1explain_setbuf(3)          Library Functions Manual          explain_setbuf(3)
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NAME

6       explain_setbuf - explain setbuf(3) errors
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SYNOPSIS

9       #include <libexplain/setbuf.h>
10       const char *explain_setbuf(FILE *fp, char *data);
11       const char *explain_errno_setbuf(int errnum, FILE *fp, char *data);
12       void explain_message_setbuf(char *message, int message_size, FILE *fp,
13       char *data);
14       void explain_message_errno_setbuf(char *message, int message_size, int
15       errnum, FILE *fp, char *data);
16

DESCRIPTION

18       These  functions may be used to obtain explanations for errors returned
19       by the setbuf(3) system call.
20
21   explain_setbuf
22       const char *explain_setbuf(FILE *fp, char *data);
23
24       The explain_setbuf function is used to  obtain  an  explanation  of  an
25       error returned by the setbuf(3) system call. The least the message will
26       contain is the value of strerror(errno), but usually it  will  do  much
27       better, and indicate the underlying cause in more detail.
28
29       The  errno global variable will be used to obtain the error value to be
30       decoded.
31
32       fp      The original fp, exactly as  passed  to  the  setbuf(3)  system
33               call.
34
35       data    The  original  data,  exactly as passed to the setbuf(3) system
36               call.
37
38       Returns:
39               The message explaining the error. This message buffer is shared
40               by  all  libexplain  functions  which do not supply a buffer in
41               their argument list.  This will be overwritten by the next call
42               to  any libexplain function which shares this buffer, including
43               other threads.
44
45       Note: This function is not thread safe, because it shares a return buf‐
46       fer across all threads, and many other functions in this library.
47
48       Example:  This  function is intended to be used in a fashion similar to
49       the following example:
50              errno = 0;
51              void result = setbuf(fp, data);
52              if (result < 0 && errno != 0)
53              {
54                  fprintf(stderr, "%s\n", explain_setbuf(fp, data));
55                  exit(EXIT_FAILURE);
56              }
57
58       The above code example is available pre‐packaged  as  the  explain_set‐
59       buf_or_die(3) function.
60
61   explain_errno_setbuf
62       const char *explain_errno_setbuf(int errnum, FILE *fp, char *data);
63
64       The  explain_errno_setbuf  function is used to obtain an explanation of
65       an error returned by the setbuf(3) system call. The least  the  message
66       will  contain  is  the value of strerror(errno), but usually it will do
67       much better, and indicate the underlying cause in more detail.
68
69       errnum  The error value to be decoded, usually obtained from the  errno
70               global  variable  just  before this function is called. This is
71               necessary if you need to call any code between the system  call
72               to  be explained and this function, because many libc functions
73               will alter the value of errno.
74
75       fp      The original fp, exactly as  passed  to  the  setbuf(3)  system
76               call.
77
78       data    The  original  data,  exactly as passed to the setbuf(3) system
79               call.
80
81       Returns:
82               The message explaining the error. This message buffer is shared
83               by  all  libexplain  functions  which do not supply a buffer in
84               their argument list.  This will be overwritten by the next call
85               to  any libexplain function which shares this buffer, including
86               other threads.
87
88       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
91       Example:  This  function is intended to be used in a fashion similar to
92       the following example:
93              errno = 0;
94              void result = setbuf(fp, data);
95              if (result < 0 && errno != 0)
96              {
97                  int err = errno;
98                  fprintf(stderr, "%s\n", explain_errno_setbuf(err, fp,
99                  data));
100                  exit(EXIT_FAILURE);
101              }
102
103       The  above  code  example is available pre‐packaged as the explain_set‐
104       buf_or_die(3) function.
105
106   explain_message_setbuf
107       void explain_message_setbuf(char *message, int message_size, FILE *fp,
108       char *data);
109
110       The explain_message_setbuf function is used to obtain an explanation of
111       an error returned by the setbuf(3) system call. The least  the  message
112       will  contain  is  the value of strerror(errno), but usually it will do
113       much better, and indicate the underlying cause in more detail.
114
115       The errno global variable will be used to obtain the error value to  be
116       decoded.
117
118       message The location in which to store the returned message. If a suit‐
119               able message return buffer is supplied, this function is thread
120               safe.
121
122       message_size
123               The  size  in  bytes  of  the  location  in  which to store the
124               returned message.
125
126       fp      The original fp, exactly as  passed  to  the  setbuf(3)  system
127               call.
128
129       data    The  original  data,  exactly as passed to the setbuf(3) system
130               call.
131
132       Example: This function is intended to be used in a fashion  similar  to
133       the following example:
134              errno = 0;
135              void result = setbuf(fp, data);
136              if (result < 0 && errno != 0)
137              {
138                  char message[3000];
139                  explain_message_setbuf(message, sizeof(message), fp, data);
140                  fprintf(stderr, "%s\n", message);
141                  exit(EXIT_FAILURE);
142              }
143
144       The  above  code  example is available pre‐packaged as the explain_set‐
145       buf_or_die(3) function.
146
147   explain_message_errno_setbuf
148       void explain_message_errno_setbuf(char *message, int message_size, int
149       errnum, FILE *fp, char *data);
150
151       The explain_message_errno_setbuf function is used to obtain an explana‐
152       tion of an error returned by the setbuf(3) system call. The  least  the
153       message  will  contain  is the value of strerror(errno), but usually it
154       will do much better, and indicate the underlying cause in more detail.
155
156       message The location in which to store the returned message. If a suit‐
157               able message return buffer is supplied, this function is thread
158               safe.
159
160       message_size
161               The size in bytes  of  the  location  in  which  to  store  the
162               returned message.
163
164       errnum  The  error value to be decoded, usually obtained from the errno
165               global variable just before this function is  called.  This  is
166               necessary  if you need to call any code between the system call
167               to be explained and this function, because many libc  functions
168               will alter the value of errno.
169
170       fp      The  original  fp,  exactly  as  passed to the setbuf(3) system
171               call.
172
173       data    The original data, exactly as passed to  the  setbuf(3)  system
174               call.
175
176       Example:  This  function is intended to be used in a fashion similar to
177       the following example:
178              errno = 0;
179              void result = setbuf(fp, data);
180              if (result < 0 && errno != 0)
181              {
182                  int err = errno;
183                  char message[3000];
184                  explain_message_errno_setbuf(message, sizeof(message), err,
185                  fp, data);
186                  fprintf(stderr, "%s\n", message);
187                  exit(EXIT_FAILURE);
188              }
189
190       The  above  code  example is available pre‐packaged as the explain_set‐
191       buf_or_die(3) function.
192

SEE ALSO

194       setbuf(3)
195               set stream buffer
196
197       explain_setbuf_or_die(3)
198               set stream buffer and report errors
199
201       libexplain version 0.40
202       Copyright (C) 2010 Peter Miller
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206                                                             explain_setbuf(3)
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