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author | Rich Felker <dalias@aerifal.cx> | 2020-06-03 19:17:19 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2020-06-03 19:17:19 -0400 |
commit | eaa0f2496700c238e7e3c112d36445f3aee06ff1 (patch) | |
tree | 41979600733c58af880b832bed70bc51814b2bc9 /src/malloc/expand_heap.c | |
parent | e07138b880dcc72d3f1b3a2d2c1af75c2484c8d7 (diff) | |
download | musl-eaa0f2496700c238e7e3c112d36445f3aee06ff1.tar.gz musl-eaa0f2496700c238e7e3c112d36445f3aee06ff1.tar.xz musl-eaa0f2496700c238e7e3c112d36445f3aee06ff1.zip |
move __expand_heap into malloc.c
this function is no longer used elsewhere, and moving it reduces the number of source files specific to the malloc implementation.
Diffstat (limited to 'src/malloc/expand_heap.c')
-rw-r--r-- | src/malloc/expand_heap.c | 71 |
1 files changed, 0 insertions, 71 deletions
diff --git a/src/malloc/expand_heap.c b/src/malloc/expand_heap.c deleted file mode 100644 index e6a3d7a0..00000000 --- a/src/malloc/expand_heap.c +++ /dev/null @@ -1,71 +0,0 @@ -#include <limits.h> -#include <stdint.h> -#include <errno.h> -#include <sys/mman.h> -#include "libc.h" -#include "syscall.h" -#include "malloc_impl.h" - -/* This function returns true if the interval [old,new] - * intersects the 'len'-sized interval below &libc.auxv - * (interpreted as the main-thread stack) or below &b - * (the current stack). It is used to defend against - * buggy brk implementations that can cross the stack. */ - -static int traverses_stack_p(uintptr_t old, uintptr_t new) -{ - const uintptr_t len = 8<<20; - uintptr_t a, b; - - b = (uintptr_t)libc.auxv; - a = b > len ? b-len : 0; - if (new>a && old<b) return 1; - - b = (uintptr_t)&b; - a = b > len ? b-len : 0; - if (new>a && old<b) return 1; - - return 0; -} - -/* Expand the heap in-place if brk can be used, or otherwise via mmap, - * using an exponential lower bound on growth by mmap to make - * fragmentation asymptotically irrelevant. The size argument is both - * an input and an output, since the caller needs to know the size - * allocated, which will be larger than requested due to page alignment - * and mmap minimum size rules. The caller is responsible for locking - * to prevent concurrent calls. */ - -void *__expand_heap(size_t *pn) -{ - static uintptr_t brk; - static unsigned mmap_step; - size_t n = *pn; - - if (n > SIZE_MAX/2 - PAGE_SIZE) { - errno = ENOMEM; - return 0; - } - n += -n & PAGE_SIZE-1; - - if (!brk) { - brk = __syscall(SYS_brk, 0); - brk += -brk & PAGE_SIZE-1; - } - - if (n < SIZE_MAX-brk && !traverses_stack_p(brk, brk+n) - && __syscall(SYS_brk, brk+n)==brk+n) { - *pn = n; - brk += n; - return (void *)(brk-n); - } - - size_t min = (size_t)PAGE_SIZE << mmap_step/2; - if (n < min) n = min; - void *area = __mmap(0, n, PROT_READ|PROT_WRITE, - MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); - if (area == MAP_FAILED) return 0; - *pn = n; - mmap_step++; - return area; -} |