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Pacify file locks on Windows

Browse source 
This change gets redbean SQLite working in write mode on Windows.
Warnings have been added to the appropriate and responsible places.
Hacking proprietary PC systems into production-worthy servers isn't
terribly high on the list of priorities. Consider BSD or Linux when
building online systems that service requests from multiple people.

Fixes #193
This commit is contained in:
Justine Tunney 2021-06-12 00:01:55 -07:00
parent 9504ebaf7e
commit 8d7d00af3a
6 changed files with 146 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

47
libc/calls/fcntl-nt.c
View file

@ -19,42 +19,47 @@
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/flock.h"
#include "libc/macros.internal.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/fileflagandattributes.h"
#include "libc/nt/enum/filelockflags.h"
#include "libc/nt/enum/filesharemode.h"
#include "libc/nt/enum/formatmessageflags.h"
#include "libc/nt/errors.h"
#include "libc/nt/files.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/byhandlefileinformation.h"
#include "libc/nt/struct/overlapped.h"
#include "libc/nt/synchronization.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/fd.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"
static textwindows int sys_fcntl_nt_lock(struct Fd *f, int cmd, uintptr_t arg) {
uint32_t flags;
struct flock *l;
uint32_t flags, err;
struct NtOverlapped ov;
int64_t pos, off, len, size;
struct NtByHandleFileInformation info;
if (!GetFileInformationByHandle(f->handle, &info)) return __winerr();
if (!SetFilePointerEx(f->handle, 0, &pos, SEEK_CUR)) return __winerr();
l = (struct flock *)arg;
len = l->l_len;
off = l->l_start;
if (!len || l->l_whence == SEEK_END) {
if (!GetFileInformationByHandle(f->handle, &info)) return __winerr();
size = (uint64_t)info.nFileSizeHigh << 32 | info.nFileSizeLow;
} else {
size = 0;
}
if (l->l_whence != SEEK_SET) {
if (l->l_whence == SEEK_CUR) {
if (!SetFilePointerEx(f->handle, 0, &pos, SEEK_CUR)) return __winerr();
size = (uint64_t)info.nFileSizeHigh << 32 | info.nFileSizeLow;
switch (l->l_whence) {
case SEEK_SET:
break;
case SEEK_CUR:
off = pos + off;
} else if (l->l_whence == SEEK_END) {
break;
case SEEK_END:
off = size - off;
} else {
break;
default:
return einval();
}
}
if (!len) len = size - off;
if (off < 0 || len < 0) return einval();
@ -62,17 +67,27 @@ static textwindows int sys_fcntl_nt_lock(struct Fd *f, int cmd, uintptr_t arg) {
if (l->l_type == F_RDLCK || l->l_type == F_WRLCK) {
flags = 0;
if (cmd == F_SETLK) flags |= kNtLockfileFailImmediately;
if (l->l_type == F_WRLCK) flags |= kNtLockfileExclusiveLock;
/* TODO: How can we make SQLite locks on Windows to work? */
/* if (l->l_type == F_WRLCK) flags |= kNtLockfileExclusiveLock; */
if (LockFileEx(f->handle, flags, 0, len, len >> 32, &ov)) {
return 0;
} else {
return __winerr();
err = GetLastError();
if (err == kNtErrorLockViolation) err = EAGAIN;
errno = err;
return -1;
}
} else if (l->l_type == F_UNLCK) {
if (UnlockFileEx(f->handle, 0, len, len >> 32, &ov)) {
return 0;
} else {
return __winerr();
err = GetLastError();
if (err == kNtErrorNotLocked) {
return 0;
} else {
errno = err;
return -1;
}
}
} else {
return einval();

3
libc/calls/fcntl.c
View file

@ -31,6 +31,9 @@
* // ...
* CHECK_NE(-1, fcntl(zfd, F_SETLK, &(struct flock){F_UNLCK}));
*
* Please be warned that locks currently do nothing on Windows since
* figuring out how to polyfill them correctly is a work in progress.
*
* @param cmd can be F_{GET,SET}{FD,FL}, etc.
* @param arg can be FD_CLOEXEC, etc. depending
* @return 0 on success, or -1 w/ errno