diff options
author | cvs2svn <> | 2013-06-05 11:57:40 +0400 |
---|---|---|
committer | cvs2svn <> | 2013-06-05 11:57:40 +0400 |
commit | 310a2eeef1d094d59ea9897be0ddb1b33869b885 (patch) | |
tree | 6c061f692be2a0be45d81351d4b9dfc06ec9fe9c /winsup/doc/faq-programming.xml | |
parent | c82eac05c783fa1cb82eac9216dab1ed8aa482ae (diff) |
This commit was manufactured by cvs2svn to create tag 'cygwin-cygwin-1_7_19-release
1_7_19-release'.
Sprout from cygwin-64bit-premerge-branch 2013-04-22 17:11:23 UTC cvs2svn 'This commit was manufactured by cvs2svn to create branch 'cygwin-64bit-'
Cherrypick from master 2013-06-05 07:57:39 UTC Corinna Vinschen <corinna@vinschen.de> ' * faq-programming.xml: Convert url to refer to new flat faq.html file.':
COPYING.NEWLIB
ChangeLog
config.guess
config.sub
config/ChangeLog
config/bootstrap-asan.mk
config/dfp.m4
config/picflag.m4
include/ChangeLog
include/elf/ChangeLog
include/elf/aarch64.h
include/elf/common.h
include/elf/mips.h
include/elf/msp430.h
include/opcode/ChangeLog
include/opcode/avr.h
include/opcode/mips.h
include/opcode/msp430.h
newlib/ChangeLog
newlib/MAINTAINERS
newlib/configure
newlib/configure.host
newlib/configure.in
newlib/libc/configure
newlib/libc/configure.in
newlib/libc/ctype/ctype_.c
newlib/libc/ctype/isalnum.c
newlib/libc/ctype/isalpha.c
newlib/libc/ctype/isblank.c
newlib/libc/ctype/iscntrl.c
newlib/libc/ctype/isdigit.c
newlib/libc/ctype/islower.c
newlib/libc/ctype/isprint.c
newlib/libc/ctype/ispunct.c
newlib/libc/ctype/isxdigit.c
newlib/libc/include/machine/ieeefp.h
newlib/libc/include/machine/setjmp.h
newlib/libc/include/reent.h
newlib/libc/include/sys/cdefs.h
newlib/libc/include/sys/config.h
newlib/libc/include/sys/features.h
newlib/libc/include/sys/reent.h
newlib/libc/include/sys/stat.h
newlib/libc/libc.texinfo
newlib/libc/machine/arm/Makefile.am
newlib/libc/machine/arm/Makefile.in
newlib/libc/machine/arm/memcpy-armv7a.S
newlib/libc/machine/arm/memcpy-armv7m.S
newlib/libc/machine/arm/memcpy-stub.c
newlib/libc/machine/arm/memcpy.S
newlib/libc/machine/arm/strcmp.S
newlib/libc/machine/configure
newlib/libc/machine/configure.in
newlib/libc/machine/powerpc/Makefile.am
newlib/libc/machine/powerpc/Makefile.in
newlib/libc/reent/reent.c
newlib/libc/stdio/fgetc.c
newlib/libc/stdio/fgetwc.c
newlib/libc/stdio/fgetws.c
newlib/libc/stdio/findfp.c
newlib/libc/stdio/fputc.c
newlib/libc/stdio/fputwc.c
newlib/libc/stdio/fputws.c
newlib/libc/stdio/getc.c
newlib/libc/stdio/getchar.c
newlib/libc/stdio/local.h
newlib/libc/stdio/putc.c
newlib/libc/stdio/putchar.c
newlib/libc/stdio/scanf.c
newlib/libc/stdio/setvbuf.c
newlib/libc/stdio/ungetwc.c
newlib/libc/stdio/vfscanf.c
newlib/libc/stdio/vfwscanf.c
newlib/libc/stdio/viprintf.c
newlib/libc/stdio/viscanf.c
newlib/libc/stdio/vprintf.c
newlib/libc/stdio/vscanf.c
newlib/libc/stdio/vwprintf.c
newlib/libc/stdio/vwscanf.c
newlib/libc/stdio/wscanf.c
newlib/libc/stdlib/Makefile.am
newlib/libc/stdlib/Makefile.in
newlib/libc/stdlib/__atexit.c
newlib/libc/stdlib/__call_atexit.c
newlib/libc/stdlib/ecvtbuf.c
newlib/libc/stdlib/mblen.c
newlib/libc/stdlib/mbrlen.c
newlib/libc/stdlib/mbrtowc.c
newlib/libc/stdlib/mbtowc.c
newlib/libc/stdlib/nano-mallocr.c
newlib/libc/stdlib/rand.c
newlib/libc/stdlib/strtod.c
newlib/libc/stdlib/wcrtomb.c
newlib/libc/stdlib/wctob.c
newlib/libc/stdlib/wctomb.c
newlib/libc/string/strtok.c
newlib/libc/time/asctime.c
newlib/libc/time/gmtime.c
newlib/libc/time/lcltime.c
newlib/libm/libm.texinfo
winsup/cygserver/ChangeLog
winsup/cygserver/ChangeLog.64bit
winsup/cygserver/Makefile.in
winsup/cygserver/bsd_helper.cc
winsup/cygserver/bsd_helper.h
winsup/cygserver/bsd_log.cc
winsup/cygserver/bsd_log.h
winsup/cygserver/bsd_mutex.cc
winsup/cygserver/client.cc
winsup/cygserver/cygserver.cc
winsup/cygserver/msg.cc
winsup/cygserver/process.h
winsup/cygserver/sem.cc
winsup/cygserver/shm.cc
winsup/cygserver/sysv_shm.cc
winsup/cygserver/threaded_queue.h
winsup/cygwin/ChangeLog
winsup/cygwin/ChangeLog.64bit
winsup/cygwin/Makefile.in
winsup/cygwin/aclocal.m4
winsup/cygwin/advapi32.cc
winsup/cygwin/autoload.cc
winsup/cygwin/automode.c
winsup/cygwin/binmode.c
winsup/cygwin/child_info.h
winsup/cygwin/common.din
winsup/cygwin/configure
winsup/cygwin/configure.ac
winsup/cygwin/cpuid.h
winsup/cygwin/cygerrno.h
winsup/cygwin/cygheap.cc
winsup/cygwin/cygheap.h
winsup/cygwin/cygmagic
winsup/cygwin/cygmalloc.h
winsup/cygwin/cygserver.h
winsup/cygwin/cygserver_ipc.h
winsup/cygwin/cygthread.cc
winsup/cygwin/cygtls.cc
winsup/cygwin/cygtls.h
winsup/cygwin/cygwin.sc.in
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winsup/cygwin/debug.h
winsup/cygwin/devices.cc
winsup/cygwin/devices.h
winsup/cygwin/devices.in
winsup/cygwin/dir.cc
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winsup/cygwin/dll_init.h
winsup/cygwin/dtable.cc
winsup/cygwin/environ.cc
winsup/cygwin/environ.h
winsup/cygwin/errno.cc
winsup/cygwin/exception.h
winsup/cygwin/exceptions.cc
winsup/cygwin/external.cc
winsup/cygwin/fcntl.cc
winsup/cygwin/fenv.cc
winsup/cygwin/fhandler.cc
winsup/cygwin/fhandler.h
winsup/cygwin/fhandler_clipboard.cc
winsup/cygwin/fhandler_console.cc
winsup/cygwin/fhandler_dev.cc
winsup/cygwin/fhandler_disk_file.cc
winsup/cygwin/fhandler_dsp.cc
winsup/cygwin/fhandler_fifo.cc
winsup/cygwin/fhandler_floppy.cc
winsup/cygwin/fhandler_mailslot.cc
winsup/cygwin/fhandler_mem.cc
winsup/cygwin/fhandler_netdrive.cc
winsup/cygwin/fhandler_proc.cc
winsup/cygwin/fhandler_process.cc
winsup/cygwin/fhandler_procnet.cc
winsup/cygwin/fhandler_procsys.cc
winsup/cygwin/fhandler_procsysvipc.cc
winsup/cygwin/fhandler_random.cc
winsup/cygwin/fhandler_raw.cc
winsup/cygwin/fhandler_registry.cc
winsup/cygwin/fhandler_serial.cc
winsup/cygwin/fhandler_socket.cc
winsup/cygwin/fhandler_tape.cc
winsup/cygwin/fhandler_termios.cc
winsup/cygwin/fhandler_tty.cc
winsup/cygwin/fhandler_virtual.cc
winsup/cygwin/fhandler_virtual.h
winsup/cygwin/fhandler_windows.cc
winsup/cygwin/fhandler_zero.cc
winsup/cygwin/flock.cc
winsup/cygwin/fork.cc
winsup/cygwin/gendef
winsup/cygwin/gentls_offsets
winsup/cygwin/glob.cc
winsup/cygwin/globals.cc
winsup/cygwin/grp.cc
winsup/cygwin/heap.cc
winsup/cygwin/hookapi.cc
winsup/cygwin/i686.din
winsup/cygwin/include/a.out.h
winsup/cygwin/include/asm/byteorder.h
winsup/cygwin/include/bits/wordsize.h
winsup/cygwin/include/cygwin/acl.h
winsup/cygwin/include/cygwin/config.h
winsup/cygwin/include/cygwin/cygwin_dll.h
winsup/cygwin/include/cygwin/grp.h
winsup/cygwin/include/cygwin/if.h
winsup/cygwin/include/cygwin/ipc.h
winsup/cygwin/include/cygwin/msg.h
winsup/cygwin/include/cygwin/sem.h
winsup/cygwin/include/cygwin/shm.h
winsup/cygwin/include/cygwin/signal.h
winsup/cygwin/include/cygwin/socket.h
winsup/cygwin/include/cygwin/stat.h
winsup/cygwin/include/cygwin/stdlib.h
winsup/cygwin/include/cygwin/sysproto.h
winsup/cygwin/include/cygwin/time.h
winsup/cygwin/include/cygwin/types.h
winsup/cygwin/include/cygwin/version.h
winsup/cygwin/include/fcntl.h
winsup/cygwin/include/fts.h
winsup/cygwin/include/ftw.h
winsup/cygwin/include/glob.h
winsup/cygwin/include/inttypes.h
winsup/cygwin/include/io.h
winsup/cygwin/include/limits.h
winsup/cygwin/include/mntent.h
winsup/cygwin/include/stdint.h
winsup/cygwin/include/sys/cygwin.h
winsup/cygwin/include/sys/dirent.h
winsup/cygwin/include/sys/resource.h
winsup/cygwin/include/sys/socket.h
winsup/cygwin/include/sys/strace.h
winsup/cygwin/init.cc
winsup/cygwin/ioctl.cc
winsup/cygwin/ipc.cc
winsup/cygwin/kernel32.cc
winsup/cygwin/lc_msg.h
winsup/cygwin/lib/_cygwin_crt0_common.cc
winsup/cygwin/lib/crt0.h
winsup/cygwin/lib/cygwin_attach_dll.c
winsup/cygwin/lib/premain0.c
winsup/cygwin/lib/premain1.c
winsup/cygwin/lib/premain2.c
winsup/cygwin/lib/premain3.c
winsup/cygwin/libc/arc4random.cc
winsup/cygwin/libc/base64.c
winsup/cygwin/libc/bsdlib.cc
winsup/cygwin/libc/fts.c
winsup/cygwin/libc/ftw.c
winsup/cygwin/libc/inet_network.c
winsup/cygwin/libc/minires-os-if.c
winsup/cygwin/libc/minires.c
winsup/cygwin/libc/nftw.c
winsup/cygwin/libc/rcmd.cc
winsup/cygwin/libc/rexec.cc
winsup/cygwin/libstdcxx_wrapper.cc
winsup/cygwin/localtime.cc
winsup/cygwin/malloc_wrapper.cc
winsup/cygwin/miscfuncs.cc
winsup/cygwin/mkimport
winsup/cygwin/mktemp.cc
winsup/cygwin/mmap.cc
winsup/cygwin/mount.cc
winsup/cygwin/mount.h
winsup/cygwin/msg.cc
winsup/cygwin/mtinfo.h
winsup/cygwin/net.cc
winsup/cygwin/netdb.cc
winsup/cygwin/nfs.h
winsup/cygwin/nlsfuncs.cc
winsup/cygwin/ntdll.h
winsup/cygwin/ntea.cc
winsup/cygwin/passwd.cc
winsup/cygwin/path.cc
winsup/cygwin/path.h
winsup/cygwin/perprocess.h
winsup/cygwin/pinfo.cc
winsup/cygwin/pinfo.h
winsup/cygwin/pipe.cc
winsup/cygwin/poll.cc
winsup/cygwin/posix.sgml
winsup/cygwin/posix_ipc.cc
winsup/cygwin/profil.c
winsup/cygwin/profil.h
winsup/cygwin/pseudo-reloc.cc
winsup/cygwin/pwdgrp.h
winsup/cygwin/regex/engine.c
winsup/cygwin/regex/regcomp.c
winsup/cygwin/registry.cc
winsup/cygwin/regparm.h
winsup/cygwin/release/1.7.19
winsup/cygwin/resource.cc
winsup/cygwin/sched.cc
winsup/cygwin/sec_acl.cc
winsup/cygwin/sec_auth.cc
winsup/cygwin/sec_helper.cc
winsup/cygwin/security.cc
winsup/cygwin/security.h
winsup/cygwin/select.cc
winsup/cygwin/select.h
winsup/cygwin/sem.cc
winsup/cygwin/shared.cc
winsup/cygwin/shared_info.h
winsup/cygwin/shm.cc
winsup/cygwin/signal.cc
winsup/cygwin/sigproc.cc
winsup/cygwin/sigproc.h
winsup/cygwin/smallprint.cc
winsup/cygwin/spawn.cc
winsup/cygwin/speclib
winsup/cygwin/spinlock.h
winsup/cygwin/strace.cc
winsup/cygwin/strfuncs.cc
winsup/cygwin/strsig.cc
winsup/cygwin/sync.cc
winsup/cygwin/sync.h
winsup/cygwin/syscalls.cc
winsup/cygwin/sysconf.cc
winsup/cygwin/syslog.cc
winsup/cygwin/termios.cc
winsup/cygwin/textmode.c
winsup/cygwin/textreadmode.c
winsup/cygwin/thread.cc
winsup/cygwin/thread.h
winsup/cygwin/timer.cc
winsup/cygwin/times.cc
winsup/cygwin/tlsoffsets.h
winsup/cygwin/tlsoffsets64.h
winsup/cygwin/tty.cc
winsup/cygwin/tty.h
winsup/cygwin/uinfo.cc
winsup/cygwin/wait.cc
winsup/cygwin/winbase.h
winsup/cygwin/wincap.cc
winsup/cygwin/wincap.h
winsup/cygwin/window.cc
winsup/cygwin/winlean.h
winsup/cygwin/winsup.h
winsup/cygwin/wow64.cc
winsup/cygwin/wow64.h
winsup/cygwin/x86_64.din
winsup/doc/.cvsignore
winsup/doc/ChangeLog
winsup/doc/Makefile.in
winsup/doc/Wishlist
winsup/doc/bodysnatcher.pl
winsup/doc/configure
winsup/doc/configure.ac
winsup/doc/cygserver.xml
winsup/doc/cygwin-api.in.xml
winsup/doc/cygwin-ug-net.xml
winsup/doc/cygwin.xsl
winsup/doc/cygwinenv.xml
winsup/doc/dll.xml
winsup/doc/effectively.xml
winsup/doc/faq-api.xml
winsup/doc/faq-copyright.xml
winsup/doc/faq-programming.xml
winsup/doc/faq-resources.xml
winsup/doc/faq-setup.xml
winsup/doc/faq-using.xml
winsup/doc/faq-what.xml
winsup/doc/faq.xml
winsup/doc/filemodes.xml
winsup/doc/gcc.xml
winsup/doc/gdb.xml
winsup/doc/highlights.xml
winsup/doc/legal.xml
winsup/doc/new-features.xml
winsup/doc/ntsec.xml
winsup/doc/ov-ex-unix.xml
winsup/doc/ov-ex-win.xml
winsup/doc/overview.xml
winsup/doc/pathnames.xml
winsup/doc/programming.xml
winsup/doc/setup-env.xml
winsup/doc/setup-files.xml
winsup/doc/setup-locale.xml
winsup/doc/setup-maxmem.xml
winsup/doc/setup-net.xml
winsup/doc/specialnames.xml
winsup/doc/textbinary.xml
winsup/doc/ug-info.xml
winsup/doc/using.xml
winsup/doc/windres.xml
winsup/doc/xidepend
winsup/lsaauth/ChangeLog
winsup/lsaauth/ChangeLog.64bit
winsup/lsaauth/Makefile.in
winsup/lsaauth/configure
winsup/lsaauth/configure.ac
winsup/utils/ChangeLog
winsup/utils/ChangeLog.64bit
winsup/utils/Makefile.in
winsup/utils/aclocal.m4
winsup/utils/configure
winsup/utils/cygcheck.cc
winsup/utils/dumper.cc
winsup/utils/dumper.h
winsup/utils/kill.cc
winsup/utils/ldd.cc
winsup/utils/locale.cc
winsup/utils/mkgroup.c
winsup/utils/mkpasswd.c
winsup/utils/module_info.cc
winsup/utils/mount.cc
winsup/utils/parse_pe.cc
winsup/utils/passwd.c
winsup/utils/path.cc
winsup/utils/ps.cc
winsup/utils/regtool.cc
winsup/utils/ssp.c
winsup/utils/strace.cc
winsup/utils/tzset.c
winsup/utils/utils.xml
Delete:
COPYING3
COPYING3.LIB
config.rpath
configure.ac
ltgcc.m4
newlib/libc/machine/aarch64/Makefile.am
newlib/libc/machine/aarch64/Makefile.in
newlib/libc/machine/aarch64/aclocal.m4
newlib/libc/machine/aarch64/configure
newlib/libc/machine/aarch64/configure.in
newlib/libc/machine/aarch64/memcmp-stub.c
newlib/libc/machine/aarch64/memcmp.S
newlib/libc/machine/aarch64/memcpy-stub.c
newlib/libc/machine/aarch64/memcpy.S
newlib/libc/machine/aarch64/memmove-stub.c
newlib/libc/machine/aarch64/memmove.S
newlib/libc/machine/aarch64/memset-stub.c
newlib/libc/machine/aarch64/memset.S
newlib/libc/machine/aarch64/setjmp.S
newlib/libc/machine/aarch64/strcmp-stub.c
newlib/libc/machine/aarch64/strcmp.S
newlib/libc/machine/aarch64/strlen-stub.c
newlib/libc/machine/aarch64/strlen.S
newlib/libc/machine/aarch64/strncmp-stub.c
newlib/libc/machine/aarch64/strncmp.S
newlib/libc/machine/aarch64/strnlen-stub.c
newlib/libc/machine/aarch64/strnlen.S
newlib/libc/machine/epiphany/Makefile.am
newlib/libc/machine/epiphany/Makefile.in
newlib/libc/machine/epiphany/aclocal.m4
newlib/libc/machine/epiphany/configure
newlib/libc/machine/epiphany/configure.in
newlib/libc/machine/epiphany/machine/stdlib.h
newlib/libc/machine/epiphany/setjmp.S
newlib/libc/machine/powerpc/times.c
newlib/libc/sys/epiphany/Makefile.am
newlib/libc/sys/epiphany/Makefile.in
newlib/libc/sys/epiphany/aclocal.m4
newlib/libc/sys/epiphany/configure
newlib/libc/sys/epiphany/configure.in
newlib/libc/sys/epiphany/e_printf.c
newlib/libm/machine/aarch64/Makefile.am
newlib/libm/machine/aarch64/Makefile.in
newlib/libm/machine/aarch64/aclocal.m4
newlib/libm/machine/aarch64/configure
newlib/libm/machine/aarch64/configure.in
newlib/libm/machine/aarch64/s_ceil.c
newlib/libm/machine/aarch64/s_floor.c
newlib/libm/machine/aarch64/s_fma.c
newlib/libm/machine/aarch64/s_fmax.c
newlib/libm/machine/aarch64/s_fmin.c
newlib/libm/machine/aarch64/s_llrint.c
newlib/libm/machine/aarch64/s_llround.c
newlib/libm/machine/aarch64/s_lrint.c
newlib/libm/machine/aarch64/s_lround.c
newlib/libm/machine/aarch64/s_nearbyint.c
newlib/libm/machine/aarch64/s_rint.c
newlib/libm/machine/aarch64/s_round.c
newlib/libm/machine/aarch64/s_trunc.c
newlib/libm/machine/aarch64/sf_ceil.c
newlib/libm/machine/aarch64/sf_floor.c
newlib/libm/machine/aarch64/sf_fma.c
newlib/libm/machine/aarch64/sf_fmax.c
newlib/libm/machine/aarch64/sf_fmin.c
newlib/libm/machine/aarch64/sf_llrint.c
newlib/libm/machine/aarch64/sf_llround.c
newlib/libm/machine/aarch64/sf_lrint.c
newlib/libm/machine/aarch64/sf_lround.c
newlib/libm/machine/aarch64/sf_nearbyint.c
newlib/libm/machine/aarch64/sf_rint.c
newlib/libm/machine/aarch64/sf_round.c
newlib/libm/machine/aarch64/sf_trunc.c
winsup/cygwin/cygwin.din
winsup/cygwin/cygwin.sc
winsup/doc/cygserver.sgml
winsup/doc/cygwin-api.in.sgml
winsup/doc/cygwin-ug-net.in.sgml
winsup/doc/cygwin-ug.in.sgml
winsup/doc/cygwin.dsl
winsup/doc/cygwinenv.sgml
winsup/doc/dll.sgml
winsup/doc/effectively.sgml
winsup/doc/faq-sections.xml
winsup/doc/filemodes.sgml
winsup/doc/gcc.sgml
winsup/doc/gdb.sgml
winsup/doc/legal.sgml
winsup/doc/new-features.sgml
winsup/doc/ntsec.sgml
winsup/doc/overview.sgml
winsup/doc/overview2.sgml
winsup/doc/pathnames.sgml
winsup/doc/programming.sgml
winsup/doc/setup-net.sgml
winsup/doc/setup.sgml
winsup/doc/setup2.sgml
winsup/doc/textbinary.sgml
winsup/doc/using.sgml
winsup/doc/windres.sgml
winsup/utils/utils.sgml
Diffstat (limited to 'winsup/doc/faq-programming.xml')
-rw-r--r-- | winsup/doc/faq-programming.xml | 333 |
1 files changed, 292 insertions, 41 deletions
diff --git a/winsup/doc/faq-programming.xml b/winsup/doc/faq-programming.xml index bfc27fac7..c01a127e6 100644 --- a/winsup/doc/faq-programming.xml +++ b/winsup/doc/faq-programming.xml @@ -1,5 +1,11 @@ +<?xml version="1.0" encoding='UTF-8'?> +<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> <!-- faq-programming.xml --> +<qandadiv id="faq.programming"> +<title>Programming Questions</title> + <qandaentry id="faq.programming.packages"> <question><para>How do I contribute a package?</para></question> <answer> @@ -48,6 +54,287 @@ package. Or compile with the <literal>-s</literal> option to gcc. </para> </answer></qandaentry> +<qandaentry id="faq.programming.64bitporting"> +<question><para>What do I have to look out for when porting applications to 64 bit Cygwin?</para></question> +<answer> + +<para>The Cygwin x86_64 toolchain is using the +<ulink url="http://en.wikipedia.org/wiki/LLP64#64-bit_data_models">LP64</ulink> +data model. That means, in contrast to Windows, which uses an +<ulink url="http://en.wikipedia.org/wiki/LLP64#64-bit_data_models">LLP64</ulink> +data model, sizeof(long) != sizeof(int), just as on Linux.</para> + +<para>For comparison:</para> + +<screen> + Cygwin Windows Cygwin + Linux x86_64 Linux + Windows x86_64 + i686 + +sizeof(int) 4 4 4 +sizeof(long) 4 4 8 +sizeof(size_t) 4 8 8 +sizeof(void*) 4 8 8 +</screen> + +<para>This difference can result in interesting problems, especially when +using Win32 functions, especially when using pointers to Windows +datatypes like LONG, ULONG, DWORD. Given that Windows is LLP64, all of +the aforementioned types are 4 byte in size, on 32 as well as on 64 bit +Windows, while `long' on 64 bit Cygwin is 8 bytes.</para> + +<para>Take the example ReadFile:</para> + +<screen> + ReadFile (HANDLE, LPVOID, DWORD, LPDWORD, LPOVERLAPPED); +</screen> + +<para>In the 32 bit Cygwin and Mingw environments, as well as in the 64 bit +Mingw environment, it is no problem to substitute DWORD with unsigned +long:</para> + +<screen> + unsigned long number_of_bytes_read; + [...] + ReadFile (fhdl, buf, buflen, &number_of_bytes_read, NULL); +</screen> + +<para>However, in 64 bit Cygwin, using LP64, number_of_bytes_read is 8 bytes +in size. But since ReadFile expects a pointer to a 4 byte type, the function +will only change the lower 4 bytes of number_of_bytes_read on return, while +the content of the upper 4 bytes stays undefined.</para> + +<para>Here are a few <emphasis>donts</emphasis> which should help porting +applications from the known ILP32 data model of 32 bit Cygwin, to the LP64 +data model of 64 bit Cygwin. Note that these are not Cygwin-only problems. +Many Linux applications suffered the same somewhat liberal handling of +datatypes when the AMD64 CPU was new.</para> + +<itemizedlist mark="bullet"> + +<listitem><para> +<emphasis>Don't</emphasis> mix up int and long in printf/scanf. This: + +<screen> + int i; long l; + printf ("%d %ld\n", l, i); +</screen> + +may not print what you think it should. Enable the gcc options -Wformat or +-Wall, which warn about type mismatches in printf/scanf functions. + +<note>Using -Wall (optionally with -Werror to drive the point home) makes a +lot of sense in general, not only when porting code to a new platform.</note> +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> mix int and long pointers. + +<screen> + long *long_ptr = (long *) &my_int; /* Uh oh! */ + *long_ptr = 42; +</screen> + +The assignment will write 8 bytes to the address of my_int. Since my_int +is only 4 bytes, <emphasis>something else</emphasis> gets randomly overwritten. +Finding this kind of bug is very hard, because you will often see a problem +which has no immediate connection to the actual bug. +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> mix int and pointers at all! This will +<emphasis>not</emphasis> work as expected anymore: + +<screen> + void *ptr; + printf ("Pointer value is %x\n", ptr); +</screen> + +%x denotes an int argument. The value printed by printf is a 4 byte value, +so on x86_64 the printed pointer value is missing its upper 4 bytes; the output +is very likely wrong. Use %p instead, which portable across architectures: + +<screen> + void *ptr; + printf ("Pointer value is %p\n", ptr); +</screen> +</para></listitem> + +<listitem><para> +Along the same lines <emphasis>don't</emphasis> use the type int in +pointer arithmetic. Don't cast pointers to int, don't cast pointer +differences to int, and don't store pointer differences in an int type. +Use the types <literal>intptr_t</literal>, <literal>uintptr_t</literal> +and <literal>ptrdiff_t</literal> instead, they are designed for performing +architecture-independent pointer arithmetic. +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> make blind assumptions about the size of a POSIX +type. For instance, <literal>time_t</literal> is 8 bytes on 64 bit Cygwin, +while it is (still, at the time of writing this) 4 bytes on 32 bit Cygwin, +since time_t is based on the type long. +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> use functions returning pointers without declaration. +For instance + +<screen> + printf ("Error message is: %s\n", strerror (errno)); +</screen> + +This code will <emphasis>crash</emphasis>, unless you included +<filename>string.h</filename>. The implicit rule in C is that an undeclared +function is of type int. But int is 4 byte and pointers are 8 byte, so the +string pointer given to printf is missing the upper 4 bytes. +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> use C base types together with Win32 functions. +Keep in mind that DWORD, LONG, ULONG are <emphasis>not</emphasis> the same +as long and unsigned long. Try to use only Win32 datatypes in conjunction +with Win32 API function calls to avoid type problems. See the above +ReadFile example. Windows functions in printf calls should be treated +carefully as well. This code is common for 32 bit code, but probably prints +the wrong value on 64 bit: + +<screen> + printf ("Error message is: %lu\n", GetLastError ()); +</screen> + +Using gcc's -Wformat option would warn about this. Casting to the requested +base type helps in this case: + +<screen> + printf ("Error message is: %lu\n", (unsigned long) GetLastError ()); +</screen> +</para></listitem> + +<listitem><para> +<emphasis>Don't</emphasis> mix Windows datatypes with POSIX type-specific +MIN/MAX values. + +<screen> + unsigned long l_max = ULONG_MAX; /* That's right. */ + ULONG w32_biggest = ULONG_MAX; /* Hey, wait! What? */ + ULONG w32_biggest = UINT_MAX; /* Ok, but borderline. */ +</screen> + +Again, keep in mind that ULONG (or DWORD) is <emphasis>not</emphasis> unsigned +long but rather unsigned int on 64 bit. +</para></listitem> + +</itemizedlist> + +</answer></qandaentry> + +<qandaentry id="faq.programming.64bitporting-fail"> +<question><para>My project doesn't build at all on 64 bit Cygwin. What's up?</para></question> +<answer> + +<para>Typically reasons for that are:</para> + +<itemizedlist mark="bullet"> + +<listitem><para><literal>__CYGWIN32__</literal> is not defined in the +64 bit toolchain. This may hit a few projects which are around since before +Y2K. Check your project for occurences of <literal>__CYGWIN32__</literal> +and change them to <literal>__CYGWIN__</literal>, which is defined in the +Cygwin toolchain since 1998, to get the same Cygwin-specific code changes done. +</para></listitem> + +<listitem><para>The project maintainers took it for granted that Cygwin is +running only on i686 CPUs and the code is making this assumption blindly. +You have to check the code for such assumptions and fix them. +</para></listitem> + +<listitem><para>The project is using autotools, the +<filename>config.sub</filename> and <filename>config.guess</filename> files +are hopelessly outdated and don't recognize +<literal>x86_64-{pc,unknown}-cygwin</literal> as valid target. Update the +project configury (cygport will do this by default) and try again. +</para></listitem> + +<listitem><para>The project uses Windows functions on Cygwin and it's suffering +from the problems described in the preceeding FAQ entry. +</para></listitem> + +</itemizedlist> + +<para>In all of this cases, please make sure to fix that upstream, or send +your patches to the upstream maintainers, so the problems get fixed for the +future.</para> + +</answer></qandaentry> + +<qandaentry id="faq.programming.64bitporting-cygwin64"> +<question><para>Why is __CYGWIN64__ not defined for 64 bit?</para></question> +<answer> + +<para>There is no <literal>__CYGWIN64__</literal> because we would like to +have a unified way to handle Cygwin code in portable projects. Using +<literal>__CYGWIN32__</literal> and <literal>__CYGWIN64__</literal> only +complicates the code for no good reason. Along the same lines you won't +find predefined macros <literal>__linux32__</literal> and +<literal>__linux64__</literal> on Linux.</para> + +<para>If you really have to differ between 32 and 64 bit in some way, you have +three choices.</para> + +<itemizedlist mark="bullet"> + +<listitem><para>If your code depends on the CPU architecture, use the +predefined compiler definition for the architecture, like this:</para> + +<screen> +#ifdef __CYGWIN__ +# ifdef __x86_64__ /* Alternatively __x86_64, __amd64__, __amd64 */ + /* Code specific for AMD64 CPU */ +# elif __X86__ + /* Code specific for ix86 CPUs */ +# else +# error Unsupported Architecture +# endif +#endif +</screen></listitem> + +<listitem><para>If your code depends on differences in the data model, you +should consider to use the <literal>__LP64__</literal> definition +instead:</para> + +<screen> +#ifdef __CYGWIN__ +# ifdef __LP64__ /* Alternatively _LP64 */ + /* Code specific for 64 bit CPUs */ +# else + /* Code specific for 32 bit CPUs */ +# endif +#endif +</screen></listitem> + +<listitem><para>If your code uses Windows functions, and some of the +functionality is 64 bit Windows-specific, use <literal>_WIN64</literal>, +which is defined on 64 bit Cygwin, as soon as you include +<filename>windows.h</filename>. This should only be used in the most +desperate of occasions, though, and <emphasis>only</emphasis> if it's +really about a difference in Windows API functionality!</para> + +<screen> +#ifdef __CYGWIN__ +# ifdef _WIN64 + /* Code specific for 64 bit Windows */ +# else + /* Code specific for 32 bit Windows */ +# endif +#endif +</screen></listitem> + +</itemizedlist> + +</answer></qandaentry> + <qandaentry id="faq.programming.glibc"> <question><para>Where is glibc?</para></question> <answer> @@ -62,7 +349,7 @@ would be difficult. <question><para>Where is Objective C?</para></question> <answer> -<para>Support for compiling Objective C is available in the <literal>gcc4-objc</literal> +<para>Support for compiling Objective C is available in the <literal>gcc{4}-objc</literal> package; resulting binaries will depend on the <literal>libobjc2</literal> package at runtime. </para> @@ -72,10 +359,8 @@ package at runtime. <question><para>Why does my make fail on Cygwin with an execvp error? </para></question> <answer> -<para>First of all, if you are using <literal>make -j[N]</literal>, then stop. It doesn't -work well. Also beware of using non-portable shell features in your -Makefiles (see tips at <ulink -url="http://cygwin.com/faq/faq.using.html#faq.using.shell-scripts" />). +<para>Beware of using non-portable shell features in your Makefiles (see tips +at <ulink url="http://cygwin.com/faq/faq.html#faq.using.shell-scripts" />). </para> <para>Errors of <literal>make: execvp: /bin/sh: Illegal Argument</literal> or <literal>make: execvp: /bin/sh: Argument list too long</literal> are often @@ -461,7 +746,7 @@ recommend trying the latest snapshot from <ulink url="http://cygwin.com/snapshots/" /> or building the DLL from CVS. </para> <para>To build a debugging version of the Cygwin DLL, you will need to follow -the instructions at <ulink url="http://cygwin.com/faq/faq-nochunks.html#faq.programming.building-cygwin" />. +the instructions at <ulink url="http://cygwin.com/faq/faq.html#faq.programming.building-cygwin" />. You can also contact the mailing list for pointers (a simple test case that demonstrates the bug is always welcome). </para> @@ -681,15 +966,6 @@ This is right <literal>gcc hello.cc -lstdc++</literal>. use <literal>struct stat</literal>. It's 64 bit aware.</para> </answer></qandaentry> -<qandaentry id="faq.programming.undeclared-functions"> -<question><para>I use a function I know is in the API, but I still get a link error.</para></question> -<answer> - -<para>The function probably isn't declared in the header files, or -the UNICODE stuff for it isn't filled in. -</para> -</answer></qandaentry> - <qandaentry id="faq.programming.libc"> <question><para>Can you make DLLs that are linked against libc ?</para></question> <answer> @@ -758,17 +1034,6 @@ data types, line numbers, local variables etc. </para> </answer></qandaentry> -<qandaentry id="faq.programming.x86-assembly"> -<question><para>Where can I find info on x86 assembly?</para></question> -<answer> - -<para>CPU reference manuals for Intel's current chips are available in -downloadable PDF form on Intel's web site: -</para> -<para><ulink url="http://developer.intel.com/">http://developer.intel.com/</ulink> -</para> -</answer></qandaentry> - <qandaentry id="faq.programming.make-scripts"> <question><para>Shell scripts aren't running properly from my makefiles?</para></question> <answer> @@ -849,18 +1114,4 @@ linker flag.</para></listitem> </orderedlist></listitem></orderedlist> </answer></qandaentry> -<qandaentry id="faq.programming.djgpp"> -<question><para>Why not use DJGPP ?</para></question> -<answer> - -<para>DJGPP is a similar idea, but for DOS instead of Win32. DJGPP uses a -"DOS extender" to provide a more reasonable operating interface for its -applications. The Cygwin toolset doesn't have to do this since all of -the applications are native WIN32. Applications compiled with the -Cygwin tools can access the Win32 API functions, so you can write -programs which use the Windows GUI. -</para> -<para>You can get more info on DJGPP by following -<ulink url="http://www.delorie.com/">http://www.delorie.com/</ulink>. -</para></answer></qandaentry> - +</qandadiv> |