diff options
| -rw-r--r-- | libc/unistd/exec.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/libc/unistd/exec.c b/libc/unistd/exec.c index b91ce0c98..381a81464 100644 --- a/libc/unistd/exec.c +++ b/libc/unistd/exec.c @@ -56,7 +56,9 @@ libc_hidden_proto(getenv) /* We do not have an MMU, so using alloca() is not an option. * Less obviously, using malloc() is not an option either since * malloc()ed memory can leak in a vfork() and exec*() situation. - * Therefore, we must use mmap() and unmap() directly. + * Therefore, we must use mmap() and unmap() directly, caching + * the result as we go. This way we minimize the leak to 1 + * allocation. */ # define EXEC_ALLOC_SIZE(VAR) size_t VAR; /* Semicolon included! */ @@ -68,22 +70,28 @@ extern void __exec_free(void *ptr, size_t size) attribute_hidden; # ifdef L___exec_alloc +void attribute_hidden __exec_free(void *ptr, size_t size) +{ + if (ptr) + munmap(ptr, size); +} + void attribute_hidden *__exec_alloc(size_t size) { - void *p; + static void *p; + static size_t old_size; + + if (old_size >= size) + return p; + else + __exec_free(p, old_size); + old_size = size; p = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0); return (p != MAP_FAILED) ? p : NULL; } -void attribute_hidden __exec_free(void *ptr, size_t size) -{ - if (ptr) { - munmap(ptr, size); - } -} - # endif #endif |