Fresh storage (...) not released before assignment
From 433253
(Difference between revisions)
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Sample code: | Sample code: | ||
| - | < | + | <pre> |
int move; | int move; | ||
int *empty; | int *empty; | ||
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move = empty[r]; | move = empty[r]; | ||
free(empty); | free(empty); | ||
| - | </ | + | </pre> |
Error message: | Error message: | ||
| - | < | + | <pre> |
game.c:115:2: Fresh storage empty (type int *) not released before assignment: | game.c:115:2: Fresh storage empty (type int *) not released before assignment: | ||
empty = state_empty(s) | empty = state_empty(s) | ||
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warning) | warning) | ||
game.c:114:2: Fresh storage empty created | game.c:114:2: Fresh storage empty created | ||
| - | </ | + | </pre> |
Solution: | Solution: | ||
The problem here is that the safe_malloc line is allocating a block of memory which empty is set to point to, but then on the next line empty is changed to point to the return of state_empty(), meaning there is now no longer anything pointing to the memory that safe_malloc returned, and thus it is lost (and leaked). To fix this code, it is simply a matter of removing the safe_malloc() line, since the memory is not required. In other situation you would need to put a free(empty) before you change the value of empty. | The problem here is that the safe_malloc line is allocating a block of memory which empty is set to point to, but then on the next line empty is changed to point to the return of state_empty(), meaning there is now no longer anything pointing to the memory that safe_malloc returned, and thus it is lost (and leaked). To fix this code, it is simply a matter of removing the safe_malloc() line, since the memory is not required. In other situation you would need to put a free(empty) before you change the value of empty. | ||
Current revision as of 02:50, 24 August 2006
Sample code:
int move;
int *empty;
empty = safe_malloc(sizeof(int)*NUM_EMPTY);
empty = state_empty(s); /* this is the bad line */
...
move = empty[r];
free(empty);
Error message:
game.c:115:2: Fresh storage empty (type int *) not released before assignment:
empty = state_empty(s)
A memory leak has been detected. Storage allocated locally is not released
before the last reference to it is lost. (Use -mustfreefresh to inhibit
warning)
game.c:114:2: Fresh storage empty created
Solution:
The problem here is that the safe_malloc line is allocating a block of memory which empty is set to point to, but then on the next line empty is changed to point to the return of state_empty(), meaning there is now no longer anything pointing to the memory that safe_malloc returned, and thus it is lost (and leaked). To fix this code, it is simply a matter of removing the safe_malloc() line, since the memory is not required. In other situation you would need to put a free(empty) before you change the value of empty.
