1explain_chmod(3) Library Functions Manual explain_chmod(3)
2
6 explain_chmod - explain chmod(2) errors
7
9 #include <libexplain/chmod.h>
10 const char *explain_chmod(const char *pathname, int mode);
11 const char *explain_errno_chmod(int errnum, const char *pathname, int
12 mode);
13 void explain_message_chmod(char *message, int message_size, const char
14 *pathname, int mode);
15 void explain_message_errno_chmod(char *message, int message_size, int
16 errnum, const char *pathname, int mode);
17
19 These functions may be used to otain explanations for chmod(2) errors.
20 explain_chmod
22 const char *explain_chmod(const char *pathname, int mode);
23 The explain_chmod function is used to obtain an explanation of an error
25 returned by the chmod(2) 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 (chmod(pathname, mode) < 0)
35 {
36 fprintf(stderr, '%s0, explain_chmod(pathname, mode));
37 exit(EXIT_FAILURE);
38 }
39 pathname
41 The original pathname, exactly as passed to the chmod(2) system
42 call.
43 mode The original mode, exactly as passed to the chmod(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_chmod
58 const char *explain_errno_chmod(int errnum, const char *pathname, int
59 mode);
60 The explain_errno_chmod function is used to obtain an explanation of an
62 error returned by the chmod(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 (chmod(pathname) < 0)
69 {
70 int err = errno;
71 fprintf(stderr, '%s0, explain_errno_chmod(err, pathname));
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 pathname
82 The original pathname, exactly as passed to the chmod(2) system
83 call.
84 mode The original mode, exactly as passed to the chmod(2) system
86 call.
87 Returns:
89 The message explaining the error. This message buffer is
90 shared by all libexplain functions which do not supply a buffer
91 in their argument list. This will be overwritten by the next
92 call to any libexplain function which shares this buffer,
93 including other threads.
94 Note: This function is not thread safe, because it shares a return buf‐
96 fer across all threads, and many other functions in this library.
97 explain_message_chmod
99 void explain_message_chmod(char *message, int message_size, const char
100 *pathname, int mode);
101 The explain_message_chmod function is used to obtain an explanation of
103 an error returned by the chmod(2) system call. The least the message
104 will contain is the value of strerror(errno), but usually it will do
105 much better, and indicate the underlying cause in more detail.
106 The errno global variable will be used to obtain the error value to be
108 decoded.
109 This function is intended to be used in a fashion similar to the fol‐
111 lowing example:
112 if (chmod(pathname, mode) < 0)
113 {
114 char message[3000];
115 explain_message_chmod(message, sizeof(message), pathname, mode);
116 fprintf(stderr, '%s0, message);
117 exit(EXIT_FAILURE);
118 }
119 message The location in which to store the returned message. Because a
121 message return buffer has been supplied, this function is
122 thread safe.
123 message_size
125 The size in bytes of the location in which to store the
126 returned message.
127 pathname
129 The original pathname, exactly as passed to the chmod(2) system
130 call.
131 mode The original mode, exactly as passed to the chmod(2) system
133 call.
134 explain_message_errno_chmod
136 void explain_message_errno_chmod(char * message, int message_size, int
137 errnum, const char *pathname, int mode);
138 The explain_message_errno_chmod function is used to obtain an explana‐
140 tion of an error returned by the chmod(2) system call. The least the
141 message will contain is the value of strerror(errnum), but usually it
142 will do much better, and indicate the underlying cause in more detail.
143 This function is intended to be used in a fashion similar to the fol‐
145 lowing example:
146 if (chmod(pathname) < 0)
147 {
148 int err = errno;
149 char message[3000];
150 explain_message_errno_chmod(message, sizeof(message), err,
151 pathname);
152 fprintf(stderr, '%s0, message);
153 exit(EXIT_FAILURE);
154 }
155 message The location in which to store the returned message. Because a
157 message return buffer has been supplied, this function is
158 thread safe.
159 message_size
161 The size in bytes of the location in which to store the
162 returned message.
163 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 pathname
171 The original pathname, exactly as passed to the chmod(2) system
172 call.
173 mode The original mode, exactly as passed to the chmod(2) system
175 call.
176
178 libexplain version 0.40
179 Copyright (C) 2008 Peter Miller
180
182 Written by Peter Miller <pmiller@opensource.org.au>
183 explain_chmod(3)