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| .TH GETNETENT_R 3 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| getnetent_r, getnetbyname_r, getnetbyaddr_r \- get |
| network entry (reentrant) |
| .SH SYNOPSIS |
| .nf |
| .B #include <netdb.h> |
| .PP |
| .BI "int getnetent_r(struct netent *restrict " result_buf , |
| .BI " char *restrict " buf ", size_t " buflen , |
| .BI " struct netent **restrict " result , |
| .BI " int *restrict " h_errnop ); |
| .BI "int getnetbyname_r(const char *restrict " name , |
| .BI " struct netent *restrict " result_buf , |
| .BI " char *restrict " buf ", size_t " buflen , |
| .BI " struct netent **restrict " result , |
| .BI " int *restrict " h_errnop ); |
| .BI "int getnetbyaddr_r(uint32_t " net ", int " type , |
| .BI " struct netent *restrict " result_buf , |
| .BI " char *restrict " buf ", size_t " buflen , |
| .BI " struct netent **restrict " result , |
| .BI " int *restrict " h_errnop ); |
| .PP |
| .fi |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR getnetent_r (), |
| .BR getnetbyname_r (), |
| .BR getnetbyaddr_r (): |
| .nf |
| Since glibc 2.19: |
| _DEFAULT_SOURCE |
| Glibc 2.19 and earlier: |
| _BSD_SOURCE || _SVID_SOURCE |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR getnetent_r (), |
| .BR getnetbyname_r (), |
| and |
| .BR getnetbyaddr_r () |
| functions are the reentrant equivalents of, respectively, |
| .BR getnetent (3), |
| .BR getnetbyname (3), |
| and |
| .BR getnetbynumber (3). |
| They differ in the way that the |
| .I netent |
| structure is returned, |
| and in the function calling signature and return value. |
| This manual page describes just the differences from |
| the nonreentrant functions. |
| .PP |
| Instead of returning a pointer to a statically allocated |
| .I netent |
| structure as the function result, |
| these functions copy the structure into the location pointed to by |
| .IR result_buf . |
| .PP |
| The |
| .I buf |
| array is used to store the string fields pointed to by the returned |
| .I netent |
| structure. |
| (The nonreentrant functions allocate these strings in static storage.) |
| The size of this array is specified in |
| .IR buflen . |
| If |
| .I buf |
| is too small, the call fails with the error |
| .BR ERANGE , |
| and the caller must try again with a larger buffer. |
| (A buffer of length 1024 bytes should be sufficient for most applications.) |
| .\" I can find no information on the required/recommended buffer size; |
| .\" the nonreentrant functions use a 1024 byte buffer -- mtk. |
| .PP |
| If the function call successfully obtains a network record, then |
| .I *result |
| is set pointing to |
| .IR result_buf ; |
| otherwise, |
| .I *result |
| is set to NULL. |
| .PP |
| The buffer pointed to by |
| .I h_errnop |
| is used to return the value that would be stored in the global variable |
| .I h_errno |
| by the nonreentrant versions of these functions. |
| .\" getnetent.3 doesn't document any use of h_errno, but nevertheless |
| .\" the nonreentrant functions no seem to set h_errno. |
| .SH RETURN VALUE |
| On success, these functions return 0. |
| On error, they return one of the positive error numbers listed in ERRORS. |
| .PP |
| On error, record not found |
| .RB ( getnetbyname_r (), |
| .BR getnetbyaddr_r ()), |
| or end of input |
| .RB ( getnetent_r ()) |
| .I result |
| is set to NULL. |
| .SH ERRORS |
| .TP |
| .B ENOENT |
| .RB ( getnetent_r ()) |
| No more records in database. |
| .TP |
| .B ERANGE |
| .I buf |
| is too small. |
| Try again with a larger buffer |
| (and increased |
| .IR buflen ). |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR getnetent_r (), |
| .BR getnetbyname_r (), |
| .BR getnetbyaddr_r () |
| T} Thread safety MT-Safe locale |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| These functions are GNU extensions. |
| Functions with similar names exist on some other systems, |
| though typically with different calling signatures. |
| .SH SEE ALSO |
| .BR getnetent (3), |
| .BR networks (5) |