1explain_setlinebuf(3) Library Functions Manual explain_setlinebuf(3)
2
6 explain_setlinebuf - explain setlinebuf(3) errors
7
9 #include <libexplain/setlinebuf.h>
10 const char *explain_setlinebuf(FILE *fp);
11 const char *explain_errno_setlinebuf(int errnum, FILE *fp);
12 void explain_message_setlinebuf(char *message, int message_size, FILE
13 *fp);
14 void explain_message_errno_setlinebuf(char *message, int message_size,
15 int errnum, FILE *fp);
16
18 These functions may be used to obtain explanations for errors returned
19 by the setlinebuf(3) system call.
20 explain_setlinebuf
22 const char *explain_setlinebuf(FILE *fp);
23 The explain_setlinebuf function is used to obtain an explanation of an
25 error returned by the setlinebuf(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 fp The original fp, exactly as passed to the setlinebuf(3) system
33 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 errno = 0;
48 void result = setlinebuf(fp);
49 if (result < 0 && errno != 0)
50 {
51 fprintf(stderr, "%s\n", explain_setlinebuf(fp));
52 exit(EXIT_FAILURE);
53 }
54 The above code example is available pre‐packaged as the explain_set‐
56 linebuf_or_die(3) function.
57 explain_errno_setlinebuf
59 const char *explain_errno_setlinebuf(int errnum, FILE *fp);
60 The explain_errno_setlinebuf function is used to obtain an explanation
62 of an error returned by the setlinebuf(3) system call. The least the
63 message will contain is the value of strerror(errno), but usually it
64 will do much better, and indicate the underlying cause in more detail.
65 errnum The error value to be decoded, usually obtained from the errno
67 global variable just before this function is called. This is
68 necessary if you need to call any code between the system call
69 to be explained and this function, because many libc functions
70 will alter the value of errno.
71 fp The original fp, exactly as passed to the setlinebuf(3) system
73 call.
74 Returns:
76 The message explaining the error. This message buffer is shared
77 by all libexplain functions which do not supply a buffer in
78 their argument list. This will be overwritten by the next call
79 to any libexplain function which shares this buffer, including
80 other threads.
81 Note: This function is not thread safe, because it shares a return buf‐
83 fer across all threads, and many other functions in this library.
84 Example: This function is intended to be used in a fashion similar to
86 the following example:
87 errno = 0;
88 void result = setlinebuf(fp);
89 if (result < 0 && errno != 0)
90 {
91 int err = errno;
92 fprintf(stderr, "%s\n", explain_errno_setlinebuf(err, fp));
93 exit(EXIT_FAILURE);
94 }
95 The above code example is available pre‐packaged as the explain_set‐
97 linebuf_or_die(3) function.
98 explain_message_setlinebuf
100 void explain_message_setlinebuf(char *message, int message_size, FILE
101 *fp);
102 The explain_message_setlinebuf function is used to obtain an explana‐
104 tion of an error returned by the setlinebuf(3) system call. The least
105 the message will contain is the value of strerror(errno), but usually
106 it will do much better, and indicate the underlying cause in more
107 detail.
108 The errno global variable will be used to obtain the error value to be
110 decoded.
111 message The location in which to store the returned message. If a suit‐
113 able message return buffer is supplied, this function is thread
114 safe.
115 message_size
117 The size in bytes of the location in which to store the
118 returned message.
119 fp The original fp, exactly as passed to the setlinebuf(3) system
121 call.
122 Example: This function is intended to be used in a fashion similar to
124 the following example:
125 errno = 0;
126 void result = setlinebuf(fp);
127 if (result < 0 && errno != 0)
128 {
129 char message[3000];
130 explain_message_setlinebuf(message, sizeof(message), fp);
131 fprintf(stderr, "%s\n", message);
132 exit(EXIT_FAILURE);
133 }
134 The above code example is available pre‐packaged as the explain_set‐
136 linebuf_or_die(3) function.
137 explain_message_errno_setlinebuf
139 void explain_message_errno_setlinebuf(char *message, int message_size,
140 int errnum, FILE *fp);
141 The explain_message_errno_setlinebuf function is used to obtain an
143 explanation of an error returned by the setlinebuf(3) system call. The
144 least the message will contain is the value of strerror(errno), but
145 usually it will do much better, and indicate the underlying cause in
146 more detail.
147 message The location in which to store the returned message. If a suit‐
149 able message return buffer is supplied, this function is thread
150 safe.
151 message_size
153 The size in bytes of the location in which to store the
154 returned message.
155 errnum The error value to be decoded, usually obtained from the errno
157 global variable just before this function is called. This is
158 necessary if you need to call any code between the system call
159 to be explained and this function, because many libc functions
160 will alter the value of errno.
161 fp The original fp, exactly as passed to the setlinebuf(3) system
163 call.
164 Example: This function is intended to be used in a fashion similar to
166 the following example:
167 errno = 0;
168 void result = setlinebuf(fp);
169 if (result < 0 && errno != 0)
170 {
171 int err = errno;
172 char message[3000];
173 explain_message_errno_setlinebuf(message, sizeof(message),
174 err, fp);
175 fprintf(stderr, "%s\n", message);
176 exit(EXIT_FAILURE);
177 }
178 The above code example is available pre‐packaged as the explain_set‐
180 linebuf_or_die(3) function.
181
183 setlinebuf(3)
184 stream buffering operations
185 explain_setlinebuf_or_die(3)
187 stream buffering operations and report errors
188
190 libexplain version 1.4
191 Copyright (C) 2010 Peter Miller
192 explain_setlinebuf(3)