1explain_execvp(3) Library Functions Manual explain_execvp(3)
2
6 explain_execvp - explain execvp(3) errors
7
9 #include <libexplain/execvp.h>
10 const char *explain_execvp(const char *pathname, char *const *argv);
11 const char *explain_errno_execvp(int errnum, const char *pathname, char
12 *const *argv);
13 void explain_message_execvp(char *message, int message_size, const char
14 *pathname, char *const *argv);
15 void explain_message_errno_execvp(char *message, int message_size, int
16 errnum, const char *pathname, char *const *argv);
17
19 These functions may be used to obtain explanations for errors returned
20 by the execvp(3) system call.
21 explain_execvp
23 const char *explain_execvp(const char *pathname, char *const *argv);
24 The explain_execvp function is used to obtain an explanation of an
26 error returned by the execvp(3) 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 This function is intended to be used in a fashion similar to the fol‐
34 lowing example:
35 if (execvp(pathname, argv) < 0)
36 {
37 fprintf(stderr, "%s\n", explain_execvp(pathname, argv));
38 exit(EXIT_FAILURE);
39 }
40 The above code example is available pre‐packaged as the
42 explain_execvp_or_die(3) function.
43 pathname
45 The original pathname, exactly as passed to the execvp(3) sys‐
46 tem call.
47 argv The original argv, exactly as passed to the execvp(3) system
49 call.
50 Returns:
52 The message explaining the error. This message buffer is
53 shared by all libexplain functions which do not supply a buffer
54 in their argument list. This will be overwritten by the next
55 call to any libexplain function which shares this buffer,
56 including other threads.
57 Note: This function is not thread safe, because it shares a return buf‐
59 fer across all threads, and many other functions in this library.
60 explain_errno_execvp
62 const char *explain_errno_execvp(int errnum, const char *pathname, char
63 *const *argv);
64 The explain_errno_execvp function is used to obtain an explanation of
66 an error returned by the execvp(3) system call. The least the message
67 will contain is the value of strerror(errnum), but usually it will do
68 much better, and indicate the underlying cause in more detail.
69 This function is intended to be used in a fashion similar to the fol‐
71 lowing example:
72 if (execvp(pathname, argv) < 0)
73 {
74 int err = errno;
75 fprintf(stderr, "%s\n", explain_errno_execvp(err,
76 pathname, argv));
77 exit(EXIT_FAILURE);
78 }
79 The above code example is available pre‐packaged as the
81 explain_execvp_or_die(3) function.
82 errnum The error value to be decoded, usually obtained from the errno
84 global variable just before this function is called. This is
85 necessary if you need to call any code between the system call
86 to be explained and this function, because many libc functions
87 will alter the value of errno.
88 pathname
90 The original pathname, exactly as passed to the execvp(3) sys‐
91 tem call.
92 argv The original argv, exactly as passed to the execvp(3) system
94 call.
95 Returns:
97 The message explaining the error. This message buffer is
98 shared by all libexplain functions which do not supply a buffer
99 in their argument list. This will be overwritten by the next
100 call to any libexplain function which shares this buffer,
101 including other threads.
102 Note: This function is not thread safe, because it shares a return buf‐
104 fer across all threads, and many other functions in this library.
105 explain_message_execvp
107 void explain_message_execvp(char *message, int message_size, const char
108 *pathname, char *const *argv);
109 The explain_message_execvp function may be used to obtain an explana‐
111 tion of an error returned by the execvp(3) system call. The least the
112 message will contain is the value of strerror(errno), but usually it
113 will do much better, and indicate the underlying cause in more detail.
114 The errno global variable will be used to obtain the error value to be
116 decoded.
117 This function is intended to be used in a fashion similar to the fol‐
119 lowing example:
120 if (execvp(pathname, argv) < 0)
121 {
122 char message[3000];
123 explain_message_execvp(message, sizeof(message), pathname, argv);
124 fprintf(stderr, "%s\n", message);
125 exit(EXIT_FAILURE);
126 }
127 The above code example is available pre‐packaged as the
129 explain_execvp_or_die(3) function.
130 message The location in which to store the returned message. If a
132 suitable message return buffer is supplied, this function is
133 thread safe.
134 message_size
136 The size in bytes of the location in which to store the
137 returned message.
138 pathname
140 The original pathname, exactly as passed to the execvp(3) sys‐
141 tem call.
142 argv The original argv, exactly as passed to the execvp(3) system
144 call.
145 explain_message_errno_execvp
147 void explain_message_errno_execvp(char *message, int message_size, int
148 errnum, const char *pathname, char *const *argv);
149 The explain_message_errno_execvp function may be used to obtain an
151 explanation of an error returned by the execvp(3) system call. The
152 least the message will contain is the value of strerror(errnum), but
153 usually it will do much better, and indicate the underlying cause in
154 more detail.
155 This function is intended to be used in a fashion similar to the fol‐
157 lowing example:
158 if (execvp(pathname, argv) < 0)
159 {
160 int err = errno;
161 char message[3000];
162 explain_message_errno_execvp(message, sizeof(message),
163 err, pathname, argv);
164 fprintf(stderr, "%s\n", message);
165 exit(EXIT_FAILURE);
166 }
167 The above code example is available pre‐packaged as the
169 explain_execvp_or_die(3) function.
170 message The location in which to store the returned message. If a
172 suitable message return buffer is supplied, this function is
173 thread safe.
174 message_size
176 The size in bytes of the location in which to store the
177 returned message.
178 errnum The error value to be decoded, usually obtained from the errno
180 global variable just before this function is called. This is
181 necessary if you need to call any code between the system call
182 to be explained and this function, because many libc functions
183 will alter the value of errno.
184 pathname
186 The original pathname, exactly as passed to the execvp(3) sys‐
187 tem call.
188 argv The original argv, exactly as passed to the execvp(3) system
190 call.
191
193 execvp(3)
194 execute a file
195 explain_execvp_or_die(3)
197 execute a file and report errors
198
200 libexplain version 1.4
201 Copyright (C) 2009 Peter Miller
202 explain_execvp(3)