getnetbyaddr_r(3)

1getnetent_r(3)             Library Functions Manual             getnetent_r(3)
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3
4

NAME

6       getnetent_r,  getnetbyname_r, getnetbyaddr_r - get network entry (reen‐
7       trant)
8

LIBRARY

10       Standard C library (libc, -lc)
11

SYNOPSIS

13       #include <netdb.h>
14
15       int getnetent_r(struct netent *restrict result_buf,
16                       char buf[restrict .buflen], size_t buflen,
17                       struct netent **restrict result,
18                       int *restrict h_errnop);
19       int getnetbyname_r(const char *restrict name,
20                       struct netent *restrict result_buf,
21                       char buf[restrict .buflen], size_t buflen,
22                       struct netent **restrict result,
23                       int *restrict h_errnop);
24       int getnetbyaddr_r(uint32_t net, int type,
25                       struct netent *restrict result_buf,
26                       char buf[restrict .buflen], size_t buflen,
27                       struct netent **restrict result,
28                       int *restrict h_errnop);
29
30   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
31
32       getnetent_r(), getnetbyname_r(), getnetbyaddr_r():
33           Since glibc 2.19:
34               _DEFAULT_SOURCE
35           glibc 2.19 and earlier:
36               _BSD_SOURCE || _SVID_SOURCE
37

DESCRIPTION

39       The getnetent_r(), getnetbyname_r(), and getnetbyaddr_r() functions are
40       the  reentrant  equivalents  of,  respectively, getnetent(3), getnetby‐
41       name(3), and getnetbynumber(3).  They differ in the way that the netent
42       structure is returned, and in the function calling signature and return
43       value.  This manual page describes just the differences from  the  non‐
44       reentrant functions.
45
46       Instead  of returning a pointer to a statically allocated netent struc‐
47       ture as the function result, these functions copy  the  structure  into
48       the location pointed to by result_buf.
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50       The  buf array is used to store the string fields pointed to by the re‐
51       turned netent structure.  (The nonreentrant  functions  allocate  these
52       strings in static storage.)  The size of this array is specified in bu‐
53       flen.  If buf is too small, the call fails with the error  ERANGE,  and
54       the  caller  must  try again with a larger buffer.  (A buffer of length
55       1024 bytes should be sufficient for most applications.)
56
57       If the function call successfully obtains a network record,  then  *re‐
58       sult is set pointing to result_buf; otherwise, *result is set to NULL.
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60       The  buffer  pointed  to  by  h_errnop is used to return the value that
61       would be stored in the global variable h_errno by the nonreentrant ver‐
62       sions of these functions.
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RETURN VALUE

65       On success, these functions return 0.  On error, they return one of the
66       positive error numbers listed in ERRORS.
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68       On error, record not found (getnetbyname_r(), getnetbyaddr_r()), or end
69       of input (getnetent_r()) result is set to NULL.
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ERRORS

72       ENOENT (getnetent_r()) No more records in database.
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74       ERANGE buf is too small.  Try again with a larger buffer (and increased
75              buflen).
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ATTRIBUTES

78       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
79       tributes(7).
80
81       ┌─────────────────────────────────────┬───────────────┬────────────────┐
82       │Interface                            │ Attribute     │ Value          │
83       ├─────────────────────────────────────┼───────────────┼────────────────┤
84       │getnetent_r(), getnetbyname_r(),     │ Thread safety │ MT-Safe locale │
85       │getnetbyaddr_r()                     │               │                │
86       └─────────────────────────────────────┴───────────────┴────────────────┘
87

VERSIONS

89       Functions with similar names exist on some other systems, though  typi‐
90       cally with different calling signatures.
91

STANDARDS

93       GNU.
94