1explain_putc(3) Library Functions Manual explain_putc(3)
2
6 explain_putc - explain putc(3) errors
7
9 #include <libexplain/putc.h>
10 const char *explain_putc(int c, FILE *fp);
11 const char *explain_errno_putc(int errnum, int c, FILE *fp);
12 void explain_message_putc(char *message, int message_size, int c, FILE
13 *fp);
14 void explain_message_errno_putc(char *message, int message_size, int
15 errnum, int c, FILE *fp);
16
18 These functions may be used to obtain explanations for errors returned
19 by the putc(3) system call.
20 explain_putc
22 const char *explain_putc(int c, FILE *fp);
23 The explain_putc function is used to obtain an explanation of an error
25 returned by the putc(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 This function is intended to be used in a fashion similar to the fol‐
33 lowing example:
34 if (putc(c, fp) == EOF)
35 {
36 fprintf(stderr, "%s\n", explain_putc(c, fp));
37 exit(EXIT_FAILURE);
38 }
39 c The original c, exactly as passed to the putc(3) system call.
41 fp The original fp, exactly as passed to the putc(3) system call.
43 Returns:
45 The message explaining the error. This message buffer is
46 shared by all libexplain functions which do not supply a buffer
47 in their argument list. This will be overwritten by the next
48 call to any libexplain function which shares this buffer,
49 including other threads.
50 Note: This function is not thread safe, because it shares a return buf‐
52 fer across all threads, and many other functions in this library.
53 explain_errno_putc
55 const char *explain_errno_putc(int errnum, int c, FILE *fp);
56 The explain_errno_putc function is used to obtain an explanation of an
58 error returned by the putc(3) system call. The least the message will
59 contain is the value of strerror(errnum), but usually it will do much
60 better, and indicate the underlying cause in more detail.
61 This function is intended to be used in a fashion similar to the fol‐
63 lowing example:
64 if (putc(c, fp) == EOF)
65 {
66 int err = errno;
67 fprintf(stderr, "%s\n", explain_errno_putc(err, c, fp));
68 exit(EXIT_FAILURE);
69 }
70 errnum The error value to be decoded, usually obtained from the errno
72 global variable just before this function is called. This is
73 necessary if you need to call any code between the system call
74 to be explained and this function, because many libc functions
75 will alter the value of errno.
76 c The original c, exactly as passed to the putc(3) system call.
78 fp The original fp, exactly as passed to the putc(3) system call.
80 Returns:
82 The message explaining the error. This message buffer is
83 shared by all libexplain functions which do not supply a buffer
84 in their argument list. This will be overwritten by the next
85 call to any libexplain function which shares this buffer,
86 including other threads.
87 Note: This function is not thread safe, because it shares a return buf‐
89 fer across all threads, and many other functions in this library.
90 explain_message_putc
92 void explain_message_putc(char *message, int message_size, int c, FILE
93 *fp);
94 The explain_message_putc function may be used to obtain an explanation
96 of an error returned by the putc(3) system call. The least the message
97 will contain is the value of strerror(errno), but usually it will do
98 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 This function is intended to be used in a fashion similar to the fol‐
104 lowing example:
105 if (putc(c, fp) == EOF)
106 {
107 char message[3000];
108 explain_message_putc(message, sizeof(message), c, fp);
109 fprintf(stderr, "%s\n", message);
110 exit(EXIT_FAILURE);
111 }
112 message The location in which to store the returned message. If a
114 suitable message return buffer is supplied, this function is
115 thread safe.
116 message_size
118 The size in bytes of the location in which to store the
119 returned message.
120 c The original c, exactly as passed to the putc(3) system call.
122 fp The original fp, exactly as passed to the putc(3) system call.
124 explain_message_errno_putc
126 void explain_message_errno_putc(char *message, int message_size, int
127 errnum, int c, FILE *fp);
128 The explain_message_errno_putc function may be used to obtain an expla‐
130 nation of an error returned by the putc(3) system call. The least the
131 message will contain is the value of strerror(errnum), but usually it
132 will do much better, and indicate the underlying cause in more detail.
133 This function is intended to be used in a fashion similar to the fol‐
135 lowing example:
136 if (putc(c, fp) == EOF)
137 {
138 int err = errno;
139 char message[3000];
140 explain_message_errno_putc(message, sizeof(message), err, c, fp);
141 fprintf(stderr, "%s\n", message);
142 exit(EXIT_FAILURE);
143 }
144 message The location in which to store the returned message. If a
146 suitable message return buffer is supplied, this function is
147 thread 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 c The original c, exactly as passed to the putc(3) system call.
160 fp The original fp, exactly as passed to the putc(3) system call.
162
164 putc(3) output of characters
165 explain_putc_or_die(3)
167 output of characters and report errors
168
170 libexplain version 1.4
171 Copyright (C) 2008 Peter Miller
172 explain_putc(3)