Bug 239604
| Summary: | FIONREAD ioctl returns the wrong result on a master pty after the slave has been closed | ||||||
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| Product: | Base System | Reporter: | martin | ||||
| Component: | kern | Assignee: | Kyle Evans <kevans> | ||||
| Status: | Closed FIXED | ||||||
| Severity: | Affects Only Me | CC: | bugs, kevans | ||||
| Priority: | --- | Flags: | kevans:
mfc-stable14+
kevans: mfc-stable13+ kevans: mfc-stable12- |
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| Version: | 11.2-RELEASE | ||||||
| Hardware: | Any | ||||||
| OS: | Any | ||||||
| URL: | https://reviews.freebsd.org/D43457 | ||||||
| Attachments: |
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A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=30189156d325fbcc9d1997d791daedc9fa3bed20 commit 30189156d325fbcc9d1997d791daedc9fa3bed20 Author: Kyle Evans <kevans@FreeBSD.org> AuthorDate: 2024-01-16 02:55:59 +0000 Commit: Kyle Evans <kevans@FreeBSD.org> CommitDate: 2024-01-16 02:55:59 +0000 kern: pts: do not special case closed slave side This would previously return 1 if the slave side of the pts was closed to force an application to read() from it and observe the EOF, but it's not clear why and this is inconsistent both with how we handle devices with similar mechanics (like pipes) and also with other kernels, such as OpenBSD/NetBSD and Linux. PR: 239604 Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D43457 sys/kern/tty_pts.c | 7 +---- tests/sys/kern/Makefile | 3 ++ tests/sys/kern/tty_pts.c (new) | 64 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 6 deletions(-) A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=984128ce2d5eb7d3374dd4b245d443ec2f5d96b2 commit 984128ce2d5eb7d3374dd4b245d443ec2f5d96b2 Author: Kyle Evans <kevans@FreeBSD.org> AuthorDate: 2024-01-16 02:55:59 +0000 Commit: Kyle Evans <kevans@FreeBSD.org> CommitDate: 2024-01-30 17:11:10 +0000 kern: pts: do not special case closed slave side This would previously return 1 if the slave side of the pts was closed to force an application to read() from it and observe the EOF, but it's not clear why and this is inconsistent both with how we handle devices with similar mechanics (like pipes) and also with other kernels, such as OpenBSD/NetBSD and Linux. PR: 239604 Reviewed by: kib (cherry picked from commit 30189156d325fbcc9d1997d791daedc9fa3bed20) sys/kern/tty_pts.c | 7 +---- tests/sys/kern/Makefile | 3 ++ tests/sys/kern/tty_pts.c (new) | 64 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 6 deletions(-) A commit in branch stable/14 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=aebaa32c3108e99cc28d9aef7229ed4fe7da18ca commit aebaa32c3108e99cc28d9aef7229ed4fe7da18ca Author: Kyle Evans <kevans@FreeBSD.org> AuthorDate: 2024-01-16 02:55:59 +0000 Commit: Kyle Evans <kevans@FreeBSD.org> CommitDate: 2024-01-30 17:11:24 +0000 kern: pts: do not special case closed slave side This would previously return 1 if the slave side of the pts was closed to force an application to read() from it and observe the EOF, but it's not clear why and this is inconsistent both with how we handle devices with similar mechanics (like pipes) and also with other kernels, such as OpenBSD/NetBSD and Linux. PR: 239604 Reviewed by: kib (cherry picked from commit 30189156d325fbcc9d1997d791daedc9fa3bed20) sys/kern/tty_pts.c | 7 +---- tests/sys/kern/Makefile | 3 ++ tests/sys/kern/tty_pts.c (new) | 64 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 6 deletions(-) Merged to all stable branches, thanks! |
Created attachment 206224 [details] Example to reproduce the bug Compile the attached example with: cc -lutil pty-fionread.c When it is run, I would expect it to print: bytes1 = 0 bytes2 = 0 but in FreeBSD it prints: bytes1 = 0 bytes2 = 1 It looks like the FIOREAD ioctl always returns 1 after the slave side of the pty has been closed, regardless of whether any data is available. This contradicts the man page and also differs from Linux (and Solaris and AIX, which have very different code to open the pty).