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NAME

       explain_fork - explain fork(2) errors

SYNOPSIS

       #include <libexplain/fork.h>
       const char *explain_fork(void);
       const char *explain_errno_fork(int errnum);
       void explain_message_fork(char *message, int message_size);
       void  explain_message_errno_fork(char  *message,  int message_size, int
       errnum);

DESCRIPTION

       These functions may be used to obtain explanations for errors  returned
       by the fork(2) system call.

   explain_fork
       const char *explain_fork(void);

       The  explain_fork function is used to obtain an explanation of an error
       returned by the fork(2)  system  call.   The  least  the  message  will
       contain  is  the  value of strerror(errno), but usually it will do much
       better, and indicate the underlying cause in more detail.

       The errno global variable will be used to obtain the error value to  be
       decoded.

       This  function  is  intended  to  be  used  in a fashion similar to the
       following example:
              if (fork() < 0)
              {
                  fprintf(stderr, "%s\n", explain_fork());
                  exit(EXIT_FAILURE);
              }

       Returns:
               The message explaining  the  error.   This  message  buffer  is
               shared by all libexplain functions which do not supply a buffer
               in their argument list.  This will be overwritten by  the  next
               call  to  any  libexplain  function  which  shares this buffer,
               including other threads.

       Note: This function is not thread safe,  because  it  shares  a  return
       buffer across all threads, and many other functions in this library.

   explain_errno_fork
       const char *explain_errno_fork(int errnum);

       The  explain_errno_fork function is used to obtain an explanation of an
       error returned by the fork(2) system call.  The least the message  will
       contain  is  the value of strerror(errnum), but usually it will do much
       better, and indicate the underlying cause in more detail.

       This function is intended to be  used  in  a  fashion  similar  to  the
       following example:
              if (fork() < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_fork(err, ));
                  exit(EXIT_FAILURE);
              }

       errnum  The  error value to be decoded, usually obtained from the errno
               global variable just before this function is called.   This  is
               necessary  if you need to call any code between the system call
               to be explained and this function, because many libc  functions
               will alter the value of errno.

       Returns:
               The  message  explaining  the  error.   This  message buffer is
               shared by all libexplain functions which do not supply a buffer
               in  their  argument list.  This will be overwritten by the next
               call to any  libexplain  function  which  shares  this  buffer,
               including other threads.

       Note:  This  function  is  not  thread safe, because it shares a return
       buffer across all threads, and many other functions in this library.

   explain_message_fork
       void explain_message_fork(char *message, int message_size);

       The explain_message_fork function may be used to  obtain an explanation
       of an error returned by the fork(2) system call.  The least the message
       will contain is the value of strerror(errno), but usually  it  will  do
       much better, and indicate the underlying cause in more detail.

       The  errno global variable will be used to obtain the error value to be
       decoded.

       This function is intended to be  used  in  a  fashion  similar  to  the
       following example:
              if (fork() < 0)
              {
                  char message[3000];
                  explain_message_fork(message, sizeof(message), );
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       message The  location  in  which  to  store the returned message.  If a
               suitable message return buffer is supplied,  this  function  is
               thread safe.

       message_size
               The  size  in  bytes  of  the  location  in  which to store the
               returned message.

   explain_message_errno_fork
       void explain_message_errno_fork(char *message,  int  message_size,  int
       errnum);

       The  explain_message_errno_fork  function  may  be  used  to  obtain an
       explanation of an error returned by the fork(2) system call.  The least
       the  message will contain is the value of strerror(errnum), but usually
       it will do much better, and  indicate  the  underlying  cause  in  more
       detail.

       This  function  is  intended  to  be  used  in a fashion similar to the
       following example:
              if (fork() < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_fork(message, sizeof(message), err, );
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       message The location in which to store  the  returned  message.   If  a
               suitable  message  return  buffer is supplied, this function is
               thread safe.

       message_size
               The size in bytes  of  the  location  in  which  to  store  the
               returned message.

       errnum  The  error value to be decoded, usually obtained from the errno
               global variable just before this function is called.   This  is
               necessary  if you need to call any code between the system call
               to be explained and this function, because many libc  functions
               will alter the value of errno.

SEE ALSO

       fork(2) create a child process

       explain_fork_or_die(3)
               create a child process and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                               explain_fork(3)