22 Feb
2012
22 Feb
'12
7:17 p.m.
Hi All.
This is interesting. It shows that (apparently) early on, assembler was
viewed as the primary programming language.
It also shows the consequences a small, apparently local decision can have:
here we are 40+ years later and GCC on Windows is still preprending
underscores to function names!
In 15 minutes I helped the guy at work solve a problem he'd been working
on for two days!
Thanks everyone,
Arnold
From: Brantley Coile <brantley(a)coraid.com>
To: Dave Horsfall <dave(a)horsfall.org>
Date: Mon, 20 Feb 2012 18:34:26 -0600
Cc: The Eunuchs Hysterical Society <tuhs(a)tuhs.org>
Subject: Re: [TUHS] why the leading under score added to function names?
correct. we could link to assembler code with _entry points and not
i> worry
about symbol collisions in the rest of the code.
iPhone email
On Feb 20, 2012, at 6:23 PM, "Dave Horsfall" <dave(a)horsfall.org> wrote:
> On Mon, 20 Feb 2012, arnold(a)skeeve.com wrote:
>
> [...]
>
>> I'm pretty sure this dates back to PDP-11 days. I'm wondering
"why?".
>> Why did the C compiler prepend an underscore to function names?
>
> Sure was the PDP-11 :-) I vaguely recall that it was to make sure that
> user functions did not conflict with predefined assembler functions, as
> that would be a pain to diagnose (much like having swap overlap root).
>
> -- Dave
22 Feb
22 Feb
9:22 p.m.
New subject: why the leading under score added to function names?
On Wed, 22 Feb 2012, arnold(a)skeeve.com wrote:
This is interesting. It shows that (apparently) early
on, assembler was
viewed as the primary programming language.
Well, C didn't exactly spring from Zeus's brow :-) A good chunk of the
C library was in assembler, as were quite a number of programs.
It also shows the consequences a small, apparently
local decision can have:
here we are 40+ years later and GCC on Windows is still preprending
underscores to function names!
When it comes to Windoze, nothing surprises me any more. Unix has evolved
over the years, but Windoze was spat out and hatched.
-- Dave
10:47 p.m.
New subject: why the leading under score added to function names?
On Wed, Feb 22, 2012 at 3:22 PM, Dave Horsfall <dave(a)horsfall.org> wrote:
On Wed, 22 Feb 2012, arnold(a)skeeve.com wrote:
relevant:
http://cm.bell-labs.com/who/dmr/hist.html
This is interesting. It shows that (apparently)
early on, assembler was
viewed as the primary programming language.
Well, C didn't exactly spring from Zeus's brow :-) A good chunk of the
C library was in assembler, as were quite a number of programs.
23 Feb
23 Feb
4:30 a.m.
New subject: why the leading under score added to function names?
On Thursday, 23 February 2012 at 8:22:17 +1100, Dave Horsfall wrote:
On Wed, 22 Feb 2012, arnold(a)skeeve.com wrote:
I'm no friend of Microsoft either, but gcc isn't exactly Microsoft.
What Arnold mentions here is Unix history in action.
Greg
--
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See complete headers for address and phone numbers.
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It also shows the consequences a small,
apparently local decision
can have: here we are 40+ years later and GCC on Windows is still
preprending underscores to function names!
When it comes to Windoze, nothing surprises me any more. Unix has
evolved over the years, but Windoze was spat out and hatched. 
25 Feb
25 Feb
6:45 p.m.
New subject: why the leading under score added to function names?
On 2/22/2012 11:30 PM, Greg 'groggy' Lehey wrote:
On Thursday, 23 February 2012 at 8:22:17 +1100, Dave
Horsfall wrote:
Yes and no. IIRC, gcc doesn't do that on, for example, Linux ELF. it's
done on windows, I assume, in deference to the windows 32-bit ABI for
cdecl calling convention functions.
Now, as far as where windows gets that from (just because something
evolved within one company doesn't mean it didn't evolve), supposedly
early versions of Microsoft C (pre-ANSI) were very conservative in terms
of adhering to the "standard" set by Unix C and K&R - this could have
extended to the prepending of underscores. For instance, this is,
according to Raymond Chen, why they added WinMain rather than extending
main (they didn't know if extensions to main would be allowed). I would
also guess it's why MSVC stdio is implemented on top of an imitation of
Unix system calls which is in turn implemented on top of DOS/windows;
and why MSVC time_t is defined as seconds since 1970. There are comments
in the code referring to XENIX in various places relating to I/O and
timestamps, so it's possible that MSVC's C library was indeed, to some
small degree, based on Unix.
On Wed, 22 Feb 2012, arnold(a)skeeve.com wrote:
I'm no friend
of Microsoft either, but gcc isn't exactly Microsoft.
What Arnold mentions here is Unix history in action.
It also shows the consequences a small,
apparently local decision
can have: here we are 40+ years later and GCC on Windows is still
preprending underscores to function names!
When it comes to Windoze, nothing
surprises me any more. Unix has
evolved over the years, but Windoze was spat out and hatched. 
7:24 p.m.
New subject: why the leading under score added to function names?
On Sat, 25 Feb 2012, Random832 wrote:
On 2/22/2012 11:30 PM, Greg 'groggy' Lehey
wrote:
Though DOS's file i/o calls, starting in 2.0, were much the same as
Unix's already. Its open, close, read, write have the same basic
semantics and at one point it was possible to have DOS require a syntax
like \dev\con for devices.
-uso.
On Thursday, 23 February 2012 at 8:22:17 +1100,
Dave Horsfall wrote:
Yes and no. IIRC, gcc doesn't do that on, for example, Linux ELF. it's
done
on windows, I assume, in deference to the windows 32-bit ABI for cdecl
calling convention functions.
Now, as far as where windows gets that from (just because something evolved
within one company doesn't mean it didn't evolve), supposedly early versions
of Microsoft C (pre-ANSI) were very conservative in terms of adhering to the
"standard" set by Unix C and K&R - this could have extended to the
prepending
of underscores. For instance, this is, according to Raymond Chen, why they
added WinMain rather than extending main (they didn't know if extensions to
main would be allowed). I would also guess it's why MSVC stdio is implemented
on top of an imitation of Unix system calls which is in turn implemented on
top of DOS/windows; and why MSVC time_t is defined as seconds since 1970.
There are comments in the code referring to XENIX in various places relating
to I/O and timestamps, so it's possible that MSVC's C library was indeed, to
some small degree, based on Unix. On Wed, 22 Feb 2012, arnold(a)skeeve.com wrote:
I'm no friend
of Microsoft either, but gcc isn't exactly Microsoft.
What Arnold mentions here is Unix history in action.
It also shows the consequences a small,
apparently local decision
can have: here we are 40+ years later and GCC on Windows is still
preprending underscores to function names!
When it comes to Windoze, nothing
surprises me any more. Unix has
evolved over the years, but Windoze was spat out and hatched. 
8:39 p.m.
New subject: why the leading under score added to function names?
Random832 scripsit:
For instance, this is, according to Raymond Chen, why
they added
WinMain rather than extending main (they didn't know if extensions to
main would be allowed).
That doesn't sound very reasonable to me. When you link a Windows
program, it still has a main() procedure provided by Windows which does
setup and then invokes WinMain().
so it's possible that MSVC's C library was
indeed, to some small
degree, based on Unix.
Without doubt. After all, there was no other source of C libraries
before ANSI; compare the Whitesmiths library, which was "meticulously
incompatibled".
--
Samuel Johnson on playing the violin: John Cowan
"Difficult do you call it, Sir? cowan(a)ccil.org
I wish it were impossible." http://www.ccil.org/~cowan
10:15 p.m.
New subject: why the leading under score added to function names?
I'm going to need to train myself to use the "reply to list" button.
Though in this case I think part of the problem was duplicate-filtering
which lost the copy that had the appropriate header.
On 2/25/2012 3:39 PM, John Cowan wrote:
Random832 scripsit:
This is not true in my experience. If it was ever true, it's not true
today (with MSVC, anyway. GCC may be different, but if there is a
'system-provided main()' it's GCC, or cygwin or mingw, and not anything
from microsoft, that is providing it). The procedure "provided by
windows" (provided by MSVC, actually) that does that is in fact called
WinMainCRTStartup. When you link a windows _console_ program, a
different function (called mainCRTStartup) which does the same setup
(plus opening a console if none is open and setting up stdio which the
WinMain version doesn't) and then invokes main().
The startup function is an interesting read - it has more work to do on
windows than the unix equivalent, because systems like signals (which
are in ANSI), file descriptor based I/O (which is not ANSI but
nevertheless is implemented in MSVC), and such, that are "naturally
occuring" on unix have to be set up. The whole program executes in a
__try/__except block to allow them to make signals work, for example.
For instance, this is, according to Raymond
Chen, why they added
WinMain rather than extending main (they didn't know if extensions to
main would be allowed).
That doesn't sound very reasonable to me. When you
link a Windows
program, it still has a main() procedure provided by Windows which does
setup and then invokes WinMain(). 
26 Feb
26 Feb
1:28 p.m.
New subject: why the leading under score added to function names?
On Feb 25, 2012, at 5:15 PM, Random832 wrote:
This is not true in my experience. If it was ever true, it's not true
today (with MSVC, anyway. GCC may be different, but if there is a
'system-provided main()' it's GCC, or cygwin or mingw, and not anything
from microsoft, that is providing it). The procedure "provided by
windows" (provided by MSVC, actually) that does that is in fact called
WinMainCRTStartup.
WinMainCRTStartup isn't the replacement for main. It's the replacement for
begin or location zero back in the old days. (Anybody remember seeing p&P6 printed by
errant programs?). There are different versions of that CRT startup (actually all
compiled from the same module with ifdefs) that start:
main - for non-MFC console apps
wmain - same thing but with wchar_t arguments (SOMETHING C/C++ standards hasn't ever
addressed to my satisfaction).
WinMain - MFC main function
wWinMain - Ditto, with wchar_t
Actually the bulk of the CRT involves converting between the command line argument as a
string and argc/argv (something UNIX does by the OS), and some gook necessary to support
C++.
The fake UNIX environment (POSIX) (read/write/seek, etc...) actually is NOT initialized
here, but when it is actually referenced.
27 Feb
27 Feb
1:30 a.m.
New subject: why the leading under score added to function names?
On Sun, Feb 26, 2012, at 08:28, Ronald Natalie wrote:
WinMainCRTStartup isn't the replacement for main.
I never said it was. My point was that there is no "main" anywhere in a
program that starts with WinMain, whereas John Cowan claimed that a
"main" exists in such programs which does the things that
WinMainCRTStartup in fact does.
main - for non-MFC console apps
wmain - same thing but with wchar_t arguments (SOMETHING C/C++ standards
hasn't ever addressed to my satisfaction).
I suspect this is partly because the unix world is a multibyte world,
and POSIX has "filenames don't have to be valid in any character set,
they're just bytes".
But Windows never had a satisfactory solution to multibyte vs wide in
pipes, either, anyway.
WinMain - MFC main function
This existed long before MFC, I suspect.
wWinMain - Ditto, with wchar_t
Actually the bulk of the CRT involves converting between the command line
argument as a string and argc/argv (something UNIX does by the OS), and
some gook necessary to support C++.
Well, not "by the OS" per se. More like, the OS only supports passing
argc/argv at any level, so the shell converts user-typed strings to
argv.
(A big gripe I have with the CRT is that its _spawn/_exec functions
don't quote strings containing spaces/etc so they can be round-tripped
by the CRT's argv initialization. And the argv code itself doesn't let
you have "wildcards in strings without quotes, literal stars in strings
with them", you have to choose between wildcards or not)
The fake UNIX environment (POSIX) (read/write/seek,
etc...) actually is
NOT initialized here, but when it is actually referenced.
mainCRTstartup does in fact call _ioinit() in the version I looked at. I
don't recall if WinMainCRTstartup does or not, it's not in front of me
now.
--
Random832
4436
days inactive
4441
days old
9 comments
9 participants
participants (9)
-
A. P. Garcia -
arnold＠skeeve.com -
Dave Horsfall -
Greg 'groggy' Lehey -
John Cowan -
Random832 -
random832＠fastmail.us
-
Ronald Natalie -
Steve Nickolas