1explain_fputs(3) Library Functions Manual explain_fputs(3)
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6 explain_fputs - explain fputs(3) errors
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9 #include <libexplain/fputs.h>
10 const char *explain_fputs(const char *s, FILE *fp);
11 const char *explain_errno_fputs(int errnum, const char *s, FILE *fp);
12 void explain_message_fputs(char *message, int message_size, const char
13 *s, FILE *fp);
14 void explain_message_errno_fputs(char *message, int message_size, int
15 errnum, const char *s, FILE *fp);
16
18 These functions may be used to obtain explanations for errors returned
19 by the fputs(3) system call.
20 explain_fputs
22 const char *explain_fputs(const char *s, FILE *fp);
23 The explain_fputs function is used to obtain an explanation of an error
25 returned by the fputs(3) system call. The least the message will con‐
26 tain is the value of strerror(errno), but usually it will do much bet‐
27 ter, 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 s The original s, exactly as passed to the fputs(3) system call.
33 fp The original fp, exactly as passed to the fputs(3) system call.
35 Returns:
37 The message explaining the error. This message buffer is shared
38 by all libexplain functions which do not supply a buffer in
39 their argument list. This will be overwritten by the next call
40 to any libexplain function which shares this buffer, including
41 other threads.
42 Note: This function is not thread safe, because it shares a return buf‐
44 fer across all threads, and many other functions in this library.
45 Example: This function is intended to be used in a fashion similar to
47 the following example:
48 if (fputs(s, fp) < 0)
49 {
50 fprintf(stderr, "%s\n", explain_fputs(s, fp));
51 exit(EXIT_FAILURE);
52 }
53 The above code example is available pre‐packaged as the
55 explain_fputs_or_die(3) function.
56 explain_errno_fputs
58 const char *explain_errno_fputs(int errnum, const char *s, FILE *fp);
59 The explain_errno_fputs function is used to obtain an explanation of an
61 error returned by the fputs(3) system call. The least the message will
62 contain is the value of strerror(errno), but usually it will do much
63 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 s The original s, exactly as passed to the fputs(3) system call.
72 fp The original fp, exactly as passed to the fputs(3) system 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 if (fputs(s, fp) < 0)
88 {
89 int err = errno;
90 fprintf(stderr, "%s\n", explain_errno_fputs(err, s, fp));
91 exit(EXIT_FAILURE);
92 }
93 The above code example is available pre‐packaged as the
95 explain_fputs_or_die(3) function.
96 explain_message_fputs
98 void explain_message_fputs(char *message, int message_size, const char
99 *s, FILE *fp);
100 The explain_message_fputs function is used to obtain an explanation of
102 an error returned by the fputs(3) system call. The least the message
103 will contain is the value of strerror(errno), but usually it will do
104 much better, and indicate the underlying cause in more detail.
105 The errno global variable will be used to obtain the error value to be
107 decoded.
108 message The location in which to store the returned message. If a suit‐
110 able message return buffer is supplied, this function is thread
111 safe.
112 message_size
114 The size in bytes of the location in which to store the
115 returned message.
116 s The original s, exactly as passed to the fputs(3) system call.
118 fp The original fp, exactly as passed to the fputs(3) system call.
120 Example: This function is intended to be used in a fashion similar to
122 the following example:
123 if (fputs(s, fp) < 0)
124 {
125 char message[3000];
126 explain_message_fputs(message, sizeof(message), s, fp);
127 fprintf(stderr, "%s\n", message);
128 exit(EXIT_FAILURE);
129 }
130 The above code example is available pre‐packaged as the
132 explain_fputs_or_die(3) function.
133 explain_message_errno_fputs
135 void explain_message_errno_fputs(char *message, int message_size, int
136 errnum, const char *s, FILE *fp);
137 The explain_message_errno_fputs function is used to obtain an explana‐
139 tion of an error returned by the fputs(3) system call. The least the
140 message will contain is the value of strerror(errno), but usually it
141 will do much better, and indicate the underlying cause in more detail.
142 message The location in which to store the returned message. If a suit‐
144 able message return buffer is supplied, this function is thread
145 safe.
146 message_size
148 The size in bytes of the location in which to store the
149 returned message.
150 errnum The error value to be decoded, usually obtained from the errno
152 global variable just before this function is called. This is
153 necessary if you need to call any code between the system call
154 to be explained and this function, because many libc functions
155 will alter the value of errno.
156 s The original s, exactly as passed to the fputs(3) system call.
158 fp The original fp, exactly as passed to the fputs(3) system call.
160 Example: This function is intended to be used in a fashion similar to
162 the following example:
163 if (fputs(s, fp) < 0)
164 {
165 int err = errno;
166 char message[3000];
167 explain_message_errno_fputs(message, sizeof(message), err,
168 s, fp);
169 fprintf(stderr, "%s\n", message);
170 exit(EXIT_FAILURE);
171 }
172 The above code example is available pre‐packaged as the
174 explain_fputs_or_die(3) function.
175
177 fputs(3)
178 write a string to a stream
179 explain_fputs_or_die(3)
181 write a string to a stream and report errors
182
184 libexplain version 1.4
185 Copyright (C) 2009 Peter Miller
186 explain_fputs(3)