1explain_fstat(3) Library Functions Manual explain_fstat(3)
2
6 explain_fstat - explain fstat(2) errors
7
9 #include <libexplain/fstat.h>
10 const char *explain_fstat(int fildes, struct stat *buf);
11 const char *explain_errno_fstat(int errnum, int fildes, struct stat
12 *buf);
13 void explain_message_fstat(char *message, int message_size, int fildes,
14 struct stat *buf);
15 void explain_message_errno_fstat(char *message, int message_size, int
16 errnum, int fildes, struct stat *buf);
17
19 These functions may be used to obtain explanations for errors returned
20 by the fstat(2) system call.
21 explain_fstat
23 const char *explain_fstat(int fildes, struct stat *buf);
24 The explain_fstat function is used to obtain an explanation of an error
26 returned by the fstat(2) system call. The least the message will con‐
27 tain is the value of strerror(errno), but usually it will do much bet‐
28 ter, and indicate the underlying cause in more detail.
29 The errno global variable will be used to obtain the error value to be
31 decoded.
32 This function is intended to be used in a fashion similar to the fol‐
34 lowing example:
35 if (fstat(fildes, buf) < 0)
36 {
37 fprintf(stderr, "%s\n", explain_fstat(fildes, buf));
38 exit(EXIT_FAILURE);
39 }
40 fildes The original fildes, exactly as passed to the fstat(2) system
42 call.
43 buf The original buf, exactly as passed to the fstat(2) system
45 call.
46 Returns:
48 The message explaining the error. This message buffer is
49 shared by all libexplain functions which do not supply a buffer
50 in their argument list. This will be overwritten by the next
51 call to any libexplain function which shares this buffer,
52 including other threads.
53 Note: This function is not thread safe, because it shares a return buf‐
55 fer across all threads, and many other functions in this library.
56 explain_errno_fstat
58 const char *explain_errno_fstat(int errnum, int fildes, struct stat
59 *buf);
60 The explain_errno_fstat function is used to obtain an explanation of an
62 error returned by the fstat(2) system call. The least the message will
63 contain is the value of strerror(errnum), but usually it will do much
64 better, and indicate the underlying cause in more detail.
65 This function is intended to be used in a fashion similar to the fol‐
67 lowing example:
68 if (fstat(fildes, buf) < 0)
69 {
70 int err = errno;
71 fprintf(stderr, "%s\n", explain_errno_fstat(err, fildes, buf));
72 exit(EXIT_FAILURE);
73 }
74 errnum The error value to be decoded, usually obtained from the errno
76 global variable just before this function is called. This is
77 necessary if you need to call any code between the system call
78 to be explained and this function, because many libc functions
79 will alter the value of errno.
80 fildes The original fildes, exactly as passed to the fstat(2) system
82 call.
83 buf The original buf, exactly as passed to the fstat(2) system
85 call.
86 Returns:
88 The message explaining the error. This message buffer is
89 shared by all libexplain functions which do not supply a buffer
90 in their argument list. This will be overwritten by the next
91 call to any libexplain function which shares this buffer,
92 including other threads.
93 Note: This function is not thread safe, because it shares a return buf‐
95 fer across all threads, and many other functions in this library.
96 explain_message_fstat
98 void explain_message_fstat(char *message, int message_size, int fildes,
99 struct stat *buf);
100 The explain_message_fstat function may be used to obtain an explana‐
102 tion of an error returned by the fstat(2) system call. The least the
103 message will contain is the value of strerror(errno), but usually it
104 will do 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 This function is intended to be used in a fashion similar to the fol‐
110 lowing example:
111 if (fstat(fildes, buf) < 0)
112 {
113 char message[3000];
114 explain_message_fstat(message, sizeof(message), fildes, buf);
115 fprintf(stderr, "%s\n", message);
116 exit(EXIT_FAILURE);
117 }
118 message The location in which to store the returned message. If a
120 suitable message return buffer is supplied, this function is
121 thread safe.
122 message_size
124 The size in bytes of the location in which to store the
125 returned message.
126 fildes The original fildes, exactly as passed to the fstat(2) system
128 call.
129 buf The original buf, exactly as passed to the fstat(2) system
131 call.
132 explain_message_errno_fstat
134 void explain_message_errno_fstat(char *message, int message_size, int
135 errnum, int fildes, struct stat *buf);
136 The explain_message_errno_fstat function may be used to obtain an
138 explanation of an error returned by the fstat(2) system call. The
139 least the message will contain is the value of strerror(errnum), but
140 usually it will do much better, and indicate the underlying cause in
141 more detail.
142 This function is intended to be used in a fashion similar to the fol‐
144 lowing example:
145 if (fstat(fildes, buf) < 0)
146 {
147 int err = errno;
148 char message[3000];
149 explain_message_errno_fstat(message, sizeof(message), err, fildes, buf);
150 fprintf(stderr, "%s\n", message);
151 exit(EXIT_FAILURE);
152 }
153 message The location in which to store the returned message. If a
155 suitable message return buffer is supplied, this function is
156 thread safe.
157 message_size
159 The size in bytes of the location in which to store the
160 returned message.
161 errnum The error value to be decoded, usually obtained from the errno
163 global variable just before this function is called. This is
164 necessary if you need to call any code between the system call
165 to be explained and this function, because many libc functions
166 will alter the value of errno.
167 fildes The original fildes, exactly as passed to the fstat(2) system
169 call.
170 buf The original buf, exactly as passed to the fstat(2) system
172 call.
173
175 fstat(2)
176 get file status
177 explain_fstat_or_die(3)
179 get file status and report errors
180
182 libexplain version 1.4
183 Copyright (C) 2008 Peter Miller
184 explain_fstat(3)