git-compat-util: prefer poll.h to sys/poll.h

POSIX specifies that <poll.h> is the correct header for poll(2) whereas <sys/poll.h> is only needed for some old libc.

Let's follow the POSIX way by default.

This effectively eliminates musl's warning:

warning redirecting incorrect #include <sys/poll.h> to <poll.h>

---
t0028, t1308.23, t3900.34 is failing under musl, Those test cases in question also fails without this patch.

- t0028 is failing because musl iconv output UTF-16 without BOM. I'm not sure if my installation is broken, or it's musl's default behavior. But, I think RFC2781, section 4.3 allows the missing BOM

- t1308.23 is failing because musl fopen is success when open directory in readonly mode. POSIX allows this behavior:
http://pubs.opengroup.org/onlinepubs/7908799/xsh/fopen.html
[EISDIR]
The named file is a directory and mode requires write access.

- t3900.34: from what I understand, musl haven't supported ISO-2022-JP, yet.
https://wiki.musl-libc.org/functional-differences-from-glibc.html#iconv

 Makefile          | 8 +++++++-
 configure.ac      | 6 ++++++
 git-compat-util.h | 5 ++++-
 3 files changed, 17 insertions(+), 2 deletions(-)

index bbfbb4292..5734efe74 100644
@@ -207,10 +207,12 @@ all::
 # Define MMAP_PREVENTS_DELETE if a file that is currently mmapped cannot be
 # deleted or cannot be replaced using rename().
 #
+# Define NO_POLL_H if you don't have poll.h.
+#
 # Define NO_SYS_POLL_H if you don't have sys/poll.h.
 #
 # Define NO_POLL if you do not have or don't want to use poll().
-# This also implies NO_SYS_POLL_H.
+# This also implies NO_POLL_H and NO_SYS_POLL_H.
 #
 # Define NEEDS_SYS_PARAM_H if you need to include sys/param.h to compile,
 # *PLEASE* REPORT to [email protected] if your platform needs this;

@@ -1459,6 +1461,7 @@ ifdef NO_GETTEXT
 	USE_GETTEXT_SCHEME ?= fallthrough
 endif
 ifdef NO_POLL
+	NO_POLL_H = YesPlease
 	NO_SYS_POLL_H = YesPlease
 	COMPAT_CFLAGS += -DNO_POLL -Icompat/poll
 	COMPAT_OBJS += compat/poll/poll.o

@@ -1497,6 +1500,9 @@ endif
 ifdef NO_SYS_SELECT_H
 	BASIC_CFLAGS += -DNO_SYS_SELECT_H
 endif
+ifdef NO_POLL_H
+	BASIC_CFLAGS += -DNO_POLL_H
+endif
 ifdef NO_SYS_POLL_H
 	BASIC_CFLAGS += -DNO_SYS_POLL_H
 endif

index e11b7976a..908e66a97 100644
@@ -792,6 +792,12 @@ AC_CHECK_HEADER([sys/select.h],
 [NO_SYS_SELECT_H=UnfortunatelyYes])
 GIT_CONF_SUBST([NO_SYS_SELECT_H])
 #
+# Define NO_POLL_H if you don't have poll.h
+AC_CHECK_HEADER([poll.h],
+[NO_POLL_H=],
+[NO_POLL_H=UnfortunatelyYes])
+GIT_CONF_SUBST([NO_POLL_H])
+#
 # Define NO_SYS_POLL_H if you don't have sys/poll.h
 AC_CHECK_HEADER([sys/poll.h],
 [NO_SYS_POLL_H=],

index 96a3f86d8..65f229f10 100644
@@ -180,9 +180,12 @@
 #include <regex.h>
 #include <utime.h>
 #include <syslog.h>
-#ifndef NO_SYS_POLL_H
+#if !defined(NO_POLL_H)
+#include <poll.h>
+#elif !defined(NO_SYS_POLL_H)
 #include <sys/poll.h>
 #else
+/* Pull the compat stuff */
 #include <poll.h>
 #endif
 #ifdef HAVE_BSD_SYSCTL

2.19.1.856.g8858448bb.dirty

I think this patch is fine. This was in SUSv2, and I don't feel bad about siding with a spec that's at least 17 years old.

While the spec may allow this, we cannot for practical reasons. There are a large number of broken Windows programs that don't honor the spec when it says to interpret UTF-16 byte sequences without a BOM as big-endian, and instead use little-endian. Since we cannot fix all the broken Windows programs people use, we need to emit the BOM in UTF-16 mode.

Does setting FREAD_READS_DIRECTORIES fix this?

brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

Yup, I agree. Thanks, both.

Yes, setting FREAD_READS_DIRECTORIES fixes this.
And, configure can set that itself.

I blindly followed the Void's build template which explicitly unset it in the configure script without investigating it.
My bad!

I'll send them a patch to fix this downstream.

Danh