Provided by: explain_0.52.D002-1_amd64 bug

NAME

       explain_getpgrp - explain getpgrp(2) errors

SYNOPSIS

       #include <libexplain/getpgrp.h>
       const char *explain_getpgrp(pid_t pid);
       const char *explain_errno_getpgrp(int errnum, pid_t pid);
       void explain_message_getpgrp(char *message, int message_size, pid_t pid);
       void explain_message_errno_getpgrp(char *message, int message_size, int errnum, pid_t
       pid);

DESCRIPTION

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

       Note:  the  getpgrp(2)  function  has  two  implementations.   The  POSIX.1 version has no
       arguments, while the BSD version has one argument.  For simplicity of implementation,  the
       argument list seen here includes the pid argument.

       The  POSIX.1 getpgid() semantics can be obtained by calling getpgrp(0) on BSD systems, and
       this is the API for libexplain, even on systems that do not use the BSD API.

   explain_getpgrp
       const char *explain_getpgrp(pid_t pid);

       The explain_getpgrp function is used to obtain an explanation of an error returned by  the
       getpgrp(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.

       pid     The original pid, exactly as passed to the getpgrp(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.

       Example:  This  function  is  intended  to  be  used in a fashion similar to the following
       example:
              pid_t result = getpgrp(pid);
              if (result < 0)
              {
                  fprintf(stderr, "%s\n", explain_getpgrp(pid));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre-packaged  as  the  explain_getpgrp_or_die(3)
       function.

   explain_errno_getpgrp
       const char *explain_errno_getpgrp(int errnum, pid_t pid);

       The  explain_errno_getpgrp  function is used to obtain an explanation of an error returned
       by the getpgrp(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.

       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 getpgrp(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.

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

       The  above  code  example  is  available  pre-packaged  as  the  explain_getpgrp_or_die(3)
       function.

   explain_message_getpgrp
       void explain_message_getpgrp(char *message, int message_size, pid_t pid);

       The explain_message_getpgrp function is used to obtain an explanation of an error returned
       by the getpgrp(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.

       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 getpgrp(2) system call.

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

       The  above  code  example  is  available  pre-packaged  as  the  explain_getpgrp_or_die(3)
       function.

   explain_message_errno_getpgrp
       void explain_message_errno_getpgrp(char *message, int message_size, int errnum, pid_t
       pid);

       The explain_message_errno_getpgrp function is used to obtain an explanation  of  an  error
       returned by the getpgrp(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.

       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 getpgrp(2) system call.

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

       The  above  code  example  is  available  pre-packaged  as  the  explain_getpgrp_or_die(3)
       function.

SEE ALSO

       getpgrp(2)
               get process group

       explain_getpgrp_or_die(3)
               get process group and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2011 Peter Miller

                                                                               explain_getpgrp(3)