1explain_putenv(3) Library Functions Manual explain_putenv(3)
2
6 explain_putenv - explain putenv(3) errors
7
9 #include <libexplain/putenv.h>
10 const char *explain_putenv(char *string);
11 const char *explain_errno_putenv(int errnum, char *string);
12 void explain_message_putenv(char *message, int message_size, char
13 *string);
14 void explain_message_errno_putenv(char *message, int message_size, int
15 errnum, char *string);
16
18 These functions may be used to obtain explanations for errors returned
19 by the putenv(3) system call.
20 explain_putenv
22 const char *explain_putenv(char *string);
23 The explain_putenv function is used to obtain an explanation of an
25 error returned by the putenv(3) 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 string The original string, exactly as passed to the putenv(3) 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 (putenv(string) < 0)
48 {
49 fprintf(stderr, "%s\n", explain_putenv(string));
50 exit(EXIT_FAILURE);
51 }
52 The above code example is available pre‐packaged as the
54 explain_putenv_or_die(3) function.
55 explain_errno_putenv
57 const char *explain_errno_putenv(int errnum, char *string);
58 The explain_errno_putenv function is used to obtain an explanation of
60 an error returned by the putenv(3) 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 string The original string, exactly as passed to the putenv(3) 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 (putenv(string) < 0)
86 {
87 int err = errno;
88 fprintf(stderr, "%s\n", explain_errno_putenv(err, string));
89 exit(EXIT_FAILURE);
90 }
91 The above code example is available pre‐packaged as the
93 explain_putenv_or_die(3) function.
94 explain_message_putenv
96 void explain_message_putenv(char *message, int message_size, char
97 *string);
98 The explain_message_putenv function is used to obtain an explanation of
100 an error returned by the putenv(3) 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 string The original string, exactly as passed to the putenv(3) system
116 call.
117 Example: This function is intended to be used in a fashion similar to
119 the following example:
120 if (putenv(string) < 0)
121 {
122 char message[3000];
123 explain_message_putenv(message, sizeof(message), string);
124 fprintf(stderr, "%s\n", message);
125 exit(EXIT_FAILURE);
126 }
127 The above code example is available pre‐packaged as the
129 explain_putenv_or_die(3) function.
130 explain_message_errno_putenv
132 void explain_message_errno_putenv(char *message, int message_size, int
133 errnum, char *string);
134 The explain_message_errno_putenv function is used to obtain an explana‐
136 tion of an error returned by the putenv(3) 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 string The original string, exactly as passed to the putenv(3) system
155 call.
156 Example: This function is intended to be used in a fashion similar to
158 the following example:
159 if (putenv(string) < 0)
160 {
161 int err = errno;
162 char message[3000];
163 explain_message_errno_putenv(message, sizeof(message), err,
164 string);
165 fprintf(stderr, "%s\n", message);
166 exit(EXIT_FAILURE);
167 }
168 The above code example is available pre‐packaged as the
170 explain_putenv_or_die(3) function.
171
173 putenv(3)
174 change or add an environment variable
175 explain_putenv_or_die(3)
177 change or add an environment variable and report errors
178
180 libexplain version 1.4
181 Copyright (C) 2010 Peter Miller
182 explain_putenv(3)