diff options
Diffstat (limited to 'winsup/cygwin/heap.cc')
| -rw-r--r-- | winsup/cygwin/heap.cc | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/winsup/cygwin/heap.cc b/winsup/cygwin/heap.cc new file mode 100644 index 000000000..7bbe882d8 --- /dev/null +++ b/winsup/cygwin/heap.cc @@ -0,0 +1,140 @@ +/* heap.cc: Cygwin heap manager. + + Copyright 1996, 1997, 1998, 1999 Cygnus Solutions. + +This file is part of Cygwin. + +This software is a copyrighted work licensed under the terms of the +Cygwin license. Please consult the file "CYGWIN_LICENSE" for +details. */ + +#include <errno.h> +#include "winsup.h" + +#define brksize ((char *) user_data->heaptop - (char *) user_data->heapbase) +#define brk (user_data->heapptr) +#define brkbase (user_data->heapbase) +#define brktop (user_data->heaptop) +#define brkchunk (cygwin_shared->heap_chunk_size ()) +#define assert(x) + +static unsigned page_const = 0; + +static int __inline +getpagesize(void) +{ + SYSTEM_INFO si; + GetSystemInfo(&si); + return (int)si.dwPageSize; +} + +/* Initialize the heap at process start up. */ + +void +heap_init () +{ + /* If we're the forkee, we must allocate the heap at exactly the same place + as our parent. If not, we don't care where it ends up. */ + + page_const = getpagesize(); + if (brkbase) + { + DWORD chunk = brkchunk; /* allocation chunk */ + /* total size commited in parent */ + DWORD allocsize = (char *) brktop - (char *) brkbase; + /* round up by chunk size */ + DWORD reserve_size = chunk * ((allocsize + (chunk - 1)) / chunk); + + /* Loop until we've managed to reserve an adequate amount of memory. */ + char *p; + for (;;) + { + p = (char *) VirtualAlloc (brkbase, reserve_size, + MEM_RESERVE, PAGE_READWRITE); + if (p) + break; + if ((reserve_size -= page_const) <= allocsize) + break; + } + if (p == NULL) + api_fatal ("1. unable to allocate heap, heap_chunk_size %d, pid %d, %E", + brkchunk, myself->pid); + if (p != brkbase) + api_fatal ("heap allocated but not at %p", brkbase); + if (! VirtualAlloc (brkbase, allocsize, MEM_COMMIT, PAGE_READWRITE)) + api_fatal ("MEM_COMMIT failed, %E"); + } + else + { + /* Initialize page mask and default heap size. Preallocate a heap + * to assure contiguous memory. */ + brk = brktop = brkbase = VirtualAlloc(NULL, brkchunk, MEM_RESERVE, PAGE_NOACCESS); + if (brkbase == NULL) + api_fatal ("2. unable to allocate heap, heap_chunk_size %d, %E", + brkchunk); + } + + page_const--; + malloc_init (); +} + +#define pround(n) (((size_t)(n) + page_const) & ~page_const) + +/* FIXME: This function no longer handles "split heaps". */ + +extern "C" void * +_sbrk(int n) +{ + char *newtop, *newbrk; + unsigned commitbytes, newbrksize; + + if (n == 0) + return brk; /* Just wanted to find current brk address */ + + newbrk = (char *) brk + n; /* Where new brk will be */ + newtop = (char *) pround (newbrk); /* Actual top of allocated memory - + on page boundary */ + + if (newtop == brktop) + goto good; + + if (n < 0) + { /* Freeing memory */ + assert(newtop < brktop); + n = (char *) brktop - newtop; + if (VirtualFree(newtop, n, MEM_DECOMMIT)) /* Give it back to OS */ + goto good; /* Didn't take */ + else + goto err; + } + + assert(newtop > brktop); + + /* Need to grab more pages from the OS. If this fails it may be because + * we have used up previously reserved memory. Or, we're just plumb out + * of memory. */ + commitbytes = pround (newtop - (char *) brktop); + if (VirtualAlloc(brktop, commitbytes, MEM_COMMIT, PAGE_READWRITE) != NULL) + goto good; + + /* Couldn't allocate memory. Maybe we can reserve some more. + Reserve either the maximum of the standard brkchunk or the requested + amount. Then attempt to actually allocate it. */ + + if ((newbrksize = brkchunk) < commitbytes) + newbrksize = commitbytes; + + if ((VirtualAlloc(brktop, newbrksize, MEM_RESERVE, PAGE_NOACCESS) != NULL) && + (VirtualAlloc(brktop, commitbytes, MEM_COMMIT, PAGE_READWRITE) != NULL)) + goto good; + +err: + set_errno (ENOMEM); + return (void *) -1; + +good: + void *oldbrk = brk; + brk = newbrk; + brktop = newtop; + return oldbrk; +} |