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

6       explain_freopen - explain freopen(3) errors
7

SYNOPSIS

9       #include <libexplain/freopen.h>
10       const  char  *explain_freopen(const  char *pathname, const char *flags,
11       FILE *fp);
12       const char *explain_errno_freopen(int  errnum,  const  char  *pathname,
13       const char *flags, FILE *fp);
14       void  explain_message_freopen(char  *message,  int  message_size, const
15       char *pathname, const char *flags, FILE *fp);
16       void explain_message_errno_freopen(char *message, int message_size, int
17       errnum, const char *pathname, const char *flags, FILE *fp);
18

DESCRIPTION

20       These  functions  may  be  used  to  obtain explanations for freopen(3)
21       errors.
22
23   explain_freopen
24       const char *explain_freopen(const char *pathname,  const  char  *flags,
25       FILE *fp);
26
27       The  explain_freopen  function  is  used to obtain an explanation of an
28       error returned by the freopen(3) system call.  The  least  the  message
29       will  contain  is  the value of strerror(errno), but usually it will do
30       much better, and indicate the underlying cause in more detail.
31
32       The errno global variable will be used to obtain the error value to  be
33       decoded.
34
35       This  function  is intended to be used in a fashion similar to the fol‐
36       lowing example:
37              if (!freopen(pathname, flags, fp))
38              {
39                  fprintf(stderr, '%s0, explain_freopen(pathname, flags, fp));
40                  exit(EXIT_FAILURE);
41              }
42
43       pathname
44               The original pathname, exactly as passed to the freopen(3) sys‐
45               tem call.
46
47       flags   The  original flags, exactly as passed to the freopen(3) system
48               call.
49
50       fp      The original fp, exactly as passed  to  the  freopen(3)  system
51               call.
52
53       Returns:
54               The  message  explaining  the  error.   This  message buffer is
55               shared by all libexplain functions which do not supply a buffer
56               in  their  argument list.  This will be overwritten by the next
57               call to any  libexplain  function  which  shares  this  buffer,
58               including other threads.
59
60       Note: This function is not thread safe, because it shares a return buf‐
61       fer across all threads, and many other functions in this library.
62
63   explain_errno_freopen
64       const char *explain_errno_freopen(int  errnum,  const  char  *pathname,
65       const char *flags, FILE *fp);
66
67       The  explain_errno_freopen function is used to obtain an explanation of
68       an error returned by the freopen(3) system call.  The least the message
69       will  contain  is the value of strerror(errnum), but usually it will do
70       much better, and indicate the underlying cause in more detail.
71
72       This function is intended to be used in a fashion similar to  the  fol‐
73       lowing example:
74              if (freopen(pathname, flags, fp))
75              {
76                  int err = errno;
77                  fprintf(stderr, '%s0, explain_errno_freopen(err, pathname,
78                      flags, fp));
79                  exit(EXIT_FAILURE);
80              }
81
82       errnum  The  error value to be decoded, usually obtained from the errno
83               global variable just before this function is called.   This  is
84               necessary  if you need to call any code between the system call
85               to be explained and this function, because many libc  functions
86               will alter the value of errno.
87
88       pathname
89               The original pathname, exactly as passed to the freopen(3) sys‐
90               tem call.
91
92       flags   The original flags, exactly as passed to the freopen(3)  system
93               call.
94
95       fp      The  original  fp,  exactly  as passed to the freopen(3) system
96               call.
97
98       Returns:
99               The message explaining  the  error.   This  message  buffer  is
100               shared by all libexplain functions which do not supply a buffer
101               in their argument list.  This will be overwritten by  the  next
102               call  to  any  libexplain  function  which  shares this buffer,
103               including other threads.
104
105       Note: This function is not thread safe, because it shares a return buf‐
106       fer across all threads, and many other functions in this library.
107
108   explain_message_freopen
109       void  explain_message_freopen(char  *message,  int  message_size, const
110       char *pathname, const char *flags, FILE *fp);
111
112       The explain_message_freopen function is used to obtain  an  explanation
113       of an error returned by the freopen(3) system call.  The least the mes‐
114       sage will contain is the value of strerror(errno), but usually it  will
115       do much better, and indicate the underlying cause in more detail.
116
117       The  errno global variable will be used to obtain the error value to be
118       decoded.
119
120       This function is intended to be used in a fashion similar to  the  fol‐
121       lowing example:
122              if (!freopen(pathname, flags, fp))
123              {
124                  char message[3000];
125                  explain_message_freopen(message, sizeof(message), pathname, flags,
126                      fp);
127                  fprintf(stderr, '%s0, message);
128                  exit(EXIT_FAILURE);
129              }
130
131       message The location in which to store the returned message.  Because a
132               message return buffer  has  been  supplied,  this  function  is
133               thread safe.
134
135       message_size
136               The  size  in  bytes  of  the  location  in  which to store the
137               returned message.
138
139       pathname
140               The original pathname, exactly as passed to the freopen(3) sys‐
141               tem call.
142
143       flags   The  original flags, exactly as passed to the freopen(3) system
144               call.
145
146       fp      The original fp, exactly as passed  to  the  freopen(3)  system
147               call.
148
149   explain_message_errno_freopen
150       void explain_message_errno_freopen(char *message, int message_size, int
151       errnum, const char *pathname, const char *flags, FILE *fp);
152
153       The explain_message_errno_freopen function is used to obtain an  expla‐
154       nation  of  an error returned by the freopen(3) system call.  The least
155       the message will contain is the value of strerror(errnum), but  usually
156       it  will  do  much  better,  and  indicate the underlying cause in more
157       detail.
158
159       This function is intended to be used in a fashion similar to  the  fol‐
160       lowing example:
161              if (!freopen(pathname, flags, fp))
162              {
163                  int err = errno;
164                  char message[3000];
165                  explain_message_errno_freopen(message, sizeof(message), err,
166                      pathname, flags, fp);
167                  fprintf(stderr, '%s0, message);
168                  exit(EXIT_FAILURE);
169              }
170
171       message The location in which to store the returned message.  Because a
172               message return buffer  has  been  supplied,  this  function  is
173               thread safe.
174
175       message_size
176               The  size  in  bytes  of  the  location  in  which to store the
177               returned message.
178
179       errnum  The error value to be decoded, usually obtained from the  errno
180               global  variable  just before this function is called.  This is
181               necessary if you need to call any code between the system  call
182               to  be explained and this function, because many libc functions
183               will alter the value of errno.
184
185       pathname
186               The original pathname, exactly as passed to the freopen(3) sys‐
187               tem call.
188
189       flags   The  original flags, exactly as passed to the freopen(3) system
190               call.
191
192       fp      The original fp, exactly as passed  to  the  freopen(3)  system
193               call.
194
196       libexplain version 0.40
197       Copyright (C) 2008 Peter Miller
198

AUTHOR

200       Written by Peter Miller <pmiller@opensource.org.au>
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204                                                            explain_freopen(3)
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