chsmack: using flags for labels

That modification prepare the addition of the option
to remove Smack labels. It seems also best to be agnostic
on what are valid smack labels (and rely on libsmack in the
futur) that maybe one day could be empty strings!

Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>

diff --git a/utils/chsmack.c b/utils/chsmack.c
index 84989e1..c0bbeec 100644 (file)
--- a/utils/chsmack.c
+++ b/utils/chsmack.c
@@ -109,14 +109,20 @@ int main(int argc, char *argv[])
        /*  Buffers are zeroed automatically by keeping them static variables.
         *  No separate memset is needed this way.
         */
-       static char access_buf[SMACK_LABEL_LEN + 1];
-       static char exec_buf[SMACK_LABEL_LEN + 1];
-       static char mmap_buf[SMACK_LABEL_LEN + 1];
        static int options_map[128];
 
-       struct stat st;
+       /* structure for recording options of label and their init */
+       struct labelset {
+               int isset; /* 0 if option not set, 1 if option set */
+               const char *value; /* value of the option set if any or NULL else */
+       };
+       struct labelset access_set = { 0, NULL }; /* for option "access" */
+       struct labelset exec_set = { 0, NULL }; /* for option "exec" */
+       struct labelset mmap_set = { 0, NULL }; /* for option "mmap" */
 
+       struct stat st;
        char *label;
+
        int follow_flag = 0;
        int transmute_flag = 0;
        int option_flag = 0;
@@ -145,13 +151,16 @@ int main(int argc, char *argv[])
 
                switch (c) {
                        case 'a':
-                               strncpy(access_buf, optarg, SMACK_LABEL_LEN + 1);
+                               access_set.isset = 1;
+                               access_set.value = optarg;
                                break;
                        case 'e':
-                               strncpy(exec_buf, optarg, SMACK_LABEL_LEN + 1);
+                               exec_set.isset = 1;
+                               exec_set.value = optarg;
                                break;
                        case 'm':
-                               strncpy(mmap_buf, optarg, SMACK_LABEL_LEN + 1);
+                               mmap_set.isset = 1;
+                               mmap_set.value = optarg;
                                break;
                        case 't':
                                transmute_flag = 1;
@@ -173,23 +182,23 @@ int main(int argc, char *argv[])
        /* setting labels */
        if (option_flag) {
                for (i = optind; i < argc; i++) {
-                       if (strlen(access_buf) > 0) {
+                       if (access_set.isset) {
                                rc = smack_set_label_for_path(argv[i],
-                                                       XATTR_NAME_SMACK, follow_flag, access_buf);
+                                                       XATTR_NAME_SMACK, follow_flag, access_set.value);
                                if (rc < 0)
                                        perror(argv[i]);
                        }
 
-                       if (strlen(exec_buf) > 0) {
+                       if (exec_set.isset) {
                                rc = smack_set_label_for_path(argv[i],
-                                                       XATTR_NAME_SMACKEXEC, follow_flag, exec_buf);
+                                                       XATTR_NAME_SMACKEXEC, follow_flag, exec_set.value);
                                if (rc < 0)
                                        perror(argv[i]);
                        }
 
-                       if (strlen(mmap_buf) > 0) {
+                       if (mmap_set.isset) {
                                rc = smack_set_label_for_path(argv[i],
-                                                       XATTR_NAME_SMACKMMAP, follow_flag, mmap_buf);
+                                                       XATTR_NAME_SMACKMMAP, follow_flag, mmap_set.value);
                                if (rc < 0)
                                        perror(argv[i]);
                        }
@@ -210,7 +219,7 @@ int main(int argc, char *argv[])
                                }
                        }
                }
-       } 
+       }
 
        /* listing labels */
        else {