Enable -Wwrite-strings

Also, fix leak from ztest_global_vars_to_zdb_args()

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13348

cmd/mount_zfs.c

@@ -108,20 +108,21 @@ mtab_is_writeable(void)
 }
 
 static int
-mtab_update(char *dataset, char *mntpoint, char *type, char *mntopts)
+mtab_update(const char *dataset, const char *mntpoint, const char *type,
+    const char *mntopts)
 {
 	struct mntent mnt;
 	FILE *fp;
 	int error;
 
-	mnt.mnt_fsname = dataset;
-	mnt.mnt_dir = mntpoint;
-	mnt.mnt_type = type;
-	mnt.mnt_opts = mntopts ? mntopts : "";
+	mnt.mnt_fsname = (char *)dataset;
+	mnt.mnt_dir = (char *)mntpoint;
+	mnt.mnt_type = (char *)type;
+	mnt.mnt_opts = (char *)(mntopts ?: "");
 	mnt.mnt_freq = 0;
 	mnt.mnt_passno = 0;
 
-	fp = setmntent("/etc/mtab", "a+");
+	fp = setmntent("/etc/mtab", "a+e");
 	if (!fp) {
 		(void) fprintf(stderr, gettext(
 		    "filesystem '%s' was mounted, but /etc/mtab "

cmd/raidz_test/raidz_test.c

@@ -69,7 +69,7 @@ static void sig_handler(int signo)
 
 static void print_opts(raidz_test_opts_t *opts, boolean_t force)
 {
-	char *verbose;
+	const char *verbose;
 	switch (opts->rto_v) {
 		case D_ALL:
 			verbose = "no";

cmd/zdb/zdb.c

@@ -102,7 +102,7 @@
 #define	ZDB_MAP_OBJECT_ID(obj) (obj)
 #endif
 
-static char *
+static const char *
 zdb_ot_name(dmu_object_type_t type)
 {
 	if (type < DMU_OT_NUMTYPES)
@@ -2922,7 +2922,7 @@ dsl_deadlist_entry_dump(void *arg, dsl_deadlist_entry_t *dle)
 }
 
 static void
-dump_blkptr_list(dsl_deadlist_t *dl, char *name)
+dump_blkptr_list(dsl_deadlist_t *dl, const char *name)
 {
 	char bytes[32];
 	char comp[32];
@@ -2963,7 +2963,7 @@ dump_blkptr_list(dsl_deadlist_t *dl, char *name)
 	if (dump_opt['d'] < 4)
 		return;
 
-	(void) printf("\n");
+	(void) putchar('\n');
 
 	dsl_deadlist_iterate(dl, dsl_deadlist_entry_dump, NULL);
 }
@@ -3098,9 +3098,8 @@ static void
 print_idstr(uint64_t id, const char *id_type)
 {
 	if (FUID_INDEX(id)) {
-		char *domain;
-
-		domain = zfs_fuid_idx_domain(&idx_tree, FUID_INDEX(id));
+		const char *domain =
+		    zfs_fuid_idx_domain(&idx_tree, FUID_INDEX(id));
 		(void) printf("\t%s     %llx [%s-%d]\n", id_type,
 		    (u_longlong_t)id, domain, (int)FUID_RID(id));
 	} else {
@@ -3643,7 +3642,7 @@ count_ds_mos_objects(dsl_dataset_t *ds)
 	}
 }
 
-static const char *objset_types[DMU_OST_NUMTYPES] = {
+static const char *const objset_types[DMU_OST_NUMTYPES] = {
 	"NONE", "META", "ZPL", "ZVOL", "OTHER", "ANY" };
 
 /*
@@ -3653,7 +3652,7 @@ static const char *objset_types[DMU_OST_NUMTYPES] = {
  * pointer to point to a descriptive error message.
  */
 static int
-parse_object_range(char *range, zopt_object_range_t *zor, char **msg)
+parse_object_range(char *range, zopt_object_range_t *zor, const char **msg)
 {
 	uint64_t flags = 0;
 	char *p, *s, *dup, *flagstr, *tmp = NULL;
@@ -4236,13 +4235,13 @@ first_label(cksum_record_t *rec)
 }
 
 static void
-print_label_numbers(char *prefix, cksum_record_t *rec)
+print_label_numbers(const char *prefix, const cksum_record_t *rec)
 {
-	printf("%s", prefix);
+	fputs(prefix, stdout);
 	for (int i = 0; i < VDEV_LABELS; i++)
 		if (rec->labels[i] == B_TRUE)
 			printf("%d ", i);
-	printf("\n");
+	putchar('\n');
 }
 
 #define	MAX_UBERBLOCK_COUNT (VDEV_UBERBLOCK_RING >> UBERBLOCK_SHIFT)
@@ -5126,7 +5125,7 @@ same_metaslab(spa_t *spa, uint64_t vdev, uint64_t off1, uint64_t off2)
  * Used to simplify reporting of the histogram data.
  */
 typedef struct one_histo {
-	char *name;
+	const char *name;
 	uint64_t *count;
 	uint64_t *len;
 	uint64_t cumulative;
@@ -8093,32 +8092,33 @@ zdb_read_block(char *thing, spa_t *spa)
 	vdev_t *vd;
 	abd_t *pabd;
 	void *lbuf, *buf;
-	char *s, *p, *dup, *vdev, *flagstr, *sizes, *tmp = NULL;
+	char *s, *p, *dup, *flagstr, *sizes, *tmp = NULL;
+	const char *vdev, *errmsg = NULL;
 	int i, error;
 	boolean_t borrowed = B_FALSE, found = B_FALSE;
 
 	dup = strdup(thing);
 	s = strtok_r(dup, ":", &tmp);
-	vdev = s ? s : "";
+	vdev = s ?: "";
 	s = strtok_r(NULL, ":", &tmp);
 	offset = strtoull(s ? s : "", NULL, 16);
 	sizes = strtok_r(NULL, ":", &tmp);
 	s = strtok_r(NULL, ":", &tmp);
-	flagstr = strdup(s ? s : "");
+	flagstr = strdup(s ?: "");
 
-	s = NULL;
-	tmp = NULL;
 	if (!zdb_parse_block_sizes(sizes, &lsize, &psize))
-		s = "invalid size(s)";
+		errmsg = "invalid size(s)";
 	if (!IS_P2ALIGNED(psize, DEV_BSIZE) || !IS_P2ALIGNED(lsize, DEV_BSIZE))
-		s = "size must be a multiple of sector size";
+		errmsg = "size must be a multiple of sector size";
 	if (!IS_P2ALIGNED(offset, DEV_BSIZE))
-		s = "offset must be a multiple of sector size";
-	if (s) {
-		(void) printf("Invalid block specifier: %s  - %s\n", thing, s);
+		errmsg = "offset must be a multiple of sector size";
+	if (errmsg) {
+		(void) printf("Invalid block specifier: %s  - %s\n",
+		    thing, errmsg);
 		goto done;
 	}
 
+	tmp = NULL;
 	for (s = strtok_r(flagstr, ":", &tmp);
 	    s != NULL;
 	    s = strtok_r(NULL, ":", &tmp)) {
@@ -8930,13 +8930,13 @@ retry_lookup:
 			    sizeof (zopt_object_range_t));
 			for (unsigned i = 0; i < zopt_object_args; i++) {
 				int err;
-				char *msg = NULL;
+				const char *msg = NULL;
 
 				err = parse_object_range(argv[i],
 				    &zopt_object_ranges[i], &msg);
 				if (err != 0)
 					fatal("Bad object or range: '%s': %s\n",
-					    argv[i], msg ? msg : "");
+					    argv[i], msg ?: "");
 			}
 		} else if (argc > 0 && dump_opt['m']) {
 			zopt_metaslab_args = argc;

cmd/zed/agents/fmd_api.c

@@ -389,7 +389,8 @@ zed_log_fault(nvlist_t *nvl, const char *uuid, const char *code)
 static const char *
 fmd_fault_mkcode(nvlist_t *fault)
 {
-	char *class, *code = "-";
+	char *class;
+	const char *code = "-";
 
 	/*
 	 * Note: message codes come from: openzfs/usr/src/cmd/fm/dicts/ZFS.po

cmd/zfs/zfs_main.c

@@ -471,7 +471,7 @@ safe_realloc(void *data, size_t size)
 }
 
 static char *
-safe_strdup(char *str)
+safe_strdup(const char *str)
 {
 	char *dupstr = strdup(str);
 
@@ -690,7 +690,8 @@ parse_depth(char *opt, int *flags)
 
 #define	PROGRESS_DELAY 2		/* seconds */
 
-static char *pt_reverse = "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b";
+static const char *pt_reverse =
+	"\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b";
 static time_t pt_begin;
 static char *pt_header = NULL;
 static boolean_t pt_shown;
@@ -703,7 +704,7 @@ start_progress_timer(void)
 }
 
 static void
-set_progress_header(char *header)
+set_progress_header(const char *header)
 {
 	assert(pt_header == NULL);
 	pt_header = safe_strdup(header);
@@ -714,7 +715,7 @@ set_progress_header(char *header)
 }
 
 static void
-update_progress(char *update)
+update_progress(const char *update)
 {
 	if (!pt_shown && time(NULL) > pt_begin) {
 		int len = strlen(update);
@@ -732,10 +733,10 @@ update_progress(char *update)
 }
 
 static void
-finish_progress(char *done)
+finish_progress(const char *done)
 {
 	if (pt_shown) {
-		(void) printf("%s\n", done);
+		(void) puts(done);
 		(void) fflush(stdout);
 	}
 	free(pt_header);
@@ -1903,8 +1904,8 @@ get_callback(zfs_handle_t *zhp, void *data)
 	nvlist_t *user_props = zfs_get_user_props(zhp);
 	zprop_list_t *pl = cbp->cb_proplist;
 	nvlist_t *propval;
-	char *strval;
-	char *sourceval;
+	const char *strval;
+	const char *sourceval;
 	boolean_t received = is_recvd_column(cbp);
 
 	for (; pl != NULL; pl = pl->pl_next) {
@@ -1973,10 +1974,10 @@ get_callback(zfs_handle_t *zhp, void *data)
 				sourcetype = ZPROP_SRC_NONE;
 				strval = "-";
 			} else {
-				verify(nvlist_lookup_string(propval,
-				    ZPROP_VALUE, &strval) == 0);
-				verify(nvlist_lookup_string(propval,
-				    ZPROP_SOURCE, &sourceval) == 0);
+				strval = fnvlist_lookup_string(propval,
+				    ZPROP_VALUE);
+				sourceval = fnvlist_lookup_string(propval,
+				    ZPROP_SOURCE);
 
 				if (strcmp(sourceval,
 				    zfs_get_name(zhp)) == 0) {
@@ -2618,9 +2619,9 @@ enum us_field_types {
 	USFIELD_OBJUSED,
 	USFIELD_OBJQUOTA
 };
-static char *us_field_hdr[] = { "TYPE", "NAME", "USED", "QUOTA",
+static const char *const us_field_hdr[] = { "TYPE", "NAME", "USED", "QUOTA",
 				    "OBJUSED", "OBJQUOTA" };
-static char *us_field_names[] = { "type", "name", "used", "quota",
+static const char *const us_field_names[] = { "type", "name", "used", "quota",
 				    "objused", "objquota" };
 #define	USFIELD_LAST	(sizeof (us_field_names) / sizeof (char *))
 
@@ -2640,8 +2641,8 @@ static int us_type_bits[] = {
 	USTYPE_SMB_USR,
 	USTYPE_ALL
 };
-static char *us_type_names[] = { "posixgroup", "posixuser", "smbgroup",
-	"smbuser", "all" };
+static const char *const us_type_names[] = { "posixgroup", "posixuser",
+	"smbgroup", "smbuser", "all" };
 
 typedef struct us_node {
 	nvlist_t	*usn_nvl;
@@ -2669,11 +2670,9 @@ typedef struct {
 } us_sort_info_t;
 
 static int
-us_field_index(char *field)
+us_field_index(const char *field)
 {
-	int i;
-
-	for (i = 0; i < USFIELD_LAST; i++) {
+	for (int i = 0; i < USFIELD_LAST; i++) {
 		if (strcmp(field, us_field_names[i]) == 0)
 			return (i);
 	}
@@ -2695,8 +2694,8 @@ us_compare(const void *larg, const void *rarg, void *unused)
 	boolean_t lvb, rvb;
 
 	for (; sortcol != NULL; sortcol = sortcol->sc_next) {
-		char *lvstr = "";
-		char *rvstr = "";
+		char *lvstr = (char *)"";
+		char *rvstr = (char *)"";
 		uint32_t lv32 = 0;
 		uint32_t rv32 = 0;
 		uint64_t lv64 = 0;
@@ -2818,7 +2817,7 @@ userspace_cb(void *arg, const char *domain, uid_t rid, uint64_t space)
 	us_cbdata_t *cb = (us_cbdata_t *)arg;
 	zfs_userquota_prop_t prop = cb->cb_prop;
 	char *name = NULL;
-	char *propname;
+	const char *propname;
 	char sizebuf[32];
 	us_node_t *node;
 	uu_avl_pool_t *avl_pool = cb->cb_avl_pool;
@@ -3018,26 +3017,25 @@ print_us_node(boolean_t scripted, boolean_t parsable, int *fields, int types,
 	while ((field = fields[cfield]) != USFIELD_LAST) {
 		nvpair_t *nvp = NULL;
 		data_type_t type;
-		uint32_t val32;
-		uint64_t val64;
-		char *strval = "-";
+		uint32_t val32 = -1;
+		uint64_t val64 = -1;
+		const char *strval = "-";
 
-		while ((nvp = nvlist_next_nvpair(nvl, nvp)) != NULL) {
+		while ((nvp = nvlist_next_nvpair(nvl, nvp)) != NULL)
 			if (strcmp(nvpair_name(nvp),
 			    us_field_names[field]) == 0)
 				break;
-		}
 
 		type = nvp == NULL ? DATA_TYPE_UNKNOWN : nvpair_type(nvp);
 		switch (type) {
 		case DATA_TYPE_UINT32:
-			(void) nvpair_value_uint32(nvp, &val32);
+			val32 = fnvpair_value_uint32(nvp);
 			break;
 		case DATA_TYPE_UINT64:
-			(void) nvpair_value_uint64(nvp, &val64);
+			val64 = fnvpair_value_uint64(nvp);
 			break;
 		case DATA_TYPE_STRING:
-			(void) nvpair_value_string(nvp, &strval);
+			strval = fnvpair_value_string(nvp);
 			break;
 		case DATA_TYPE_UNKNOWN:
 			break;
@@ -3048,7 +3046,7 @@ print_us_node(boolean_t scripted, boolean_t parsable, int *fields, int types,
 		switch (field) {
 		case USFIELD_TYPE:
 			if (type == DATA_TYPE_UINT32)
-				strval = (char *)us_type2str(val32);
+				strval = us_type2str(val32);
 			break;
 		case USFIELD_NAME:
 			if (type == DATA_TYPE_UINT64) {
@@ -3095,12 +3093,12 @@ print_us_node(boolean_t scripted, boolean_t parsable, int *fields, int types,
 
 		if (!first) {
 			if (scripted)
-				(void) printf("\t");
+				(void) putchar('\t');
 			else
-				(void) printf("  ");
+				(void) fputs("  ", stdout);
 		}
 		if (scripted)
-			(void) printf("%s", strval);
+			(void) fputs(strval, stdout);
 		else if (field == USFIELD_TYPE || field == USFIELD_NAME)
 			(void) printf("%-*s", (int)width[field], strval);
 		else
@@ -3110,7 +3108,7 @@ print_us_node(boolean_t scripted, boolean_t parsable, int *fields, int types,
 		cfield++;
 	}
 
-	(void) printf("\n");
+	(void) putchar('\n');
 }
 
 static void
@@ -3476,15 +3474,15 @@ print_dataset(zfs_handle_t *zhp, list_cbdata_t *cb)
 	char property[ZFS_MAXPROPLEN];
 	nvlist_t *userprops = zfs_get_user_props(zhp);
 	nvlist_t *propval;
-	char *propstr;
+	const char *propstr;
 	boolean_t right_justify;
 
 	for (; pl != NULL; pl = pl->pl_next) {
 		if (!first) {
 			if (cb->cb_scripted)
-				(void) printf("\t");
+				(void) putchar('\t');
 			else
-				(void) printf("  ");
+				(void) fputs("  ", stdout);
 		} else {
 			first = B_FALSE;
 		}
@@ -3521,8 +3519,8 @@ print_dataset(zfs_handle_t *zhp, list_cbdata_t *cb)
 			    pl->pl_user_prop, &propval) != 0)
 				propstr = "-";
 			else
-				verify(nvlist_lookup_string(propval,
-				    ZPROP_VALUE, &propstr) == 0);
+				propstr = fnvlist_lookup_string(propval,
+				    ZPROP_VALUE);
 			right_justify = B_FALSE;
 		}
 
@@ -3532,14 +3530,14 @@ print_dataset(zfs_handle_t *zhp, list_cbdata_t *cb)
 		 * format specifier.
 		 */
 		if (cb->cb_scripted || (pl->pl_next == NULL && !right_justify))
-			(void) printf("%s", propstr);
+			(void) fputs(propstr, stdout);
 		else if (right_justify)
 			(void) printf("%*s", (int)pl->pl_width, propstr);
 		else
 			(void) printf("%-*s", (int)pl->pl_width, propstr);
 	}
 
-	(void) printf("\n");
+	(void) putchar('\n');
 }
 
 /*
@@ -6419,7 +6417,7 @@ print_holds(boolean_t scripted, int nwidth, int tagwidth, nvlist_t *nvl)
 {
 	int i;
 	nvpair_t *nvp = NULL;
-	char *hdr_cols[] = { "NAME", "TAG", "TIMESTAMP" };
+	const char *const hdr_cols[] = { "NAME", "TAG", "TIMESTAMP" };
 	const char *col;
 
 	if (!scripted) {
@@ -6607,7 +6605,7 @@ typedef struct get_all_state {
 static int
 get_one_dataset(zfs_handle_t *zhp, void *data)
 {
-	static char *spin[] = { "-", "\\", "|", "/" };
+	static const char *const spin[] = { "-", "\\", "|", "/" };
 	static int spinval = 0;
 	static int spincheck = 0;
 	static time_t last_spin_time = (time_t)0;
@@ -6893,10 +6891,7 @@ share_mount_one(zfs_handle_t *zhp, int op, int flags, enum sa_protocol protocol,
 		break;
 
 	case OP_MOUNT:
-		if (options == NULL)
-			mnt.mnt_mntopts = "";
-		else
-			mnt.mnt_mntopts = (char *)options;
+		mnt.mnt_mntopts = (char *)(options ?: "");
 
 		if (!hasmntopt(&mnt, MNTOPT_REMOUNT) &&
 		    zfs_is_mounted(zhp, NULL)) {
@@ -7616,7 +7611,7 @@ zfs_do_unshare(int argc, char **argv)
 }
 
 static int
-find_command_idx(char *command, int *idx)
+find_command_idx(const char *command, int *idx)
 {
 	int i;
 
@@ -7881,7 +7876,6 @@ static int
 zfs_do_channel_program(int argc, char **argv)
 {
 	int ret, fd, c;
-	char *progbuf, *filename, *poolname;
 	size_t progsize, progread;
 	nvlist_t *outnvl = NULL;
 	uint64_t instrlimit = ZCP_DEFAULT_INSTRLIMIT;
@@ -7938,8 +7932,8 @@ zfs_do_channel_program(int argc, char **argv)
 		goto usage;
 	}
 
-	poolname = argv[0];
-	filename = argv[1];
+	const char *poolname = argv[0];
+	const char *filename = argv[1];
 	if (strcmp(filename, "-") == 0) {
 		fd = 0;
 		filename = "standard input";
@@ -7964,7 +7958,7 @@ zfs_do_channel_program(int argc, char **argv)
 	 */
 	progread = 0;
 	progsize = 1024;
-	progbuf = safe_malloc(progsize);
+	char *progbuf = safe_malloc(progsize);
 	do {
 		ret = read(fd, progbuf + progread, progsize - progread);
 		progread += ret;
@@ -8010,14 +8004,17 @@ zfs_do_channel_program(int argc, char **argv)
 		 * exists.  Otherwise, generate an appropriate error message,
 		 * falling back on strerror() for an unexpected return code.
 		 */
-		char *errstring = NULL;
+		const char *errstring = NULL;
 		const char *msg = gettext("Channel program execution failed");
 		uint64_t instructions = 0;
 		if (outnvl != NULL && nvlist_exists(outnvl, ZCP_RET_ERROR)) {
+			char *es = NULL;
 			(void) nvlist_lookup_string(outnvl,
-			    ZCP_RET_ERROR, &errstring);
-			if (errstring == NULL)
+			    ZCP_RET_ERROR, &es);
+			if (es == NULL)
 				errstring = strerror(ret);
+			else
+				errstring = es;
 			if (ret == ETIME) {
 				(void) nvlist_lookup_uint64(outnvl,
 				    ZCP_ARG_INSTRLIMIT, &instructions);
@@ -8601,7 +8598,7 @@ main(int argc, char **argv)
 {
 	int ret = 0;
 	int i = 0;
-	char *cmdname;
+	const char *cmdname;
 	char **newargv;
 
 	(void) setlocale(LC_ALL, "");

cmd/zpool/zpool_iter.c

@@ -442,9 +442,8 @@ static void
 vdev_run_cmd(vdev_cmd_data_t *data, char *cmd)
 {
 	int rc;
-	char *argv[2] = {cmd, 0};
-	char *env[5] = {"PATH=/bin:/sbin:/usr/bin:/usr/sbin", NULL, NULL, NULL,
-	    NULL};
+	char *argv[2] = {cmd};
+	char *env[5] = {(char *)"PATH=/bin:/sbin:/usr/bin:/usr/sbin"};
 	char **lines = NULL;
 	int lines_cnt = 0;
 	int i;

cmd/zpool/zpool_main.c

@@ -711,7 +711,7 @@ print_vdev_tree(zpool_handle_t *zhp, const char *name, nvlist_t *nv, int indent,
 
 	for (c = 0; c < children; c++) {
 		uint64_t is_log = B_FALSE, is_hole = B_FALSE;
-		char *class = "";
+		char *class = (char *)"";
 
 		(void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_HOLE,
 		    &is_hole);
@@ -723,7 +723,7 @@ print_vdev_tree(zpool_handle_t *zhp, const char *name, nvlist_t *nv, int indent,
 		(void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_LOG,
 		    &is_log);
 		if (is_log)
-			class = VDEV_ALLOC_BIAS_LOG;
+			class = (char *)VDEV_ALLOC_BIAS_LOG;
 		(void) nvlist_lookup_string(child[c],
 		    ZPOOL_CONFIG_ALLOCATION_BIAS, &class);
 		if (strcmp(match, class) != 0)
@@ -804,7 +804,7 @@ prop_list_contains_feature(nvlist_t *proplist)
  * Add a property pair (name, string-value) into a property nvlist.
  */
 static int
-add_prop_list(const char *propname, char *propval, nvlist_t **props,
+add_prop_list(const char *propname, const char *propval, nvlist_t **props,
     boolean_t poolprop)
 {
 	zpool_prop_t prop = ZPOOL_PROP_INVAL;
@@ -905,7 +905,8 @@ add_prop_list(const char *propname, char *propval, nvlist_t **props,
  * Set a default property pair (name, string-value) in a property nvlist
  */
 static int
-add_prop_list_default(const char *propname, char *propval, nvlist_t **props)
+add_prop_list_default(const char *propname, const char *propval,
+    nvlist_t **props)
 {
 	char *pval;
 
@@ -2069,15 +2070,13 @@ typedef struct status_cbdata {
 } status_cbdata_t;
 
 /* Return 1 if string is NULL, empty, or whitespace; return 0 otherwise. */
-static int
-is_blank_str(char *str)
+static boolean_t
+is_blank_str(const char *str)
 {
-	while (str != NULL && *str != '\0') {
+	for (; str != NULL && *str != '\0'; ++str)
 		if (!isblank(*str))
-			return (0);
-		str++;
-	}
-	return (1);
+			return (B_FALSE);
+	return (B_TRUE);
 }
 
 /* Print command output lines for specific vdev in a specific pool */
@@ -2086,7 +2085,7 @@ zpool_print_cmd(vdev_cmd_data_list_t *vcdl, const char *pool, char *path)
 {
 	vdev_cmd_data_t *data;
 	int i, j;
-	char *val;
+	const char *val;
 
 	for (i = 0; i < vcdl->count; i++) {
 		if ((strcmp(vcdl->data[i].path, path) != 0) ||
@@ -2117,17 +2116,17 @@ zpool_print_cmd(vdev_cmd_data_list_t *vcdl, const char *pool, char *path)
 
 			printf("%*s", vcdl->uniq_cols_width[j], val);
 			if (j < vcdl->uniq_cols_cnt - 1)
-				printf("  ");
+				fputs("  ", stdout);
 		}
 
 		/* Print out any values that aren't in a column at the end */
 		for (j = data->cols_cnt; j < data->lines_cnt; j++) {
 			/* Did we have any columns?  If so print a spacer. */
 			if (vcdl->uniq_cols_cnt > 0)
-				printf("  ");
+				fputs("  ", stdout);
 
 			val = data->lines[j];
-			printf("%s", val ? val : "");
+			fputs(val ?: "", stdout);
 		}
 		break;
 	}
@@ -2240,7 +2239,7 @@ print_status_trim(vdev_stat_t *vs, boolean_t verbose)
  * Return the color associated with a health string.  This includes returning
  * NULL for no color change.
  */
-static char *
+static const char *
 health_str_to_color(const char *health)
 {
 	if (strcmp(health, gettext("FAULTED")) == 0 ||
@@ -2276,7 +2275,7 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 	const char *state;
 	char *type;
 	char *path = NULL;
-	char *rcolor = NULL, *wcolor = NULL, *ccolor = NULL;
+	const char *rcolor = NULL, *wcolor = NULL, *ccolor = NULL;
 
 	if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
 	    &child, &children) != 0)
@@ -2318,13 +2317,13 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 			ccolor = ANSI_RED;
 
 		if (cb->cb_literal) {
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(rcolor, "%5llu",
 			    (u_longlong_t)vs->vs_read_errors);
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(wcolor, "%5llu",
 			    (u_longlong_t)vs->vs_write_errors);
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(ccolor, "%5llu",
 			    (u_longlong_t)vs->vs_checksum_errors);
 		} else {
@@ -2332,11 +2331,11 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 			zfs_nicenum(vs->vs_write_errors, wbuf, sizeof (wbuf));
 			zfs_nicenum(vs->vs_checksum_errors, cbuf,
 			    sizeof (cbuf));
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(rcolor, "%5s", rbuf);
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(wcolor, "%5s", wbuf);
-			printf(" ");
+			fputc(' ', stdout);
 			printf_color(ccolor, "%5s", cbuf);
 		}
 		if (cb->cb_print_slow_ios) {
@@ -2671,7 +2670,7 @@ print_class_vdevs(zpool_handle_t *zhp, status_cbdata_t *cb, nvlist_t *nv,
 		    &is_log);
 
 		if (is_log) {
-			bias = VDEV_ALLOC_CLASS_LOGS;
+			bias = (char *)VDEV_ALLOC_CLASS_LOGS;
 		} else {
 			(void) nvlist_lookup_string(child[c],
 			    ZPOOL_CONFIG_ALLOCATION_BIAS, &bias);
@@ -2711,8 +2710,8 @@ show_import(nvlist_t *config, boolean_t report_error)
 	char *name;
 	uint64_t guid;
 	uint64_t hostid = 0;
-	char *msgid;
-	char *hostname = "unknown";
+	const char *msgid;
+	const char *hostname = "unknown";
 	nvlist_t *nvroot, *nvinfo;
 	zpool_status_t reason;
 	zpool_errata_t errata;
@@ -3252,7 +3251,7 @@ import_pools(nvlist_t *pools, nvlist_t *props, char *mntopts, int flags,
 			if (first)
 				first = B_FALSE;
 			else if (!do_all)
-				(void) putchar('\n');
+				(void) fputc('\n', stdout);
 
 			if (do_all) {
 				err |= do_import(config, NULL, mntopts,
@@ -4848,7 +4847,7 @@ children:
 			(void) nvlist_lookup_uint64(newchild[c],
 			    ZPOOL_CONFIG_IS_LOG, &islog);
 			if (islog) {
-				bias = VDEV_ALLOC_CLASS_LOGS;
+				bias = (char *)VDEV_ALLOC_CLASS_LOGS;
 			} else {
 				(void) nvlist_lookup_string(newchild[c],
 				    ZPOOL_CONFIG_ALLOCATION_BIAS, &bias);
@@ -5382,7 +5381,7 @@ terminal_height(void)
 static void
 print_zpool_script_help(char *name, char *path)
 {
-	char *argv[] = {path, "-h", NULL};
+	char *argv[] = {path, (char *)"-h", NULL};
 	char **lines = NULL;
 	int lines_cnt = 0;
 	int rc;
@@ -5434,7 +5433,7 @@ print_zpool_dir_scripts(char *dirpath)
  * Print out help text for all zpool status/iostat -c scripts.
  */
 static void
-print_zpool_script_list(char *subcommand)
+print_zpool_script_list(const char *subcommand)
 {
 	char *dir, *sp, *tmp;
 
@@ -5979,7 +5978,7 @@ print_pool(zpool_handle_t *zhp, list_cbdata_t *cb)
 	zprop_list_t *pl = cb->cb_proplist;
 	boolean_t first = B_TRUE;
 	char property[ZPOOL_MAXPROPLEN];
-	char *propstr;
+	const char *propstr;
 	boolean_t right_justify;
 	size_t width;
 
@@ -6214,7 +6213,7 @@ print_list_stats(zpool_handle_t *zhp, const char *name, nvlist_t *nv,
 
 			if (nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_LOG,
 			    &islog) == 0 && islog) {
-				bias = VDEV_ALLOC_CLASS_LOGS;
+				bias = (char *)VDEV_ALLOC_CLASS_LOGS;
 			} else {
 				(void) nvlist_lookup_string(child[c],
 				    ZPOOL_CONFIG_ALLOCATION_BIAS, &bias);
@@ -8118,7 +8117,7 @@ status_callback(zpool_handle_t *zhp, void *data)
 {
 	status_cbdata_t *cbp = data;
 	nvlist_t *config, *nvroot;
-	char *msgid;
+	const char *msgid;
 	zpool_status_t reason;
 	zpool_errata_t errata;
 	const char *health;
@@ -8163,12 +8162,12 @@ status_callback(zpool_handle_t *zhp, void *data)
 	printf("  ");
 	printf_color(ANSI_BOLD, gettext("pool:"));
 	printf(" %s\n", zpool_get_name(zhp));
-	printf(" ");
+	fputc(' ', stdout);
 	printf_color(ANSI_BOLD, gettext("state: "));
 
 	printf_color(health_str_to_color(health), "%s", health);
 
-	printf("\n");
+	fputc('\n', stdout);
 
 	switch (reason) {
 	case ZPOOL_STATUS_MISSING_DEV_R:
@@ -10485,8 +10484,8 @@ print_wait_status_row(wait_data_t *wd, zpool_handle_t *zhp, int row)
 	pool_checkpoint_stat_t *pcs = NULL;
 	pool_scan_stat_t *pss = NULL;
 	pool_removal_stat_t *prs = NULL;
-	char *headers[] = {"DISCARD", "FREE", "INITIALIZE", "REPLACE",
-	    "REMOVE", "RESILVER", "SCRUB", "TRIM"};
+	const char *const headers[] = {"DISCARD", "FREE", "INITIALIZE",
+	    "REPLACE", "REMOVE", "RESILVER", "SCRUB", "TRIM"};
 	int col_widths[ZPOOL_WAIT_NUM_ACTIVITIES];
 
 	/* Calculate the width of each column */
@@ -10508,7 +10507,7 @@ print_wait_status_row(wait_data_t *wd, zpool_handle_t *zhp, int row)
 			if (wd->wd_enabled[i])
 				(void) printf("%*s", col_widths[i], headers[i]);
 		}
-		(void) printf("\n");
+		(void) fputc('\n', stdout);
 	}
 
 	/* Bytes of work remaining in each activity */
@@ -10795,11 +10794,9 @@ found:;
 }
 
 static int
-find_command_idx(char *command, int *idx)
+find_command_idx(const char *command, int *idx)
 {
-	int i;
-
-	for (i = 0; i < NCOMMAND; i++) {
+	for (int i = 0; i < NCOMMAND; ++i) {
 		if (command_table[i].name == NULL)
 			continue;
 

cmd/zpool/zpool_vdev.c

@@ -274,7 +274,7 @@ make_leaf_vdev(nvlist_t *props, const char *arg, boolean_t is_primary)
 	char path[MAXPATHLEN];
 	struct stat64 statbuf;
 	nvlist_t *vdev = NULL;
-	char *type = NULL;
+	const char *type = NULL;
 	boolean_t wholedisk = B_FALSE;
 	uint64_t ashift = 0;
 	int err;

cmd/zpool_influxdb/zpool_influxdb.c

@@ -90,7 +90,7 @@ char metric_data_type = 'u';
 uint64_t metric_value_mask = UINT64_MAX;
 uint64_t timestamp = 0;
 int complained_about_sync = 0;
-char *tags = "";
+const char *tags = "";
 
 typedef int (*stat_printer_f)(nvlist_t *, const char *, const char *);
 
@@ -131,7 +131,7 @@ escape_string(const char *s)
  * print key=value where value is a uint64_t
  */
 static void
-print_kv(char *key, uint64_t value)
+print_kv(const char *key, uint64_t value)
 {
 	printf("%s=%llu%c", key,
 	    (u_longlong_t)value & metric_value_mask, metric_data_type);
@@ -152,9 +152,9 @@ print_scan_status(nvlist_t *nvroot, const char *pool_name)
 	uint64_t remaining_time;
 	pool_scan_stat_t *ps = NULL;
 	double pct_done;
-	char *state[DSS_NUM_STATES] = {
+	const char *const state[DSS_NUM_STATES] = {
 	    "none", "scanning", "finished", "canceled"};
-	char *func;
+	const char *func;
 
 	(void) nvlist_lookup_uint64_array(nvroot,
 	    ZPOOL_CONFIG_SCAN_STATS,
@@ -262,17 +262,15 @@ static char *
 get_vdev_name(nvlist_t *nvroot, const char *parent_name)
 {
 	static char vdev_name[256];
-	char *vdev_type = NULL;
 	uint64_t vdev_id = 0;
 
-	if (nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE,
-	    &vdev_type) != 0) {
-		vdev_type = "unknown";
-	}
+	char *vdev_type = (char *)"unknown";
+	nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE, &vdev_type);
+
 	if (nvlist_lookup_uint64(
-	    nvroot, ZPOOL_CONFIG_ID, &vdev_id) != 0) {
+	    nvroot, ZPOOL_CONFIG_ID, &vdev_id) != 0)
 		vdev_id = UINT64_MAX;
-	}
+
 	if (parent_name == NULL) {
 		(void) snprintf(vdev_name, sizeof (vdev_name), "%s",
 		    vdev_type);
@@ -298,22 +296,15 @@ static char *
 get_vdev_desc(nvlist_t *nvroot, const char *parent_name)
 {
 	static char vdev_desc[2 * MAXPATHLEN];
-	char *vdev_type = NULL;
-	uint64_t vdev_id = 0;
 	char vdev_value[MAXPATHLEN];
-	char *vdev_path = NULL;
 	char *s, *t;
 
-	if (nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE, &vdev_type) != 0) {
-		vdev_type = "unknown";
-	}
-	if (nvlist_lookup_uint64(nvroot, ZPOOL_CONFIG_ID, &vdev_id) != 0) {
-		vdev_id = UINT64_MAX;
-	}
-	if (nvlist_lookup_string(
-	    nvroot, ZPOOL_CONFIG_PATH, &vdev_path) != 0) {
-		vdev_path = NULL;
-	}
+	char *vdev_type = (char *)"unknown";
+	uint64_t vdev_id = UINT64_MAX;
+	char *vdev_path = NULL;
+	nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE, &vdev_type);
+	nvlist_lookup_uint64(nvroot, ZPOOL_CONFIG_ID, &vdev_id);
+	nvlist_lookup_string(nvroot, ZPOOL_CONFIG_PATH, &vdev_path);
 
 	if (parent_name == NULL) {
 		s = escape_string(vdev_type);
@@ -393,8 +384,8 @@ print_vdev_latency_stats(nvlist_t *nvroot, const char *pool_name,
 
 	/* short_names become part of the metric name and are influxdb-ready */
 	struct lat_lookup {
-	    char *name;
-	    char *short_name;
+	    const char *name;
+	    const char *short_name;
 	    uint64_t sum;
 	    uint64_t *array;
 	};
@@ -487,8 +478,8 @@ print_vdev_size_stats(nvlist_t *nvroot, const char *pool_name,
 
 	/* short_names become the field name */
 	struct size_lookup {
-	    char *name;
-	    char *short_name;
+	    const char *name;
+	    const char *short_name;
 	    uint64_t sum;
 	    uint64_t *array;
 	};
@@ -579,8 +570,8 @@ print_queue_stats(nvlist_t *nvroot, const char *pool_name,
 
 	/* short_names are used for the field name */
 	struct queue_lookup {
-	    char *name;
-	    char *short_name;
+	    const char *name;
+	    const char *short_name;
 	};
 	struct queue_lookup queue_type[] = {
 	    {ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE,	"sync_r_active"},
@@ -632,8 +623,8 @@ print_top_level_vdev_stats(nvlist_t *nvroot, const char *pool_name)
 
 	/* short_names become part of the metric name */
 	struct queue_lookup {
-	    char *name;
-	    char *short_name;
+	    const char *name;
+	    const char *short_name;
 	};
 	struct queue_lookup queue_type[] = {
 	    {ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE, "sync_r_active_queue"},
@@ -789,7 +780,7 @@ main(int argc, char *argv[])
 {
 	int opt;
 	int ret = 8;
-	char *line = NULL;
+	char *line = NULL, *ttags = NULL;
 	size_t len, tagslen = 0;
 	struct option long_options[] = {
 	    {"execd", no_argument, NULL, 'e'},
@@ -817,15 +808,17 @@ main(int argc, char *argv[])
 			sum_histogram_buckets = 1;
 			break;
 		case 't':
+			free(ttags);
 			tagslen = strlen(optarg) + 2;
-			tags = calloc(1, tagslen);
-			if (tags == NULL) {
+			ttags = calloc(1, tagslen);
+			if (ttags == NULL) {
 				fprintf(stderr,
 				    "error: cannot allocate memory "
 				    "for tags\n");
 				exit(1);
 			}
-			(void) snprintf(tags, tagslen, ",%s", optarg);
+			(void) snprintf(ttags, tagslen, ",%s", optarg);
+			tags = ttags;
 			break;
 		default:
 			usage(argv[0]);

cmd/ztest.c

@@ -264,7 +264,7 @@ extern unsigned long zfs_reconstruct_indirect_damage_fraction;
 
 static ztest_shared_opts_t *ztest_shared_opts;
 static ztest_shared_opts_t ztest_opts;
-static char *ztest_wkeydata = "abcdefghijklmnopqrstuvwxyz012345";
+static const char *const ztest_wkeydata = "abcdefghijklmnopqrstuvwxyz012345";
 
 typedef struct ztest_shared_ds {
 	uint64_t	zd_seq;
@@ -623,10 +623,10 @@ static void sig_handler(int signo)
 
 #define	FATAL_MSG_SZ	1024
 
-char *fatal_msg;
+static const char *fatal_msg;
 
 static __attribute__((format(printf, 2, 3))) __attribute__((noreturn)) void
-fatal(int do_perror, char *message, ...)
+fatal(int do_perror, const char *message, ...)
 {
 	va_list args;
 	int save_errno = errno;
@@ -724,7 +724,7 @@ typedef struct ztest_option {
 	const char	*long_opt_param;
 	const char	*comment;
 	unsigned int	default_int;
-	char		*default_str;
+	const char	*default_str;
 } ztest_option_t;
 
 /*
@@ -1200,30 +1200,31 @@ ztest_is_draid_spare(const char *name)
 }
 
 static nvlist_t *
-make_vdev_file(char *path, char *aux, char *pool, size_t size, uint64_t ashift)
+make_vdev_file(const char *path, const char *aux, const char *pool,
+    size_t size, uint64_t ashift)
 {
-	char *pathbuf;
+	char *pathbuf = NULL;
 	uint64_t vdev;
 	nvlist_t *file;
 	boolean_t draid_spare = B_FALSE;
 
-	pathbuf = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
 
 	if (ashift == 0)
 		ashift = ztest_get_ashift();
 
 	if (path == NULL) {
+		pathbuf = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
 		path = pathbuf;
 
 		if (aux != NULL) {
 			vdev = ztest_shared->zs_vdev_aux;
-			(void) snprintf(path, MAXPATHLEN,
+			(void) snprintf(pathbuf, MAXPATHLEN,
 			    ztest_aux_template, ztest_opts.zo_dir,
 			    pool == NULL ? ztest_opts.zo_pool : pool,
 			    aux, vdev);
 		} else {
 			vdev = ztest_shared->zs_vdev_next_leaf++;
-			(void) snprintf(path, MAXPATHLEN,
+			(void) snprintf(pathbuf, MAXPATHLEN,
 			    ztest_dev_template, ztest_opts.zo_dir,
 			    pool == NULL ? ztest_opts.zo_pool : pool, vdev);
 		}
@@ -1251,7 +1252,7 @@ make_vdev_file(char *path, char *aux, char *pool, size_t size, uint64_t ashift)
 }
 
 static nvlist_t *
-make_vdev_raid(char *path, char *aux, char *pool, size_t size,
+make_vdev_raid(const char *path, const char *aux, const char *pool, size_t size,
     uint64_t ashift, int r)
 {
 	nvlist_t *raid, **child;
@@ -1302,8 +1303,8 @@ make_vdev_raid(char *path, char *aux, char *pool, size_t size,
 }
 
 static nvlist_t *
-make_vdev_mirror(char *path, char *aux, char *pool, size_t size,
-    uint64_t ashift, int r, int m)
+make_vdev_mirror(const char *path, const char *aux, const char *pool,
+    size_t size, uint64_t ashift, int r, int m)
 {
 	nvlist_t *mirror, **child;
 	int c;
@@ -1330,8 +1331,8 @@ make_vdev_mirror(char *path, char *aux, char *pool, size_t size,
 }
 
 static nvlist_t *
-make_vdev_root(char *path, char *aux, char *pool, size_t size, uint64_t ashift,
-    const char *class, int r, int m, int t)
+make_vdev_root(const char *path, const char *aux, const char *pool, size_t size,
+    uint64_t ashift, const char *class, int r, int m, int t)
 {
 	nvlist_t *root, **child;
 	int c;
@@ -3371,7 +3372,7 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 	spa_t *spa = ztest_spa;
 	vdev_t *rvd = spa->spa_root_vdev;
 	spa_aux_vdev_t *sav;
-	char *aux;
+	const char *aux;
 	char *path;
 	uint64_t guid = 0;
 	int error, ignore_err = 0;
@@ -5271,7 +5272,7 @@ ztest_zap(ztest_ds_t *zd, uint64_t id)
 	dmu_tx_t *tx;
 	char propname[100], txgname[100];
 	int error;
-	char *hc[2] = { "s.acl.h", ".s.open.h.hyLZlg" };
+	const char *const hc[2] = { "s.acl.h", ".s.open.h.hyLZlg" };
 
 	od = umem_alloc(sizeof (ztest_od_t), UMEM_NOFAIL);
 	ztest_od_init(od, id, FTAG, 0, DMU_OT_ZAP_OTHER, 0, 0, 0);
@@ -6636,11 +6637,8 @@ ztest_global_vars_to_zdb_args(void)
 	char **args = calloc(2*ztest_opts.zo_gvars_count + 1, sizeof (char *));
 	char **cur = args;
 	for (size_t i = 0; i < ztest_opts.zo_gvars_count; i++) {
-		char *kv = ztest_opts.zo_gvars[i];
-		*cur = "-o";
-		cur++;
-		*cur = strdup(kv);
-		cur++;
+		*cur++ = (char *)"-o";
+		*cur++ = ztest_opts.zo_gvars[i];
 	}
 	ASSERT3P(cur, ==, &args[2*ztest_opts.zo_gvars_count]);
 	*cur = NULL;
@@ -6891,7 +6889,7 @@ ztest_trim(ztest_ds_t *zd, uint64_t id)
  * Verify pool integrity by running zdb.
  */
 static void
-ztest_run_zdb(char *pool)
+ztest_run_zdb(const char *pool)
 {
 	int status;
 	char *bin;
@@ -6949,12 +6947,12 @@ out:
 }
 
 static void
-ztest_walk_pool_directory(char *header)
+ztest_walk_pool_directory(const char *header)
 {
 	spa_t *spa = NULL;
 
 	if (ztest_opts.zo_verbose >= 6)
-		(void) printf("%s\n", header);
+		(void) puts(header);
 
 	mutex_enter(&spa_namespace_lock);
 	while ((spa = spa_next(spa)) != NULL)
@@ -7206,7 +7204,7 @@ ztest_thread(void *arg)
 }
 
 static void
-ztest_dataset_name(char *dsname, char *pool, int d)
+ztest_dataset_name(char *dsname, const char *pool, int d)
 {
 	(void) snprintf(dsname, ZFS_MAX_DATASET_NAME_LEN, "%s/ds_%d", pool, d);
 }