1explain_lchmod(3) Library Functions Manual explain_lchmod(3)
2
6 explain_lchmod - explain lchmod(2) errors
7
9 #include <libexplain/lchmod.h>
10 const char *explain_lchmod(const char *pathname, mode_t mode);
11 const char *explain_errno_lchmod(int errnum, const char *pathname,
12 mode_t mode);
13 void explain_message_lchmod(char *message, int message_size, const char
14 *pathname, mode_t mode);
15 void explain_message_errno_lchmod(char *message, int message_size, int
16 errnum, const char *pathname, mode_t mode);
17
19 These functions may be used to obtain explanations for errors returned
20 by the lchmod(2) system call.
21 explain_lchmod
23 const char *explain_lchmod(const char *pathname, mode_t mode);
24 The explain_lchmod function is used to obtain an explanation of an
26 error returned by the lchmod(2) system call. The least the message will
27 contain is the value of strerror(errno), but usually it will do much
28 better, 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 pathname
34 The original pathname, exactly as passed to the lchmod(2) sys‐
35 tem call.
36 mode The original mode, exactly as passed to the lchmod(2) system
38 call.
39 Returns:
41 The message explaining the error. This message buffer is shared
42 by all libexplain functions which do not supply a buffer in
43 their argument list. This will be overwritten by the next call
44 to any libexplain function which shares this buffer, including
45 other threads.
46 Note: This function is not thread safe, because it shares a return buf‐
48 fer across all threads, and many other functions in this library.
49 Example: This function is intended to be used in a fashion similar to
51 the following example:
52 if (lchmod(pathname, mode) < 0)
53 {
54 fprintf(stderr, "%s\n", explain_lchmod(pathname, mode));
55 exit(EXIT_FAILURE);
56 }
57 The above code example is available pre-packaged as the explain_lch‐
59 mod_or_die(3) function.
60 explain_errno_lchmod
62 const char *explain_errno_lchmod(int errnum, const char *pathname,
63 mode_t mode);
64 The explain_errno_lchmod function is used to obtain an explanation of
66 an error returned by the lchmod(2) system call. The least the message
67 will contain is the value of strerror(errno), but usually it will do
68 much better, and indicate the underlying cause in more detail.
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 pathname
77 The original pathname, exactly as passed to the lchmod(2) sys‐
78 tem call.
79 mode The original mode, exactly as passed to the lchmod(2) system
81 call.
82 Returns:
84 The message explaining the error. This message buffer is shared
85 by all libexplain functions which do not supply a buffer in
86 their argument list. This will be overwritten by the next call
87 to any libexplain function which shares this buffer, including
88 other threads.
89 Note: This function is not thread safe, because it shares a return buf‐
91 fer across all threads, and many other functions in this library.
92 Example: This function is intended to be used in a fashion similar to
94 the following example:
95 if (lchmod(pathname, mode) < 0)
96 {
97 int err = errno;
98 fprintf(stderr, "%s\n", explain_errno_lchmod(err, pathname,
99 mode));
100 exit(EXIT_FAILURE);
101 }
102 The above code example is available pre-packaged as the explain_lch‐
104 mod_or_die(3) function.
105 explain_message_lchmod
107 void explain_message_lchmod(char *message, int message_size, const char
108 *pathname, mode_t mode);
109 The explain_message_lchmod function is used to obtain an explanation of
111 an error returned by the lchmod(2) 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 The errno global variable will be used to obtain the error value to be
116 decoded.
117 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 message_size
123 The size in bytes of the location in which to store the
124 returned message.
125 pathname
127 The original pathname, exactly as passed to the lchmod(2) sys‐
128 tem call.
129 mode The original mode, exactly as passed to the lchmod(2) system
131 call.
132 Example: This function is intended to be used in a fashion similar to
134 the following example:
135 if (lchmod(pathname, mode) < 0)
136 {
137 char message[3000];
138 explain_message_lchmod(message, sizeof(message), pathname,
139 mode);
140 fprintf(stderr, "%s\n", message);
141 exit(EXIT_FAILURE);
142 }
143 The above code example is available pre-packaged as the explain_lch‐
145 mod_or_die(3) function.
146 explain_message_errno_lchmod
148 void explain_message_errno_lchmod(char *message, int message_size, int
149 errnum, const char *pathname, mode_t mode);
150 The explain_message_errno_lchmod function is used to obtain an explana‐
152 tion of an error returned by the lchmod(2) 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 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 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 lchmod(2) sys‐
172 tem call.
173 mode The original mode, exactly as passed to the lchmod(2) system
175 call.
176 Example: This function is intended to be used in a fashion similar to
178 the following example:
179 if (lchmod(pathname, mode) < 0)
180 {
181 int err = errno;
182 char message[3000];
183 explain_message_errno_lchmod(message, sizeof(message), err,
184 pathname, mode);
185 fprintf(stderr, "%s\n", message);
186 exit(EXIT_FAILURE);
187 }
188 The above code example is available pre-packaged as the explain_lch‐
190 mod_or_die(3) function.
191
193 lchmod(2)
194 change permissions of a file
195 explain_lchmod_or_die(3)
197 change permissions of a file and report errors
198
200 libexplain version 1.4
201 Copyright (C) 2012 Peter Miller
202 explain_lchmod(3)