From: José Bollo Date: Wed, 12 Feb 2014 17:31:20 +0000 (+0100) Subject: tests: Adding some comments X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=531ff89d83ccc021c32b4e360b43a299abcc7e79;p=framework%2Fsecurity%2Fsmack.git tests: Adding some comments Signed-off-by: José Bollo --- diff --git a/tests/generator.c b/tests/generator.c index ac1871c..c57720e 100644 --- a/tests/generator.c +++ b/tests/generator.c @@ -3,16 +3,31 @@ #include struct label { - char *label; - int counter; - char *rules; + char *label; /* the label */ + int counter; /* count of emitted occurences of the label within rules */ + char *rules; /* indicator of the object referenced by this subject label in emitted rules */ }; +/* + * Returns a new random number from 0 to 'count'-1. + * + * Examples: + * alea(5) -> 2 + * alea(5) -> 0 + */ int alea(int count) { return random() % count; } +/* + * Returns the count of bits set to one in + * the number 'n'. + * + * Examples: + * count_set_bits(30) -> 4 + * count_set_bits(5) -> 1 + */ int count_set_bits(int n) { int result = 0; @@ -23,6 +38,18 @@ int count_set_bits(int n) return result; } +/* + * Gets a random access code such that + * result & 'ref' == 0. + * + * This coulded be coded as: return alea(1<<6) & ~ref; + * but using the algorithm below may improves + * the randomness (perhaps). + * + * Examples: + * random_code(0) -> 17 == 021 + * random_code(17) -> 44 == 054 + */ int random_code(int ref) { int nb = 6 - count_set_bits(ref); @@ -41,6 +68,14 @@ int random_code(int ref) return result; } +/* + * Anti NULL pointer barrier. + * + * Returns the given pointer except if that pointer is NULL + * in which case a message is prompted to stderr stating + * the memory depletion and the program is exited with + * a return code of 1. + */ void *check_ptr(void *ptr) { if (!ptr) { @@ -50,14 +85,23 @@ void *check_ptr(void *ptr) return ptr; } +/* + * Generates an array of 'count' labels randomly generated. + * The generated labels have from 'lenmin' to 'lenmax' characters. + * They are only alphabetics then valid for Smack. + * + * Returns: the generated array. For each label, the structure + * is initialised such that .count==0 and .rules[0..'count'-1]==0. + */ struct label *gen_labels(int count, int lenmin, int lenmax) { struct label *result; int i; + result = check_ptr(calloc(count, sizeof(struct label))); for (i = 0; i < count; i++) { int len = lenmin + (lenmin == lenmax ? 0 : alea(lenmax-lenmin)); - result[i].label = check_ptr(calloc(1+len, 1)); + result[i].label = check_ptr(calloc(1 + len, 1)); while (len) result[i].label[--len] = 'A' + (char)(alea(26)); result[i].rules = check_ptr(calloc(count, sizeof(char))); @@ -66,6 +110,14 @@ struct label *gen_labels(int count, int lenmin, int lenmax) return result; } +/* + * Reads the array of 'count' labels from stdin. + * No check is performed on labels then there is no + * guaranty of validity for Smack. + * + * Returns: the read array. For each label, the structure + * is initialised such that .count==0 and .rules[0..'count'-1]==0. + */ struct label *read_labels(int count) { struct label *result; @@ -75,13 +127,26 @@ struct label *read_labels(int count) result = check_ptr(calloc(count, sizeof(struct label))); for (i = 0; i < count; i++) { tmp = getline(&(result[i].label), &tmp, stdin); - result[i].label[tmp-1] = 0; + result[i].label[tmp - 1] = 0; result[i].rules = check_ptr(calloc(count, sizeof(char))); } return result; } +/* + * Computes into 'buffer' the string corresponding to the + * given access 'code'. No null character is appended at + * the end of the generated string. + * + * The 'buffer' MUST have at least 6 characters. + * + * Returns the length of the string generated. + * + * Examples: + * code_to_string(5) -> 2, "rx" + * code_to_string(19) -> 3, "rwt" + */ int code_to_string(int code, char *buffer) { static char *flags = "rwxatl"; @@ -98,6 +163,14 @@ int code_to_string(int code, char *buffer) return len; } +/* + * Generates an array of 'count' access rights randomly generated. + * + * Statistically 1/3 of the generated rights are modification rights + * and 2/3 are setting rights. + * + * Returns: the generated array. + */ char **genrights(int count) { char buffer[20]; @@ -116,6 +189,19 @@ char **genrights(int count) return result; } +/* + * Chooses randomly a subject label within the array of 'labels' that have + * 'nlab' elements with the constraint that a label cant be choosen + * more than 'max_reoccurance' times. + * + * If the constraint can't be ensured, a message is prompted to stderr + * and the program exited with the status 1. + * + * The field .counter is read to know the count of previous occurence + * for the labels. + * + * Returns: the index of the selected label within 'labels'. + */ int pick_subj_label(struct label *labels, int nlab, int max_reoccurance) { int startidx = alea(nlab); @@ -133,7 +219,32 @@ int pick_subj_label(struct label *labels, int nlab, int max_reoccurance) return idx; } - +/* + * Chooses randomly an object label associated to the nominal subject + * label of index *'subj' within the array of 'labels' that have + * 'nlab' elements with the constraints that: + * - a label can't be choosen more than 'max_reoccurance' times + * - the subject index is nominaly *'subj' + * + * The subject is nominaly of index *'subj' what means that is the + * constraint of occurences can't be achieved with that nominal + * subject, an other subject is tried for use. + * + * If the constraint can't be ensured, a message is prompted to stderr + * and the program exited with the status 1. + * + * The field .counter is read to know the count of previous occurence + * for the labels (object or subject). + * + * The array labels[idxsub].rules[idxobj] is read to check is the + * rule was already given. + * + * When the pair (subject, object) is found, the related occurence + * data of 'labels' are updated as a side effect. + * + * Returns: the index of the selected object label within 'labels' and + * the index of the finally selected subject label in *'subj'. + */ int pick_obj_label(struct label *labels, int nlab, int max_reoccurance, int *subj) { int startidx = alea(nlab); @@ -163,6 +274,7 @@ int pick_obj_label(struct label *labels, int nlab, int max_reoccurance, int *sub return idx; } +/* main */ int main(int argc, char **argv) { int lab_cnt = 500; @@ -173,6 +285,8 @@ int main(int argc, char **argv) int lab_stdin = 0; struct label *labels; char **rights; + + /* read options */ while (*++argv) { char c; int n; @@ -200,11 +314,15 @@ int main(int argc, char **argv) exit(1); } } + + /* create data: labels and rights */ if (lab_stdin) labels = read_labels(lab_cnt); else labels = gen_labels(lab_cnt, 4, 24); rights = genrights(rig_cnt); + + /* generate the rules */ while (rul_cnt--) { int sub = pick_subj_label(labels, lab_cnt, lab_max); int obj = pick_obj_label(labels, lab_cnt, lab_max, &sub);