1explain_setreuid(3) Library Functions Manual explain_setreuid(3)
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6 explain_setreuid - explain setreuid(2) errors
7
9 #include <libexplain/setreuid.h>
10 const char *explain_setreuid(uid_t ruid, uid_t euid);
11 const char *explain_errno_setreuid(int errnum, uid_t ruid, uid_t euid);
12 void explain_message_setreuid(char *message, int message_size, uid_t
13 ruid, uid_t euid);
14 void explain_message_errno_setreuid(char *message, int message_size,
15 int errnum, uid_t ruid, uid_t euid);
16
18 These functions may be used to obtain explanations for errors returned
19 by the setreuid(2) system call.
20 explain_setreuid
22 const char *explain_setreuid(uid_t ruid, uid_t euid);
23 The explain_setreuid function is used to obtain an explanation of an
25 error returned by the setreuid(2) system call. The least the message
26 will contain is the value of strerror(errno), but usually it will do
27 much 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 ruid The original ruid, exactly as passed to the setreuid(2) system
33 call.
34 euid The original euid, exactly as passed to the setreuid(2) system
36 call.
37 Returns:
39 The message explaining the error. This message buffer is shared
40 by all libexplain functions which do not supply a buffer in
41 their argument list. This will be overwritten by the next call
42 to any libexplain function which shares this buffer, including
43 other threads.
44 Note: This function is not thread safe, because it shares a return buf‐
46 fer across all threads, and many other functions in this library.
47 Example: This function is intended to be used in a fashion similar to
49 the following example:
50 if (setreuid(ruid, euid) < 0)
51 {
52 fprintf(stderr, "%s\n", explain_setreuid(ruid, euid));
53 exit(EXIT_FAILURE);
54 }
55 The above code example is available pre-packaged as the
57 explain_setreuid_or_die(3) function.
58 explain_errno_setreuid
60 const char *explain_errno_setreuid(int errnum, uid_t ruid, uid_t euid);
61 The explain_errno_setreuid function is used to obtain an explanation of
63 an error returned by the setreuid(2) system call. The least the mes‐
64 sage will contain is the value of strerror(errno), but usually it will
65 do much better, and indicate the underlying cause in more detail.
66 errnum The error value to be decoded, usually obtained from the errno
68 global variable just before this function is called. This is
69 necessary if you need to call any code between the system call
70 to be explained and this function, because many libc functions
71 will alter the value of errno.
72 ruid The original ruid, exactly as passed to the setreuid(2) system
74 call.
75 euid The original euid, exactly as passed to the setreuid(2) system
77 call.
78 Returns:
80 The message explaining the error. This message buffer is shared
81 by all libexplain functions which do not supply a buffer in
82 their argument list. This will be overwritten by the next call
83 to any libexplain function which shares this buffer, including
84 other threads.
85 Note: This function is not thread safe, because it shares a return buf‐
87 fer across all threads, and many other functions in this library.
88 Example: This function is intended to be used in a fashion similar to
90 the following example:
91 if (setreuid(ruid, euid) < 0)
92 {
93 int err = errno;
94 fprintf(stderr, "%s\n", explain_errno_setreuid(err, ruid,
95 euid));
96 exit(EXIT_FAILURE);
97 }
98 The above code example is available pre-packaged as the
100 explain_setreuid_or_die(3) function.
101 explain_message_setreuid
103 void explain_message_setreuid(char *message, int message_size, uid_t
104 ruid, uid_t euid);
105 The explain_message_setreuid function is used to obtain an explanation
107 of an error returned by the setreuid(2) system call. The least the
108 message will contain is the value of strerror(errno), but usually it
109 will do much better, and indicate the underlying cause in more detail.
110 The errno global variable will be used to obtain the error value to be
112 decoded.
113 message The location in which to store the returned message. If a suit‐
115 able message return buffer is supplied, this function is thread
116 safe.
117 message_size
119 The size in bytes of the location in which to store the
120 returned message.
121 ruid The original ruid, exactly as passed to the setreuid(2) system
123 call.
124 euid The original euid, exactly as passed to the setreuid(2) system
126 call.
127 Example: This function is intended to be used in a fashion similar to
129 the following example:
130 if (setreuid(ruid, euid) < 0)
131 {
132 char message[3000];
133 explain_message_setreuid(message, sizeof(message), ruid,
134 euid);
135 fprintf(stderr, "%s\n", message);
136 exit(EXIT_FAILURE);
137 }
138 The above code example is available pre-packaged as the
140 explain_setreuid_or_die(3) function.
141 explain_message_errno_setreuid
143 void explain_message_errno_setreuid(char *message, int message_size,
144 int errnum, uid_t ruid, uid_t euid);
145 The explain_message_errno_setreuid function is used to obtain an expla‐
147 nation of an error returned by the setreuid(2) system call. The least
148 the message will contain is the value of strerror(errno), but usually
149 it will do much better, and indicate the underlying cause in more
150 detail.
151 message The location in which to store the returned message. If a suit‐
153 able message return buffer is supplied, this function is thread
154 safe.
155 message_size
157 The size in bytes of the location in which to store the
158 returned message.
159 errnum The error value to be decoded, usually obtained from the errno
161 global variable just before this function is called. This is
162 necessary if you need to call any code between the system call
163 to be explained and this function, because many libc functions
164 will alter the value of errno.
165 ruid The original ruid, exactly as passed to the setreuid(2) system
167 call.
168 euid The original euid, exactly as passed to the setreuid(2) system
170 call.
171 Example: This function is intended to be used in a fashion similar to
173 the following example:
174 if (setreuid(ruid, euid) < 0)
175 {
176 int err = errno;
177 char message[3000];
178 explain_message_errno_setreuid(message, sizeof(message),
179 err, ruid, euid);
180 fprintf(stderr, "%s\n", message);
181 exit(EXIT_FAILURE);
182 }
183 The above code example is available pre-packaged as the
185 explain_setreuid_or_die(3) function.
186
188 setreuid(2)
189 set the real and effective user ID
190 explain_setreuid_or_die(3)
192 set the real and effective user ID and report errors
193
195 libexplain version 1.4
196 Copyright (C) 2012 Peter Miller
197 explain_setreuid(3)