gh-95174: Handle missing dup() and constants in WASI (GH-95229)

- check for ``dup()`` libc function
- handle missing ``F_DUPFD`` in ``dup2()`` replacement function
- add workaround for WASI libc bug in MSG_TRUNC
- ESHUTDOWN is missing, use EPIPE instead
- POLLPRI is missing, define as 0 (no-op)

5 files changed, 26 insertions, 2 deletions

diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 1ce7d86..3847349 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -4685,6 +4685,8 @@ exit:
     return return_value;
 }
 
+#if ((defined(HAVE_DUP3) || defined(F_DUPFD) || defined(MS_WINDOWS)))
+
 PyDoc_STRVAR(os_dup2__doc__,
 "dup2($module, /, fd, fd2, inheritable=True)\n"
 "--\n"
@@ -4740,6 +4742,8 @@ exit:
     return return_value;
 }
 
+#endif /* ((defined(HAVE_DUP3) || defined(F_DUPFD) || defined(MS_WINDOWS))) */
+
 #if defined(HAVE_LOCKF)
 
 PyDoc_STRVAR(os_lockf__doc__,
@@ -9105,6 +9109,10 @@ exit:
     #define OS_TCSETPGRP_METHODDEF
 #endif /* !defined(OS_TCSETPGRP_METHODDEF) */
 
+#ifndef OS_DUP2_METHODDEF
+    #define OS_DUP2_METHODDEF
+#endif /* !defined(OS_DUP2_METHODDEF) */
+
 #ifndef OS_LOCKF_METHODDEF
     #define OS_LOCKF_METHODDEF
 #endif /* !defined(OS_LOCKF_METHODDEF) */
@@ -9352,4 +9360,4 @@ exit:
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=bae15f09a1b3d2e7 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=9ff792e207a18392 input=a9049054013a1b77]*/
diff --git a/Modules/errnomodule.c b/Modules/errnomodule.c
index bf6766e..0516e73 100644
--- a/Modules/errnomodule.c
+++ b/Modules/errnomodule.c
@@ -280,6 +280,10 @@ errno_exec(PyObject *module)
 #ifdef ENOANO
     add_errcode("ENOANO", ENOANO, "No anode");
 #endif
+#if defined(__wasi__) && !defined(ESHUTDOWN)
+    // WASI SDK 16 does not have ESHUTDOWN, shutdown results in EPIPE.
+    #define ESHUTDOWN EPIPE
+#endif
 #ifdef ESHUTDOWN
     add_errcode("ESHUTDOWN", ESHUTDOWN, "Cannot send after transport endpoint shutdown");
 #else
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 40229bc..2e89e2f 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -9316,7 +9316,9 @@ os_dup_impl(PyObject *module, int fd)
     return _Py_dup(fd);
 }
 
-
+// dup2() is either provided by libc or dup2.c with AC_REPLACE_FUNCS().
+// dup2.c provides working dup2() if and only if F_DUPFD is available.
+#if (defined(HAVE_DUP3) || defined(F_DUPFD) || defined(MS_WINDOWS))
 /*[clinic input]
 os.dup2 -> int
     fd: int
@@ -9416,6 +9418,7 @@ os_dup2_impl(PyObject *module, int fd, int fd2, int inheritable)
 
     return res;
 }
+#endif
 
 
 #ifdef HAVE_LOCKF
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index 5c36eaa..4eea928 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -63,6 +63,11 @@ extern void bzero(void *, int);
 #  define SOCKET int
 #endif
 
+// WASI SDK 16 does not have POLLPRIO, define as no-op
+#if defined(__wasi__) && !defined(POLLPRI)
+#  define POLLPRI 0
+#endif
+
 typedef struct {
     PyObject *close;
     PyTypeObject *poll_Type;
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 9b4155e..5641613 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -7786,6 +7786,10 @@ PyInit__socket(void)
     PyModule_AddIntMacro(m, MSG_EOR);
 #endif
 #ifdef  MSG_TRUNC
+    // workaround for https://github.com/WebAssembly/wasi-libc/issues/305
+    #if defined(__wasi__) && !defined(__WASI_RIFLAGS_RECV_DATA_TRUNCATED)
+    #  define __WASI_RIFLAGS_RECV_DATA_TRUNCATED 2
+    #endif
     PyModule_AddIntMacro(m, MSG_TRUNC);
 #endif
 #ifdef  MSG_CTRUNC