package FFI::Platypus::Memory; use strict; use warnings; use 5.008004; use FFI::Platypus; use Exporter qw( import ); # ABSTRACT: Memory functions for FFI our $VERSION = '2.08'; # VERSION our @EXPORT = qw( malloc free calloc realloc memcpy memset strdup strndup strcpy ); my $ffi = FFI::Platypus->new( api => 2 ); $ffi->lib(undef); $ffi->bundle; sub _ffi { $ffi } $ffi->attach(malloc => ['size_t'] => 'opaque' => '$'); $ffi->attach(free => ['opaque'] => 'void' => '$'); $ffi->attach(calloc => ['size_t', 'size_t'] => 'opaque' => '$$'); $ffi->attach(realloc => ['opaque', 'size_t'] => 'opaque' => '$$'); $ffi->attach(memcpy => ['opaque', 'opaque', 'size_t'] => 'opaque' => '$$$'); $ffi->attach(memset => ['opaque', 'int', 'size_t'] => 'opaque' => '$$$'); $ffi->attach(strcpy => ['opaque', 'string'] => 'opaque' => '$$'); my $_strdup_impl = 'not-loaded'; sub _strdup_impl { $_strdup_impl } eval { die "do not use c impl" if ($ENV{FFI_PLATYPUS_MEMORY_STRDUP_IMPL}||'libc') eq 'ffi'; $ffi->attach(strdup => ['string'] => 'opaque' => '$'); $_strdup_impl = 'libc'; }; if($@ && $^O eq 'MSWin32') { eval { die "do not use c impl" if ($ENV{FFI_PLATYPUS_MEMORY_STRDUP_IMPL}||'libc') eq 'ffi'; $ffi->attach([ _strdup => 'strdup' ] => ['string'] => 'opaque' => '$'); $_strdup_impl = 'libc'; }; } if($@) { warn "using bundled strdup"; $_strdup_impl = 'ffi'; $ffi->attach([ ffi_platypus_memory__strdup => 'strdup' ] => ['string'] => 'opaque' => '$'); } my $_strndup_impl = 'not-loaded'; sub _strndup_impl { $_strndup_impl } eval { die "do not use c impl" if ($ENV{FFI_PLATYPUS_MEMORY_STRDUP_IMPL}||'libc') eq 'ffi'; $ffi->attach(strndup => ['string','size_t'] => 'opaque' => '$$'); $_strndup_impl = 'libc'; }; if($@) { $_strndup_impl = 'ffi'; $ffi->attach([ ffi_platypus_memory__strndup => 'strndup' ] => ['string','size_t'] => 'opaque' => '$$'); } # used internally by FFI::Platypus::Type::WideString, may go away. eval { $ffi->attach( [ wcslen => '_wcslen' ] => [ 'opaque' ] => 'size_t' => '$' ) }; eval { $ffi->attach( [ wcsnlen => '_wcsnlen' ] => [ 'string', 'size_t' ] => 'size_t' => '$$' ) }; 1; __END__ =pod =encoding UTF-8 =head1 NAME FFI::Platypus::Memory - Memory functions for FFI =head1 VERSION version 2.08 =head1 SYNOPSIS use FFI::Platypus::Memory; # allocate 64 bytes of memory using the # libc malloc function. my $pointer = malloc 64; # use that memory wisely ... # free the memory when you are done. free $pointer; =head1 DESCRIPTION This module provides an interface to common memory functions provided by the standard C library. They may be useful when constructing interfaces to C libraries with FFI. It works mostly with the C<opaque> type and it is worth reviewing the section on opaque pointers in L<FFI::Platypus::Type>. Allocating memory and forgetting to free it is a common source of memory leaks in C and when using this module. Very recent Perls have a C<defer> keyword that lets you automatically call functions like C<free> when a block ends. This can be especially handy when you have multiple code paths or possible exceptions to keep track of. use feature 'defer'; use FFI::Platypus::Memory qw( malloc free ); sub run { my $ptr = malloc 66; defer { free $ptr }; my $data = do_something($ptr); # do not need to remember to place free $ptr here, as it will # run through defer. return $data; } If you are not lucky enough to have the C<defer> feature in your version of Perl you may be able to use L<Feature::Compat::Defer>, which will use the feature if available, and provides its own mostly compatible version if not. =head1 FUNCTIONS =head2 calloc my $pointer = calloc $count, $size; The C<calloc> function contiguously allocates enough space for I<$count> objects that are I<$size> bytes of memory each. =head2 free free $pointer; The C<free> function frees the memory allocated by C<malloc>, C<calloc>, C<realloc> or C<strdup>. It is important to only free memory that you yourself have allocated. A good way to crash your program is to try and free a pointer that some C library has returned to you. =head2 malloc my $pointer = malloc $size; The C<malloc> function allocates I<$size> bytes of memory. =head2 memcpy memcpy $dst_pointer, $src_pointer, $size; The C<memcpy> function copies I<$size> bytes from I<$src_pointer> to I<$dst_pointer>. It also returns I<$dst_pointer>. =head2 memset memset $buffer, $value, $length; The C<memset> function writes I<$length> bytes of I<$value> to the address specified by I<$buffer>. =head2 realloc my $new_pointer = realloc $old_pointer, $size; The C<realloc> function reallocates enough memory to fit I<$size> bytes. It copies the existing data and frees I<$old_pointer>. If you pass C<undef> in as I<$old_pointer>, then it behaves exactly like C<malloc>: my $pointer = realloc undef, 64; # same as malloc 64 =head2 strcpy strcpy $opaque, $string; Copies the string to the memory location pointed to by C<$opaque>. =head2 strdup my $pointer = strdup $string; The C<strdup> function allocates enough memory to contain I<$string> and then copies it to that newly allocated memory. This version of C<strdup> returns an opaque pointer type, not a string type. This may seem a little strange, but returning a string type would not be very useful in Perl. =head2 strndup my $pointer = strndup $string, $max; The same as C<strdup> above, except at most C<$max> characters will be copied in the new string. =head1 SEE ALSO =over 4 =item L<FFI::Platypus> Main Platypus documentation. =back =head1 AUTHOR Author: Graham Ollis E<lt>plicease@cpan.orgE<gt> Contributors: Bakkiaraj Murugesan (bakkiaraj) Dylan Cali (calid) pipcet Zaki Mughal (zmughal) Fitz Elliott (felliott) Vickenty Fesunov (vyf) Gregor Herrmann (gregoa) Shlomi Fish (shlomif) Damyan Ivanov Ilya Pavlov (Ilya33) Petr Písař (ppisar) Mohammad S Anwar (MANWAR) Håkon Hægland (hakonhagland, HAKONH) Meredith (merrilymeredith, MHOWARD) Diab Jerius (DJERIUS) Eric Brine (IKEGAMI) szTheory José Joaquín Atria (JJATRIA) Pete Houston (openstrike, HOUSTON) =head1 COPYRIGHT AND LICENSE This software is copyright (c) 2015-2022 by Graham Ollis. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. =cut