APR::Status(3) Perl Interface to the APR_STATUS_IS_* macros

Synopsis

  use APR::Status ();
  eval { $obj->mp_method() };
  if ($@ && $ref $@ eq 'APR::Error' && APR::Status::is_EAGAIN($@)) {
      # APR_STATUS_IS_EAGAIN(s) of apr_errno.h is satisfied
  }

Description

An interface to apr_errno.h composite error codes.

As discussed in the "APR::Error" manpage, it is possible to handle APR/Apache/mod_perl exceptions in the following way: 

  eval { $obj->mp_method() };
  if ($@ && $ref $@ eq 'APR::Error' && $@ == $some_code)
      warn "handled exception: $@";
  }

However, in cases where $some_code is an APR::Const constant, there may be more than one condition satisfying the intent of this exception. For this purpose the APR C library provides in apr_errno.h a series of macros, "APR_STATUS_IS_*", which are the recommended way to check for such conditions. For example, the "APR_STATUS_IS_EAGAIN" macro is defined as 

  #define APR_STATUS_IS_EAGAIN(s)         ((s) == APR_EAGAIN \
                  || (s) == APR_OS_START_SYSERR + ERROR_NO_DATA \
                  || (s) == APR_OS_START_SYSERR + SOCEWOULDBLOCK \
                  || (s) == APR_OS_START_SYSERR + ERROR_LOCK_VIOLATION)

The purpose of "APR::Status" is to provide functions corresponding to these macros.

Functions

is_EACCES

Check if the error is matching "EACCES" and its variants (corresponds to the "APR_STATUS_IS_EACCES" macro). 

  $status = APR::Status::is_EACCES($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

An example of using "is_EACCES" is when reading the contents of a file where access may be forbidden: 

  eval { $obj->slurp_filename(0) };
  if ($@) {
      return Apache2::Const::FORBIDDEN
          if ref $@ eq 'APR::Error' && APR::Status::is_EACCES($@);
      die $@;
   }

Due to possible variants in conditions matching "EACCES", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::EACCES" directly.

is_EAGAIN

Check if the error is matching "EAGAIN" and its variants (corresponds to the "APR_STATUS_IS_EAGAIN" macro). 

  $status = APR::Status::is_EAGAIN($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

For example, here is how you may want to handle socket read exceptions and do retries: 

  use APR::Status ();
  # ....
  my $tries = 0;
  my $buffer;
  RETRY: my $rlen = eval { $socket->recv($buffer, SIZE) };
  if ($@ && ref($@) && APR::Status::is_EAGAIN($@)) {
      if ($tries++ < 3) {
          goto RETRY;
      }
      else {
          # do something else
      }
  }
  else {
      die "eval block has failed: $@";
  }

Notice that just checking against "APR::Const::EAGAIN" may work on some Unices, but then it will certainly break on win32. Thefore make sure to use this macro and not "APR::Const::EAGAIN" unless you know what you are doing.

is_ENOENT

Check if the error is matching "ENOENT" and its variants (corresponds to the "APR_STATUS_IS_ENOENT" macro). 

  $status = APR::Status::is_ENOENT($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

An example of using "is_ENOENT" is when reading the contents of a file which may not exist: 

  eval { $obj->slurp_filename(0) };
  if ($@) {
      return Apache2::Const::NOT_FOUND
          if ref $@ eq 'APR::Error' && APR::Status::is_ENOENT($@);
      die $@;
  }

Due to possible variants in conditions matching "ENOENT", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::ENOENT" directly.

is_EOF

Check if the error is matching "EOF" and its variants (corresponds to the "APR_STATUS_IS_EOF" macro). 

  $status = APR::Status::is_EOF($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

Due to possible variants in conditions matching "EOF", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::EOF" directly.

is_ECONNABORTED

Check if the error is matching "ECONNABORTED" and its variants (corresponds to the "APR_STATUS_IS_ECONNABORTED" macro). 

  $status = APR::Status::is_ECONNABORTED($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

Due to possible variants in conditions matching "ECONNABORTED", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::ECONNABORTED" directly.

is_ECONNRESET

Check if the error is matching "ECONNRESET" and its variants (corresponds to the "APR_STATUS_IS_ECONNRESET" macro). 

  $status = APR::Status::is_ECONNRESET($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

Due to possible variants in conditions matching "ECONNRESET", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::ECONNRESET" directly.

is_TIMEUP

Check if the error is matching "TIMEUP" and its variants (corresponds to the "APR_STATUS_IS_TIMEUP" macro). 

  $status = APR::Status::is_TIMEUP($error_code);
arg1: $error_code (integer or "APR::Error object" )
The error code or to check, normally $@ blessed into "APR::Error object".
ret: $status ( boolean )
since: 2.0.00

Due to possible variants in conditions matching "TIMEUP", the use of this function is recommended for checking error codes against this value, rather than just using "APR::Const::TIMEUP" directly.

See Also

mod_perl 2.0 documentation.

Copyright

mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.

Authors

The mod_perl development team and numerous contributors.

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