1explain_getresgid(3) Library Functions Manual explain_getresgid(3)
2
6 explain_getresgid - explain getresgid(2) errors
7
9 #include <libexplain/getresgid.h>
10 const char *explain_getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
11 const char *explain_errno_getresgid(int errnum, gid_t *rgid, gid_t
12 *egid, gid_t *sgid);
13 void explain_message_getresgid(char *message, int message_size, gid_t
14 *rgid, gid_t *egid, gid_t *sgid);
15 void explain_message_errno_getresgid(char *message, int message_size,
16 int errnum, gid_t *rgid, gid_t *egid, gid_t *sgid);
17
19 These functions may be used to obtain explanations for errors returned
20 by the getresgid(2) system call.
21 explain_getresgid
23 const char *explain_getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
24 The explain_getresgid function is used to obtain an explanation of an
26 error returned by the getresgid(2) system call. The least the message
27 will contain is the value of strerror(errno), but usually it will do
28 much 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 rgid The original rgid, exactly as passed to the getresgid(2) system
34 call.
35 egid The original egid, exactly as passed to the getresgid(2) system
37 call.
38 sgid The original sgid, exactly as passed to the getresgid(2) system
40 call.
41 Returns:
43 The message explaining the error. This message buffer is shared
44 by all libexplain functions which do not supply a buffer in
45 their argument list. This will be overwritten by the next call
46 to any libexplain function which shares this buffer, including
47 other threads.
48 Note: This function is not thread safe, because it shares a return buf‐
50 fer across all threads, and many other functions in this library.
51 Example: This function is intended to be used in a fashion similar to
53 the following example:
54 if (getresgid(rgid, egid, sgid) < 0)
55 {
56 fprintf(stderr, "%s\n", explain_getresgid(rgid, egid,
57 sgid));
58 exit(EXIT_FAILURE);
59 }
60 The above code example is available pre-packaged as the explain_getres‐
62 gid_or_die(3) function.
63 explain_errno_getresgid
65 const char *explain_errno_getresgid(int errnum, gid_t *rgid, gid_t
66 *egid, gid_t *sgid);
67 The explain_errno_getresgid function is used to obtain an explanation
69 of an error returned by the getresgid(2) system call. The least the
70 message will contain is the value of strerror(errno), but usually it
71 will do much better, and indicate the underlying cause in more detail.
72 errnum The error value to be decoded, usually obtained from the errno
74 global variable just before this function is called. This is
75 necessary if you need to call any code between the system call
76 to be explained and this function, because many libc functions
77 will alter the value of errno.
78 rgid The original rgid, exactly as passed to the getresgid(2) system
80 call.
81 egid The original egid, exactly as passed to the getresgid(2) system
83 call.
84 sgid The original sgid, exactly as passed to the getresgid(2) system
86 call.
87 Returns:
89 The message explaining the error. This message buffer is shared
90 by all libexplain functions which do not supply a buffer in
91 their argument list. This will be overwritten by the next call
92 to any libexplain function which shares this buffer, including
93 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 Example: This function is intended to be used in a fashion similar to
99 the following example:
100 if (getresgid(rgid, egid, sgid) < 0)
101 {
102 int err = errno;
103 fprintf(stderr, "%s\n", explain_errno_getresgid(err, rgid,
104 egid, sgid));
105 exit(EXIT_FAILURE);
106 }
107 The above code example is available pre-packaged as the explain_getres‐
109 gid_or_die(3) function.
110 explain_message_getresgid
112 void explain_message_getresgid(char *message, int message_size, gid_t
113 *rgid, gid_t *egid, gid_t *sgid);
114 The explain_message_getresgid function is used to obtain an explanation
116 of an error returned by the getresgid(2) system call. The least the
117 message will contain is the value of strerror(errno), but usually it
118 will do much better, and indicate the underlying cause in more detail.
119 The errno global variable will be used to obtain the error value to be
121 decoded.
122 message The location in which to store the returned message. If a suit‐
124 able message return buffer is supplied, this function is thread
125 safe.
126 message_size
128 The size in bytes of the location in which to store the
129 returned message.
130 rgid The original rgid, exactly as passed to the getresgid(2) system
132 call.
133 egid The original egid, exactly as passed to the getresgid(2) system
135 call.
136 sgid The original sgid, exactly as passed to the getresgid(2) system
138 call.
139 Example: This function is intended to be used in a fashion similar to
141 the following example:
142 if (getresgid(rgid, egid, sgid) < 0)
143 {
144 char message[3000];
145 explain_message_getresgid(message, sizeof(message), rgid,
146 egid, sgid);
147 fprintf(stderr, "%s\n", message);
148 exit(EXIT_FAILURE);
149 }
150 The above code example is available pre-packaged as the explain_getres‐
152 gid_or_die(3) function.
153 explain_message_errno_getresgid
155 void explain_message_errno_getresgid(char *message, int message_size,
156 int errnum, gid_t *rgid, gid_t *egid, gid_t *sgid);
157 The explain_message_errno_getresgid function is used to obtain an
159 explanation of an error returned by the getresgid(2) system call. The
160 least the message will contain is the value of strerror(errno), but
161 usually it will do much better, and indicate the underlying cause in
162 more detail.
163 message The location in which to store the returned message. If a suit‐
165 able message return buffer is supplied, this function is thread
166 safe.
167 message_size
169 The size in bytes of the location in which to store the
170 returned message.
171 errnum The error value to be decoded, usually obtained from the errno
173 global variable just before this function is called. This is
174 necessary if you need to call any code between the system call
175 to be explained and this function, because many libc functions
176 will alter the value of errno.
177 rgid The original rgid, exactly as passed to the getresgid(2) system
179 call.
180 egid The original egid, exactly as passed to the getresgid(2) system
182 call.
183 sgid The original sgid, exactly as passed to the getresgid(2) system
185 call.
186 Example: This function is intended to be used in a fashion similar to
188 the following example:
189 if (getresgid(rgid, egid, sgid) < 0)
190 {
191 int err = errno;
192 char message[3000];
193 explain_message_errno_getresgid(message, sizeof(message),
194 err, rgid, egid, sgid);
195 fprintf(stderr, "%s\n", message);
196 exit(EXIT_FAILURE);
197 }
198 The above code example is available pre-packaged as the explain_getres‐
200 gid_or_die(3) function.
201
203 getresgid(2)
204 get real, effective and saved group IDs
205 explain_getresgid_or_die(3)
207 get real, effective and saved group IDs and report errors
208
210 libexplain version 1.4
211 Copyright (C) 2012 Peter Miller
212 explain_getresgid(3)