1explain_fork(3)            Library Functions Manual            explain_fork(3)
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NAME

6       explain_fork - explain fork(2) errors
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SYNOPSIS

9       #include <libexplain/fork.h>
10       const char *explain_fork(void);
11       const char *explain_errno_fork(int errnum);
12       void explain_message_fork(char *message, int message_size);
13       void  explain_message_errno_fork(char  *message,  int message_size, int
14       errnum);
15

DESCRIPTION

17       These functions may be used to obtain explanations for errors  returned
18       by the fork(2) system call.
19
20   explain_fork
21       const char *explain_fork(void);
22
23       The  explain_fork function is used to obtain an explanation of an error
24       returned by the fork(2) system call.  The least the message  will  con‐
25       tain  is the value of strerror(errno), but usually it will do much bet‐
26       ter, and indicate the underlying cause in more detail.
27
28       The errno global variable will be used to obtain the error value to  be
29       decoded.
30
31       This  function  is intended to be used in a fashion similar to the fol‐
32       lowing example:
33              if (fork() < 0)
34              {
35                  fprintf(stderr, "%s\n", explain_fork());
36                  exit(EXIT_FAILURE);
37              }
38
39       Returns:
40               The message explaining  the  error.   This  message  buffer  is
41               shared by all libexplain functions which do not supply a buffer
42               in their argument list.  This will be overwritten by  the  next
43               call  to  any  libexplain  function  which  shares this buffer,
44               including other threads.
45
46       Note: This function is not thread safe, because it shares a return buf‐
47       fer across all threads, and many other functions in this library.
48
49   explain_errno_fork
50       const char *explain_errno_fork(int errnum);
51
52       The  explain_errno_fork function is used to obtain an explanation of an
53       error returned by the fork(2) system call.  The least the message  will
54       contain  is  the value of strerror(errnum), but usually it will do much
55       better, and indicate the underlying cause in more detail.
56
57       This function is intended to be used in a fashion similar to  the  fol‐
58       lowing example:
59              if (fork() < 0)
60              {
61                  int err = errno;
62                  fprintf(stderr, "%s\n", explain_errno_fork(err, ));
63                  exit(EXIT_FAILURE);
64              }
65
66       errnum  The  error value to be decoded, usually obtained from the errno
67               global variable just before this function is called.   This  is
68               necessary  if you need to call any code between the system call
69               to be explained and this function, because many libc  functions
70               will alter the value of errno.
71
72       Returns:
73               The  message  explaining  the  error.   This  message buffer is
74               shared by all libexplain functions which do not supply a buffer
75               in  their  argument list.  This will be overwritten by the next
76               call to any  libexplain  function  which  shares  this  buffer,
77               including other threads.
78
79       Note: This function is not thread safe, because it shares a return buf‐
80       fer across all threads, and many other functions in this library.
81
82   explain_message_fork
83       void explain_message_fork(char *message, int message_size);
84
85       The explain_message_fork function may be used to  obtain an explanation
86       of an error returned by the fork(2) system call.  The least the message
87       will contain is the value of strerror(errno), but usually  it  will  do
88       much better, and indicate the underlying cause in more detail.
89
90       The  errno global variable will be used to obtain the error value to be
91       decoded.
92
93       This function is intended to be used in a fashion similar to  the  fol‐
94       lowing example:
95              if (fork() < 0)
96              {
97                  char message[3000];
98                  explain_message_fork(message, sizeof(message), );
99                  fprintf(stderr, "%s\n", message);
100                  exit(EXIT_FAILURE);
101              }
102
103       message The  location  in  which  to  store the returned message.  If a
104               suitable message return buffer is supplied,  this  function  is
105               thread safe.
106
107       message_size
108               The  size  in  bytes  of  the  location  in  which to store the
109               returned message.
110
111   explain_message_errno_fork
112       void explain_message_errno_fork(char *message,  int  message_size,  int
113       errnum);
114
115       The explain_message_errno_fork function may be used to obtain an expla‐
116       nation of an error returned by the fork(2) system call.  The least  the
117       message  will  contain is the value of strerror(errnum), but usually it
118       will do much better, and indicate the underlying cause in more detail.
119
120       This function is intended to be used in a fashion similar to  the  fol‐
121       lowing example:
122              if (fork() < 0)
123              {
124                  int err = errno;
125                  char message[3000];
126                  explain_message_errno_fork(message, sizeof(message), err, );
127                  fprintf(stderr, "%s\n", message);
128                  exit(EXIT_FAILURE);
129              }
130
131       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
135       message_size
136               The  size  in  bytes  of  the  location  in  which to store the
137               returned message.
138
139       errnum  The error value to be decoded, usually obtained from the  errno
140               global  variable  just before this function is called.  This is
141               necessary if you need to call any code between the system  call
142               to  be explained and this function, because many libc functions
143               will alter the value of errno.
144

SEE ALSO

146       fork(2) create a child process
147
148       explain_fork_or_die(3)
149               create a child process and report errors
150
152       libexplain version 1.4
153       Copyright (C) 2008 Peter Miller
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157                                                               explain_fork(3)
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