zkey: Add build dependency to OpenSSL (libcrypto)

The integrity support for the properties file routines use
SHA-256 to build a hash of the keys and values of a property file.
The codes uses the EVP_DigestInit_ex, EVP_DigestUpdate, and
EVP_DigestFinal from the libcrypto library (OpenSSL).

Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

README.md

@@ -264,6 +264,7 @@ build options:
 | pfm            | `HAVE_PFM`         | cpacfstats                            |
 | net-snmp       | `HAVE_SNMP`        | osasnmpd                              |
 | glibc-static   | `HAVE_LIBC_STATIC` | zfcpdump                              |
+| openssl        | `HAVE_OPENSSL`     | zkey                                  |
 
 This table lists additional build or install options:
 
@@ -366,3 +367,8 @@ the different tools are provided:
   For running znetconf these programs are required:
   - modprobe (kmod)
   - vmcp (s390-tools)
+
+* zkey:
+  For building the zkey tools you need openssl version 0.9.7 or newer installed
+  (openssl-devel.rpm). Tip: you may skip the zkey build by adding
+  `HAVE_OPENSSL=0` to the make invocation.

zkey/Makefile

@@ -1,9 +1,26 @@
 include ../common.mak
 
+ifeq (${HAVE_OPENSSL},0)
+
+all:
+	$(SKIP) HAVE_OPENSSL=0
+
+install:
+	$(SKIP) HAVE_OPENSSL=0
+
+else
+
+check_dep:
+	$(call check_dep, \
+		"zkey", \
+		"openssl/evp.h", \
+		"openssl-devel", \
+		"HAVE_OPENSSL=0")
+
 CPPFLAGS += -I../include
 LDLIBS += -ldl -lcrypto
 
-all: zkey
+all: check_dep zkey
 
 libs = $(rootdir)/libutil/libutil.a
 
@@ -18,6 +35,8 @@ install: all
 	$(INSTALL) -d -m 755 $(DESTDIR)$(MANDIR)/man1
 	$(INSTALL) -m 644 -c zkey.1 $(DESTDIR)$(MANDIR)/man1
 
+endif
+
 clean:
 	rm -f *.o zkey