| 29 Dec 2025 |
 emily | stuff like hardening flags doesn't have that kind of effect | 00:49:40 |
 Ihar Hrachyshka | The behaviour of these macros is undefined if the fd argument is less than 0 or greater than or equal to FD_SETSIZE.
Admittedly, there's nothing in POSIX that forces the value, but Apple decided to force it in libSystem. So maybe I should replace the wording that this could be related to POSIX certification with something better... | 00:50:01 |
 Randy Eckenrode | The unwrapped case is a good argument not to do this by default, especially with more languages handling compilation themselves (e.g., Rust, Swift, Zig). | 00:51:13 |
| Randy Eckenrode | * | 00:51:26 |
| Ihar Hrachyshka | ack. are we ok with glib local change? | 00:51:53 |
| emily | fwiw it looks like the flag actually redirects select to a variant with a different suffix | 00:52:12 |
| emily | non-pointer fd_set ABI would still be an issue though (for both Apple and us) | 00:52:29 |
| emily | let's see what upstream says? hopefully it can get merged there and we can just backport it | 00:53:11 |
| emily | I'm wondering if glib could just do the heap allocation thing, but I guess that would be more major surgery | 00:53:20 |
| emily | I'm a bit worried about the scope of glib_conf | 00:53:33 |
| Ihar Hrachyshka | it's on stack atm. | 00:53:36 |
| emily | e.g. is it set just for glib sources or for the sources of all programs that use glib? | 00:53:40 |
| Ihar Hrachyshka | afaiu this is for building glib. | 00:53:56 |
| Ihar Hrachyshka | (not for dependencies) | 00:54:16 |
| Ihar Hrachyshka | * (not for children users) | 00:54:23 |
| emily | https://gitlab.gnome.org/GNOME/glib/-/blob/2f8a985d6f603257707f1805713c42df72532a01/glib/gtypes.h does #include <glibconfig.h> | 00:54:33 |
| emily | (and is included by other public glib headers) | 00:54:46 |
| Ihar Hrachyshka | glibconfig.h ! config.h? | 00:54:54 |
| Randy Eckenrode | Is it possible to add a test? Like try to have g_pol work with a large number of fds? Would that be an okay test? | 00:54:57 |
| Randy Eckenrode | * Is it possible to add a test? Like try to have g_poll work with a large number of fds? Would that be an okay test? | 00:55:19 |
| emily | hmm, though I have no glibconfig.h | 00:55:33 |
| Ihar Hrachyshka | https://github.com/GNOME/glib/blob/main/glib/glibconfig.h.in | 00:56:02 |
| Randy Eckenrode | I wonder if the change should be localized to just the g_poll implementation. | 00:56:08 |
| Ihar Hrachyshka | the glib_conf meson declaration affects config.h used to build glib | 00:56:26 |
| emily | ok, going by glib_conf.set('_GNU_SOURCE', 1) I suppose it ought to be local :) | 00:56:43 |
| Randy Eckenrode | I pondered whether to use a heuristic to malloc enough, but doesn’t the set size have to cover all fds in the process? | 00:56:53 |
| emily | won't work, since it has to be set early enough for headers | 00:56:56 |
| emily | you'd at least need to make it scoped to the file | 00:57:03 |
| Ihar Hrachyshka |
I wonder if the change should be localized to just the g_poll implementation.
it is already. The BROKEN_POLL macro is only used in g_poll.
| 00:57:36 |
| emily | btw, doesn't the check against FD_SETSIZE prevent potential heap overflow? | 00:58:01 |
