1explain_fdopendir(3) Library Functions Manual explain_fdopendir(3)
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6 explain_fdopendir - explain fdopendir(3) errors
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9 #include <libexplain/fdopendir.h>
10 const char *explain_fdopendir(int fildes);
11 const char *explain_errno_fdopendir(int errnum, int fildes);
12 void explain_message_fdopendir(char *message, int message_size, int
13 fildes);
14 void explain_message_errno_fdopendir(char *message, int message_size,
15 int errnum, int fildes);
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18 These functions may be used to obtain explanations for errors returned
19 by the fdopendir(3) system call.
20 explain_fdopendir
22 const char *explain_fdopendir(int fildes);
23 The explain_fdopendir function is used to obtain an explanation of an
25 error returned by the fdopendir(3) system call. The least the message
26 will contain is the value of strerror(errno), but usually it will do
27 much better, and indicate the underlying cause in more detail.
28 The errno global variable will be used to obtain the error value to be
30 decoded.
31 fildes The original fildes, exactly as passed to the fdopendir(3) sys‐
33 tem call.
34 Returns:
36 The message explaining the error. This message buffer is shared
37 by all libexplain functions which do not supply a buffer in
38 their argument list. This will be overwritten by the next call
39 to any libexplain function which shares this buffer, including
40 other threads.
41 Note: This function is not thread safe, because it shares a return buf‐
43 fer across all threads, and many other functions in this library.
44 Example: This function is intended to be used in a fashion similar to
46 the following example:
47 DIR *result = fdopendir(fildes);
48 if (!result)
49 {
50 fprintf(stderr, "%s\n", explain_fdopendir(fildes));
51 exit(EXIT_FAILURE);
52 }
53 The above code example is available pre‐packaged as the
55 explain_fdopendir_or_die(3) function.
56 explain_errno_fdopendir
58 const char *explain_errno_fdopendir(int errnum, int fildes);
59 The explain_errno_fdopendir function is used to obtain an explanation
61 of an error returned by the fdopendir(3) system call. The least the
62 message will contain is the value of strerror(errno), but usually it
63 will do much better, and indicate the underlying cause in more detail.
64 errnum The error value to be decoded, usually obtained from the errno
66 global variable just before this function is called. This is
67 necessary if you need to call any code between the system call
68 to be explained and this function, because many libc functions
69 will alter the value of errno.
70 fildes The original fildes, exactly as passed to the fdopendir(3) sys‐
72 tem call.
73 Returns:
75 The message explaining the error. This message buffer is shared
76 by all libexplain functions which do not supply a buffer in
77 their argument list. This will be overwritten by the next call
78 to any libexplain function which shares this buffer, including
79 other threads.
80 Note: This function is not thread safe, because it shares a return buf‐
82 fer across all threads, and many other functions in this library.
83 Example: This function is intended to be used in a fashion similar to
85 the following example:
86 DIR *result = fdopendir(fildes);
87 if (!result)
88 {
89 int err = errno;
90 fprintf(stderr, "%s\n", explain_errno_fdopendir(err,
91 fildes));
92 exit(EXIT_FAILURE);
93 }
94 The above code example is available pre‐packaged as the
96 explain_fdopendir_or_die(3) function.
97 explain_message_fdopendir
99 void explain_message_fdopendir(char *message, int message_size, int
100 fildes);
101 The explain_message_fdopendir function is used to obtain an explanation
103 of an error returned by the fdopendir(3) system call. The least the
104 message will contain is the value of strerror(errno), but usually it
105 will do much better, and indicate the underlying cause in more detail.
106 The errno global variable will be used to obtain the error value to be
108 decoded.
109 message The location in which to store the returned message. If a suit‐
111 able message return buffer is supplied, this function is thread
112 safe.
113 message_size
115 The size in bytes of the location in which to store the
116 returned message.
117 fildes The original fildes, exactly as passed to the fdopendir(3) sys‐
119 tem call.
120 Example: This function is intended to be used in a fashion similar to
122 the following example:
123 DIR *result = fdopendir(fildes);
124 if (!result)
125 {
126 char message[3000];
127 explain_message_fdopendir(message, sizeof(message), fildes);
128 fprintf(stderr, "%s\n", message);
129 exit(EXIT_FAILURE);
130 }
131 The above code example is available pre‐packaged as the
133 explain_fdopendir_or_die(3) function.
134 explain_message_errno_fdopendir
136 void explain_message_errno_fdopendir(char *message, int message_size,
137 int errnum, int fildes);
138 The explain_message_errno_fdopendir function is used to obtain an
140 explanation of an error returned by the fdopendir(3) system call. The
141 least the message will contain is the value of strerror(errno), but
142 usually it will do much better, and indicate the underlying cause in
143 more detail.
144 message The location in which to store the returned message. If a suit‐
146 able message return buffer is supplied, this function is thread
147 safe.
148 message_size
150 The size in bytes of the location in which to store the
151 returned message.
152 errnum The error value to be decoded, usually obtained from the errno
154 global variable just before this function is called. This is
155 necessary if you need to call any code between the system call
156 to be explained and this function, because many libc functions
157 will alter the value of errno.
158 fildes The original fildes, exactly as passed to the fdopendir(3) sys‐
160 tem call.
161 Example: This function is intended to be used in a fashion similar to
163 the following example:
164 DIR *result = fdopendir(fildes);
165 if (!result)
166 {
167 int err = errno;
168 char message[3000];
169 explain_message_errno_fdopendir(message, sizeof(message),
170 err, fildes);
171 fprintf(stderr, "%s\n", message);
172 exit(EXIT_FAILURE);
173 }
174 The above code example is available pre‐packaged as the
176 explain_fdopendir_or_die(3) function.
177
179 fdopendir(3)
180 open a directory
181 explain_fdopendir_or_die(3)
183 open a directory and report errors
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186 libexplain version 1.4
187 Copyright (C) 2009 Peter Miller
188 explain_fdopendir(3)