afsd: Fix problems found by static analysis

Several static analysis tools have identified various problems:
 - files left open from early returns/exits       (infer)
 - missing checks to ensure *alloc was successful (infer)
 - memory leaks due to not freeing storage before
   a return                                       (infer)
 - unused variables                               (cppcheck)

To resolve the above problems:
 - close files before returning/exiting
 - add checks to ensure *alloc was successful before using the memory
 - free storage before returning
 - remove unused variables

This commit is a reorganization of commits submitted by Pat Riehecky,
who ran the static analysis tools and developed the fixes.

Change-Id: If45d64c370ad68d1e844b6aa5881f9dbd75300c9
Reviewed-on: https://gerrit.openafs.org/14671
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>

src/afsd/afsd.c

@@ -896,6 +896,7 @@ CreateCacheFile(char *fname, struct stat *statp)
     if (statp != NULL) {
 	closeResult = fstat(cfd, statp);
 	if (closeResult) {
+	    close(cfd);
 	    printf
 		("%s: Can't stat newly-created AFS cache file '%s' (code %d)\n",
 		 rn, fname, errno);
@@ -1519,6 +1520,7 @@ BkgHandler(void)
     char dstName[256];
 
     uspc = calloc(1, sizeof(struct afs_uspc_param));
+    opr_Assert(uspc != NULL);
     memset(srcName, 0, sizeof(srcName));
     memset(dstName, 0, sizeof(dstName));
 
@@ -1538,7 +1540,7 @@ BkgHandler(void)
 		 * like a AFS_USPC_SHUTDOWN, in case we're running with an
 		 * older kernel module.
 		 */
-		return;
+		goto done;
 	    }
 
 	    sleep(1);
@@ -1549,7 +1551,7 @@ BkgHandler(void)
 	switch (uspc->reqtype) {
 	case AFS_USPC_SHUTDOWN:
 	    /* Client is shutting down */
-	    return;
+	    goto done;
 
 	case AFS_USPC_NOOP:
 	    /* noop */
@@ -1638,6 +1640,9 @@ BkgHandler(void)
 	    break;
 	}
     }
+
+ done:
+    free(uspc);
 }
 #endif
 
@@ -2152,9 +2157,6 @@ CheckOptions(struct cmd_syndesc *as)
 #ifdef	AFS_SUN5_ENV
     struct stat st;
 #endif
-#ifdef AFS_SGI_ENV
-    struct sched_param sp;
-#endif
 
 #ifdef AFS_SGI_VNODE_GLUE
     if (afs_init_kernel_config(-1) < 0) {
@@ -3260,6 +3262,7 @@ fork_syscall_impl(int rx, int wait, const char *rn, int syscall, va_list ap)
     struct afsd_syscall_args *args;
 
     args = malloc(sizeof(*args));
+    opr_Assert(args != NULL);
     afsd_syscall_populate(args, syscall, ap);
     args->rxpri = rx;
     args->rn = rn;

src/afsd/afsd_fuse.c

@@ -401,6 +401,9 @@ fuafsd_write(const char *path, const char *abuf, size_t len, off_t offset,
 {
 	int fd, code;
 	char *buf = malloc(len);
+	if (buf == NULL) {
+		return -ENOMEM;
+	}
 
 	fd = fi->fh;
 	memcpy(buf, abuf, len);

src/afsd/afsd_kernel.c

@@ -491,6 +491,7 @@ HandleMTab(char *cacheMountDir)
     }
 
     dir = strdup(cacheMountDir);
+    opr_Assert(dir != NULL);
 
     /* trim trailing slashes; don't look at dir[0] in case we are somehow
      * just "/" */
@@ -606,6 +607,7 @@ afsd_mount_afs(const char *rn, const char *cacheMountDir)
     }
 
     mountDir = strdup(cacheMountDir);
+    opr_Assert(mountDir != NULL);
     HandleMTab(mountDir);
     free(mountDir);
 }