getnetent_r(3) Library Functions Manual getnetent_r(3)
NAME
getnetent_r, getnetbyname_r, getnetbyaddr_r - get network entry (reen-
trant)
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <netdb.h>
int getnetent_r(struct netent *restrict result_buf,
char buf[restrict .buflen], size_t buflen,
struct netent **restrict result,
int *restrict h_errnop);
int getnetbyname_r(const char *restrict name,
struct netent *restrict result_buf,
char buf[restrict .buflen], size_t buflen,
struct netent **restrict result,
int *restrict h_errnop);
int getnetbyaddr_r(uint32_t net, int type,
struct netent *restrict result_buf,
char buf[restrict .buflen], size_t buflen,
struct netent **restrict result,
int *restrict h_errnop);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getnetent_r(), getnetbyname_r(), getnetbyaddr_r():
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
The getnetent_r(), getnetbyname_r(), and getnetbyaddr_r() functions are
the reentrant equivalents of, respectively, getnetent(3), getnetby-
name(3), and getnetbynumber(3). They differ in the way that the netent
structure is returned, and in the function calling signature and return
value. This manual page describes just the differences from the non-
reentrant functions.
Instead of returning a pointer to a statically allocated netent struc-
ture as the function result, these functions copy the structure into
the location pointed to by result_buf.
The buf array is used to store the string fields pointed to by the re-
turned netent structure. (The nonreentrant functions allocate these
strings in static storage.) The size of this array is specified in bu-
flen. If buf is too small, the call fails with the error ERANGE, and
the caller must try again with a larger buffer. (A buffer of length
1024 bytes should be sufficient for most applications.)
If the function call successfully obtains a network record, then *re-
sult is set pointing to result_buf; otherwise, *result is set to NULL.
The buffer pointed to by h_errnop is used to return the value that
would be stored in the global variable h_errno by the nonreentrant ver-
sions of these functions.
RETURN VALUE
On success, these functions return 0. On error, they return one of the
positive error numbers listed in ERRORS.
On error, record not found (getnetbyname_r(), getnetbyaddr_r()), or end
of input (getnetent_r()) result is set to NULL.
ERRORS
ENOENT (getnetent_r()) No more records in database.
ERANGE buf is too small. Try again with a larger buffer (and increased
buflen).
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌─────────────────────────────────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼────────────────┤
│getnetent_r(), getnetbyname_r(), │ Thread safety │ MT-Safe locale │
│getnetbyaddr_r() │ │ │
└─────────────────────────────────────┴───────────────┴────────────────┘
STANDARDS
These functions are GNU extensions. Functions with similar names exist
on some other systems, though typically with different calling signa-
tures.
SEE ALSO
getnetent(3), networks(5)
Linux man-pages 6.03 2023-02-05 getnetent_r(3)
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