libspl: getexecname() cleanup and gethostid() fixes, /proc/sys/kernel/spl/hostid fix for recent kernels in SPL

lib/libspl/Makefile.am

@@ -21,6 +21,8 @@ libspl_assert_la_SOURCES = \
 	assert.c
 
 USER_C = \
+	libspl_impl.h \
+	getexecname.c \
 	list.c \
 	mkdirp.c \
 	page.c \

lib/libspl/getexecname.c

@@ -0,0 +1,59 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+
+#include <limits.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "libspl_impl.h"
+
+
+const char *
+getexecname(void)
+{
+	static char execname[PATH_MAX + 1] = "";
+	static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
+
+	char *ptr = execname;
+	ssize_t rc;
+
+	(void) pthread_mutex_lock(&mtx);
+
+	if (strlen(execname) == 0) {
+		rc = getexecname_impl(execname);
+		if (rc == -1) {
+			execname[0] = '\0';
+			ptr = NULL;
+		} else {
+			execname[rc] = '\0';
+		}
+	}
+
+	(void) pthread_mutex_unlock(&mtx);
+	return (ptr);
+}

lib/libspl/libspl_impl.h

@@ -0,0 +1,24 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+
+extern ssize_t getexecname_impl(char *execname);

lib/libspl/os/freebsd/getexecname.c

@@ -20,52 +20,21 @@
  * CDDL HEADER END
  */
 
-
-#include <errno.h>
+#include <stdint.h>
 #include <limits.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
 #include <sys/param.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
-#include <unistd.h>
+#include "../../libspl_impl.h"
 
-const char *
-getexecname(void)
+__attribute__((visibility("hidden"))) ssize_t
+getexecname_impl(char *execname)
 {
-	static char execname[PATH_MAX + 1] = "";
-	static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
-	char *ptr = NULL;
-	ssize_t rc;
-
-	(void) pthread_mutex_lock(&mtx);
-
-	if (strlen(execname) == 0) {
-		int error, name[4];
-		size_t len;
+	size_t len = PATH_MAX;
+	int name[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
 
-		name[0] = CTL_KERN;
-		name[1] = KERN_PROC;
-		name[2] = KERN_PROC_PATHNAME;
-		name[3] = -1;
-		len = PATH_MAX;
-		error = sysctl(name, nitems(name), execname, &len, NULL, 0);
-		if (error != 0) {
-			rc = -1;
-		} else {
-			rc = len;
-		}
-		if (rc == -1) {
-			execname[0] = '\0';
-		} else {
-			execname[rc] = '\0';
-			ptr = execname;
-		}
-	} else {
-		ptr = execname;
-	}
+	if (sysctl(name, nitems(name), execname, &len, NULL, 0) != 0)
+		return (-1);
 
-	(void) pthread_mutex_unlock(&mtx);
-	return (ptr);
+	return (len);
 }

lib/libspl/os/linux/getexecname.c

@@ -19,41 +19,14 @@
  *
  * CDDL HEADER END
  */
-/*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
- */
-
 
 #include <limits.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
+#include <stdint.h>
 #include <unistd.h>
+#include "../../libspl_impl.h"
 
-const char *
-getexecname(void)
+__attribute__((visibility("hidden"))) ssize_t
+getexecname_impl(char *execname)
 {
-	static char execname[PATH_MAX + 1] = "";
-	static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
-	char *ptr = NULL;
-	ssize_t rc;
-
-	(void) pthread_mutex_lock(&mtx);
-
-	if (strlen(execname) == 0) {
-		rc = readlink("/proc/self/exe",
-		    execname, sizeof (execname) - 1);
-		if (rc == -1) {
-			execname[0] = '\0';
-		} else {
-			execname[rc] = '\0';
-			ptr = execname;
-		}
-	} else {
-		ptr = execname;
-	}
-
-	(void) pthread_mutex_unlock(&mtx);
-	return (ptr);
+	return (readlink("/proc/self/exe", execname, PATH_MAX));
 }

lib/libspl/os/linux/gethostid.c

@@ -40,47 +40,40 @@ get_spl_hostid(void)
 	 * Allow the hostid to be subverted for testing.
 	 */
 	env = getenv("ZFS_HOSTID");
-	if (env) {
-		hostid = strtoull(env, NULL, 0);
-		return (hostid & HOSTID_MASK);
-	}
+	if (env)
+		return (strtoull(env, NULL, 0));
 
-	f = fopen("/sys/module/spl/parameters/spl_hostid", "re");
+	f = fopen("/proc/sys/kernel/spl/hostid", "re");
 	if (!f)
 		return (0);
 
-	if (fscanf(f, "%lu", &hostid) != 1)
+	if (fscanf(f, "%lx", &hostid) != 1)
 		hostid = 0;
 
 	fclose(f);
 
-	return (hostid & HOSTID_MASK);
+	return (hostid);
 }
 
 unsigned long
 get_system_hostid(void)
 {
-	unsigned long system_hostid = get_spl_hostid();
+	unsigned long hostid = get_spl_hostid();
+
 	/*
-	 * We do not use the library call gethostid() because
-	 * it generates a hostid value that the kernel is
-	 * unaware of, if the spl_hostid module parameter has not
-	 * been set and there is no system hostid file (e.g.
-	 * /etc/hostid).  The kernel and userspace must agree.
+	 * We do not use gethostid(3) because it can return a bogus ID,
+	 * depending on the libc and /etc/hostid presence,
+	 * and the kernel and userspace must agree.
 	 * See comments above hostid_read() in the SPL.
 	 */
-	if (system_hostid == 0) {
-		int fd, rc;
-		unsigned long hostid;
-		int hostid_size = 4;  /* 4 bytes regardless of arch */
-
-		fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC);
+	if (hostid == 0) {
+		int fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC);
 		if (fd >= 0) {
-			rc = read(fd, &hostid, hostid_size);
-			if (rc > 0)
-				system_hostid = (hostid & HOSTID_MASK);
-			close(fd);
+			if (read(fd, &hostid, 4) < 0)
+				hostid = 0;
+			(void) close(fd);
 		}
 	}
-	return (system_hostid);
+
+	return (hostid & HOSTID_MASK);
 }