Fixes for issues found with cppcheck tool

The patch fixes small number of errors/false positives reported by `cppcheck`,
static analysis tool for C/C++.

cppcheck 1.72

$ cppcheck . --force --quiet
[cmd/zfs/zfs_main.c:4444]: (error) Possible null pointer dereference: who_perm
[cmd/zfs/zfs_main.c:4445]: (error) Possible null pointer dereference: who_perm
[cmd/zfs/zfs_main.c:4446]: (error) Possible null pointer dereference: who_perm
[cmd/zpool/zpool_iter.c:317]: (error) Uninitialized variable: nvroot
[cmd/zpool/zpool_vdev.c:1526]: (error) Memory leak: child
[lib/libefi/rdwr_efi.c:1118]: (error) Memory leak: efi_label
[lib/libuutil/uu_misc.c:207]: (error) va_list 'args' was opened but not closed by va_end().
[lib/libzfs/libzfs_import.c:1554]: (error) Dangerous usage of 'diskname' (strncpy doesn't always null-terminate it).
[lib/libzfs/libzfs_sendrecv.c:3279]: (error) Dereferencing 'cp' after it is deallocated / released
[tests/zfs-tests/cmd/file_write/file_write.c:154]: (error) Possible null pointer dereference: operation
[tests/zfs-tests/cmd/randfree_file/randfree_file.c:90]: (error) Memory leak: buf
[cmd/zinject/zinject.c:1068]: (error) Uninitialized variable: dataset
[module/icp/io/sha2_mod.c:698]: (error) Uninitialized variable: blocks_per_int64

Signed-off-by: Gvozden Neskovic <[email protected]>
Signed-off-by: Chunwei Chen <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1392

2 files changed, 10 insertions, 4 deletions

diff --git a/tests/zfs-tests/cmd/file_write/file_write.c b/tests/zfs-tests/cmd/file_write/file_write.c
index 43fd96ac4..046794820 100644
--- a/tests/zfs-tests/cmd/file_write/file_write.c
+++ b/tests/zfs-tests/cmd/file_write/file_write.c
@@ -127,7 +127,10 @@ main(int argc, char **argv)
 		err++;
 	}
 
-	if (err) usage(prog);
+	if (err) {
+		usage(prog); /* no return */
+		return (1);
+	}
 
 	/*
 	 * Prepare the buffer and determine the requested operation
diff --git a/tests/zfs-tests/cmd/randfree_file/randfree_file.c b/tests/zfs-tests/cmd/randfree_file/randfree_file.c
index 8e7487c41..ff30c24c0 100644
--- a/tests/zfs-tests/cmd/randfree_file/randfree_file.c
+++ b/tests/zfs-tests/cmd/randfree_file/randfree_file.c
@@ -83,23 +83,26 @@ main(int argc, char *argv[])
 	else
 		usage(argv[0]);
 
-	buf = (char *)malloc(filesize);
-
 	if ((fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, mode)) < 0) {
 		perror("open");
 		return (1);
 	}
+
+	buf = (char *)malloc(filesize);
+
 	if (write(fd, buf, filesize) < filesize) {
+		free(buf);
 		perror("write");
 		return (1);
 	}
 
+	free(buf);
+
 	if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 	    start_off, off_len) < 0) {
 		perror("fallocate");
 		return (1);
 	}
 
-	free(buf);
 	return (0);
 }