The checkers code implicitly uses a sort-of OOP class/instance model,
but very clumsily. Separate the checker "class" and "instance" cleanly,
and do a few further cleanups (constifications etc) on the way.

Reviewed-by: Benjamin Marzinski <bmarz...@redhat.com>
Signed-off-by: Martin Wilck <mwi...@suse.com>
---
 libmultipath/checkers.c          | 131 ++++++++++++++++---------------
 libmultipath/checkers.h          |  23 ++----
 libmultipath/checkers/directio.c |   2 +-
 libmultipath/checkers/tur.c      |   2 +-
 libmultipath/print.c             |   2 +-
 libmultipath/propsel.c           |  19 ++---
 6 files changed, 89 insertions(+), 90 deletions(-)

diff --git a/libmultipath/checkers.c b/libmultipath/checkers.c
index 90313c35..848c4c34 100644
--- a/libmultipath/checkers.c
+++ b/libmultipath/checkers.c
@@ -8,6 +8,19 @@
 #include "checkers.h"
 #include "vector.h"
 
+struct checker_class {
+       struct list_head node;
+       void *handle;
+       int refcount;
+       int sync;
+       char name[CHECKER_NAME_LEN];
+       int (*check)(struct checker *);
+       int (*init)(struct checker *);       /* to allocate the context */
+       void (*free)(struct checker *);      /* to free the context */
+       const char **msgtable;
+       short msgtable_size;
+};
+
 char *checker_state_names[] = {
        "wild",
        "unchecked",
@@ -23,38 +36,30 @@ char *checker_state_names[] = {
 
 static LIST_HEAD(checkers);
 
-char * checker_state_name (int i)
+const char *checker_state_name(int i)
 {
        return checker_state_names[i];
 }
 
-int init_checkers (char *multipath_dir)
-{
-       if (!add_checker(multipath_dir, DEFAULT_CHECKER))
-               return 1;
-       return 0;
-}
-
-struct checker * alloc_checker (void)
+static struct checker_class *alloc_checker_class(void)
 {
-       struct checker *c;
+       struct checker_class *c;
 
-       c = MALLOC(sizeof(struct checker));
+       c = MALLOC(sizeof(struct checker_class));
        if (c) {
                INIT_LIST_HEAD(&c->node);
                c->refcount = 1;
-               c->fd = -1;
        }
        return c;
 }
 
-void free_checker (struct checker * c)
+void free_checker_class(struct checker_class *c)
 {
        if (!c)
                return;
        c->refcount--;
        if (c->refcount) {
-               condlog(3, "%s checker refcount %d",
+               condlog(4, "%s checker refcount %d",
                        c->name, c->refcount);
                return;
        }
@@ -71,17 +76,17 @@ void free_checker (struct checker * c)
 
 void cleanup_checkers (void)
 {
-       struct checker * checker_loop;
-       struct checker * checker_temp;
+       struct checker_class *checker_loop;
+       struct checker_class *checker_temp;
 
        list_for_each_entry_safe(checker_loop, checker_temp, &checkers, node) {
-               free_checker(checker_loop);
+               free_checker_class(checker_loop);
        }
 }
 
-struct checker * checker_lookup (char * name)
+static struct checker_class *checker_class_lookup(const char *name)
 {
-       struct checker * c;
+       struct checker_class *c;
 
        if (!name || !strlen(name))
                return NULL;
@@ -92,14 +97,15 @@ struct checker * checker_lookup (char * name)
        return NULL;
 }
 
-struct checker * add_checker (char *multipath_dir, char * name)
+static struct checker_class *add_checker_class(const char *multipath_dir,
+                                              const char *name)
 {
        char libname[LIB_CHECKER_NAMELEN];
        struct stat stbuf;
-       struct checker * c;
+       struct checker_class *c;
        char *errstr;
 
-       c = alloc_checker();
+       c = alloc_checker_class();
        if (!c)
                return NULL;
        snprintf(c->name, CHECKER_NAME_LEN, "%s", name);
@@ -158,12 +164,11 @@ struct checker * add_checker (char *multipath_dir, char * 
name)
                c->name, c->msgtable_size);
 
 done:
-       c->fd = -1;
        c->sync = 1;
        list_add(&c->node, &checkers);
        return c;
 out:
-       free_checker(c);
+       free_checker_class(c);
        return NULL;
 }
 
@@ -176,16 +181,16 @@ void checker_set_fd (struct checker * c, int fd)
 
 void checker_set_sync (struct checker * c)
 {
-       if (!c)
+       if (!c || !c->cls)
                return;
-       c->sync = 1;
+       c->cls->sync = 1;
 }
 
 void checker_set_async (struct checker * c)
 {
-       if (!c)
+       if (!c || !c->cls)
                return;
-       c->sync = 0;
+       c->cls->sync = 0;
 }
 
 void checker_enable (struct checker * c)
@@ -204,11 +209,11 @@ void checker_disable (struct checker * c)
 
 int checker_init (struct checker * c, void ** mpctxt_addr)
 {
-       if (!c)
+       if (!c || !c->cls)
                return 1;
        c->mpcontext = mpctxt_addr;
-       if (c->init)
-               return c->init(c);
+       if (c->cls->init)
+               return c->cls->init(c);
        return 0;
 }
 
@@ -220,15 +225,16 @@ void checker_clear (struct checker *c)
 
 void checker_put (struct checker * dst)
 {
-       struct checker * src;
+       struct checker_class *src;
 
-       if (!dst || !strlen(dst->name))
+       if (!dst)
                return;
-       src = checker_lookup(dst->name);
-       if (dst->free)
-               dst->free(dst);
+       src = dst->cls;
+
+       if (src && src->free)
+               src->free(dst);
        checker_clear(dst);
-       free_checker(src);
+       free_checker_class(src);
 }
 
 int checker_check (struct checker * c, int path_state)
@@ -243,32 +249,35 @@ int checker_check (struct checker * c, int path_state)
                c->msgid = CHECKER_MSGID_DISABLED;
                return PATH_UNCHECKED;
        }
-       if (!strncmp(c->name, NONE, 4))
+       if (!strncmp(c->cls->name, NONE, 4))
                return path_state;
 
        if (c->fd < 0) {
                c->msgid = CHECKER_MSGID_NO_FD;
                return PATH_WILD;
        }
-       r = c->check(c);
+       r = c->cls->check(c);
 
        return r;
 }
 
-int checker_selected (struct checker * c)
+int checker_selected(const struct checker *c)
 {
        if (!c)
                return 0;
-       if (!strncmp(c->name, NONE, 4))
-               return 1;
-       return (c->check) ? 1 : 0;
+       return c->cls != NULL;
 }
 
 const char *checker_name(const struct checker *c)
 {
-       if (!c)
+       if (!c || !c->cls)
                return NULL;
-       return c->name;
+       return c->cls->name;
+}
+
+int checker_is_sync(const struct checker *c)
+{
+       return c && c->cls && c->cls->sync;
 }
 
 static const char *generic_msg[CHECKER_GENERIC_MSGTABLE_SIZE] = {
@@ -309,31 +318,29 @@ void checker_clear_message (struct checker *c)
        c->msgid = CHECKER_MSGID_NONE;
 }
 
-void checker_get (char *multipath_dir, struct checker * dst, char * name)
+void checker_get(const char *multipath_dir, struct checker *dst,
+                const char *name)
 {
-       struct checker * src = NULL;
+       struct checker_class *src = NULL;
 
        if (!dst)
                return;
 
        if (name && strlen(name)) {
-               src = checker_lookup(name);
+               src = checker_class_lookup(name);
                if (!src)
-                       src = add_checker(multipath_dir, name);
+                       src = add_checker_class(multipath_dir, name);
        }
-       if (!src) {
-               dst->check = NULL;
+       dst->cls = src;
+       if (!src)
                return;
-       }
-       dst->fd = src->fd;
-       dst->sync = src->sync;
-       strncpy(dst->name, src->name, CHECKER_NAME_LEN);
-       dst->msgid = CHECKER_MSGID_NONE;
-       dst->check = src->check;
-       dst->init = src->init;
-       dst->free = src->free;
-       dst->msgtable = src->msgtable;
-       dst->msgtable_size = src->msgtable_size;
-       dst->handle = NULL;
+
        src->refcount++;
 }
+
+int init_checkers(const char *multipath_dir)
+{
+       if (!add_checker_class(multipath_dir, DEFAULT_CHECKER))
+               return 1;
+       return 0;
+}
diff --git a/libmultipath/checkers.h b/libmultipath/checkers.h
index 3cd46bdf..b2e8f9aa 100644
--- a/libmultipath/checkers.h
+++ b/libmultipath/checkers.h
@@ -116,32 +116,22 @@ enum {
        CHECKER_MSGTABLE_SIZE = 100,    /* max msg table size for checkers */
 };
 
+struct checker_class;
 struct checker {
-       struct list_head node;
-       void *handle;
-       int refcount;
+       struct checker_class *cls;
        int fd;
-       int sync;
        unsigned int timeout;
        int disable;
-       char name[CHECKER_NAME_LEN];
        short msgid;                         /* checker-internal extra status */
        void * context;                      /* store for persistent data */
        void ** mpcontext;                   /* store for persistent data shared
                                                multipath-wide. Use MALLOC if
                                                you want to stuff data in. */
-       int (*check)(struct checker *);
-       int (*init)(struct checker *);       /* to allocate the context */
-       void (*free)(struct checker *);      /* to free the context */
-       const char**msgtable;
-       short msgtable_size;
 };
 
-char * checker_state_name (int);
-int init_checkers (char *);
+const char *checker_state_name(int);
+int init_checkers(const char *);
 void cleanup_checkers (void);
-struct checker * add_checker (char *, char *);
-struct checker * checker_lookup (char *);
 int checker_init (struct checker *, void **);
 void checker_clear (struct checker *);
 void checker_put (struct checker *);
@@ -152,7 +142,8 @@ void checker_set_fd (struct checker *, int);
 void checker_enable (struct checker *);
 void checker_disable (struct checker *);
 int checker_check (struct checker *, int);
-int checker_selected (struct checker *);
+int checker_selected(const struct checker *);
+int checker_is_sync(const struct checker *);
 const char *checker_name (const struct checker *);
 /*
  * This returns a string that's best prepended with "$NAME checker",
@@ -160,7 +151,7 @@ const char *checker_name (const struct checker *);
  */
 const char *checker_message(const struct checker *);
 void checker_clear_message (struct checker *c);
-void checker_get (char *, struct checker *, char *);
+void checker_get(const char *, struct checker *, const char *);
 
 /* Prototypes for symbols exported by path checker dynamic libraries (.so) */
 int libcheck_check(struct checker *);
diff --git a/libmultipath/checkers/directio.c b/libmultipath/checkers/directio.c
index c4a0712e..1b00b775 100644
--- a/libmultipath/checkers/directio.c
+++ b/libmultipath/checkers/directio.c
@@ -202,7 +202,7 @@ int libcheck_check (struct checker * c)
        if (!ct)
                return PATH_UNCHECKED;
 
-       ret = check_state(c->fd, ct, c->sync, c->timeout);
+       ret = check_state(c->fd, ct, checker_is_sync(c), c->timeout);
 
        switch (ret)
        {
diff --git a/libmultipath/checkers/tur.c b/libmultipath/checkers/tur.c
index a27474f9..63b19624 100644
--- a/libmultipath/checkers/tur.c
+++ b/libmultipath/checkers/tur.c
@@ -323,7 +323,7 @@ int libcheck_check(struct checker * c)
        if (!ct)
                return PATH_UNCHECKED;
 
-       if (c->sync)
+       if (checker_is_sync(c))
                return tur_check(c->fd, c->timeout, &c->msgid);
 
        /*
diff --git a/libmultipath/print.c b/libmultipath/print.c
index 7b610b94..fc40b0f0 100644
--- a/libmultipath/print.c
+++ b/libmultipath/print.c
@@ -615,7 +615,7 @@ static int
 snprint_path_checker (char * buff, size_t len, const struct path * pp)
 {
        const struct checker * c = &pp->checker;
-       return snprint_str(buff, len, c->name);
+       return snprint_str(buff, len, checker_name(c));
 }
 
 static int
diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index fdb5953a..970a3b5c 100644
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -479,26 +479,27 @@ check_rdac(struct path * pp)
 int select_checker(struct config *conf, struct path *pp)
 {
        const char *origin;
-       char *checker_name;
+       char *ckr_name;
        struct checker * c = &pp->checker;
 
        if (pp->detect_checker == DETECT_CHECKER_ON) {
                origin = autodetect_origin;
                if (check_rdac(pp)) {
-                       checker_name = RDAC;
+                       ckr_name = RDAC;
                        goto out;
                } else if (pp->tpgs > 0) {
-                       checker_name = TUR;
+                       ckr_name = TUR;
                        goto out;
                }
        }
-       do_set(checker_name, conf->overrides, checker_name, overrides_origin);
-       do_set_from_hwe(checker_name, pp, checker_name, hwe_origin);
-       do_set(checker_name, conf, checker_name, conf_origin);
-       do_default(checker_name, DEFAULT_CHECKER);
+       do_set(checker_name, conf->overrides, ckr_name, overrides_origin);
+       do_set_from_hwe(checker_name, pp, ckr_name, hwe_origin);
+       do_set(checker_name, conf, ckr_name, conf_origin);
+       do_default(ckr_name, DEFAULT_CHECKER);
 out:
-       checker_get(conf->multipath_dir, c, checker_name);
-       condlog(3, "%s: path_checker = %s %s", pp->dev, c->name, origin);
+       checker_get(conf->multipath_dir, c, ckr_name);
+       condlog(3, "%s: path_checker = %s %s", pp->dev,
+               checker_name(c), origin);
        if (conf->checker_timeout) {
                c->timeout = conf->checker_timeout;
                condlog(3, "%s: checker timeout = %u s %s",
-- 
2.19.1

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