AIX support for System.Native/PAL (dotnet/corefx#30012)

* AIX support for System.Native/PAL

Somewhat incomplete, but at least on Mono version, gets it compiling,
so work on it can be done; as I believe the nopped out functions aren't
hooked up to Mono's BCL yet. For now, if merged, would let me get back
to working on a patch for UnicodeEncoding ;)

See mono/corefxdotnet/corefx#69 for the description.

This is for Mono, as CoreCLR doesn't run under AIX or i.

* make some of the suggested changes

* fix networking.c, defines in io

* fix errenous define, stupid me

* Forgot to include where AIX deviates from the rest of the world on poll

* Handle F_DUPFD_CLOEXEC properly

* fix possible bug there; be defensive; and explain why

* Don't make AIX change the PAL_POLL* values

These need to be the same on all platforms. Currently, it seems
that pal_io.c doesn't actually use these values (yet?) so I've
disabled the check there. pal_console is the only consumer of a
definition there, but it's not built for Mono and thus AIX yet, so
I haven't touched it.

Useful dump of AIX poll values:

    POLLIN = 0x0001,   /* non-urgent readable data available */
    POLLPRI = 0x0004,  /* urgent readable data available */
    POLLOUT = 0x0002,  /* data can be written without blocked */
    POLLERR = 0x4000,  /* an error occurred */
    POLLHUP = 0x2000,  /* the file descriptor hung up */
    POLLNVAL = 0x8000, /* the requested events were invalid */

And of finding the users of these definitions within the directory
"srcNative/Unix/System.Native":

$ grep -R POLL | grep -v EPOLL
pal_console.cpp:    struct pollfd fd = { .fd = STDIN_FILENO, .events = POLLIN };
pal_io.c:// HACK: AIX values are different; this file doesn't actually use POLL* yet, so
pal_io.c:c_static_assert(PAL_POLLIN == POLLIN);
pal_io.c:c_static_assert(PAL_POLLPRI == POLLPRI);
pal_io.c:c_static_assert(PAL_POLLOUT == POLLOUT);
pal_io.c:c_static_assert(PAL_POLLERR == POLLERR);
pal_io.c:c_static_assert(PAL_POLLHUP == POLLHUP);
pal_io.c:c_static_assert(PAL_POLLNVAL == POLLNVAL);
pal_io.h:    PAL_POLLIN = 0x0001,   /* non-urgent readable data available */
pal_io.h:    PAL_POLLPRI = 0x0002,  /* urgent readable data available */
pal_io.h:    PAL_POLLOUT = 0x0004,  /* data can be written without blocked */
pal_io.h:    PAL_POLLERR = 0x0008,  /* an error occurred */
pal_io.h:    PAL_POLLHUP = 0x0010,  /* the file descriptor hung up */
pal_io.h:    PAL_POLLNVAL = 0x0020, /* the requested events were invalid */

* We actually /do/ need to translate PollEvents after all

stupid me, I didn't notice

* fix ConvertDirent's fallback case to use proper if brace style

* don't make it a TODO as this requires more work later; consistent ifdef

* Initial attempt at CMake detection for things

* Add the CMake checks to pal_config too

* remove my stupid typo

* consistent ifdef/if

* check for poll function

the #else case on pal_networking hasn't changed because it's a stub
for now. when it becomes a real boy someday, it'll get an #elif for
`HAVE_POLL`.

* change func check to incl check for poll; mono does this too


Commit migrated from https://github.com/dotnet/corefx/commit/eedd1c2784fd1c597428187985df00567bc00f86

1 files changed, 5 insertions, 0 deletions

diff --git a/src/libraries/Native/Unix/System.Native/pal_random.c b/src/libraries/Native/Unix/System.Native/pal_random.c
index a46896e8771..979df55000e 100644
--- a/src/libraries/Native/Unix/System.Native/pal_random.c
+++ b/src/libraries/Native/Unix/System.Native/pal_random.c
@@ -40,7 +40,12 @@ void SystemNative_GetNonCryptographicallySecureRandomBytes(uint8_t* buffer, int3
 
             do
             {
+#if HAVE_O_CLOEXEC
                 fd = open("/dev/urandom", O_RDONLY, O_CLOEXEC);
+#else
+                fd = open("/dev/urandom", O_RDONLY);
+                fcntl(fd, F_SETFD, FD_CLOEXEC);
+#endif
             }
             while ((fd == -1) && (errno == EINTR));