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a1eaacb1 | 1 | '\" t |
ca1a4bba MK |
2 | .\" Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
4 | .\" | |
5fbde956 | 5 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
ca1a4bba | 6 | .\" |
4c1c5274 | 7 | .TH getprotoent_r 3 (date) "Linux man-pages (unreleased)" |
ca1a4bba MK |
8 | .SH NAME |
9 | getprotoent_r, getprotobyname_r, getprotobynumber_r \- get | |
10 | protocol entry (reentrant) | |
42009080 AC |
11 | .SH LIBRARY |
12 | Standard C library | |
13 | .RI ( libc ", " \-lc ) | |
ca1a4bba MK |
14 | .SH SYNOPSIS |
15 | .nf | |
16 | .B #include <netdb.h> | |
c6d039a3 | 17 | .P |
698bf790 | 18 | .BI "int getprotoent_r(struct protoent *restrict " result_buf , |
1eed67e7 | 19 | .BI " char " buf "[restrict ." buflen "], size_t " buflen , |
698bf790 AC |
20 | .BI " struct protoent **restrict " result ); |
21 | .BI "int getprotobyname_r(const char *restrict " name , | |
22 | .BI " struct protoent *restrict " result_buf , | |
1eed67e7 | 23 | .BI " char " buf "[restrict ." buflen "], size_t " buflen , |
698bf790 | 24 | .BI " struct protoent **restrict " result ); |
ca1a4bba | 25 | .BI "int getprotobynumber_r(int " proto , |
698bf790 | 26 | .BI " struct protoent *restrict " result_buf , |
1eed67e7 | 27 | .BI " char " buf "[restrict ." buflen "], size_t " buflen , |
698bf790 | 28 | .BI " struct protoent **restrict " result ); |
c6d039a3 | 29 | .P |
ca1a4bba | 30 | .fi |
d39ad78f | 31 | .RS -4 |
ca1a4bba MK |
32 | Feature Test Macro Requirements for glibc (see |
33 | .BR feature_test_macros (7)): | |
d39ad78f | 34 | .RE |
c6d039a3 | 35 | .P |
ca1a4bba MK |
36 | .BR getprotoent_r (), |
37 | .BR getprotobyname_r (), | |
38 | .BR getprotobynumber_r (): | |
9d2adbae | 39 | .nf |
51c612fb MK |
40 | Since glibc 2.19: |
41 | _DEFAULT_SOURCE | |
75c018a1 | 42 | glibc 2.19 and earlier: |
51c612fb | 43 | _BSD_SOURCE || _SVID_SOURCE |
9d2adbae | 44 | .fi |
ca1a4bba MK |
45 | .SH DESCRIPTION |
46 | The | |
47 | .BR getprotoent_r (), | |
48 | .BR getprotobyname_r (), | |
49 | and | |
50 | .BR getprotobynumber_r () | |
51 | functions are the reentrant equivalents of, respectively, | |
52 | .BR getprotoent (3), | |
53 | .BR getprotobyname (3), | |
54 | and | |
55 | .BR getprotobynumber (3). | |
56 | They differ in the way that the | |
57 | .I protoent | |
58 | structure is returned, | |
59 | and in the function calling signature and return value. | |
60 | This manual page describes just the differences from | |
54d75d6c | 61 | the nonreentrant functions. |
c6d039a3 | 62 | .P |
ca1a4bba MK |
63 | Instead of returning a pointer to a statically allocated |
64 | .I protoent | |
65 | structure as the function result, | |
66 | these functions copy the structure into the location pointed to by | |
67 | .IR result_buf . | |
c6d039a3 | 68 | .P |
ca1a4bba MK |
69 | The |
70 | .I buf | |
71 | array is used to store the string fields pointed to by the returned | |
72 | .I protoent | |
73 | structure. | |
54d75d6c | 74 | (The nonreentrant functions allocate these strings in static storage.) |
ca1a4bba MK |
75 | The size of this array is specified in |
76 | .IR buflen . | |
77 | If | |
78 | .I buf | |
79 | is too small, the call fails with the error | |
80 | .BR ERANGE , | |
81 | and the caller must try again with a larger buffer. | |
82 | (A buffer of length 1024 bytes should be sufficient for most applications.) | |
83 | .\" I can find no information on the required/recommended buffer size; | |
54d75d6c | 84 | .\" the nonreentrant functions use a 1024 byte buffer. |
ca1a4bba | 85 | .\" The 1024 byte value is also what the Solaris man page suggests. -- mtk |
c6d039a3 | 86 | .P |
ca1a4bba MK |
87 | If the function call successfully obtains a protocol record, then |
88 | .I *result | |
89 | is set pointing to | |
90 | .IR result_buf ; | |
91 | otherwise, | |
92 | .I *result | |
93 | is set to NULL. | |
47297adb | 94 | .SH RETURN VALUE |
ca1a4bba | 95 | On success, these functions return 0. |
535f0df5 | 96 | On error, they return one of the positive error numbers listed in ERRORS. |
c6d039a3 | 97 | .P |
ca1a4bba MK |
98 | On error, record not found |
99 | .RB ( getprotobyname_r (), | |
100 | .BR getprotobynumber_r ()), | |
101 | or end of input | |
102 | .RB ( getprotoent_r ()) | |
103 | .I result | |
104 | is set to NULL. | |
105 | .SH ERRORS | |
106 | .TP | |
107 | .B ENOENT | |
108 | .RB ( getprotoent_r ()) | |
109 | No more records in database. | |
110 | .TP | |
111 | .B ERANGE | |
112 | .I buf | |
113 | is too small. | |
114 | Try again with a larger buffer | |
115 | (and increased | |
116 | .IR buflen ). | |
252c5d6b ZL |
117 | .SH ATTRIBUTES |
118 | For an explanation of the terms used in this section, see | |
119 | .BR attributes (7). | |
120 | .TS | |
121 | allbox; | |
c466875e | 122 | lbx lb lb |
252c5d6b ZL |
123 | l l l. |
124 | Interface Attribute Value | |
125 | T{ | |
9e54434e BR |
126 | .na |
127 | .nh | |
252c5d6b | 128 | .BR getprotoent_r (), |
252c5d6b | 129 | .BR getprotobyname_r (), |
252c5d6b ZL |
130 | .BR getprotobynumber_r () |
131 | T} Thread safety MT-Safe locale | |
132 | .TE | |
4131356c | 133 | .SH VERSIONS |
ca1a4bba MK |
134 | Functions with similar names exist on some other systems, |
135 | though typically with different calling signatures. | |
4131356c AC |
136 | .SH STANDARDS |
137 | GNU. | |
a14af333 | 138 | .SH EXAMPLES |
ca1a4bba MK |
139 | The program below uses |
140 | .BR getprotobyname_r () | |
141 | to retrieve the protocol record for the protocol named | |
142 | in its first command-line argument. | |
143 | If a second (integer) command-line argument is supplied, | |
144 | it is used as the initial value for | |
145 | .IR buflen ; | |
146 | if | |
147 | .BR getprotobyname_r () | |
148 | fails with the error | |
149 | .BR ERANGE , | |
150 | the program retries with larger buffer sizes. | |
151 | The following shell session shows a couple of sample runs: | |
c6d039a3 | 152 | .P |
ca1a4bba | 153 | .in +4n |
e646a1ba | 154 | .EX |
b43a3b30 | 155 | .RB "$" " ./a.out tcp 1" |
ca1a4bba MK |
156 | ERANGE! Retrying with larger buffer |
157 | getprotobyname_r() returned: 0 (success) (buflen=78) | |
158 | p_name=tcp; p_proto=6; aliases=TCP | |
b43a3b30 | 159 | .RB "$" " ./a.out xxx 1" |
ca1a4bba MK |
160 | ERANGE! Retrying with larger buffer |
161 | getprotobyname_r() returned: 0 (success) (buflen=100) | |
162 | Call failed/record not found | |
b8302363 | 163 | .EE |
ca1a4bba | 164 | .in |
9c330504 | 165 | .SS Program source |
d84d0300 | 166 | \& |
b0b6ab4e | 167 | .\" SRC BEGIN (getprotoent_r.c) |
e7d0bb47 | 168 | .EX |
ca1a4bba MK |
169 | #define _GNU_SOURCE |
170 | #include <ctype.h> | |
ad3868f0 | 171 | #include <errno.h> |
ca1a4bba | 172 | #include <netdb.h> |
ca1a4bba | 173 | #include <stdio.h> |
ad3868f0 | 174 | #include <stdlib.h> |
ca1a4bba | 175 | #include <string.h> |
fe5dba13 | 176 | \& |
ca1a4bba | 177 | #define MAX_BUF 10000 |
fe5dba13 | 178 | \& |
ca1a4bba MK |
179 | int |
180 | main(int argc, char *argv[]) | |
181 | { | |
182 | int buflen, erange_cnt, s; | |
183 | struct protoent result_buf; | |
184 | struct protoent *result; | |
185 | char buf[MAX_BUF]; | |
fe5dba13 | 186 | \& |
ca1a4bba | 187 | if (argc < 2) { |
d1a71985 | 188 | printf("Usage: %s proto\-name [buflen]\en", argv[0]); |
ca1a4bba MK |
189 | exit(EXIT_FAILURE); |
190 | } | |
fe5dba13 | 191 | \& |
ca1a4bba MK |
192 | buflen = 1024; |
193 | if (argc > 2) | |
194 | buflen = atoi(argv[2]); | |
fe5dba13 | 195 | \& |
ca1a4bba | 196 | if (buflen > MAX_BUF) { |
d1a71985 | 197 | printf("Exceeded buffer limit (%d)\en", MAX_BUF); |
ca1a4bba MK |
198 | exit(EXIT_FAILURE); |
199 | } | |
fe5dba13 | 200 | \& |
ca1a4bba MK |
201 | erange_cnt = 0; |
202 | do { | |
203 | s = getprotobyname_r(argv[1], &result_buf, | |
d917c31d | 204 | buf, buflen, &result); |
ca1a4bba MK |
205 | if (s == ERANGE) { |
206 | if (erange_cnt == 0) | |
d1a71985 | 207 | printf("ERANGE! Retrying with larger buffer\en"); |
ca1a4bba | 208 | erange_cnt++; |
fe5dba13 | 209 | \& |
ca1a4bba | 210 | /* Increment a byte at a time so we can see exactly |
46b20ca1 | 211 | what size buffer was required. */ |
fe5dba13 | 212 | \& |
ca1a4bba | 213 | buflen++; |
fe5dba13 | 214 | \& |
ca1a4bba | 215 | if (buflen > MAX_BUF) { |
d1a71985 | 216 | printf("Exceeded buffer limit (%d)\en", MAX_BUF); |
ca1a4bba MK |
217 | exit(EXIT_FAILURE); |
218 | } | |
219 | } | |
220 | } while (s == ERANGE); | |
fe5dba13 | 221 | \& |
d1a71985 | 222 | printf("getprotobyname_r() returned: %s (buflen=%d)\en", |
d917c31d AC |
223 | (s == 0) ? "0 (success)" : (s == ENOENT) ? "ENOENT" : |
224 | strerror(s), buflen); | |
fe5dba13 | 225 | \& |
ca1a4bba | 226 | if (s != 0 || result == NULL) { |
d1a71985 | 227 | printf("Call failed/record not found\en"); |
ca1a4bba MK |
228 | exit(EXIT_FAILURE); |
229 | } | |
fe5dba13 | 230 | \& |
ca1a4bba | 231 | printf("p_name=%s; p_proto=%d; aliases=", |
d917c31d | 232 | result_buf.p_name, result_buf.p_proto); |
88893a77 | 233 | for (char **p = result_buf.p_aliases; *p != NULL; p++) |
ca1a4bba | 234 | printf("%s ", *p); |
d1a71985 | 235 | printf("\en"); |
fe5dba13 | 236 | \& |
ca1a4bba MK |
237 | exit(EXIT_SUCCESS); |
238 | } | |
e7d0bb47 | 239 | .EE |
b0b6ab4e | 240 | .\" SRC END |
47297adb | 241 | .SH SEE ALSO |
ca1a4bba | 242 | .BR getprotoent (3), |
ca1a4bba | 243 | .BR protocols (5) |