Index: lib/libkvm/kvm.c
===================================================================
--- lib/libkvm/kvm.c
+++ lib/libkvm/kvm.c
@@ -384,7 +384,7 @@
 	kd->argspc = 0;
 	kd->argv = 0;
 
-	if (uf == 0)
+	if (uf == NULL)
 		uf = getbootfile();
 	else if (strlen(uf) >= MAXPATHLEN) {
 		_kvm_err(kd, kd->program, "exec file name too long");
@@ -394,7 +394,7 @@
 		_kvm_err(kd, kd->program, "bad flags arg");
 		goto failed;
 	}
-	if (mf == 0)
+	if (mf == NULL)
 		mf = _PATH_MEM;
 
 	if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) {
@@ -471,7 +471,7 @@
 	/*
 	 * Copy out the error if doing sane error semantics.
 	 */
-	if (errout != 0)
+	if (errout != NULL)
 		strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
 	(void)kvm_close(kd);
 	return (0);
@@ -484,7 +484,9 @@
 	kvm_t *kd;
 
 	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
-		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
+		if (errout != NULL)
+			(void)strlcpy(errout, strerror(errno),
+			    _POSIX2_LINE_MAX);
 		return (0);
 	}
 	return (_kvm_open(kd, uf, mf, flag, errout));
@@ -513,7 +515,9 @@
 	kvm_t *kd;
 
 	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
-		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
+		if (errout != NULL)
+			(void)strlcpy(errout, strerror(errno),
+			    _POSIX2_LINE_MAX);
 		return (0);
 	}
 	kd->resolve_symbol = resolver;
Index: lib/libkvm/kvm_amd64.c
===================================================================
--- lib/libkvm/kvm_amd64.c
+++ lib/libkvm/kvm_amd64.c
@@ -118,7 +118,7 @@
 	amd64_pml4e_t *PML4;
 
 	kd->vmst = (struct vmstate *)_kvm_malloc(kd, sizeof(*kd->vmst));
-	if (kd->vmst == 0) {
+	if (kd->vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
@@ -153,6 +153,10 @@
 	}
 	pa = le64toh(pa);
 	PML4 = _kvm_malloc(kd, AMD64_PAGE_SIZE);
+	if (PML4 == NULL) {
+		_kvm_err(kd, kd->program, "cannot allocate PML4");
+		return (-1);
+	}
 	if (kvm_read2(kd, pa, PML4, AMD64_PAGE_SIZE) != AMD64_PAGE_SIZE) {
 		_kvm_err(kd, kd->program, "cannot read KPML4phys");
 		return (-1);
@@ -188,7 +192,7 @@
 	 * If we are initializing (kernel page table descriptor pointer
 	 * not yet set) then return pa == va to avoid infinite recursion.
 	 */
-	if (vm->PML4 == 0) {
+	if (vm->PML4 == NULL) {
 		s = _kvm_pa2off(kd, va, pa);
 		if (s == 0) {
 			_kvm_err(kd, kd->program,
Index: lib/libkvm/kvm_arm.c
===================================================================
--- lib/libkvm/kvm_arm.c
+++ lib/libkvm/kvm_arm.c
@@ -117,7 +117,7 @@
 	}
 
 	vm = _kvm_malloc(kd, sizeof(*vm));
-	if (vm == 0) {
+	if (vm == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
@@ -168,6 +168,10 @@
 		return (-1);
 	}
 	l1pt = _kvm_malloc(kd, ARM_L1_TABLE_SIZE);
+	if (l1pt == NULL) {
+		_kvm_err(kd, kd->program, "cannot allocate l1pt");
+		return (-1);
+	}
 	if (kvm_read2(kd, pa, l1pt, ARM_L1_TABLE_SIZE) != ARM_L1_TABLE_SIZE) {
 		_kvm_err(kd, kd->program, "cannot read l1pt");
 		free(l1pt);
Index: lib/libkvm/kvm_file.c
===================================================================
--- lib/libkvm/kvm_file.c
+++ lib/libkvm/kvm_file.c
@@ -71,6 +71,7 @@
 #define KREADN(kd, addr, obj, cnt) \
 	(kvm_read(kd, addr, obj, (cnt)) != (ssize_t)(cnt))
 
+#if 0
 /*
  * Get file structures.
  */
@@ -111,7 +112,7 @@
 			free(ofiles);
 			ofiles = (struct file **)_kvm_malloc(kd,
 				ocnt * sizeof(struct file *));
-			if (ofiles == 0)
+			if (ofiles == NULL)
 				return (0);
 		}
 		if (KREADN(kd, (u_long)filed.fd_ofiles, ofiles,
@@ -152,15 +153,23 @@
 	return (0);
 
 }
+#endif
 
 char *
+#if 0
 kvm_getfiles(kvm_t *kd, int op, int arg, int *cnt)
+#else
+kvm_getfiles(kvm_t *kd, int op __unused, int arg __unused, int *cnt __unused)
+#endif
 {
+#if 0
 	int mib[2], st, n, nfiles, nprocs;
 	size_t size;
+#endif
 
 	_kvm_syserr(kd, kd->program, "kvm_getfiles has been broken for years");
-	return (0);
+	return (NULL);
+#if 0
 	if (ISALIVE(kd)) {
 		size = 0;
 		mib[0] = CTL_KERN;
@@ -168,19 +177,19 @@
 		st = sysctl(mib, 2, NULL, &size, NULL, 0);
 		if (st == -1) {
 			_kvm_syserr(kd, kd->program, "kvm_getfiles");
-			return (0);
+			return (NULL);
 		}
-		if (kd->argspc == 0)
+		if (kd->argspc == NULL)
 			kd->argspc = (char *)_kvm_malloc(kd, size);
 		else if (kd->arglen < (int)size)
 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc, size);
-		if (kd->argspc == 0)
-			return (0);
+		if (kd->argspc == NULL)
+			return (NULL);
 		kd->arglen = size;
 		st = sysctl(mib, 2, kd->argspc, &size, NULL, 0);
 		if (st != 0) {
 			_kvm_syserr(kd, kd->program, "kvm_getfiles");
-			return (0);
+			return (NULL);
 		}
 		nfiles = size / sizeof(struct xfile);
 	} else {
@@ -196,31 +205,32 @@
 				;
 			_kvm_err(kd, kd->program,
 				 "%s: no such symbol", p->n_name);
-			return (0);
+			return (NULL);
 		}
 		if (KREAD(kd, nl[1].n_value, &nprocs)) {
 			_kvm_err(kd, kd->program, "can't read nprocs");
-			return (0);
+			return (NULL);
 		}
 		if (KREAD(kd, nl[2].n_value, &nfiles)) {
 			_kvm_err(kd, kd->program, "can't read nfiles");
-			return (0);
+			return (NULL);
 		}
 		size = sizeof(void *) + (nfiles + 10) * sizeof(struct file);
-		if (kd->argspc == 0)
+		if (kd->argspc == NULL)
 			kd->argspc = (char *)_kvm_malloc(kd, size);
 		else if (kd->arglen < (int)size)
 			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc, size);
-		if (kd->argspc == 0)
-			return (0);
+		if (kd->argspc == NULL)
+			return (NULL);
 		kd->arglen = size;
 		n = kvm_deadfiles(kd, op, arg, nl[0].n_value, nprocs);
 		if (n != nfiles) {
 			_kvm_err(kd, kd->program, "inconsistant nfiles");
-			return (0);
+			return (NULL);
 		}
 		nfiles = n;
 	}
 	*cnt = nfiles;
 	return (kd->argspc);
+#endif
 }
Index: lib/libkvm/kvm_i386.c
===================================================================
--- lib/libkvm/kvm_i386.c
+++ lib/libkvm/kvm_i386.c
@@ -162,6 +162,10 @@
 		}
 		pa = le32toh(pa);
 		PTD = _kvm_malloc(kd, 4 * I386_PAGE_SIZE);
+		if (PTD == NULL) {
+			_kvm_err(kd, kd->program, "cannot allocate PTD");
+			return (-1);
+		}
 		for (i = 0; i < 4; i++) {
 			if (kvm_read2(kd, pa + (i * sizeof(pa64)), &pa64,
 			    sizeof(pa64)) != sizeof(pa64)) {
@@ -195,6 +199,10 @@
 		}
 		pa = le32toh(pa);
 		PTD = _kvm_malloc(kd, I386_PAGE_SIZE);
+		if (PTD == NULL) {
+			_kvm_err(kd, kd->program, "cannot allocate PTD");
+			return (-1);
+		}
 		if (kvm_read2(kd, pa, PTD, I386_PAGE_SIZE) != I386_PAGE_SIZE) {
 			_kvm_err(kd, kd->program, "cannot read PTD");
 			return (-1);
@@ -228,7 +236,7 @@
 	 * If we are initializing (kernel page table descriptor pointer
 	 * not yet set) then return pa == va to avoid infinite recursion.
 	 */
-	if (PTD == 0) {
+	if (PTD == NULL) {
 		s = _kvm_pa2off(kd, va, pa);
 		if (s == 0) {
 			_kvm_err(kd, kd->program,
@@ -318,7 +326,7 @@
 	 * If we are initializing (kernel page table descriptor pointer
 	 * not yet set) then return pa == va to avoid infinite recursion.
 	 */
-	if (PTD == 0) {
+	if (PTD == NULL) {
 		s = _kvm_pa2off(kd, va, pa);
 		if (s == 0) {
 			_kvm_err(kd, kd->program,
Index: lib/libkvm/kvm_minidump_aarch64.c
===================================================================
--- lib/libkvm/kvm_minidump_aarch64.c
+++ lib/libkvm/kvm_minidump_aarch64.c
@@ -81,7 +81,7 @@
 	off_t off;
 
 	vmst = _kvm_malloc(kd, sizeof(*vmst));
-	if (vmst == 0) {
+	if (vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
Index: lib/libkvm/kvm_minidump_amd64.c
===================================================================
--- lib/libkvm/kvm_minidump_amd64.c
+++ lib/libkvm/kvm_minidump_amd64.c
@@ -81,7 +81,7 @@
 	off_t off;
 
 	vmst = _kvm_malloc(kd, sizeof(*vmst));
-	if (vmst == 0) {
+	if (vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
Index: lib/libkvm/kvm_minidump_arm.c
===================================================================
--- lib/libkvm/kvm_minidump_arm.c
+++ lib/libkvm/kvm_minidump_arm.c
@@ -84,7 +84,7 @@
 	off_t off;
 
 	vmst = _kvm_malloc(kd, sizeof(*vmst));
-	if (vmst == 0) {
+	if (vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
Index: lib/libkvm/kvm_minidump_i386.c
===================================================================
--- lib/libkvm/kvm_minidump_i386.c
+++ lib/libkvm/kvm_minidump_i386.c
@@ -81,7 +81,7 @@
 	off_t off;
 
 	vmst = _kvm_malloc(kd, sizeof(*vmst));
-	if (vmst == 0) {
+	if (vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
Index: lib/libkvm/kvm_minidump_mips.c
===================================================================
--- lib/libkvm/kvm_minidump_mips.c
+++ lib/libkvm/kvm_minidump_mips.c
@@ -89,7 +89,7 @@
 	off_t off;
 
 	vmst = _kvm_malloc(kd, sizeof(*vmst));
-	if (vmst == 0) {
+	if (vmst == NULL) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
Index: lib/libkvm/kvm_proc.c
===================================================================
--- lib/libkvm/kvm_proc.c
+++ lib/libkvm/kvm_proc.c
@@ -544,7 +544,7 @@
 			size += size / 10;
 			kd->procbase = (struct kinfo_proc *)
 			    _kvm_realloc(kd, kd->procbase, size);
-			if (kd->procbase == 0)
+			if (kd->procbase == NULL)
 				return (0);
 			osize = size;
 			st = sysctl(mib, temp_op == KERN_PROC_ALL ||
@@ -614,7 +614,7 @@
 		}
 		size = nprocs * sizeof(struct kinfo_proc);
 		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
-		if (kd->procbase == 0)
+		if (kd->procbase == NULL)
 			return (0);
 
 		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,