1explain_nice(3) Library Functions Manual explain_nice(3)
2
6 explain_nice - explain nice(2) errors
7
9 #include <libexplain/nice.h>
10 const char *explain_nice(int inc);
11 const char *explain_errno_nice(int errnum, int inc);
12 void explain_message_nice(char *message, int message_size, int inc);
13 void explain_message_errno_nice(char *message, int message_size, int
14 errnum, int inc);
15
17 These functions may be used to obtain explanations for errors returned
18 by the nice(2) system call.
19 explain_nice
21 const char *explain_nice(int inc);
22 The explain_nice function is used to obtain an explanation of an error
24 returned by the nice(2) system call. The least the message will contain
25 is the value of strerror(errno), but usually it will do much better,
26 and indicate the underlying cause in more detail.
27 The errno global variable will be used to obtain the error value to be
29 decoded.
30 inc The original inc, exactly as passed to the nice(2) system call.
32 Returns:
34 The message explaining the error. This message buffer is shared
35 by all libexplain functions which do not supply a buffer in
36 their argument list. This will be overwritten by the next call
37 to any libexplain function which shares this buffer, including
38 other threads.
39 Note: This function is not thread safe, because it shares a return buf‐
41 fer across all threads, and many other functions in this library.
42 Example: This function is intended to be used in a fashion similar to
44 the following example:
45 int result = nice(inc);
46 if (result < 0)
47 {
48 fprintf(stderr, "%s\n", explain_nice(inc));
49 exit(EXIT_FAILURE);
50 }
51 The above code example is available pre‐packaged as the
53 explain_nice_or_die(3) function.
54 explain_errno_nice
56 const char *explain_errno_nice(int errnum, int inc);
57 The explain_errno_nice function is used to obtain an explanation of an
59 error returned by the nice(2) system call. The least the message will
60 contain is the value of strerror(errno), but usually it will do much
61 better, and indicate the underlying cause in more detail.
62 errnum The error value to be decoded, usually obtained from the errno
64 global variable just before this function is called. This is
65 necessary if you need to call any code between the system call
66 to be explained and this function, because many libc functions
67 will alter the value of errno.
68 inc The original inc, exactly as passed to the nice(2) system call.
70 Returns:
72 The message explaining the error. This message buffer is shared
73 by all libexplain functions which do not supply a buffer in
74 their argument list. This will be overwritten by the next call
75 to any libexplain function which shares this buffer, including
76 other threads.
77 Note: This function is not thread safe, because it shares a return buf‐
79 fer across all threads, and many other functions in this library.
80 Example: This function is intended to be used in a fashion similar to
82 the following example:
83 int result = nice(inc);
84 if (result < 0)
85 {
86 int err = errno;
87 fprintf(stderr, "%s\n", explain_errno_nice(err, inc));
88 exit(EXIT_FAILURE);
89 }
90 The above code example is available pre‐packaged as the
92 explain_nice_or_die(3) function.
93 explain_message_nice
95 void explain_message_nice(char *message, int message_size, int inc);
96 The explain_message_nice function is used to obtain an explanation of
98 an error returned by the nice(2) system call. The least the message
99 will contain is the value of strerror(errno), but usually it will do
100 much better, and indicate the underlying cause in more detail.
101 The errno global variable will be used to obtain the error value to be
103 decoded.
104 message The location in which to store the returned message. If a suit‐
106 able message return buffer is supplied, this function is thread
107 safe.
108 message_size
110 The size in bytes of the location in which to store the
111 returned message.
112 inc The original inc, exactly as passed to the nice(2) system call.
114 Example: This function is intended to be used in a fashion similar to
116 the following example:
117 int result = nice(inc);
118 if (result < 0)
119 {
120 char message[3000];
121 explain_message_nice(message, sizeof(message), inc);
122 fprintf(stderr, "%s\n", message);
123 exit(EXIT_FAILURE);
124 }
125 The above code example is available pre‐packaged as the
127 explain_nice_or_die(3) function.
128 explain_message_errno_nice
130 void explain_message_errno_nice(char *message, int message_size, int
131 errnum, int inc);
132 The explain_message_errno_nice function is used to obtain an explana‐
134 tion of an error returned by the nice(2) system call. The least the
135 message will contain is the value of strerror(errno), but usually it
136 will do much better, and indicate the underlying cause in more detail.
137 message The location in which to store the returned message. If a suit‐
139 able message return buffer is supplied, this function is thread
140 safe.
141 message_size
143 The size in bytes of the location in which to store the
144 returned message.
145 errnum The error value to be decoded, usually obtained from the errno
147 global variable just before this function is called. This is
148 necessary if you need to call any code between the system call
149 to be explained and this function, because many libc functions
150 will alter the value of errno.
151 inc The original inc, exactly as passed to the nice(2) system call.
153 Example: This function is intended to be used in a fashion similar to
155 the following example:
156 int result = nice(inc);
157 if (result < 0)
158 {
159 int err = errno;
160 char message[3000];
161 explain_message_errno_nice(message, sizeof(message), err,
162 inc);
163 fprintf(stderr, "%s\n", message);
164 exit(EXIT_FAILURE);
165 }
166 The above code example is available pre‐packaged as the
168 explain_nice_or_die(3) function.
169
171 nice(2) change process priority
172 explain_nice_or_die(3)
174 change process priority and report errors
175
177 libexplain version 0.40
178 Copyright (C) 2009 Peter Miller
179 explain_nice(3)