1explain_readdir(3) Library Functions Manual explain_readdir(3)
2
6 explain_readdir - explain readdir(2) errors
7
9 #include <libexplain/readdir.h>
10 const char *explain_readdir(DIR *dir);
11 const char *explain_errno_readdir(int errnum, DIR *dir);
12 void explain_message_readdir(char *message, int message_size, DIR
13 *dir);
14 void explain_message_errno_readdir(char *message, int message_size, int
15 errnum, DIR *dir);
16
18 These functions may be used to obtain explanations for errors returned
19 by the readdir(2) system call.
20 explain_readdir
22 const char *explain_readdir(DIR *dir);
23 The explain_readdir function is used to obtain an explanation of an
25 error returned by the readdir(2) 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 This function is intended to be used in a fashion similar to the fol‐
33 lowing example:
34 errno = 0;
35 struct dirent *dep = readdir(dir);
36 if (!dep && errno != 0)
37 {
38 fprintf(stderr, "%s\n", explain_readdir(dir));
39 exit(EXIT_FAILURE);
40 }
41 dir The original dir, exactly as passed to the readdir(2) system
43 call.
44 Returns:
46 The message explaining the error. This message buffer is
47 shared by all libexplain functions which do not supply a buffer
48 in their argument list. This will be overwritten by the next
49 call to any libexplain function which shares this buffer,
50 including other threads.
51 Note: This function is not thread safe, because it shares a return buf‐
53 fer across all threads, and many other functions in this library.
54 explain_errno_readdir
56 const char *explain_errno_readdir(int errnum, DIR *dir);
57 The explain_errno_readdir function is used to obtain an explanation of
59 an error returned by the readdir(2) system call. The least the message
60 will contain is the value of strerror(errnum), but usually it will do
61 much better, and indicate the underlying cause in more detail.
62 This function is intended to be used in a fashion similar to the fol‐
64 lowing example:
65 errno = 0;
66 struct dirent *dep = readdir(dir);
67 int err = errno;
68 if (!dep && errno != 0)
69 {
70 fprintf(stderr, "%s\n", explain_errno_readdir(err, dir));
71 exit(EXIT_FAILURE);
72 }
73 errnum The error value to be decoded, usually obtained from the errno
75 global variable just before this function is called. This is
76 necessary if you need to call any code between the system call
77 to be explained and this function, because many libc functions
78 will alter the value of errno.
79 dir The original dir, exactly as passed to the readdir(2) system
81 call.
82 Returns:
84 The message explaining the error. This message buffer is
85 shared by all libexplain functions which do not supply a buffer
86 in their argument list. This will be overwritten by the next
87 call to any libexplain function which shares this buffer,
88 including other threads.
89 Note: This function is not thread safe, because it shares a return buf‐
91 fer across all threads, and many other functions in this library.
92 explain_message_readdir
94 void explain_message_readdir(char *message, int message_size, DIR
95 *dir);
96 The explain_message_readdir function may be used to obtain an explana‐
98 tion of an error returned by the readdir(2) system call. The least the
99 message will contain is the value of strerror(errno), but usually it
100 will do much better, and indicate the underlying cause in more detail.
101 The errno global variable will be used to obtain the error value to be
103 decoded.
104 This function is intended to be used in a fashion similar to the fol‐
106 lowing example:
107 errno = 0;
108 struct dirent *dep = readdir(dir);
109 if (!dep && errno != 0)
110 {
111 char message[3000];
112 explain_message_readdir(message, sizeof(message), dir);
113 fprintf(stderr, "%s\n", message);
114 exit(EXIT_FAILURE);
115 }
116 message The location in which to store the returned message. If a
118 suitable message return buffer is supplied, this function is
119 thread safe.
120 message_size
122 The size in bytes of the location in which to store the
123 returned message.
124 dir The original dir, exactly as passed to the readdir(2) system
126 call.
127 explain_message_errno_readdir
129 void explain_message_errno_readdir(char *message, int message_size, int
130 errnum, DIR *dir);
131 The explain_message_errno_readdir function may be used to obtain an
133 explanation of an error returned by the readdir(2) system call. The
134 least the message will contain is the value of strerror(errnum), but
135 usually it will do much better, and indicate the underlying cause in
136 more detail.
137 This function is intended to be used in a fashion similar to the fol‐
139 lowing example:
140 errno = 0;
141 struct dirent *dep = readdir(dir);
142 int err = errno;
143 if (!dep && errno != 0)
144 {
145 char message[3000];
146 explain_message_errno_readdir(message, sizeof(message), err, dir);
147 fprintf(stderr, "%s\n", message);
148 exit(EXIT_FAILURE);
149 }
150 message The location in which to store the returned message. If a
152 suitable message return buffer is supplied, this function is
153 thread safe.
154 message_size
156 The size in bytes of the location in which to store the
157 returned message.
158 errnum The error value to be decoded, usually obtained from the errno
160 global variable just before this function is called. This is
161 necessary if you need to call any code between the system call
162 to be explained and this function, because many libc functions
163 will alter the value of errno.
164 dir The original dir, exactly as passed to the readdir(2) system
166 call.
167
169 readdir(2)
170 read directory entry
171 explain_readdir_or_die(3)
173 read directory entry and report errors
174
176 libexplain version 1.4
177 Copyright (C) 2008 Peter Miller
178 explain_readdir(3)