Provided by: libexplain-dev_1.4.D001-8_amd64 bug

NAME

       explain_waitpid - explain waitpid(2) errors

SYNOPSIS

       #include <libexplain/waitpid.h>
       const char *explain_waitpid(int pid, int *status, int options);
       const char *explain_errno_waitpid(int errnum, int pid, int *status, int options);
       void  explain_message_waitpid(char  *message,  int message_size, int pid, int *status, int
       options);
       void explain_message_errno_waitpid(char *message, int message_size, int errnum,  int  pid,
       int *status, int options);

DESCRIPTION

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

   explain_waitpid
       const char *explain_waitpid(int pid, int *status, int options);

       The explain_waitpid function is used to obtain an explanation of an error returned by  the
       waitpid(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 (waitpid(pid, status, options) < 0)
              {
                  fprintf(stderr, "%s\n", explain_waitpid(pid, status, options));
                  exit(EXIT_FAILURE);
              }

       pid     The original pid, exactly as passed to the waitpid(2) system call.

       status  The original status, exactly as passed to the waitpid(2) system call.

       options The original options, exactly as passed to the waitpid(2) system call.

       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_waitpid
       const char *explain_errno_waitpid(int errnum, int pid, int *status, int options);

       The  explain_errno_waitpid  function is used to obtain an explanation of an error returned
       by the waitpid(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 (waitpid(pid, status, options) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_waitpid(err,
                      pid, status, options));
                  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.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

       status  The original status, exactly as passed to the waitpid(2) system call.

       options The original options, exactly as passed to the waitpid(2) system call.

       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_waitpid
       void  explain_message_waitpid(char  *message,  int message_size, int pid, int *status, int
       options);

       The explain_message_waitpid function may be used to  obtain an  explanation  of  an  error
       returned  by  the waitpid(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 (waitpid(pid, status, options) < 0)
              {
                  char message[3000];
                  explain_message_waitpid(message, sizeof(message), pid, status, options);
                  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.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

       status  The original status, exactly as passed to the waitpid(2) system call.

       options The original options, exactly as passed to the waitpid(2) system call.

   explain_message_errno_waitpid
       void explain_message_errno_waitpid(char *message, int message_size, int errnum,  int  pid,
       int *status, int options);

       The  explain_message_errno_waitpid  function  may  be  used to obtain an explanation of an
       error returned by the waitpid(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 (waitpid(pid, status, options) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_waitpid(message, sizeof(message), err,
                      pid, status, options);
                  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.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

       status  The original status, exactly as passed to the waitpid(2) system call.

       options The original options, exactly as passed to the waitpid(2) system call.

SEE ALSO

       waitpid(2)
               wait for process to change state

       explain_waitpid_or_die(3)
               wait for process to change state and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

                                                                               explain_waitpid(3)