1explain_accept(3) Library Functions Manual explain_accept(3)
2
6 explain_accept - explain accept(2) errors
7
9 #include <libexplain/accept.h>
10 const char *explain_accept(int fildes, struct sockaddr *sock_addr,
11 socklen_t *sock_addr_size);
12 const char *explain_errno_accept(int errnum, int fildes, struct sock‐
13 addr *sock_addr, socklen_t *sock_addr_size);
14 void explain_message_accept(char *message, int message_size, int
15 fildes, struct sockaddr *sock_addr, socklen_t *sock_addrlen);
16 void explain_message_errno_accept(char *message, int message_size, int
17 errnum, int fildes, struct sockaddr *sock_addr, socklen_t
18 *sock_addr_size);
19
21 These functions may be used to obtain explanations for errors returned
22 by the accept(2) system call.
23 explain_accept
25 const char *explain_accept(int fildes, struct sockaddr *sock_addr,
26 socklen_t *sock_addr_size);
27 The explain_accept function is used to obtain an explanation of an
29 error returned by the accept(2) system call. The least the message
30 will contain is the value of strerror(errno), but usually it will do
31 much better, and indicate the underlying cause in more detail.
32 The errno global variable will be used to obtain the error value to be
34 decoded.
35 This function is intended to be used in a fashion similar to the fol‐
37 lowing example:
38 if (accept(fildes, sock_addr, sock_addr_size) < 0)
39 {
40 fprintf(stderr, "%s\n", explain_accept(fildes, sock_addr,
41 sock_addr_size));
42 exit(EXIT_FAILURE);
43 }
44 The above code example is available pre‐packaged as the
46 explain_accept_or_die(3) function.
47 fildes The original fildes, exactly as passed to the accept(2) system
49 call.
50 sock_addr
52 The original sock_addr, exactly as passed to the accept(2) sys‐
53 tem call.
54 sock_addr_size
56 The original sock_addr_size, exactly as passed to the accept(2)
57 system call.
58 Returns:
60 The message explaining the error. This message buffer is
61 shared by all libexplain functions which do not supply a buffer
62 in their argument list. This will be overwritten by the next
63 call to any libexplain function which shares this buffer,
64 including other threads.
65 Note: This function is not thread safe, because it shares a return buf‐
67 fer across all threads, and many other functions in this library.
68 explain_errno_accept
70 const char *explain_errno_accept(int errnum, int fildes, struct sock‐
71 addr *sock_addr, socklen_t *sock_addr_size);
72 The explain_errno_accept function is used to obtain an explanation of
74 an error returned by the accept(2) system call. The least the message
75 will contain is the value of strerror(errnum), but usually it will do
76 much better, and indicate the underlying cause in more detail.
77 This function is intended to be used in a fashion similar to the fol‐
79 lowing example:
80 if (accept(fildes, sock_addr, sock_addr_size) < 0)
81 {
82 int err = errno;
83 fprintf(stderr, "%s\n", explain_errno_accept(err, fildes, sock_addr,
84 sock_addr_size));
85 exit(EXIT_FAILURE);
86 }
87 The above code example is available pre‐packaged as the
89 explain_accept_or_die(3) function.
90 errnum The error value to be decoded, usually obtained from the errno
92 global variable just before this function is called. This is
93 necessary if you need to call any code between the system call
94 to be explained and this function, because many libc functions
95 will alter the value of errno.
96 fildes The original fildes, exactly as passed to the accept(2) system
98 call.
99 sock_addr
101 The original sock_addr, exactly as passed to the accept(2) sys‐
102 tem call.
103 sock_addr_size
105 The original sock_addr_size, exactly as passed to the accept(2)
106 system call.
107 Returns:
109 The message explaining the error. This message buffer is
110 shared by all libexplain functions which do not supply a buffer
111 in their argument list. This will be overwritten by the next
112 call to any libexplain function which shares this buffer,
113 including other threads.
114 Note: This function is not thread safe, because it shares a return buf‐
116 fer across all threads, and many other functions in this library.
117 explain_message_accept
119 void explain_message_accept(char *message, int message_size, int
120 fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);
121 The explain_message_accept function may be used to obtain an explana‐
123 tion of an error returned by the accept(2) system call. The least the
124 message will contain is the value of strerror(errno), but usually it
125 will do much better, and indicate the underlying cause in more detail.
126 The errno global variable will be used to obtain the error value to be
128 decoded.
129 This function is intended to be used in a fashion similar to the fol‐
131 lowing example:
132 if (accept(fildes, sock_addr, sock_addr_size) < 0)
133 {
134 char message[3000];
135 explain_message_accept(message, sizeof(message), fildes, sock_addr,
136 sock_addr_size);
137 fprintf(stderr, "%s\n", message);
138 exit(EXIT_FAILURE);
139 }
140 The above code example is available pre‐packaged as the
142 explain_accept_or_die(3) function.
143 message The location in which to store the returned message. If a
145 suitable message return buffer is supplied, this function is
146 thread safe.
147 message_size
149 The size in bytes of the location in which to store the
150 returned message.
151 fildes The original fildes, exactly as passed to the accept(2) system
153 call.
154 sock_addr
156 The original sock_addr, exactly as passed to the accept(2) sys‐
157 tem call.
158 sock_addr_size
160 The original sock_addr_size, exactly as passed to the accept(2)
161 system call.
162 explain_message_errno_accept
164 void explain_message_errno_accept(char *message, int message_size, int
165 errnum, int fildes, struct sockaddr *sock_addr, socklen_t
166 *sock_addr_size);
167 The explain_message_errno_accept function may be used to obtain an
169 explanation of an error returned by the accept(2) system call. The
170 least the message will contain is the value of strerror(errnum), but
171 usually it will do much better, and indicate the underlying cause in
172 more detail.
173 This function is intended to be used in a fashion similar to the fol‐
175 lowing example:
176 if (accept(fildes, sock_addr, sock_addr_size) < 0)
177 {
178 int err = errno;
179 char message[3000];
180 explain_message_errno_accept(message, sizeof(message), err, fildes,
181 sock_addr, sock_addr_size);
182 fprintf(stderr, "%s\n", message);
183 exit(EXIT_FAILURE);
184 }
185 The above code example is available pre‐packaged as the
187 explain_accept_or_die(3) function.
188 message The location in which to store the returned message. If a
190 suitable message return buffer is supplied, this function is
191 thread safe.
192 message_size
194 The size in bytes of the location in which to store the
195 returned message.
196 errnum The error value to be decoded, usually obtained from the errno
198 global variable just before this function is called. This is
199 necessary if you need to call any code between the system call
200 to be explained and this function, because many libc functions
201 will alter the value of errno.
202 fildes The original fildes, exactly as passed to the accept(2) system
204 call.
205 sock_addr
207 The original sock_addr, exactly as passed to the accept(2) sys‐
208 tem call.
209 sock_addr_size
211 The original sock_addr_size, exactly as passed to the accept(2)
212 system call.
213
215 accept(2)
216 accept a connection on a socket
217 explain_accept_or_die(3)
219 accept a connection on a socket and report errors
220
222 libexplain version 1.4
223 Copyright (C) 2008 Peter Miller
224 explain_accept(3)