1explain_setgid(3) Library Functions Manual explain_setgid(3)
2
6 explain_setgid - explain setgid(2) errors
7
9 #include <libexplain/setgid.h>
10 const char *explain_setgid(gid_t gid);
11 const char *explain_errno_setgid(int errnum, gid_t gid);
12 void explain_message_setgid(char *message, int message_size, gid_t
13 gid);
14 void explain_message_errno_setgid(char *message, int message_size, int
15 errnum, gid_t gid);
16
18 These functions may be used to obtain explanations for errors returned
19 by the setgid(2) system call.
20 explain_setgid
22 const char *explain_setgid(gid_t gid);
23 The explain_setgid function is used to obtain an explanation of an
25 error returned by the setgid(2) system call. The least the message will
26 contain is the value of strerror(errno), but usually it will do much
27 better, 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 gid The original gid, exactly as passed to the setgid(2) system
33 call.
34 Returns:
36 The message explaining the error. This message buffer is shared
37 by all libexplain functions which do not supply a buffer in
38 their argument list. This will be overwritten by the next call
39 to any libexplain function which shares this buffer, including
40 other threads.
41 Note: This function is not thread safe, because it shares a return buf‐
43 fer across all threads, and many other functions in this library.
44 Example: This function is intended to be used in a fashion similar to
46 the following example:
47 if (setgid(gid) < 0)
48 {
49 fprintf(stderr, "%s\n", explain_setgid(gid));
50 exit(EXIT_FAILURE);
51 }
52 The above code example is available pre-packaged as the explain_set‐
54 gid_or_die(3) function.
55 explain_errno_setgid
57 const char *explain_errno_setgid(int errnum, gid_t gid);
58 The explain_errno_setgid function is used to obtain an explanation of
60 an error returned by the setgid(2) system call. The least the message
61 will contain is the value of strerror(errno), but usually it will do
62 much better, and indicate the underlying cause in more detail.
63 errnum The error value to be decoded, usually obtained from the errno
65 global variable just before this function is called. This is
66 necessary if you need to call any code between the system call
67 to be explained and this function, because many libc functions
68 will alter the value of errno.
69 gid The original gid, exactly as passed to the setgid(2) system
71 call.
72 Returns:
74 The message explaining the error. This message buffer is shared
75 by all libexplain functions which do not supply a buffer in
76 their argument list. This will be overwritten by the next call
77 to any libexplain function which shares this buffer, including
78 other threads.
79 Note: This function is not thread safe, because it shares a return buf‐
81 fer across all threads, and many other functions in this library.
82 Example: This function is intended to be used in a fashion similar to
84 the following example:
85 if (setgid(gid) < 0)
86 {
87 int err = errno;
88 fprintf(stderr, "%s\n", explain_errno_setgid(err, gid));
89 exit(EXIT_FAILURE);
90 }
91 The above code example is available pre-packaged as the explain_set‐
93 gid_or_die(3) function.
94 explain_message_setgid
96 void explain_message_setgid(char *message, int message_size, gid_t
97 gid);
98 The explain_message_setgid function is used to obtain an explanation of
100 an error returned by the setgid(2) system call. The least the message
101 will contain is the value of strerror(errno), but usually it will do
102 much better, and indicate the underlying cause in more detail.
103 The errno global variable will be used to obtain the error value to be
105 decoded.
106 message The location in which to store the returned message. If a suit‐
108 able message return buffer is supplied, this function is thread
109 safe.
110 message_size
112 The size in bytes of the location in which to store the
113 returned message.
114 gid The original gid, exactly as passed to the setgid(2) system
116 call.
117 Example: This function is intended to be used in a fashion similar to
119 the following example:
120 if (setgid(gid) < 0)
121 {
122 char message[3000];
123 explain_message_setgid(message, sizeof(message), gid);
124 fprintf(stderr, "%s\n", message);
125 exit(EXIT_FAILURE);
126 }
127 The above code example is available pre-packaged as the explain_set‐
129 gid_or_die(3) function.
130 explain_message_errno_setgid
132 void explain_message_errno_setgid(char *message, int message_size, int
133 errnum, gid_t gid);
134 The explain_message_errno_setgid function is used to obtain an explana‐
136 tion of an error returned by the setgid(2) system call. The least the
137 message will contain is the value of strerror(errno), but usually it
138 will do much better, and indicate the underlying cause in more detail.
139 message The location in which to store the returned message. If a suit‐
141 able message return buffer is supplied, this function is thread
142 safe.
143 message_size
145 The size in bytes of the location in which to store the
146 returned message.
147 errnum The error value to be decoded, usually obtained from the errno
149 global variable just before this function is called. This is
150 necessary if you need to call any code between the system call
151 to be explained and this function, because many libc functions
152 will alter the value of errno.
153 gid The original gid, exactly as passed to the setgid(2) system
155 call.
156 Example: This function is intended to be used in a fashion similar to
158 the following example:
159 if (setgid(gid) < 0)
160 {
161 int err = errno;
162 char message[3000];
163 explain_message_errno_setgid(message, sizeof(message), err,
164 gid);
165 fprintf(stderr, "%s\n", message);
166 exit(EXIT_FAILURE);
167 }
168 The above code example is available pre-packaged as the explain_set‐
170 gid_or_die(3) function.
171
173 setgid(2)
174 set group identity
175 explain_setgid_or_die(3)
177 set group identity and report errors
178
180 libexplain version 1.4
181 Copyright (C) 2012 Peter Miller
182 explain_setgid(3)