Fixes (#819)

* remove ndk_patches/sys-shm.h.patch
add a note about libandroid-shmem and posix semaphores

* libandroid-shmem: enable package

* separate function to replace autoconf guess scripts

README.md

@@ -123,9 +123,12 @@ Common porting problems
 * mempcpy(3) is a GNU extension. We have added it to <string.h> provided TERMUX_EXPOSE_MEMPCPY is defined,
   so use something like CFLAGS+=" -DTERMUX_EXPOSE_MEMPCPY=1" for packages expecting that function to exist.
 
-* Android uses a customized version of shared memory managemnt known as ashmem. Standard shm and semaphore libc
-  wrappers (semget(2), shmat(2) and others) aren't available. Direct syscalls can be used with
-  `CFLAGS+=" -DTERMUX_SHMEM_STUBS=1 -DTERMUX_SEMOPS_STUBS=1"`.
+* Android uses a customized version of shared memory managemnt known as ashmem. libandroid-shmem wraps SYSV shared
+  memory calls to standard ashmem operations. Use it with `LDFLAGS+=" -landroid-shmem`.
+
+* SYSV semaphore libc wrappers (semget(2), semop(2) and others) aren't available. Direct syscalls can be used with
+  `CFLAGS+=" -DTERMUX_SEMOPS_STUBS=1"`. Using this requires privelege escalation i.e. only root can do it. Use
+  unnamed POSIX semaphores instead (named semaphores are unimplemented).
 
 dlopen() and RTLD_* flags
 =================================

build-package.sh

@@ -218,7 +218,7 @@ termux_step_setup_variables() {
 	TERMUX_STANDALONE_TOOLCHAIN="$TERMUX_TOPDIR/_lib/toolchain-${TERMUX_ARCH}-ndk${TERMUX_NDK_VERSION}-api${TERMUX_API_LEVEL}"
 	# Bump the below version if a change is made in toolchain setup to ensure
 	# that everyone gets an updated toolchain:
-	TERMUX_STANDALONE_TOOLCHAIN+="-v14"
+	TERMUX_STANDALONE_TOOLCHAIN+="-v15"
 
 	export TERMUX_TAR="tar"
 	export TERMUX_TOUCH="touch"
@@ -619,12 +619,17 @@ termux_step_setup_toolchain() {
 termux_step_patch_package() {
 	cd "$TERMUX_PKG_SRCDIR"
 	# Suffix patch with ".patch32" or ".patch64" to only apply for these bitnesses:
+	shopt -s nullglob
 	for patch in $TERMUX_PKG_BUILDER_DIR/*.patch{$TERMUX_ARCH_BITS,}; do
 		test -f "$patch" && sed "s%\@TERMUX_PREFIX\@%${TERMUX_PREFIX}%g" "$patch" | \
 			sed "s%\@TERMUX_HOME\@%${TERMUX_ANDROID_HOME}%g" | \
 			patch --silent -p1
 	done
+}
 
+# Replace autotools build-aux/config.{sub,guess} with ours to add android targets.
+termux_step_replace_guess_scripts () {
+	cd "$TERMUX_PKG_SRCDIR"
 	find . -name config.sub -exec chmod u+w '{}' \; -exec cp "$TERMUX_SCRIPTDIR/scripts/config.sub" '{}' \;
 	find . -name config.guess -exec chmod u+w '{}' \; -exec cp "$TERMUX_SCRIPTDIR/scripts/config.guess" '{}' \;
 }
@@ -1023,6 +1028,7 @@ termux_step_post_extract_package
 termux_step_handle_hostbuild
 termux_step_setup_toolchain
 termux_step_patch_package
+termux_step_replace_guess_scripts
 cd "$TERMUX_PKG_BUILDDIR"
 termux_step_pre_configure
 cd "$TERMUX_PKG_BUILDDIR"

ndk_patches/sys-shm.h.patch

@@ -1,20 +0,0 @@
---- /home/vishal/Android/Sdk/ndk-bundle/platforms/android-21/arch-arm/usr/include/sys/shm.h	2016-10-12 15:11:58.000000000 +0530
-+++ ./usr/include/sys/shm.h	2017-01-24 08:21:49.997228838 +0530
-@@ -31,4 +31,17 @@
- 
- #include <linux/shm.h>
- 
-+#ifdef TERMUX_SHMEM_STUBS
-+
-+#include <sys/syscall.h>
-+#include <limits.h>
-+
-+#define SHMLBA PAGE_SIZE
-+#define shmget(key, size, shmflg) syscall(__NR_shmget, key, size, shmflg)
-+#define shmctl(shmid, cmd, buf) syscall(__NR_shmctl, shmid, cmd, buf)
-+#define shmat(shmid, shmaddr, shmflg) syscall(__NR_shmat, shmid, shmaddr, shmflg)
-+#define shmdt(shmaddr) syscall(__NR_shmdt, shmaddr)
-+
-+#endif /* TERMUX_SHMEM_STUBS */
-+
- #endif /* _SYS_SHM_H_ */