Port to FreeBSD #86

vrza · 2022-06-08T10:27:49Z

Ported to FreeBSD
Makefile now compatible with both GNU make and BSD make

Caveat: needs GNU binutils 2.38 which is not yet in the FreeBSD ports tree, and binutils.sh will not compile it cleanly as configuration fails to include headers /usr/local/include. Did not want to go down this rabbit hole for now, as perhaps arrival of binutils 2.38 in FreeBSD ports will solve it.

Closes #81

- support BSD tar(1) - support BSD install(1) - remove dependency on working directory from binutils and gzip build scripts - explicit dependency on GNU make (gmake(1))

OpenBSD doesn't seem to allow ioctl(2) to write directly to the data segment in constructor code. Passing a heap pointer instead.

taviso · 2022-06-10T14:03:32Z

Thanks so much for working on this - I think we can merge most of this!

I think must be alloca() defined somewhere, and if not we can just use #define alloca __builtin_alloca, but we can't just s/alloca/malloc/, because it will leak memory.

vrza · 2022-06-10T17:07:13Z

@taviso Yeah, good catch. While BSD does not have strndupa(3), it does have plain alloca(3), but it's declared in stdlib.h rather than alloca.h. Fixed.

taviso · 2022-06-15T05:42:02Z

Sorry for the slow response here - I've been working on tests and the showme bug!
Now that I have some tests I'm less worried about big changes.

vrza · 2022-06-15T09:17:39Z

Great, having a regression test suite is super helpful.

Perhaps setting up an automated CI workflow is in order.

Not sure about a cheap way to run CI for FreeBSD, OpenBSD, Solaris etc. GitHub Actions is free (as in beer), integrates with the GitHub workflow out of the box, and supports Linux and MacOS runners out of the box, so might be a decent starting point. Maybe there's a way to spin up VMs in their CI runner hosts.

The regression test suite should be portable as well.

taviso · 2022-06-16T04:50:00Z

wrappers.c

@@ -417,7 +419,7 @@ struct unixdirent * __unix_readdir(DIR *dirp)
    return NULL;
 }

-sighandler_t __unix_signal(int signum, sighandler_t handler)


It seems like FreeBSD does have sig_t though, I think we should add something like this:

#ifdef __FreeBSD__ typedef sig_t sighandler_t; #endif

I don't think that it's a good idea to use GNU as a baseline and then add an exception for each system that's not GNU. Maintaining many platform-specific code paths with #ifdefs on our end could get out of hand quickly.

Rather we should leverage the POSIX standard in the first place, and in the second place we should leverage GNU's compatibility features. GNU libc knows about POSIX, and knows about BSD, and offers so-called Feature Test Macros for compatibility purposes. There's a good writeup about FTMs on on LWN, and more info in glibc documentation and in the feature_test_macros(7) man page.

Concretely, using -D_DEFAULT_SOURCE instead of -D_GNU_SOURCE would make BSD sig_t translate into GNU sighandler_t. Howeve I'm interested in the reasoning behind using _GNU_SOURCE in the first place?

However, while using _DEFAULT_SOURCE and sig_t would work with GNU/Linux and all BSDs, it would not work on e.g. System V, which happens to be the system that this version of 123 was originally built for! I strongly feel that if we're porting this old SVR4 Lotus 123 to other platforms we should observe POSIX and System V APIs first and foremost, and only reach for GNU and BSD APIs and tooling where it's necessary to do so. This might be a matter of personal opinion, but nevertheless a matter I feel we should have some alignment on.

Anyways, hope this explains why I choose to observe the POSIX standard whenever possible, and in this particular case. This particular case is in alignment with the C standard as well.

taviso · 2022-06-16T04:53:38Z

wrappers.c

@@ -426,10 +428,10 @@ sighandler_t __unix_signal(int signum, sighandler_t handler)
        [16] = SIGUSR1,
        [17] = SIGUSR2,
        [18] = SIGCHLD,
-        [19] = SIGPWR,
+        [19] = SIGCONT,


The intention here is to map UNIX signal numbers to Linux numbers, and it thinks 19 is SIGPWR. If FreeBSD doesn't have it, I think it should be -1, maybe just

#ifdef SIGPWR [19] = SIGPWR, #else [19] = -1, #endif

Hm, while I did quickly hack this by finding some supposedly portable list of magic numbers online, I'm not absolutely clear about the intention behind this lookup table, perhaps you could help clarify it.

SIGPWR seems to be a Linux-specific symbol, and many other symbols in this table are not defined in the POSIX standard, not sure if they are defined on System V either. Is the original code, or our extensions to it, registering a handler for signal 19?

Similarly, magic numbers in the table (SIGUSR1, SIGUSR2, SIGCHLD...) that are not specific to Linux were likely the same on System V, so it eludes me why they would need to be translated. I can comment out all of these and the program seems to run fine, so I'm confused.

Finally, how did we arrive at translating the magic number 19 to the value of SIGPWR? On my Linux system, for example, SIGPWR is 30.

taviso · 2022-06-16T04:54:56Z

wrappers.c

@@ -23,6 +23,10 @@ extern int __unix_errno;
 #define SI86FPHW 40
 #define FP_387 3

+#define TCGETS 0x5401


Hmm, maybe we're just missing an include?

No, I don't believe that BSD defines these ioctl(2) magic numbers. They are likely included on Linux for compatibility with legacy software, but according to the POSIX standard we should use tcgetattr(fd, argp) instead.

taviso · 2022-06-16T04:56:13Z

patch.c

 #include <stdio.h>
 #include <stdint.h>
-#include <alloca.h>


I think maybe just wrap this in #ifdef __Linux__

Although it doesn't seem to be standardised, alloca is not specific to Linux, but rather a GNU extension to the C compiler, implemented at least by GCC and clang, possibly other compilers. A comment in FreeBSD stdlib.h sheds some light:

/* * The alloca() function can't be implemented in C, and on some * platforms it can't be implemented at all as a callable function. * The GNU C compiler provides a built-in alloca() which we can use. * On platforms where alloca() is not in libc, programs which use it * will fail to link when compiled with non-GNU compilers. */ #if __GNUC__ >= 2 #undef alloca /* some GNU bits try to get cute and define this on their own */ #define alloca(sz) __builtin_alloca(sz) #endif

Similar to the discussion about sig_t, if we define _DEFAULT_SOURCE then glibc stdlib.h will know it should pull in alloca.h, so that's another place where using _DEFAULT_SOURCE can help wuith portability.

taviso · 2022-06-16T04:58:12Z

Makefile

@@ -1,74 +1,79 @@
+platform != uname -s
+undefine != ./detect-os-symbol-list-file.sh undefine


Seems okay, but maybe we can just do undefine undefine-$(shell uname).lst? I dunno if that is portable though!

AFAIK syntax-wise that should be portable between GNU and BSD make , but on systems for which you don't have an explicit list file, the build will error out with file not found. The shell script provides a default if it doesn't have explicit rules about the host system.

emaste · 2022-09-06T15:49:52Z

Not sure about a cheap way to run CI for FreeBSD, OpenBSD, Solaris etc.

FreeBSD CI can be done via Cirrus-CI, although that still leaves the others.

vrza added 28 commits June 5, 2022 09:10

Ignore local gzip build

09a6d81

Shell script portability improvements

65683f9

- support BSD tar(1) - support BSD install(1) - remove dependency on working directory from binutils and gzip build scripts - explicit dependency on GNU make (gmake(1))

Portable detection of ncurses linker lib flags

731619f

More portable Makefile

8892e2a

$(RM) might not be set

dbd71a8

Remove GNU-specific $(sort) and |

dc94021

Helper shell script to install keymaps

0db1e6f

More Makefile compatibility

98e7eac

Use more portable strndup instad of strndupa

d85e398

Use malloc instead of GNU-specific alloca

91a047f

Remove non-portable sighandler_t

3ce58b8

Better ncurses linker flags detection

8a040b3

Use malloc instead of alloca

296be70

More portable install(1) invocation

be48ef6

More portable install(1) invocation

f5e373d

Fix missing include

a075613

Consistent install invocation

d8914be

Include malloc through stdlib.h

8683a84

Build GNU as with binutils

2ade82f

Drop non-portable nproc

da75cce

Add locally built as to gitignore

e62f142

Port to FreeBSD

5d88b62

Find GNU make in PATH

98c3ace

Remove commented out code

0777099

Fix install(1) invocation

1404255

Merge branch 'main' into openbsd-1

0d1ee00

Fix typo

1faceb1

Undefine init_showme on FreeBSD

3fcb192

vrza mentioned this pull request Jun 8, 2022

Minor portability improvements #74

Open

Shell script to detect OS-specific symbol list file

2116cb3

vrza added 2 commits June 8, 2022 13:59

Use kebab case for script name

76e1872

Fix build on NetBSD

2c8f2d4

vrza mentioned this pull request Jun 8, 2022

NetBSD port #77

Open

vrza added 3 commits June 8, 2022 15:43

Localize fwrite on Linux

aac3764

Symbol undefine list for OpenBSD

8c8a21e

Add environ to OpenBSD undefine list

067bea0

vrza mentioned this pull request Jun 9, 2022

OpenBSD port #87

Open

Workaround for OpenBSD

522c490

OpenBSD doesn't seem to allow ioctl(2) to write directly to the data segment in constructor code. Passing a heap pointer instead.

Revert some malloc changes

a44ff9c

vrza added 5 commits June 10, 2022 19:20

Rebuild list undefine.openbsd

6b9e561

Quote command substitution

546186d

Merge updates from main

587d6bd

Merge branch 'main' into openbsd-1

0e0e810

Include alloca from stdlib.h for portability

5a0db70

taviso reviewed Jun 16, 2022

View reviewed changes

vrza added 2 commits June 17, 2022 14:16

Don't use non-portable -v

e644cf5

Don't use non-portable -v

9d413c8

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Port to FreeBSD #86

Port to FreeBSD #86

vrza commented Jun 8, 2022

taviso commented Jun 10, 2022

vrza commented Jun 10, 2022 •

edited

taviso commented Jun 15, 2022

vrza commented Jun 15, 2022

taviso Jun 16, 2022

vrza Jun 16, 2022 •

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taviso Jun 16, 2022

vrza Jun 16, 2022 •

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taviso Jun 16, 2022

vrza Jun 16, 2022 •

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taviso Jun 16, 2022

vrza Jun 16, 2022

taviso Jun 16, 2022

vrza Jun 16, 2022 •

edited

emaste commented Sep 6, 2022

		@@ -1,74 +1,79 @@
		platform != uname -s
		undefine != ./detect-os-symbol-list-file.sh undefine

Port to FreeBSD #86

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Port to FreeBSD #86

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vrza commented Jun 8, 2022

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