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Cygwin: pipe: Fix hang due to inadvertent 0-length raw_write() and some signal fixes #91

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Merged
merged 3 commits into from
Mar 31, 2025
Merged

Cygwin: pipe: Fix hang due to inadvertent 0-length raw_write() and some signal fixes #91

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5c97a05
Cygwin: pipe: Fix hang due to inadvertent 0-length raw_write()
dscho Mar 27, 2025
4fbceca
Cygwin: signal: Clear direction flag in sigdeleyed
dscho Mar 31, 2025
529a0f0
Cygwin: signal: Copy context to alternate stack in the SA_ONSTACK case
dscho Mar 31, 2025
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8 changes: 8 additions & 0 deletions winsup/cygwin/exceptions.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1807,6 +1807,13 @@ _cygtls::call_signal_handler ()
to 16 byte. */
uintptr_t new_sp = ((uintptr_t) _my_tls.altstack.ss_sp
+ _my_tls.altstack.ss_size) & ~0xf;
/* Copy context1 to the alternate signal stack area, because the
context1 allocated in the normal stack area is not accessible
from the signal handler that uses alternate signal stack. */
thiscontext = (ucontext_t *) ((new_sp - sizeof (ucontext_t)) & ~0xf);
memcpy (thiscontext, &context1, sizeof (ucontext_t));
new_sp = (uintptr_t) thiscontext;

/* In assembler: Save regs on new stack, move to alternate stack,
call thisfunc, revert stack regs. */
#ifdef __x86_64__
Expand Down Expand Up @@ -1850,6 +1857,7 @@ _cygtls::call_signal_handler ()
#else
#error unimplemented for this target
#endif
memcpy (&context1, thiscontext, sizeof (ucontext_t));
}
else
/* No alternate signal stack requested or available, just call
Expand Down
2 changes: 1 addition & 1 deletion winsup/cygwin/fhandler/pipe.cc
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Expand Up @@ -1158,7 +1158,7 @@ fhandler_pipe::set_pipe_buf_size ()
status = NtQueryInformationFile (get_handle (), &io, &fpli, sizeof fpli,
FilePipeLocalInformation);
if (NT_SUCCESS (status))
pipe_buf_size = fpli.InboundQuota;
pipe_buf_size = fpli.InboundQuota < PIPE_BUF ? PIPE_BUF : fpli.InboundQuota;
}

int
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8 changes: 8 additions & 0 deletions winsup/cygwin/release/3.6.1
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Expand Up @@ -3,3 +3,11 @@ Fixes:

- Console mode is really restored to the previous mode.
Addresses: https://github.com/msys2/msys2-runtime/issues/268

- Clear direction flag in sigdeleyed before calling signal handler.
Addresses: https://cygwin.com/pipermail/cygwin/2025-March/257704.html

- Copy context to alternate signal stack area in call_signal_handler()
in the SA_ONSTACK case, because locally-copied context on the normal
stack area is not accessible from the signal handler.
Addresses: https://cygwin.com/pipermail/cygwin/2025-March/257714.html
1 change: 1 addition & 0 deletions winsup/cygwin/scripts/gendef
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Expand Up @@ -179,6 +179,7 @@ sigdelayed:
movq %rsp,%rbp
pushf
.seh_pushreg %rax # fake, there's no .seh_pushreg for the flags
cld # x86_64 ABI requires direction flag cleared
# stack is aligned or unaligned on entry!
# make sure it is aligned from here on
# We could be called from an interrupted thread which doesn't know
Expand Down