libutil: make TOOLS_LIBDIR and TOOLS_DATADIR configurable

Add generic functions

util_sysdir();
util_sysdir_path()

and their special cases supplied for users:

util_libdir();
util_libdir_path();
util_datadir();
util_datadir_path()

The function util_sysdir() determines the absolute name of a
s390-tools system directory. It could be data, or library directory.

The function util_sysdir_path() determines the absolute name of a
file installed in the s390-tools system directory.

The function util_libdir() determines the absolute name of a
s390-tools library directory. By default that name is defined
by the compile-time macro TOOLS_LIBDIR (/lib/s390-tools).
Users can specify an override by setting environment variable
S390TOOLS_LIBDIR.

The function util_libdir_path() determines the absolute name of a
file installed in the s390-tools library directory.

The function util_datadir() determines the absolute name of a
s390-tools system data directory. By default the name is defined
by the compile-time macro TOOLS_DATADIR (/usr/share/s390-tools/).
Users can specify an override by setting environment variable
S390TOOLS_DATADIR.

The function util_datadir_path() determines the absolute name of a
file installed in the s390-tools data directory.

The ability to override the setting for TOOLS_LIBDIR and
TOOLS_DATADIR is required for implementing tests on tools that are
not installed in their default system path locations.

Signed-off-by: Eduard Shishkin <edward6@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

include/lib/util_base.h

@@ -20,6 +20,10 @@ void util_hexdump(FILE *fh, const char *tag, const void *data, int cnt);
 void util_hexdump_grp(FILE *fh, const char *tag, const void *data, int group,
 		      int cnt, int indent);
 void util_print_indented(const char *str, int indent);
+const char *util_libdir(void);
+const char *util_libdir_path(const char *filename);
+const char *util_datadir(void);
+const char *util_datadir_path(const char *filename);
 
 static inline void util_ptr_vec_free(void **ptr_vec, int count)
 {

include/lib/zt_common.h

@@ -52,6 +52,7 @@
 #define TOOLS_LIBDIR	STRINGIFY (S390_TOOLS_LIBDIR)
 #define TOOLS_SYSCONFDIR STRINGIFY (S390_TOOLS_SYSCONFDIR)
 #define TOOLS_BINDIR	STRINGIFY (S390_TOOLS_BINDIR)
+#define TOOLS_DATADIR	STRINGIFY (S390_TOOLS_DATADIR)
 
 #define __noreturn __attribute__((noreturn))
 #define __packed __attribute__((packed))

libutil/util_base.c

@@ -9,6 +9,8 @@
  * it under the terms of the MIT license. See LICENSE for details.
  */
 
+#include <err.h>
+#include <limits.h>
 #include <string.h>
 
 #include "lib/util_base.h"
@@ -91,3 +93,91 @@ void util_print_indented(const char *str, int indent)
 	printf("\n");
 	free(desc_ptr);
 }
+
+/**
+ * Determines the absolute name of an s390-tools system directory
+ * (it could be data, or library directory)
+ */
+static const char *util_sysdir(const char *env_var, const char *default_dir)
+{
+	return secure_getenv(env_var) ?: default_dir;
+}
+
+/**
+ * Determines the absolute name of a file installed in the s390-tools
+ * system directory
+ */
+static const char *util_sysdir_path(const char *filename, const char *dirname)
+{
+	static char libdir_pathname[PATH_MAX];
+	int ret;
+
+	ret = snprintf(libdir_pathname, sizeof(libdir_pathname),
+		       "%s/%s", dirname, filename);
+
+	if (ret < 0 || ret >= (int)sizeof(libdir_pathname))
+		errx(EXIT_FAILURE,
+		     "Could not compose absolute pathname of %s and %s",
+                     dirname, filename);
+	return libdir_pathname;
+}
+
+/**
+ * Determines the absolute name of a s390-tools library directory
+ *
+ * Resources are handled by the library
+ *
+ * @returns Pointer to a buffer, which contains the null-terminated name
+ */
+const char *util_libdir(void)
+{
+	return util_sysdir("S390TOOLS_LIBDIR", TOOLS_LIBDIR);
+}
+
+/**
+ * Determines the absolute name of a file installed in the s390-tools
+ * library directory by its relative name.
+ *
+ * Resources are handled by the library. A second call of this function
+ * overwrites previously returned data. Care must be taken when attempting
+ * to do a second call.
+ *
+ * @param[in] filename Null-terminated file name relative to the s390-tools
+ *                     library directory
+ * @returns Pointer to a buffer of PATH_MAX size, which contains the
+ *          null-terminated absolute name
+ */
+const char *util_libdir_path(const char *filename)
+{
+	return util_sysdir_path(filename, util_libdir());
+}
+
+/**
+ * Determines the absolute name of a s390-tools data directory
+ *
+ * Resources are handled by the library
+ *
+ * @returns Pointer to a buffer which contains the null-terminated name
+ */
+const char *util_datadir(void)
+{
+	return util_sysdir("S390TOOLS_DATADIR", TOOLS_DATADIR);
+}
+
+/**
+ * Determines the absolute name of a file installed in the s390-tools
+ * data directory by its relative name.
+ *
+ * Resources are handled by the library. A second call of this function
+ * overwrites previously returned data. Care must be taken when attempting
+ * to do a second call.
+ *
+ * @param[in] filename Null-terminated file name relative to the s390-tools
+ *            data directory
+ * @returns Pointer to a buffer of PATH_MAX size, which contains the
+ *          null-terminated absolute name
+ */
+const char *util_datadir_path(const char *filename)
+{
+	return util_sysdir_path(filename, util_datadir());
+}