1explain_asprintf(3) Library Functions Manual explain_asprintf(3)
2
6 explain_asprintf - explain asprintf(3) errors
7
9 #include <libexplain/asprintf.h>
10 const char *explain_asprintf(, ...);
11 const char *explain_errno_asprintf(int errnum, , ...);
12 void explain_message_asprintf(char *message, int message_size, , ...);
13 void explain_message_errno_asprintf(char *message, int message_size,
14 int errnum, , ...);
15
17 These functions may be used to obtain explanations for errors returned
18 by the asprintf(3) system call.
19 explain_asprintf
21 const char *explain_asprintf(, ...);
22 The explain_asprintf function is used to obtain an explanation of an
24 error returned by the asprintf(3) system call. The least the message
25 will contain is the value of strerror(errno), but usually it will do
26 much better, and indicate the underlying cause in more detail.
27 The errno global variable will be used to obtain the error value to be
29 decoded.
30 Returns:
32 The message explaining the error. This message buffer is shared
33 by all libexplain functions which do not supply a buffer in
34 their argument list. This will be overwritten by the next call
35 to any libexplain function which shares this buffer, including
36 other threads.
37 Note: This function is not thread safe, because it shares a return buf‐
39 fer across all threads, and many other functions in this library.
40 Example: This function is intended to be used in a fashion similar to
42 the following example:
43 errno = 0;
44 int result = asprintf();
45 if (result < 0 || errno != 0)
46 {
47 fprintf(stderr, "%s\n", explain_asprintf());
48 exit(EXIT_FAILURE);
49 }
50 The above code example is available pre-packaged as the
52 explain_asprintf_or_die(3) function.
53 explain_errno_asprintf
55 const char *explain_errno_asprintf(int errnum, , ...);
56 The explain_errno_asprintf function is used to obtain an explanation of
58 an error returned by the asprintf(3) system call. The least the mes‐
59 sage will contain is the value of strerror(errno), but usually it will
60 do much better, and indicate the underlying cause in more detail.
61 errnum The error value to be decoded, usually obtained from the errno
63 global variable just before this function is called. This is
64 necessary if you need to call any code between the system call
65 to be explained and this function, because many libc functions
66 will alter the value of errno.
67 Returns:
69 The message explaining the error. This message buffer is shared
70 by all libexplain functions which do not supply a buffer in
71 their argument list. This will be overwritten by the next call
72 to any libexplain function which shares this buffer, including
73 other threads.
74 Note: This function is not thread safe, because it shares a return buf‐
76 fer across all threads, and many other functions in this library.
77 Example: This function is intended to be used in a fashion similar to
79 the following example:
80 errno = 0;
81 int result = asprintf();
82 if (result < 0 || errno != 0)
83 {
84 int err = errno;
85 fprintf(stderr, "%s\n", explain_errno_asprintf(err, ));
86 exit(EXIT_FAILURE);
87 }
88 The above code example is available pre-packaged as the
90 explain_asprintf_or_die(3) function.
91 explain_message_asprintf
93 void explain_message_asprintf(char *message, int message_size, , ...);
94 The explain_message_asprintf function is used to obtain an explanation
96 of an error returned by the asprintf(3) system call. The least the
97 message will contain is the value of strerror(errno), but usually it
98 will do much better, and indicate the underlying cause in more detail.
99 The errno global variable will be used to obtain the error value to be
101 decoded.
102 message The location in which to store the returned message. If a suit‐
104 able message return buffer is supplied, this function is thread
105 safe.
106 message_size
108 The size in bytes of the location in which to store the
109 returned message.
110 Example: This function is intended to be used in a fashion similar to
112 the following example:
113 errno = 0;
114 int result = asprintf();
115 if (result < 0 || errno != 0)
116 {
117 char message[3000];
118 explain_message_asprintf(message, sizeof(message), );
119 fprintf(stderr, "%s\n", message);
120 exit(EXIT_FAILURE);
121 }
122 The above code example is available pre-packaged as the
124 explain_asprintf_or_die(3) function.
125 explain_message_errno_asprintf
127 void explain_message_errno_asprintf(char *message, int message_size,
128 int errnum, , ...);
129 The explain_message_errno_asprintf function is used to obtain an expla‐
131 nation of an error returned by the asprintf(3) system call. The least
132 the message will contain is the value of strerror(errno), but usually
133 it will do much better, and indicate the underlying cause in more
134 detail.
135 message The location in which to store the returned message. If a suit‐
137 able message return buffer is supplied, this function is thread
138 safe.
139 message_size
141 The size in bytes of the location in which to store the
142 returned message.
143 errnum The error value to be decoded, usually obtained from the errno
145 global variable just before this function is called. This is
146 necessary if you need to call any code between the system call
147 to be explained and this function, because many libc functions
148 will alter the value of errno.
149 Example: This function is intended to be used in a fashion similar to
151 the following example:
152 errno = 0;
153 int result = asprintf();
154 if (result < 0 || errno != 0)
155 {
156 int err = errno;
157 char message[3000];
158 explain_message_errno_asprintf(message, sizeof(message),
159 err, );
160 fprintf(stderr, "%s\n", message);
161 exit(EXIT_FAILURE);
162 }
163 The above code example is available pre-packaged as the
165 explain_asprintf_or_die(3) function.
166
168 asprintf(3)
169 print to allocated string
170 explain_asprintf_or_die(3)
172 print to allocated string and report errors
173
175 libexplain version 1.4
176 Copyright (C) 2013 Peter Miller
177 explain_asprintf(3)