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return chunks split off by memalign using __bin_chunk instead of free

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this change serves multiple purposes:

1. it ensures that static linking of memalign-family functions will
pull in the system malloc implementation, thereby causing link errors
if an attempt is made to link the system memalign functions with a
replacement malloc (incomplete allocator replacement).

2. it eliminates calls to free that are unpaired with allocations,
which are confusing when setting breakpoints or tracing execution.

as a bonus, making __bin_chunk external may discourage aggressive and
unnecessary inlining of it.
This commit is contained in:
Rich Felker 2018-04-19 20:56:26 -04:00
parent 3c2cbbe7ba
commit 72141795d4
3 changed files with 8 additions and 7 deletions
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3
src/internal/malloc_impl.h
View File

@ -36,4 +36,7 @@ struct bin {
#define IS_MMAPPED(c) !((c)->csize & (C_INUSE)) #define IS_MMAPPED(c) !((c)->csize & (C_INUSE))
__attribute__((__visibility__("hidden")))
void __bin_chunk(struct chunk *);
#endif #endif

10
src/malloc/malloc.c
View File

@ -263,8 +263,6 @@ static int pretrim(struct chunk *self, size_t n, int i, int j)
return 1; return 1;
} }
static void bin_chunk(struct chunk *);
static void trim(struct chunk *self, size_t n) static void trim(struct chunk *self, size_t n)
{ {
size_t n1 = CHUNK_SIZE(self); size_t n1 = CHUNK_SIZE(self);
@ -280,7 +278,7 @@ static void trim(struct chunk *self, size_t n)
next->psize = n1-n | C_INUSE; next->psize = n1-n | C_INUSE;
self->csize = n | C_INUSE; self->csize = n | C_INUSE;
bin_chunk(split); __bin_chunk(split);
} }
void *malloc(size_t n) void *malloc(size_t n)
@ -436,7 +434,7 @@ copy_free_ret:
return new; return new;
} }
static void bin_chunk(struct chunk *self) void __bin_chunk(struct chunk *self)
{ {
struct chunk *next = NEXT_CHUNK(self); struct chunk *next = NEXT_CHUNK(self);
size_t final_size, new_size, size; size_t final_size, new_size, size;
@ -524,7 +522,7 @@ void free(void *p)
if (IS_MMAPPED(self)) if (IS_MMAPPED(self))
unmap_chunk(self); unmap_chunk(self);
else else
bin_chunk(self); __bin_chunk(self);
} }
void __malloc_donate(char *start, char *end) void __malloc_donate(char *start, char *end)
@ -543,5 +541,5 @@ void __malloc_donate(char *start, char *end)
struct chunk *c = MEM_TO_CHUNK(start), *n = MEM_TO_CHUNK(end); struct chunk *c = MEM_TO_CHUNK(start), *n = MEM_TO_CHUNK(end);
c->psize = n->csize = C_INUSE; c->psize = n->csize = C_INUSE;
c->csize = n->psize = C_INUSE | (end-start); c->csize = n->psize = C_INUSE | (end-start);
bin_chunk(c); __bin_chunk(c);
} }

2
src/malloc/memalign.c
View File

@ -48,7 +48,7 @@ void *__memalign(size_t align, size_t len)
n->psize = c->csize = C_INUSE | (new-mem); n->psize = c->csize = C_INUSE | (new-mem);
n->csize = t->psize -= new-mem; n->csize = t->psize -= new-mem;
free(mem); __bin_chunk(c);
return new; return new;
} }