1explain_getc(3) Library Functions Manual explain_getc(3)
2
6 explain_getc - explain getc(3) errors
7
9 #include <libexplain/getc.h>
10 const char *explain_getc(FILE *fp);
11 const char *explain_errno_getc(int errnum, FILE *fp);
12 void explain_message_getc(char *message, int message_size, FILE *fp);
13 void explain_message_errno_getc(char *message, int message_size, int
14 errnum, FILE *fp);
15
17 These functions may be used to obtain explanations for errors returned
18 by the getc(3) system call.
19 explain_getc
21 const char *explain_getc(FILE *fp);
22 The explain_getc function is used to obtain an explanation of an error
24 returned by the getc(3) system call. The least the message will con‐
25 tain is the value of strerror(errno), but usually it will do much bet‐
26 ter, 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 This function is intended to be used in a fashion similar to the fol‐
32 lowing example:
33 int c = getc(fp);
34 if (c == EOF && ferror(fp))
35 {
36 fprintf(stderr, "%s\n", explain_getc(fp));
37 exit(EXIT_FAILURE);
38 }
39 fp The original fp, exactly as passed to the getc(3) system call.
41 Returns:
43 The message explaining the error. This message buffer is
44 shared by all libexplain functions which do not supply a buffer
45 in their argument list. This will be overwritten by the next
46 call to any libexplain function which shares this buffer,
47 including other threads.
48 Note: This function is not thread safe, because it shares a return buf‐
50 fer across all threads, and many other functions in this library.
51 explain_errno_getc
53 const char *explain_errno_getc(int errnum, FILE *fp);
54 The explain_errno_getc function is used to obtain an explanation of an
56 error returned by the getc(3) system call. The least the message will
57 contain is the value of strerror(errnum), but usually it will do much
58 better, and indicate the underlying cause in more detail.
59 This function is intended to be used in a fashion similar to the fol‐
61 lowing example:
62 int c = getc(fp);
63 if (c == EOF && ferror(fp))
64 {
65 int err = errno;
66 fprintf(stderr, "%s\n", explain_errno_getc(err, fp));
67 exit(EXIT_FAILURE);
68 }
69 errnum The error value to be decoded, usually obtained from the errno
71 global variable just before this function is called. This is
72 necessary if you need to call any code between the system call
73 to be explained and this function, because many libc functions
74 will alter the value of errno.
75 fp The original fp, exactly as passed to the getc(3) system call.
77 Returns:
79 The message explaining the error. This message buffer is
80 shared by all libexplain functions which do not supply a buffer
81 in their argument list. This will be overwritten by the next
82 call to any libexplain function which shares this buffer,
83 including other threads.
84 Note: This function is not thread safe, because it shares a return buf‐
86 fer across all threads, and many other functions in this library.
87 explain_message_getc
89 void explain_message_getc(char *message, int message_size, FILE *fp);
90 The explain_message_getc function may be used to obtain an explanation
92 of an error returned by the getc(3) system call. The least the message
93 will contain is the value of strerror(errno), but usually it will do
94 much better, and indicate the underlying cause in more detail.
95 The errno global variable will be used to obtain the error value to be
97 decoded.
98 This function is intended to be used in a fashion similar to the fol‐
100 lowing example:
101 int c = getc(fp);
102 if (c == EOF && ferror(fp))
103 {
104 char message[3000];
105 explain_message_getc(message, sizeof(message), fp);
106 fprintf(stderr, "%s\n", message);
107 exit(EXIT_FAILURE);
108 }
109 message The location in which to store the returned message. If a
111 suitable message return buffer is supplied, this function is
112 thread safe.
113 message_size
115 The size in bytes of the location in which to store the
116 returned message.
117 fp The original fp, exactly as passed to the getc(3) system call.
119 explain_message_errno_getc
121 void explain_message_errno_getc(char *message, int message_size, int
122 errnum, FILE *fp);
123 The explain_message_errno_getc function may be used to obtain an expla‐
125 nation of an error returned by the getc(3) system call. The least the
126 message will contain is the value of strerror(errnum), but usually it
127 will do much better, and indicate the underlying cause in more detail.
128 This function is intended to be used in a fashion similar to the fol‐
130 lowing example:
131 int c = getc(fp);
132 if (c == EOF && ferror(fp))
133 {
134 int err = errno;
135 char message[3000];
136 explain_message_errno_getc(message, sizeof(message), err, fp);
137 fprintf(stderr, "%s\n", message);
138 exit(EXIT_FAILURE);
139 }
140 message The location in which to store the returned message. If a
142 suitable message return buffer is supplied, this function is
143 thread safe.
144 message_size
146 The size in bytes of the location in which to store the
147 returned message.
148 errnum The error value to be decoded, usually obtained from the errno
150 global variable just before this function is called. This is
151 necessary if you need to call any code between the system call
152 to be explained and this function, because many libc functions
153 will alter the value of errno.
154 fp The original fp, exactly as passed to the getc(3) system call.
156
158 getc(3) input of characters
159 explain_getc_or_die(3)
161 input of characters and report errors
162
164 libexplain version 1.4
165 Copyright (C) 2008 Peter Miller
166 explain_getc(3)