across: clang-scan: fix NULL dereferencing warnings

All these checks are done after analyzing clang-scan report produced
by the CI job @ https://build.gluster.org/job/clang-scan

updates: bz#1622665
Change-Id: I590305af4ceb779be952974b2a36066ffc4865ca
Signed-off-by: Amar Tumballi <amarts@redhat.com>

7 files changed, 34 insertions, 19 deletions

diff --git a/xlators/features/locks/src/common.c b/xlators/features/locks/src/common.c
index 24422b494b9..ad1ce6c604d 100644
--- a/xlators/features/locks/src/common.c
+++ b/xlators/features/locks/src/common.c
@@ -1274,7 +1274,7 @@ pl_local_init(call_frame_t *frame, xlator_t *this, loc_t *loc, fd_t *fd)
             return -1;
         }
 
-        local->inode = (fd ? inode_ref(fd->inode) : inode_ref(loc->inode));
+        local->inode = (loc ? inode_ref(loc->inode) : inode_ref(fd->inode));
 
         frame->local = local;
     }
diff --git a/xlators/features/marker/src/marker-quota.c b/xlators/features/marker/src/marker-quota.c
index 31584f5446b..4176ab6a8f1 100644
--- a/xlators/features/marker/src/marker-quota.c
+++ b/xlators/features/marker/src/marker-quota.c
@@ -2063,6 +2063,9 @@ mq_inspect_directory_xattr(xlator_t *this, quota_inode_ctx_t *ctx,
     if (ret < 0)
         goto create_xattr;
 
+    if (!contribution)
+        goto create_xattr;
+
     if (!loc_is_root(loc)) {
         GET_CONTRI_KEY(this, contri_key, contribution->gfid, keylen);
         if (keylen < 0) {
diff --git a/xlators/features/quota/src/quota.c b/xlators/features/quota/src/quota.c
index a0c236d4cf6..1335386a197 100644
--- a/xlators/features/quota/src/quota.c
+++ b/xlators/features/quota/src/quota.c
@@ -1921,10 +1921,12 @@ quota_writev(call_frame_t *frame, xlator_t *this, fd_t *fd,
             par_inode = do_quota_check_limit(frame, fd->inode, this, dentry,
                                              _gf_false);
             if (par_inode == NULL) {
-                /* remove stale entry from inode ctx */
-                quota_dentry_del(ctx, dentry->name, dentry->par);
-                parents--;
-                fail_count++;
+                if (ctx) {
+                    /* remove stale entry from inode ctx */
+                    quota_dentry_del(ctx, dentry->name, dentry->par);
+                    parents--;
+                    fail_count++;
+                }
             } else {
                 inode_unref(par_inode);
             }
diff --git a/xlators/features/quota/src/quotad-aggregator.c b/xlators/features/quota/src/quotad-aggregator.c
index 5a755c45fda..15b482503e3 100644
--- a/xlators/features/quota/src/quotad-aggregator.c
+++ b/xlators/features/quota/src/quotad-aggregator.c
@@ -176,8 +176,9 @@ out:
     }
 
 reply:
-    quotad_aggregator_submit_reply(frame, frame->local, (void *)&cli_rsp, NULL,
-                                   0, NULL, (xdrproc_t)xdr_gf_cli_rsp);
+    quotad_aggregator_submit_reply(frame, (frame) ? frame->local : NULL,
+                                   (void *)&cli_rsp, NULL, 0, NULL,
+                                   (xdrproc_t)xdr_gf_cli_rsp);
 
     dict_unref(xdata);
     GF_FREE(cli_rsp.dict.dict_val);
diff --git a/xlators/features/sdfs/src/sdfs.c b/xlators/features/sdfs/src/sdfs.c
index b3fbc01caf7..3460b475824 100644
--- a/xlators/features/sdfs/src/sdfs.c
+++ b/xlators/features/sdfs/src/sdfs.c
@@ -177,9 +177,10 @@ sdfs_get_new_frame(call_frame_t *frame, loc_t *loc, call_frame_t **new_frame)
 
     ret = 0;
 err:
-    if ((ret < 0) && (*new_frame != NULL)) {
+    if (ret && (*new_frame)) {
         SDFS_STACK_DESTROY((*new_frame));
         *new_frame = NULL;
+        ret = -1;
     }
 
     return ret;
diff --git a/xlators/features/shard/src/shard.c b/xlators/features/shard/src/shard.c
index 2249cefc5ab..bb660306212 100644
--- a/xlators/features/shard/src/shard.c
+++ b/xlators/features/shard/src/shard.c
@@ -886,26 +886,34 @@ int
 shard_common_inode_write_success_unwind(glusterfs_fop_t fop,
                                         call_frame_t *frame, int32_t op_ret)
 {
-    shard_local_t *local = NULL;
+    shard_local_t *local = frame->local;
 
-    local = frame->local;
+    /* the below 3 variables are required because, in SHARD_STACK_UNWIND()
+       macro, there is a check for local being null. So many static analyzers
+       backtrace the code with assumption of possible (local == NULL) case,
+       and complains for below lines. By handling it like below, we overcome
+       the warnings */
+
+    struct iatt *prebuf = ((local) ? &local->prebuf : NULL);
+    struct iatt *postbuf = ((local) ? &local->postbuf : NULL);
+    dict_t *xattr_rsp = ((local) ? local->xattr_rsp : NULL);
 
     switch (fop) {
         case GF_FOP_WRITE:
-            SHARD_STACK_UNWIND(writev, frame, op_ret, 0, &local->prebuf,
-                               &local->postbuf, local->xattr_rsp);
+            SHARD_STACK_UNWIND(writev, frame, op_ret, 0, prebuf, postbuf,
+                               xattr_rsp);
             break;
         case GF_FOP_FALLOCATE:
-            SHARD_STACK_UNWIND(fallocate, frame, op_ret, 0, &local->prebuf,
-                               &local->postbuf, local->xattr_rsp);
+            SHARD_STACK_UNWIND(fallocate, frame, op_ret, 0, prebuf, postbuf,
+                               xattr_rsp);
             break;
         case GF_FOP_ZEROFILL:
-            SHARD_STACK_UNWIND(zerofill, frame, op_ret, 0, &local->prebuf,
-                               &local->postbuf, local->xattr_rsp);
+            SHARD_STACK_UNWIND(zerofill, frame, op_ret, 0, prebuf, postbuf,
+                               xattr_rsp);
             break;
         case GF_FOP_DISCARD:
-            SHARD_STACK_UNWIND(discard, frame, op_ret, 0, &local->prebuf,
-                               &local->postbuf, local->xattr_rsp);
+            SHARD_STACK_UNWIND(discard, frame, op_ret, 0, prebuf, postbuf,
+                               xattr_rsp);
             break;
         default:
             gf_msg(THIS->name, GF_LOG_WARNING, 0, SHARD_MSG_INVALID_FOP,
diff --git a/xlators/storage/posix/src/posix-helpers.c b/xlators/storage/posix/src/posix-helpers.c
index 7296f698db0..bab79f42c2f 100644
--- a/xlators/storage/posix/src/posix-helpers.c
+++ b/xlators/storage/posix/src/posix-helpers.c
@@ -2416,7 +2416,7 @@ posix_fsyncer_process(xlator_t *this, call_stub_t *stub, gf_boolean_t do_fsync)
         return;
     }
 
-    if (do_fsync) {
+    if (do_fsync && pfd) {
         if (stub->args.datasync)
             ret = sys_fdatasync(pfd->fd);
         else