man3/getnetent_r.3

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  24 .TH GETNETENT_R 3  2010-09-10 "GNU" "Linux Programmer's Manual"
  25 .SH NAME
  26 getnetent_r, getnetbyname_r, getnetbyaddr_r \- get
  27 network entry (reentrant)
  28 .SH SYNOPSIS
  29 .nf
  30 .B #include <netdb.h>
  31 .sp
  32 .BI "int getnetent_r(struct netent *" result_buf ", char *" buf ,
  33 .BI "                size_t " buflen ", struct netent **" result ,
  34 .BI "                int *" h_errnop );
  35 .sp
  36 .BI "int getnetbyname_r(const char *" name ,
  37 .BI "                struct netent *" result_buf ", char *" buf ,
  38 .BI "                size_t " buflen ", struct netent **" result ,
  39 .BI "                int *" h_errnop );
  40 .sp
  41 .BI "int getnetbyaddr_r(uint32_t " net ", int " type ,
  42 .BI "                struct netent *" result_buf ", char *" buf ,
  43 .BI "                size_t " buflen ", struct netent **" result ,
  44 .BI "                int *" h_errnop );
  45 .sp
  46 .fi
  47 .in -4n
  48 Feature Test Macro Requirements for glibc (see
  49 .BR feature_test_macros (7)):
  50 .ad l
  51 .in
  52 .sp
  53 .BR getnetent_r (),
  54 .BR getnetbyname_r (),
  55 .BR getnetbyaddr_r ():
  56 .RS 4
  57 _BSD_SOURCE || _SVID_SOURCE
  58 .RE
  59 .ad b
  60 .SH DESCRIPTION
  61 The
  62 .BR getnetent_r (),
  63 .BR getnetbyname_r (),
  64 and
  65 .BR getnetbyaddr_r ()
  66 functions are the reentrant equivalents of, respectively,
  67 .BR getnetent (3),
  68 .BR getnetbyname (3),
  69 and
  70 .BR getnetbynumber (3).
  71 They differ in the way that the
  72 .I netent
  73 structure is returned,
  74 and in the function calling signature and return value.
  75 This manual page describes just the differences from
  76 the nonreentrant functions.
  77
  78 Instead of returning a pointer to a statically allocated
  79 .I netent
  80 structure as the function result,
  81 these functions copy the structure into the location pointed to by
  82 .IR result_buf .
  83
  84 The
  85 .I buf
  86 array is used to store the string fields pointed to by the returned
  87 .I netent
  88 structure.
  89 (The nonreentrant functions allocate these strings in static storage.)
  90 The size of this array is specified in
  91 .IR buflen .
  92 If
  93 .I buf
  94 is too small, the call fails with the error
  95 .BR ERANGE ,
  96 and the caller must try again with a larger buffer.
  97 (A buffer of length 1024 bytes should be sufficient for most applications.)
  98 .\" I can find no information on the required/recommended buffer size;
  99 .\" the nonreentrant functions use a 1024 byte buffer -- mtk.
 100
 101 If the function call successfully obtains a network record, then
 102 .I *result
 103 is set pointing to
 104 .IR result_buf ;
 105 otherwise,
 106 .I *result
 107 is set to NULL.
 108
 109 The buffer pointed to by
 110 .I h_errnop
 111 is used to return the value that would be stored in the global variable
 112 .I h_errno
 113 by the nonreentrant versions of these functions.
 114 .\" getnetent.3 doesn't document any use of h_errno, but nevertheless
 115 .\" the nonreentrant functions no seem to set h_errno.
 116 .SH RETURN VALUE
 117 On success, these functions return 0.
 118 On error, they return one of the positive error numbers listed in ERRORS.
 119
 120 On error, record not found
 121 .RB ( getnetbyname_r (),
 122 .BR getnetbyaddr_r ()),
 123 or end of input
 124 .RB ( getnetent_r ())
 125 .I result
 126 is set to NULL.
 127 .SH ERRORS
 128 .TP
 129 .B ENOENT
 130 .RB ( getnetent_r ())
 131 No more records in database.
 132 .TP
 133 .B ERANGE
 134 .I buf
 135 is too small.
 136 Try again with a larger buffer
 137 (and increased
 138 .IR buflen ).
 139 .SH CONFORMING TO
 140 These functions are GNU extensions.
 141 Functions with similar names exist on some other systems,
 142 though typically with different calling signatures.
 143 .SH SEE ALSO
 144 .BR getnetent (3),
 145 .BR networks (5)