Get mmap() working with WIN32 MSVC
- We have pretty high quality POSIX polyfills now - We no longer need to override malloc() Tracked by issue #91 Improves upon #341pull/564/head^2
Justine Tunney
1 year ago
parent
e4881686b4
commit
cbddf4661b
@ -0,0 +1,570 @@
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// Lightweight Portable mmap() Polyfill
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//
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// 1. Supports POSIX.1
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//
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// The baseline POSIX standard doesn't specify MAP_ANONYMOUS. This
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// library makes sure, on the hypothetical UNIX systems that don't
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// have it, or on the mainstream UNIX platforms where the user has
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// chosen to define _POSIX_C_SOURCE that cause headers to undefine
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// it, this implementation will fallback to creating a secure temp
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// file, for each anonymous mapping.
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//
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// 2. Supports Windows w/ Visual Studio
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//
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// On Windows Vista and later an API exists that's almost as good as
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// mmap(). However code that uses this library should conform to the
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// subset of behaviors Microsoft accommodates.
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//
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// Caveats
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//
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// - You should just assume the page size is 64kb. That's how it is on
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// Windows and it usually goes faster to assume that elsewhere too.
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//
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// - Not designed to support mprotect() at the moment. In order to
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// support this, we'd need to consider _open(O_ACCMODE) on Windows
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// and then have mmap() be more greedy about permissions.
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//
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// - There's limited support for being clever with memory intervals.
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// For example, you can't punch a hole in a memory map on Windows.
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// This abstraction does aim to offer more flexibility than WIN32.
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// There should also be good error reporting for unsupported uses.
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#include "mmap.h"
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#ifdef NEED_POSIX_MMAP
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#include <stdlib.h>
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static void *PosixMmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset) {
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int tfd;
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void* res;
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char path[] = "/tmp/llama.dat.XXXXXX";
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if (~flags & MAP_ANONYMOUS) {
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res = mmap(addr, length, prot, flags, fd, offset);
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} else if ((tfd = mkstemp(path)) != -1) {
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unlink(path);
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if (!ftruncate(tfd, length)) {
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res = mmap(addr, length, prot, flags & ~MAP_ANONYMOUS, tfd, 0);
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} else {
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res = MAP_FAILED;
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}
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close(tfd);
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} else {
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res = MAP_FAILED;
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}
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return res;
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}
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#elif defined(NEED_WIN32_MMAP)
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#include <errno.h>
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#include <stdio.h>
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#include <assert.h>
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#include <inttypes.h>
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struct WinMap { // O(n) no ordering no overlaps
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HANDLE hand; // zero means array slots empty
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HANDLE fand; // for the original file, or -1
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uintptr_t addr; // base address (64 kb aligned)
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uintptr_t length; // byte size (>0, rounded 64kb)
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};
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struct WinMaps {
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int n;
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struct WinMap *p;
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volatile long lock;
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};
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static struct WinMaps g_winmaps;
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static inline uintptr_t Min(uintptr_t x, uintptr_t y) {
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return y > x ? x : y;
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}
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static inline uintptr_t Max(uintptr_t x, uintptr_t y) {
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return y < x ? x : y;
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}
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static inline uintptr_t Roundup(uintptr_t x, intptr_t a) {
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assert(a > 0);
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assert(!(a & (a - 1)));
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return (x + (a - 1)) & -a;
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}
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static inline void Lock(void) {
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long x;
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for (;;) {
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x = InterlockedExchange(&g_winmaps.lock, 1);
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if (!x) break;
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assert(x == 1);
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}
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}
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static inline void Unlock(void) {
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assert(g_winmaps.lock == 1);
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g_winmaps.lock = 0;
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}
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static int WinStrerror(int err, char *buf, int size) {
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return FormatMessageA(
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FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
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NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
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buf, size, NULL);
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}
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#ifdef NDEBUG
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#define LogError(thing) (void)0
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#else
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static void LogError(const char* file, int line, const char* thing) {
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#define LogError(thing) LogError(__FILE__, __LINE__, thing)
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fprintf(stderr, "%s:%d: error: %s\n", file, line, thing);
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}
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#endif
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#ifdef NDEBUG
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#define LogWindowsError(thing) (void)0
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#else
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static void LogWindowsError(const char* file, int line, const char* thing) {
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#define LogWindowsError(thing) LogWindowsError(__FILE__, __LINE__, thing)
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char s[256];
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int e = GetLastError();
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WinStrerror(e, s, sizeof(s));
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fprintf(stderr, "%s:%d: error[%#x]: %s failed: %s\n", file, line, e, thing, s);
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}
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#endif
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static void *Recalloc(void *ptr, uint64_t newSize) {
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HANDLE heap = GetProcessHeap();
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if (!ptr) {
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return HeapAlloc(heap, HEAP_ZERO_MEMORY, newSize);
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}
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if (!newSize) {
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HeapFree(heap, 0, ptr);
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return 0;
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}
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return HeapReAlloc(heap, HEAP_ZERO_MEMORY, ptr, newSize);
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}
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uint64_t WinSeek(int fd, uint64_t offset, int whence) {
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HANDLE hFile;
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DWORD winwhence;
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LARGE_INTEGER distanceToMove;
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LARGE_INTEGER newFilePointer;
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distanceToMove.QuadPart = offset;
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switch (whence) {
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case SEEK_SET:
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winwhence = FILE_BEGIN;
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break;
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case SEEK_CUR:
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winwhence = FILE_CURRENT;
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break;
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case SEEK_END:
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winwhence = FILE_END;
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break;
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default:
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LogError("bad lseek() whence");
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errno = EINVAL;
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return -1;
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}
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hFile = (HANDLE)_get_osfhandle(fd);
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if (hFile == INVALID_HANDLE_VALUE) {
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LogWindowsError("_get_osfhandle");
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errno = EBADF;
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return -1;
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}
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if (GetFileType(hFile) != FILE_TYPE_DISK) {
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LogError("bad file type for lseek()");
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errno = ESPIPE;
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return -1;
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}
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if (!SetFilePointerEx(hFile, distanceToMove, &newFilePointer, winwhence)) {
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LogWindowsError("SetFilePointerEx");
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errno = EPERM;
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return -1;
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}
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return newFilePointer.QuadPart;
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}
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int WinFtruncate(int fd, uint64_t length) {
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HANDLE hFile;
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LARGE_INTEGER old, neu;
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hFile = (HANDLE)_get_osfhandle(fd);
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if (hFile == INVALID_HANDLE_VALUE) {
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LogWindowsError("_get_osfhandle");
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errno = EBADF;
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return -1;
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}
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// save current file position
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old.QuadPart = 0;
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neu.QuadPart = 0;
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if (!SetFilePointerEx(hFile, neu, &old, FILE_CURRENT)) {
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LogWindowsError("SetFilePointerEx#1");
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return -1;
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}
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// set current position to new file size
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neu.QuadPart = length;
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if (!SetFilePointerEx(hFile, neu, NULL, FILE_BEGIN)) {
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LogWindowsError("SetFilePointerEx#2");
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return -1;
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}
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// change the file size
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if (!SetEndOfFile(hFile)) {
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LogWindowsError("SetEndOfFile");
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SetFilePointerEx(hFile, old, NULL, FILE_BEGIN);
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return -1;
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}
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// restore the original file position
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// win32 allows this to exceed the end of file
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if (!SetFilePointerEx(hFile, old, NULL, FILE_BEGIN)) {
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LogWindowsError("SetFilePointerEx>3");
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return -1;
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}
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return 0;
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}
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int WinMadvise(void *addr, uintptr_t length, int advice) {
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switch (advice) {
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case MADV_NORMAL:
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case MADV_DONTNEED:
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case MADV_SEQUENTIAL:
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return 0;
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case MADV_RANDOM:
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case MADV_WILLNEED: {
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HANDLE proc;
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WIN32_MEMORY_RANGE_ENTRY entry;
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proc = GetCurrentProcess();
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entry.VirtualAddress = addr;
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entry.NumberOfBytes = length;
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if (!PrefetchVirtualMemory(proc, 1, &entry, 0)) {
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LogWindowsError("PrefetchVirtualMemory");
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errno = ENOMEM;
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return -1;
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}
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return 0;
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}
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default:
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errno = EINVAL;
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return -1;
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}
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}
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int WinUnmap(void *addr, uintptr_t length) {
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void *view;
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HANDLE hand;
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HANDLE fand;
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int i, err = 0;
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uintptr_t a, b;
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uintptr_t x, y;
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// compute the requested interval
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// 1. length can't be zero
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// 2. length is rounded up to the page size
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// 3. addr must be aligned to page boundary
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a = (uintptr_t)addr;
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b = a + Roundup(length, 65536);
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if (!length) {
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LogError("tried to munmap zero bytes");
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errno = EINVAL;
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return -1;
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}
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if (a & 65535) {
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LogError("tried to munmap an address that's not 64kb aligned");
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errno = EINVAL;
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return -1;
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}
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// 1. we permit unmapping multiple maps in one call
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// 2. we don't care if the matched mappings aren't contiguous
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// 3. it's an error if a matched mapping only partially overlaps
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// 4. similar to close() we release all resources possible on error
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Lock();
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for (i = 0; i < g_winmaps.n; ++i) {
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if (!g_winmaps.p[i].hand) {
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// this array slot is empty
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continue;
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}
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// compute overlap between known mapping and requested interval
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x = Max(a, g_winmaps.p[i].addr);
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y = Min(b, g_winmaps.p[i].addr + g_winmaps.p[i].length);
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if (x >= y) {
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// there isn't any overlap
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continue;
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}
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if (y - x != g_winmaps.p[i].length) {
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// requested interval partially overlapped this mapping
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// therefore we can't unmap it and must report an error
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LogError("tried to partially unmap a mapping");
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err = ENOMEM;
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continue;
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}
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// save the information we care about
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view = (void *)g_winmaps.p[i].addr;
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hand = g_winmaps.p[i].hand;
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fand = g_winmaps.p[i].fand;
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// delete this mapping from the global array
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g_winmaps.p[i].hand = 0;
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// perform the systems operations
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// safe to release lock since g_winmaps.n is monotonic
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Unlock();
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if (!UnmapViewOfFile(view)) {
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LogWindowsError("UnmapViewOfFile");
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}
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if (!CloseHandle(hand)) {
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LogWindowsError("CloseHandle#1");
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}
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if (fand != INVALID_HANDLE_VALUE) {
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if (!CloseHandle(fand)) {
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LogWindowsError("CloseHandle#2");
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}
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}
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Lock();
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}
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Unlock();
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if (err) {
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errno = err;
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return -1;
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}
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return 0;
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}
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void* WinMap(void *addr, uintptr_t length, int prot, int flags, int fd, uint64_t offset) {
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int i;
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LPVOID res;
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HANDLE hand;
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HANDLE hFile;
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DWORD access;
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DWORD wiprot;
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uintptr_t fsize;
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if (!length) {
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LogError("mmap(length) was zero");
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errno = EINVAL;
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return MAP_FAILED;
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}
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length = Roundup(length, 65536);
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if ((uintptr_t)addr & 65535) {
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if (~flags & MAP_FIXED) {
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addr = 0;
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} else {
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LogError("MAP_FIXED used with address that's not 64kb aligned");
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errno = EINVAL;
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return MAP_FAILED;
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}
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}
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// these are the logical flag equivalents for creating mappings. please
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// note that any subsequent virtualprotect calls must be a subset of the
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// permissions we're using here. that's not a supported use case for us
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if (flags & MAP_PRIVATE) {
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// private mapping
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if (prot & PROT_EXEC) {
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if (prot & PROT_WRITE) {
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if (flags & MAP_ANONYMOUS) {
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wiprot = PAGE_EXECUTE_READWRITE;
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access = FILE_MAP_READ | FILE_MAP_WRITE | FILE_MAP_EXECUTE;
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} else {
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wiprot = PAGE_EXECUTE_WRITECOPY;
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access = FILE_MAP_COPY | FILE_MAP_EXECUTE;
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}
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} else {
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wiprot = PAGE_EXECUTE_READ;
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access = FILE_MAP_READ | FILE_MAP_EXECUTE;
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}
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} else if (prot & PROT_WRITE) {
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if (flags & MAP_ANONYMOUS) {
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wiprot = PAGE_READWRITE;
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access = FILE_MAP_READ | FILE_MAP_WRITE;
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} else {
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wiprot = PAGE_WRITECOPY;
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access = FILE_MAP_COPY;
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}
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} else {
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wiprot = PAGE_READONLY;
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access = FILE_MAP_READ;
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}
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} else {
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// shared mapping
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if (prot & PROT_EXEC) {
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if (prot & PROT_WRITE) {
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wiprot = PAGE_EXECUTE_READWRITE;
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access = FILE_MAP_READ | FILE_MAP_WRITE | FILE_MAP_EXECUTE;
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} else {
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wiprot = PAGE_EXECUTE_READ;
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access = FILE_MAP_READ | FILE_MAP_EXECUTE;
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}
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} else if (prot & PROT_WRITE) {
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wiprot = PAGE_READWRITE;
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access = FILE_MAP_READ | FILE_MAP_WRITE;
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} else {
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wiprot = PAGE_READONLY;
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access = FILE_MAP_READ;
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}
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}
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if (flags & MAP_ANONYMOUS) {
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hFile = INVALID_HANDLE_VALUE;
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fsize = length;
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offset = 0;
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} else {
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fsize = 0;
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hFile = (HANDLE)_get_osfhandle(fd);
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if (hFile == INVALID_HANDLE_VALUE) {
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LogWindowsError("_get_osfhandle");
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errno = EBADF;
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return MAP_FAILED;
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}
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if (!DuplicateHandle(GetCurrentProcess(), hFile,
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GetCurrentProcess(), &hFile,
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0, FALSE, DUPLICATE_SAME_ACCESS)) {
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LogWindowsError("DuplicateHandle");
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errno = EBADF;
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return MAP_FAILED;
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}
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}
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if (flags & MAP_FIXED) {
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if (!addr) {
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// zero chance of microsoft letting us map the null page
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if (hFile != INVALID_HANDLE_VALUE) {
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CloseHandle(hFile);
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}
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errno = EINVAL;
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return MAP_FAILED;
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} else {
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// blow away any existing mappings on requested interval
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if (WinUnmap(addr, length) == -1) {
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// can only happen if we partially overlap an existing mapping
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assert(errno == ENOMEM);
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if (hFile != INVALID_HANDLE_VALUE) {
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CloseHandle(hFile);
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}
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return MAP_FAILED;
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}
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}
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}
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hand = CreateFileMapping(hFile, 0, wiprot,
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(DWORD)(fsize >> 32),
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(DWORD)fsize,
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0);
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if (!hand) {
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LogWindowsError("CreateFileMapping");
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if (hFile != INVALID_HANDLE_VALUE) {
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CloseHandle(hFile);
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}
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errno = EPERM;
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return MAP_FAILED;
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}
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res = MapViewOfFileEx(hand, access,
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(DWORD)(offset >> 32),
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(DWORD)offset,
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length, addr);
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if (!res) {
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LogWindowsError("MapViewOfFileEx");
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if (hFile != INVALID_HANDLE_VALUE) {
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CloseHandle(hFile);
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}
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CloseHandle(hand);
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errno = EPERM;
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return MAP_FAILED;
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}
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if (flags & MAP_FIXED) {
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// this assertion could legitimately fail if two threads engage in a
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// race to create a MAP_FIXED mapping at the same address and that's
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// certainly not the kind of use case we're designed to support here
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assert(res == addr);
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}
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// record our new mapping in the global array
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Lock();
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for (i = 0; i < g_winmaps.n; ++i) {
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if (!g_winmaps.p[i].hand) {
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// we found an empty slot
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break;
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}
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}
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if (i == g_winmaps.n) {
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// we need to grow the array
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// it's important to use kernel32 memory
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// our malloc implementation depends on this
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int n2;
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struct WinMap *p2;
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p2 = g_winmaps.p;
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n2 = g_winmaps.n;
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if (n2) {
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n2 += n2 >> 1;
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} else {
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n2 = 7;
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}
|
||||
if ((p2 = (struct WinMap*)Recalloc(p2, n2 * sizeof(*p2)))) {
|
||||
g_winmaps.p = p2;
|
||||
g_winmaps.n = n2;
|
||||
} else {
|
||||
Unlock();
|
||||
LogError("recalloc failed");
|
||||
UnmapViewOfFile(res);
|
||||
CloseHandle(hand);
|
||||
if (hFile != INVALID_HANDLE_VALUE) {
|
||||
CloseHandle(hFile);
|
||||
}
|
||||
errno = ENOMEM;
|
||||
return MAP_FAILED;
|
||||
}
|
||||
}
|
||||
g_winmaps.p[i].hand = hand;
|
||||
g_winmaps.p[i].fand = hFile;
|
||||
g_winmaps.p[i].addr = (uintptr_t)res;
|
||||
g_winmaps.p[i].length = length;
|
||||
Unlock();
|
||||
return res;
|
||||
}
|
||||
|
||||
int WinMsync(void *addr, uintptr_t length, int flags) {
|
||||
int i, err;
|
||||
HANDLE hand;
|
||||
uintptr_t x, y;
|
||||
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) {
|
||||
LogError("bad msync flags");
|
||||
errno = EINVAL;
|
||||
return -1;
|
||||
}
|
||||
// 1. we do nothing if length is zero (unlike win32 api)
|
||||
// 2. the requested interval may envelop multiple known mappings
|
||||
// 3. we don't care if those mappings aren't contiguous or a hole exists
|
||||
// 4. the requested interval may specify a subrange of any given mapping
|
||||
Lock();
|
||||
for (err = i = 0; i < g_winmaps.n; ++i) {
|
||||
if (!g_winmaps.p[i].hand) {
|
||||
// this array slot is empty
|
||||
continue;
|
||||
}
|
||||
// compute overlap between known mapping and requested interval
|
||||
x = Max((uintptr_t)addr, g_winmaps.p[i].addr);
|
||||
y = Min((uintptr_t)addr + length, g_winmaps.p[i].addr + g_winmaps.p[i].length);
|
||||
if (x >= y) {
|
||||
// there isn't any overlap
|
||||
continue;
|
||||
}
|
||||
// it's safe to release lock temporarily, since g_winmaps.n is monotonic
|
||||
// any race conditions in handle being deleted should be caught by win32
|
||||
hand = g_winmaps.p[i].fand;
|
||||
Unlock();
|
||||
// ensure coherency and that filesystem flush *will* happen
|
||||
if (!FlushViewOfFile((void*)x, y - x)) {
|
||||
LogWindowsError("FlushViewOfFile");
|
||||
err = EPERM;
|
||||
}
|
||||
if (flags & MS_SYNC) {
|
||||
// ensure that filesystem flush *has* happened
|
||||
if (!FlushFileBuffers(hand)) {
|
||||
LogWindowsError("FlushFileBuffers");
|
||||
err = EPERM;
|
||||
}
|
||||
}
|
||||
Lock();
|
||||
}
|
||||
Unlock();
|
||||
if (err) {
|
||||
errno = err;
|
||||
return -1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
#else // NEED_*_MAP
|
||||
|
||||
// this is a normal unix platform
|
||||
// add some content to this object so the apple linker doesn't whine
|
||||
int justine_mmap_module;
|
||||
|
||||
#endif // NEED_*_MMAP
|
||||
Loading…
Reference in New Issue