1explain_signalfd(3) Library Functions Manual explain_signalfd(3)
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6 explain_signalfd - explain signalfd(2) errors
7
9 #include <libexplain/signalfd.h>
10 const char *explain_signalfd(int fildes, const sigset_t *mask, int
11 flags);
12 const char *explain_errno_signalfd(int errnum, int fildes, const
13 sigset_t *mask, int flags);
14 void explain_message_signalfd(char *message, int message_size, int
15 fildes, const sigset_t *mask, int flags);
16 void explain_message_errno_signalfd(char *message, int message_size,
17 int errnum, int fildes, const sigset_t *mask, int flags);
18
20 These functions may be used to obtain explanations for errors returned
21 by the signalfd(2) system call.
22 explain_signalfd
24 const char *explain_signalfd(int fildes, const sigset_t *mask, int
25 flags);
26 The explain_signalfd function is used to obtain an explanation of an
28 error returned by the signalfd(2) system call. The least the message
29 will contain is the value of strerror(errno), but usually it will do
30 much better, and indicate the underlying cause in more detail.
31 The errno global variable will be used to obtain the error value to be
33 decoded.
34 fildes The original fildes, exactly as passed to the signalfd(2) sys‐
36 tem call.
37 mask The original mask, exactly as passed to the signalfd(2) system
39 call.
40 flags The original flags, exactly as passed to the signalfd(2) system
42 call.
43 Returns:
45 The message explaining the error. This message buffer is shared
46 by all libexplain functions which do not supply a buffer in
47 their argument list. This will be overwritten by the next call
48 to any libexplain function which shares this buffer, including
49 other threads.
50 Note: This function is not thread safe, because it shares a return buf‐
52 fer across all threads, and many other functions in this library.
53 Example: This function is intended to be used in a fashion similar to
55 the following example:
56 int result = signalfd(fildes, mask, flags);
57 if (result < 0)
58 {
59 fprintf(stderr, "%s\n", explain_signalfd(fildes, mask,
60 flags));
61 exit(EXIT_FAILURE);
62 }
63 The above code example is available pre‐packaged as the explain_sig‐
65 nalfd_or_die(3) function.
66 explain_errno_signalfd
68 const char *explain_errno_signalfd(int errnum, int fildes, const
69 sigset_t *mask, int flags);
70 The explain_errno_signalfd function is used to obtain an explanation of
72 an error returned by the signalfd(2) system call. The least the mes‐
73 sage will contain is the value of strerror(errno), but usually it will
74 do much better, and indicate the underlying cause in more detail.
75 errnum The error value to be decoded, usually obtained from the errno
77 global variable just before this function is called. This is
78 necessary if you need to call any code between the system call
79 to be explained and this function, because many libc functions
80 will alter the value of errno.
81 fildes The original fildes, exactly as passed to the signalfd(2) sys‐
83 tem call.
84 mask The original mask, exactly as passed to the signalfd(2) system
86 call.
87 flags The original flags, exactly as passed to the signalfd(2) system
89 call.
90 Returns:
92 The message explaining the error. This message buffer is shared
93 by all libexplain functions which do not supply a buffer in
94 their argument list. This will be overwritten by the next call
95 to any libexplain function which shares this buffer, including
96 other threads.
97 Note: This function is not thread safe, because it shares a return buf‐
99 fer across all threads, and many other functions in this library.
100 Example: This function is intended to be used in a fashion similar to
102 the following example:
103 int result = signalfd(fildes, mask, flags);
104 if (result < 0)
105 {
106 int err = errno;
107 fprintf(stderr, "%s\n", explain_errno_signalfd(err, fildes,
108 mask, flags));
109 exit(EXIT_FAILURE);
110 }
111 The above code example is available pre‐packaged as the explain_sig‐
113 nalfd_or_die(3) function.
114 explain_message_signalfd
116 void explain_message_signalfd(char *message, int message_size, int
117 fildes, const sigset_t *mask, int flags);
118 The explain_message_signalfd function is used to obtain an explanation
120 of an error returned by the signalfd(2) system call. The least the
121 message will contain is the value of strerror(errno), but usually it
122 will do much better, and indicate the underlying cause in more detail.
123 The errno global variable will be used to obtain the error value to be
125 decoded.
126 message The location in which to store the returned message. If a suit‐
128 able message return buffer is supplied, this function is thread
129 safe.
130 message_size
132 The size in bytes of the location in which to store the
133 returned message.
134 fildes The original fildes, exactly as passed to the signalfd(2) sys‐
136 tem call.
137 mask The original mask, exactly as passed to the signalfd(2) system
139 call.
140 flags The original flags, exactly as passed to the signalfd(2) system
142 call.
143 Example: This function is intended to be used in a fashion similar to
145 the following example:
146 int result = signalfd(fildes, mask, flags);
147 if (result < 0)
148 {
149 char message[3000];
150 explain_message_signalfd(message, sizeof(message), fildes,
151 mask, flags);
152 fprintf(stderr, "%s\n", message);
153 exit(EXIT_FAILURE);
154 }
155 The above code example is available pre‐packaged as the explain_sig‐
157 nalfd_or_die(3) function.
158 explain_message_errno_signalfd
160 void explain_message_errno_signalfd(char *message, int message_size,
161 int errnum, int fildes, const sigset_t *mask, int flags);
162 The explain_message_errno_signalfd function is used to obtain an expla‐
164 nation of an error returned by the signalfd(2) system call. The least
165 the message will contain is the value of strerror(errno), but usually
166 it will do much better, and indicate the underlying cause in more
167 detail.
168 message The location in which to store the returned message. If a suit‐
170 able message return buffer is supplied, this function is thread
171 safe.
172 message_size
174 The size in bytes of the location in which to store the
175 returned message.
176 errnum The error value to be decoded, usually obtained from the errno
178 global variable just before this function is called. This is
179 necessary if you need to call any code between the system call
180 to be explained and this function, because many libc functions
181 will alter the value of errno.
182 fildes The original fildes, exactly as passed to the signalfd(2) sys‐
184 tem call.
185 mask The original mask, exactly as passed to the signalfd(2) system
187 call.
188 flags The original flags, exactly as passed to the signalfd(2) system
190 call.
191 Example: This function is intended to be used in a fashion similar to
193 the following example:
194 int result = signalfd(fildes, mask, flags);
195 if (result < 0)
196 {
197 int err = errno;
198 char message[3000];
199 explain_message_errno_signalfd(message, sizeof(message),
200 err, fildes, mask, flags);
201 fprintf(stderr, "%s\n", message);
202 exit(EXIT_FAILURE);
203 }
204 The above code example is available pre‐packaged as the explain_sig‐
206 nalfd_or_die(3) function.
207
209 signalfd(2)
210 create a file descriptor for accepting signals
211 explain_signalfd_or_die(3)
213 create a file descriptor for accepting signals and report
214 errors
215
217 libexplain version 1.4
218 Copyright (C) 2009 Peter Miller
219 explain_signalfd(3)