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fix: add null check and optimize memory alloc #196

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fix: add null check and optimize memory alloc #196

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20 changes: 14 additions & 6 deletions src/match.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,10 @@ char *strcasechr(const char *s, char c) {
}

int has_match(const char *needle, const char *haystack) {
if (!needle || !haystack || !*needle) {
return 0;
}

while (*needle) {
char nch = *needle++;

Expand Down Expand Up @@ -108,7 +112,7 @@ static inline void match_row(const struct match_struct *match, int row, score_t
}

score_t match(const char *needle, const char *haystack) {
if (!*needle)
if (!needle || !haystack || !*needle)
return SCORE_MIN;

struct match_struct match;
Expand Down Expand Up @@ -173,13 +177,18 @@ score_t match_positions(const char *needle, const char *haystack, size_t *positi
return SCORE_MAX;
}

// Allocate for both D and M matrices in one contiguous block
score_t *block = (score_t*)malloc(sizeof(score_t) * MATCH_MAX_LEN * n * 2);
if (!block) {
return SCORE_MIN;
}
/*
* D[][] Stores the best score for this position ending with a match.
* M[][] Stores the best possible score at this position.
*/
score_t (*D)[MATCH_MAX_LEN], (*M)[MATCH_MAX_LEN];
M = malloc(sizeof(score_t) * MATCH_MAX_LEN * n);
D = malloc(sizeof(score_t) * MATCH_MAX_LEN * n);
score_t (*D)[MATCH_MAX_LEN] = (score_t(*)[MATCH_MAX_LEN])block;
score_t (*M)[MATCH_MAX_LEN] = (score_t(*)[MATCH_MAX_LEN])(block
+ MATCH_MAX_LEN * n);

match_row(&match, 0, D[0], M[0], D[0], M[0]);
for (int i = 1; i < n; i++) {
Expand Down Expand Up @@ -217,8 +226,7 @@ score_t match_positions(const char *needle, const char *haystack, size_t *positi

score_t result = M[n - 1][m - 1];

free(M);
free(D);
free(block);

return result;
}