Merge branch 'patch-4' into 'master'

New kernel compatibility; obstack; pthread_getname_np

The gcompat loader compiled as a static binary doesn't work on Linux since [a4ff8e8620d3f4](https://github.com/torvalds/linux/commit/a4ff8e8620d3f4f50ac4b41e8067b7d395056843), failing with an error like:
```
[349055.473655] 13325 (cmake): Uhuuh, elf segment at 0000000000400000 requested but the memory is mapped already
```
This is because the actual binary we want to run is also loaded at 0x400000. While it's actually okay to overlap the binary, since we're going to call `execve` again, the kernel doesn't allow the overlap anymore. Fix that by compiling the loader as static PIE, so it can be put at a different address.

Also add `pthread_getname_np` and the option to link `obstack`.

See merge request !4

1 files changed, 27 insertions, 12 deletions

diff --git a/Makefile b/Makefile
index 934422f..6a36129 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,6 @@
 LIBGCOMPAT_INCLUDE = \
-	libgcompat/alias.h
+	libgcompat/alias.h \
+	libgcompat/internal.h
 LIBGCOMPAT_SRC = \
 	libgcompat/ctype.c		\
 	libgcompat/cxx_thread.c		\
@@ -43,36 +44,50 @@ LOADER_OBJ = ${LOADER_SRC:.c=.o}
 LOADER_NAME = ld-linux.so.2
 LOADER_PATH = /lib/${LOADER_NAME}
 
-ifdef WITH_LIBUCONTEXT
+PKG_CONFIG ?= pkg-config
 
-LIBUCONTEXT_LIBS   = -Wl,--no-as-needed -lucontext
+ifdef WITH_LIBUCONTEXT
 LIBUCONTEXT_CFLAGS = -DWITH_LIBUCONTEXT
+LIBUCONTEXT_LIBS   = -lucontext
+endif
+
+ifndef WITH_OBSTACK
+WITH_OBSTACK = $(shell \
+  for pkg in obstack obstack-standalone; do \
+    ${PKG_CONFIG} --exists "$$pkg" && { echo "$$pkg"; exit 0; } \
+  done; echo "no")
+endif
 
+ifneq (${WITH_OBSTACK},no)
+OBSTACK_CFLAGS = $(shell ${PKG_CONFIG} --cflags ${WITH_OBSTACK}) -DWITH_OBSTACK
+OBSTACK_LIBS   = $(shell ${PKG_CONFIG} --libs ${WITH_OBSTACK})
 endif
 
 all: ${LIBGCOMPAT_NAME} ${LOADER_NAME}
 
 ${LIBGCOMPAT_NAME}: ${LIBGCOMPAT_OBJ}
-	$(CC) -o ${LIBGCOMPAT_NAME} -Wl,-soname,${LIBGCOMPAT_NAME} \
-		-shared ${LIBGCOMPAT_OBJ} ${LIBUCONTEXT_LIBS}
+	${CC} ${CFLAGS} ${LDFLAGS} -shared -Wl,-soname,${LIBGCOMPAT_NAME} \
+		-o ${LIBGCOMPAT_NAME} ${LIBGCOMPAT_OBJ} \
+		-Wl,--no-as-needed ${LIBUCONTEXT_LIBS} ${OBSTACK_LIBS}
 
 ${LIBGCOMPAT_OBJ}: ${LIBGCOMPAT_INCLUDE}
 
 ${LOADER_NAME}: ${LOADER_OBJ}
-	$(CC) -o ${LOADER_NAME} -fPIE -static ${LOADER_OBJ}
+	${CC} ${CFLAGS} ${LDFLAGS} -static-pie -o ${LOADER_NAME} ${LOADER_OBJ}
 
 .c.o:
-	$(CC) -c -D_BSD_SOURCE -DLIBGCOMPAT=\"${LIBGCOMPAT_PATH}\" \
-		-DLINKER=\"${LINKER_PATH}\" -DLOADER=\"${LOADER_NAME}\" \
-		-Ilibgcompat ${LIBUCONTEXT_CFLAGS} \
-		-fPIC -std=c99 -Wall -Wextra -Wno-frame-address \
-		-Wno-unused-parameter ${CFLAGS} ${CPPFLAGS} -o $@ $<
+	${CC} ${CPPFLAGS} ${CFLAGS} -c -D_BSD_SOURCE \
+		-DLIBGCOMPAT='"${LIBGCOMPAT_PATH}"' \
+		-DLINKER='"${LINKER_PATH}"' -DLOADER='"${LOADER_NAME}"' \
+		-fPIC -Ilibgcompat -std=c99 \
+		-Wall -Wextra -Wno-frame-address -Wno-unused-parameter \
+		${LIBUCONTEXT_CFLAGS} ${OBSTACK_CFLAGS} -o $@ $<
 
 clean:
 	rm -f libgcompat/*.o loader/*.o ${LIBGCOMPAT_NAME} ${LOADER_NAME}
 
 format:
-	clang-format -i ${LIBGCOMPAT_SRC} ${LOADER_SRC}
+	clang-format -i ${LIBGCOMPAT_INCLUDE} ${LIBGCOMPAT_SRC} ${LOADER_SRC}
 
 install: all
 	install -D -m755 ${LIBGCOMPAT_NAME} ${DESTDIR}/${LIBGCOMPAT_PATH}