[RFC PATCH 08/20] libmultipath: fix compiler warnings for -Wcast-qual

[Martin Wilck <mwilck@suse.com>]

Fix the warnings that were caused by adding the -Wcast-qual compiler
flag in the previous patch.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 kpartx/devmapper.c          |  3 ++-
 libmpathcmd/mpath_cmd.c     |  2 +-
 libmultipath/checkers/rbd.c |  4 ++--
 libmultipath/devmapper.c    |  3 ++-
 libmultipath/discovery.c    | 12 ++++++------
 libmultipath/list.h         |  4 ++--
 libmultipath/memory.h       |  8 +++++++-
 libmultipath/structs.c      |  2 +-
 libmultipath/structs.h      |  2 +-
 libmultipath/uevent.c       |  6 +++---
 libmultipath/util.c         |  6 +++---
 multipathd/main.c           | 10 +++++-----
 12 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/kpartx/devmapper.c b/kpartx/devmapper.c
index 4469fa848de8..eb9dac639175 100644
--- a/kpartx/devmapper.c
+++ b/kpartx/devmapper.c
@@ -11,6 +11,7 @@
 #include <sys/sysmacros.h>
 #include "devmapper.h"
 
+#define FREE_CONST(p) do { free((void*)(long)p); p = NULL; } while(0)
 #define _UUID_PREFIX "part"
 #define UUID_PREFIX _UUID_PREFIX "%d-"
 #define _UUID_PREFIX_LEN (sizeof(_UUID_PREFIX) - 1)
@@ -695,7 +696,7 @@ int dm_find_part(const char *parent, const char *delim, int part,
 	} else
 		*part_uuid = uuid;
 out:
-	free((void*)tmp);
+	FREE_CONST(tmp);
 	return r;
 }
 
diff --git a/libmpathcmd/mpath_cmd.c b/libmpathcmd/mpath_cmd.c
index af618cff917c..29d148ce8aff 100644
--- a/libmpathcmd/mpath_cmd.c
+++ b/libmpathcmd/mpath_cmd.c
@@ -64,7 +64,7 @@ static size_t write_all(int fd, const void *buf, size_t len)
 		}
 		if (!n)
 			return total;
-		buf = n + (char *)buf;
+		buf = n + (const char *)buf;
 		len -= n;
 		total += n;
 	}
diff --git a/libmultipath/checkers/rbd.c b/libmultipath/checkers/rbd.c
index 2c1800976e40..b1d99b4c81f6 100644
--- a/libmultipath/checkers/rbd.c
+++ b/libmultipath/checkers/rbd.c
@@ -288,7 +288,7 @@ void libcheck_free(struct checker * c)
 static int rbd_is_blacklisted(struct rbd_checker_context *ct, char *msg)
 {
 	char *addr_tok, *start, *save;
-	char *cmd[2];
+	const char *cmd[2];
 	char *blklist, *stat;
 	size_t blklist_len, stat_len;
 	int ret;
@@ -436,7 +436,7 @@ static int sysfs_write_rbd_remove(const char *buf, int buf_len)
 
 static int rbd_rm_blacklist(struct rbd_checker_context *ct)
 {
-	char *cmd[2];
+	const char *cmd[2];
 	char *stat, *cmd_str;
 	size_t stat_len;
 	int ret;
diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index f61838cbe369..607aea8dc1fc 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <time.h>
 
+#define FREE_CONST(p) do { free((void*)(unsigned long)p); p = NULL; } while(0)
 #define MAX_WAIT 5
 #define LOOPS_PER_SEC 5
 
@@ -1426,7 +1427,7 @@ void dm_reassign_deps(char *table, const char *dep, const char *newdep)
 	n += strlen(newdep);
 	p += strlen(dep);
 	strcat(n, p);
-	free(newtable);
+	FREE_CONST(newtable);
 }
 
 int dm_reassign_table(const char *name, char *old, char *new)
diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index 98bddee52c8f..645224c1029c 100644
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -121,7 +121,7 @@ path_discover (vector pathvec, struct config * conf,
 	if (!devname)
 		return PATHINFO_FAILED;
 
-	pp = find_path_by_dev(pathvec, (char *)devname);
+	pp = find_path_by_dev(pathvec, devname);
 	if (!pp) {
 		char devt[BLK_DEV_SIZE];
 		dev_t devnum = udev_device_get_devnum(udevice);
@@ -905,12 +905,12 @@ static int
 parse_vpd_pg83(const unsigned char *in, size_t in_len,
 	       char *out, size_t out_len)
 {
-	unsigned char *d;
-	unsigned char *vpd = NULL;
+	const unsigned char *d;
+	const unsigned char *vpd = NULL;
 	int len = -ENODATA, vpd_type, vpd_len, prio = -1, i, naa_prio;
 
-	d = (unsigned char *)in + 4;
-	while (d < (unsigned char *)in + in_len) {
+	d = in + 4;
+	while (d < in + in_len) {
 		/* Select 'association: LUN' */
 		if ((d[1] & 0x30) != 0) {
 			d += d[3] + 4;
@@ -1027,7 +1027,7 @@ parse_vpd_pg83(const unsigned char *in, size_t in_len,
 				out[len] = '\0';
 			}
 		} else if (vpd_type == 0x1) {
-			unsigned char *p;
+			const unsigned char *p;
 			int p_len;
 
 			out[0] = '1';
diff --git a/libmultipath/list.h b/libmultipath/list.h
index 2b1dcf396695..c9110ac9de7e 100644
--- a/libmultipath/list.h
+++ b/libmultipath/list.h
@@ -18,8 +18,8 @@
  * @member:	the name of the member within the struct.
  *
  */
-#define container_of(ptr, type, member) ({			\
-	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
+#define container_of(ptr, type, member) ({		\
+	typeof( ((type *)0)->member ) *__mptr = (ptr);	\
 	(type *)( (char *)__mptr - offsetof(type,member) );})
 
 /*
diff --git a/libmultipath/memory.h b/libmultipath/memory.h
index 927619b58a62..63f59d80584c 100644
--- a/libmultipath/memory.h
+++ b/libmultipath/memory.h
@@ -43,6 +43,7 @@ int debug;
 		      (__FILE__), (char *)(__FUNCTION__), (__LINE__)) )
 #define STRDUP(n)    ( dbg_strdup((n), \
 		      (__FILE__), (char *)(__FUNCTION__), (__LINE__)) )
+#define FREE_CONST(p) do { FREE((void*)(unsigned long)p); } while(0)
 
 /* Memory debug prototypes defs */
 extern void *dbg_malloc(unsigned long, char *, char *, int);
@@ -54,7 +55,12 @@ extern void dbg_free_final(char *);
 #else
 
 #define MALLOC(n)    (calloc(1,(n)))
-#define FREE(p)      do { free((void*)p); p = NULL; } while(0)
+#define FREE(p)      do { free(p); p = NULL; } while(0)
+/*
+ * Double cast to avoid warnings with -Wcast-qual
+ * use this for valid free() operations on const pointers
+ */
+#define FREE_CONST(p) do { free((void*)(unsigned long)p); p = NULL; } while(0)
 #define REALLOC(p,n) (realloc((p),(n)))
 #define STRDUP(n)    (strdup(n))
 
diff --git a/libmultipath/structs.c b/libmultipath/structs.c
index 1ade1a6705ad..4db08451824d 100644
--- a/libmultipath/structs.c
+++ b/libmultipath/structs.c
@@ -418,7 +418,7 @@ find_mp_by_str (vector mpvec, char * str)
 }
 
 struct path *
-find_path_by_dev (vector pathvec, char * dev)
+find_path_by_dev (vector pathvec, const char * dev)
 {
 	int i;
 	struct path * pp;
diff --git a/libmultipath/structs.h b/libmultipath/structs.h
index 71b37cc20674..bccc845a1222 100644
--- a/libmultipath/structs.h
+++ b/libmultipath/structs.h
@@ -387,7 +387,7 @@ struct multipath * find_mp_by_str (vector mp, char * wwid);
 struct multipath * find_mp_by_minor (vector mp, int minor);
 
 struct path * find_path_by_devt (vector pathvec, const char * devt);
-struct path * find_path_by_dev (vector pathvec, char * dev);
+struct path * find_path_by_dev (vector pathvec, const char * dev);
 struct path * first_path (struct multipath * mpp);
 
 int pathcountgr (struct pathgroup *, int);
diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
index 8f4129ca7fd0..685ef3362c6d 100644
--- a/libmultipath/uevent.c
+++ b/libmultipath/uevent.c
@@ -157,7 +157,7 @@ static int uevent_get_env_positive_int(const struct uevent *uev,
 void
 uevent_get_wwid(struct uevent *uev)
 {
-	char *uid_attribute;
+	const char *uid_attribute;
 	const char *val;
 	struct config * conf;
 
@@ -167,8 +167,8 @@ uevent_get_wwid(struct uevent *uev)
 
 	val = uevent_get_env_var(uev, uid_attribute);
 	if (val)
-		uev->wwid = (char*)val;
-	free(uid_attribute);
+		uev->wwid = val;
+	FREE_CONST(uid_attribute);
 }
 
 bool
diff --git a/libmultipath/util.c b/libmultipath/util.c
index 0b43d29d1236..d3dd3eb524d0 100644
--- a/libmultipath/util.c
+++ b/libmultipath/util.c
@@ -32,7 +32,7 @@ strchop(char *str)
 int
 basenamecpy (const char * str1, char * str2, int str2len)
 {
-	char *p;
+	const char *p;
 
 	if (!str1 || !strlen(str1))
 		return 0;
@@ -43,7 +43,7 @@ basenamecpy (const char * str1, char * str2, int str2len)
 	if (!str2)
 		return 0;
 
-	p = (char *)str1 + (strlen(str1) - 1);
+	p = str1 + (strlen(str1) - 1);
 
 	while (*--p != '/' && p != str1)
 		continue;
@@ -454,7 +454,7 @@ int safe_write(int fd, const void *buf, size_t count)
 			return -errno;
 		}
 		count -= r;
-		buf = (char *)buf + r;
+		buf = (const char *)buf + r;
 	}
 	return 0;
 }
diff --git a/multipathd/main.c b/multipathd/main.c
index a8a0c302e8fe..b900bb3ec2e3 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -408,7 +408,7 @@ uev_add_map (struct uevent * uev, struct vectors * vecs)
 	pthread_testcancel();
 	rc = ev_add_map(uev->kernel, alias, vecs);
 	lock_cleanup_pop(vecs->lock);
-	FREE(alias);
+	FREE_CONST(alias);
 	return rc;
 }
 
@@ -532,7 +532,7 @@ uev_remove_map (struct uevent * uev, struct vectors * vecs)
 	remove_map_and_stop_waiter(mpp, vecs, 1);
 out:
 	lock_cleanup_pop(vecs->lock);
-	FREE(alias);
+	FREE_CONST(alias);
 	return 0;
 }
 
@@ -1028,11 +1028,11 @@ uev_pathfail_check(struct uevent *uev, struct vectors *vecs)
 				pp->dev);
 out_lock:
 	lock_cleanup_pop(vecs->lock);
-	FREE(devt);
-	FREE(action);
+	FREE_CONST(devt);
+	FREE_CONST(action);
 	return r;
 out:
-	FREE(action);
+	FREE_CONST(action);
 	return 1;
 }
 
-- 
2.16.1