminator. The value of |
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21 | <[errnum]> is usually a copy of <<errno>>. If <<errnum>> is not a known |
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22 | error number, the result is the empty string. |
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23 | |
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24 | See <<strerror>> for how strings are mapped to <<errnum>>. |
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25 | |
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26 | RETURNS |
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27 | There are two variants: the GNU version always returns a NUL-terminated |
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28 | string, which is <[buffer]> if all went well, but which is another |
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29 | pointer if <[n]> was too small (leaving <[buffer]> untouched). If the |
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30 | return is not <[buffer]>, your application must not modify that string. |
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31 | The POSIX version returns 0 on success, <[EINVAL]> if <<errnum>> was not |
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32 | recognized, and <[ERANGE]> if <[n]> was too small. The variant chosen |
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33 | depends on macros that you define before inclusion of <<string.h>>. |
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34 | |
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35 | PORTABILITY |
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36 | <<strerror_r>> with a <[char *]> result is a GNU extension. |
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37 | <<strerror_r>> with an <[int]> result is required by POSIX 2001. |
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38 | This function is compliant only if <<_user_strerror>> is not provided, |
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39 | or if it is thread-safe and uses separate storage according to whether |
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40 | the second argument of that function is non-zero. For more details |
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41 | on <<_user_strerror>>, see the <<strerror>> documentation. |
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42 | |
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43 | POSIX states that the contents of <[buf]> are unspecified on error, |
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44 | although this implementation guarantees a NUL-terminated string for |
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45 | all except <[n]> of 0. |
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46 | |
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47 | POSIX recommends that unknown <[errnum]> result in a message including |
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48 | that value, however it is not a requirement and this implementation |
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49 | provides only an empty string (unless you provide <<_user_strerror>>). |
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50 | POSIX also recommends that unknown <[errnum]> fail with EINVAL even |
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51 | when providing such a message, however it is not a requirement and |
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52 | this implementation will return success if <<_user_strerror>> provided |
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53 | a non-empty alternate string without assigning into its third argument. |
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54 | |
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55 | <<strerror_r>> requires no supporting OS subroutines. |
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56 | |
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57 | */ |
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58 | |
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59 | #undef __STRICT_ANSI__ |
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60 | #define _GNU_SOURCE |
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61 | #include <errno.h> |
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62 | #include <string.h> |
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63 | #undef strerror_r |
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64 | |
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65 | /* For backwards-compatible linking, this must be the GNU signature; |
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66 | see xpg_strerror_r.c for the POSIX version. */ |
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67 | char * |
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68 | strerror_r (int errnum, |
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69 | char *buffer, |
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70 | size_t n) |
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71 | { |
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72 | char *error = _strerror_r (_REENT, errnum, 1, NULL); |
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73 | |
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74 | if (strlen (error) >= n) |
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75 | return error; |
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76 | return strcpy (buffer, error); |
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77 | } |
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