[Libguestfs] [PATCH v2 2/3] build: Ensure zlib is statically linked before using it.

[Richard W.M. Jones]

From: "Richard W.M. Jones" <rjones at redhat.com>

---
 README             |  2 +-
 configure.ac       | 31 ++++++++++++++++++++++++++++++-
 helper/Makefile.am |  1 +
 helper/init.c      |  8 ++++----
 4 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/README b/README
index 6542471..3461d9d 100644
--- a/README
+++ b/README
@@ -68,7 +68,7 @@ are building:
   qemu >= 0.13
   kernel >= 2.6.36
 
-  zlib - if your kernel uses gzipped modules
+  zlib (statically linked) - if your kernel uses gzipped modules
 
 Building and installing
 -----------------------
diff --git a/configure.ac b/configure.ac
index c190e2c..b3144a4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -102,7 +102,36 @@ dnl For ArchLinux handler.
 AC_CHECK_PROG(PACMAN,[pacman],[pacman],[no])
 
 dnl Support for gzipped kernel modules.
-AC_CHECK_LIB([z],[gzopen])
+AC_CHECK_HEADER([zlib.h],[
+    AC_CHECK_LIB([z],[gzopen],[
+        AC_MSG_CHECKING([for gzip static library])
+        old_CFLAGS="$CFLAGS"
+        old_LDFLAGS="$LDFLAGS"
+        old_LIBS="$LIBS"
+        CFLAGS="$CFLAGS -static"
+        LDFLAGS="$LDFLAGS -static"
+        LIBS="$LIBS -lz"
+        AC_LINK_IFELSE([
+            #include <stdio.h>
+            #include <stdlib.h>
+            #include <zlib.h>
+            int main () { gzFile g = gzopen ("test", "rb"); exit (g ? 1 : 0); }
+        ],[
+            zlib_static=yes
+            ZLIB_STATIC_LIBS="-lz"
+            AC_MSG_RESULT([yes])
+        ],[
+            AC_MSG_RESULT([no])
+        ])
+        CFLAGS="$old_CFLAGS"
+        LDFLAGS="$old_LDFLAGS"
+        LIBS="$old_LIBS"
+    ])
+])
+if test "x$zlib_static" = "xyes"; then
+    AC_DEFINE([HAVE_ZLIB],[1],[Define if you have static zlib])
+    AC_SUBST([ZLIB_STATIC_LIBS])
+fi
 
 dnl mke2fs.
 AC_PATH_PROG([MKE2FS],[mke2fs],[no],
diff --git a/helper/Makefile.am b/helper/Makefile.am
index 55826d7..de32299 100644
--- a/helper/Makefile.am
+++ b/helper/Makefile.am
@@ -43,6 +43,7 @@ noinst_PROGRAMS = init
 init_SOURCES = init.c
 init_CFLAGS = -static
 init_LDFLAGS = -static
+init_LDADD = $(ZLIB_STATIC_LIBS)
 
 CLEANFILES = ext2init.S
 
diff --git a/helper/init.c b/helper/init.c
index c53bf9d..4c10bff 100644
--- a/helper/init.c
+++ b/helper/init.c
@@ -41,7 +41,7 @@
 
 #include <asm/unistd.h>
 
-#ifdef HAVE_LIBZ
+#ifdef HAVE_ZLIB
 #include <zlib.h>
 #endif
 
@@ -97,7 +97,7 @@ main ()
   print_uptime ();
   fprintf (stderr, "supermin: ext2 mini initrd starting up: "
            PACKAGE_VERSION
-#ifdef HAVE_LIBZ
+#ifdef HAVE_ZLIB
            " zlib"
 #endif
            "\n");
@@ -268,7 +268,7 @@ insmod (const char *filename)
   if (verbose)
     fprintf (stderr, "supermin: internal insmod %s\n", filename);
 
-#ifdef HAVE_LIBZ
+#ifdef HAVE_ZLIB
   gzFile gzfp = gzopen (filename, "rb");
   int capacity = 64*1024;
   char *buf = (char *) malloc (capacity);
@@ -328,7 +328,7 @@ insmod (const char *filename)
      */
   }
 
-#ifdef HAVE_LIBZ
+#ifdef HAVE_ZLIB
   free (buf);
 #endif
 }
-- 
1.8.3.1