mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-07-02 17:28:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Make mmap() work better

Browse source 
- Mapping file offsets now works on Windows
- Mapping stack memory now works on OpenBSD
This commit is contained in:
Justine Tunney 2021-02-03 00:10:12 -08:00
parent 23a14b537c
commit 27c899af56
10 changed files with 71 additions and 56 deletions
Download patch file Download diff file Expand all files Collapse all files

14
libc/runtime/mmap.c
View file

@ -52,13 +52,14 @@
* @param flags can have MAP_ANONYMOUS, MAP_SHARED, MAP_PRIVATE, etc.
* @param fd is an open()'d file descriptor whose contents shall be
* mapped, and is ignored if MAP_ANONYMOUS is specified
* @param offset specifies absolute byte index of fd's file for mapping,
* and should be zero if MAP_ANONYMOUS is specified
* @param off specifies absolute byte index of fd's file for mapping,
* should be zero if MAP_ANONYMOUS is specified, and sadly needs
* to be 64kb aligned too
* @return virtual base address of new mapping, or MAP_FAILED w/ errno
*/
void *mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) {
int i, x, n, a, b;
struct DirectMap dm;
int i, x, n, a, b, f;
if (!size) return VIP(einval());
if (!ALIGNED(off)) return VIP(einval());
if (!ALIGNED(addr)) return VIP(einval());
@ -84,7 +85,12 @@ void *mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) {
}
addr = (void *)(intptr_t)((int64_t)x << 16);
}
dm = __mmap(addr, size, prot, flags | MAP_FIXED, fd, off);
f = flags | MAP_FIXED;
if (IsOpenbsd() && (f & MAP_GROWSDOWN)) { /* openbsd:dubstack */
dm = __mmap(addr, size, prot, f & ~MAP_GROWSDOWN, fd, off);
if (dm.addr == MAP_FAILED) return MAP_FAILED;
}
dm = __mmap(addr, size, prot, f, fd, off);
if (dm.addr == MAP_FAILED || dm.addr != addr) {
return MAP_FAILED;
}