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Improve handling of weird reparse points

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On Windows file system tools like `ls` would print errors when they find
things like WSL symlinks, which can't be read by WIN32. I don't know how
they got on my hard drive but this change ensures Cosmo will handle them
more gracefully. If a reparse point can't be followed, then fstatat will
return information about the link itself. If readlink encounters reparse
points that are WIN32 symlinks, then it'll log more helpful details when
using MODE=dbg (a.k.a. cosmocc -mdbg). Speaking of which, this change is
also going to help you troubleshoot locks; when you build your app using
the cosmocc -mdbg flag your --strace logs will now show lock acquisition
This commit is contained in:
Justine Tunney 2024-09-02 18:33:09 -07:00
parent 90460ceb3c
commit 79516bf08e
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
4 changed files with 57 additions and 48 deletions
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29
libc/calls/fstatat-nt.c
View file

@ -16,11 +16,11 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/fds.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/stat.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/errno.h"
#include "libc/intrin/fds.h"
#include "libc/nt/createfile.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/creationdisposition.h"
@ -97,14 +97,27 @@ TryAgain:
0)) != -1) {
rc = st ? sys_fstat_nt_handle(fh, path16, st) : 0;
CloseHandle(fh);
} else if (dwDesiredAccess == kNtFileGenericRead &&
(GetLastError() == kNtErrorAccessDenied ||
GetLastError() == kNtErrorSharingViolation)) {
dwDesiredAccess = kNtFileReadAttributes;
errno = e;
goto TryAgain;
} else {
rc = __winerr();
uint32_t dwErrorCode = GetLastError();
if (dwDesiredAccess == kNtFileGenericRead &&
(dwErrorCode == kNtErrorAccessDenied ||
dwErrorCode == kNtErrorSharingViolation)) {
dwDesiredAccess = kNtFileReadAttributes;
errno = e;
goto TryAgain;
} else if (!(flags & AT_SYMLINK_NOFOLLOW) &&
dwErrorCode == kNtErrorCantAccessFile) {
// ERROR_CANT_ACCESS_FILE (1920) usually means that the I/O system
// a WSL symlink is accessed from WIN32 API. Falling back with the
// failed to traverse a filesystem reparse point. For example when
// details of the link itself is better than providing nothing. It
// should never be like this on UNIX but Windows gets a bit screwy
flags |= AT_SYMLINK_NOFOLLOW;
errno = e;
goto TryAgain;
} else {
rc = __winerr();
}
}
ALLOW_SIGNALS;

10
libc/calls/linkat-nt.c
View file

@ -18,14 +18,15 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/intrin/strace.h"
#include "libc/limits.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/stack.h"
#include "libc/str/str.h"
textwindows int sys_linkat_nt(int olddirfd, const char *oldpath, int newdirfd,
const char *newpath) {
textwindows int sys_linkat_nt(int olddirfd, const char *oldpath, //
int newdirfd, const char *newpath) {
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Wframe-larger-than="
struct {
@ -36,7 +37,10 @@ textwindows int sys_linkat_nt(int olddirfd, const char *oldpath, int newdirfd,
#pragma GCC pop_options
if (__mkntpathat(olddirfd, oldpath, 0, M.oldpath16) != -1 &&
__mkntpathat(newdirfd, newpath, 0, M.newpath16) != -1) {
if (CreateHardLink(M.newpath16, M.oldpath16, NULL)) {
bool32 ok = CreateHardLink(M.newpath16, M.oldpath16, NULL);
NTTRACE("CreateHardLink(%#hs, %#hs, NULL) → {%hhhd, %d}", M.newpath16,
M.oldpath16, ok, GetLastError());
if (ok) {
return 0;
} else {
return __fix_enotdir3(__winerr(), M.newpath16, M.oldpath16);

54
libc/calls/read-nt.c
View file

@ -172,9 +172,8 @@ static textwindows void FreeKeystroke(struct Dll **list, struct Dll *key) {
static textwindows void FreeKeystrokes(struct Dll **list) {
struct Dll *key;
while ((key = dll_first(*list))) {
while ((key = dll_first(*list)))
FreeKeystroke(list, key);
}
}
static textwindows void OpenConsole(void) {
@ -248,9 +247,8 @@ static textwindows int ProcessKeyEvent(const struct NtInputRecord *r, char *p) {
uint16_t cks = r->Event.KeyEvent.dwControlKeyState;
// ignore keyup events
if (!r->Event.KeyEvent.bKeyDown && (!c || vk != kNtVkMenu)) {
if (!r->Event.KeyEvent.bKeyDown && (!c || vk != kNtVkMenu))
return 0;
}
#if 0
// this code is useful for troubleshooting why keys don't work
@ -310,25 +308,21 @@ static textwindows int ProcessKeyEvent(const struct NtInputRecord *r, char *p) {
__keystroke.utf16hs = c;
return 0;
}
if (IsLowSurrogate(c)) {
if (IsLowSurrogate(c))
c = MergeUtf16(__keystroke.utf16hs, c);
}
// enter sends \r with raw terminals
// make it a multics newline instead
if (c == '\r' && !(__ttyconf.magic & kTtyNoCr2Nl)) {
if (c == '\r' && !(__ttyconf.magic & kTtyNoCr2Nl))
c = '\n';
}
// ctrl-space (^@) is literally zero
if (c == ' ' && (cks & (kNtLeftCtrlPressed | kNtRightCtrlPressed))) {
if (c == ' ' && (cks & (kNtLeftCtrlPressed | kNtRightCtrlPressed)))
c = '\0';
}
// make backspace (^?) distinguishable from ctrl-h (^H)
if (c == kNtVkBack && !(cks & (kNtLeftCtrlPressed | kNtRightCtrlPressed))) {
if (c == kNtVkBack && !(cks & (kNtLeftCtrlPressed | kNtRightCtrlPressed)))
c = 0177;
}
// handle ctrl-\ and ctrl-c
// note we define _POSIX_VDISABLE as zero
@ -407,12 +401,10 @@ static textwindows int ProcessMouseEvent(const struct NtInputRecord *r,
}
}
} else if ((bs || currentbs) && (__ttyconf.magic & kTtyXtMouse)) {
if (bs && (ev & kNtMouseMoved) && currentbs) {
if (bs && (ev & kNtMouseMoved) && currentbs)
e |= 32; // dragging
}
if ((bs | currentbs) & kNtRightmostButtonPressed) {
if ((bs | currentbs) & kNtRightmostButtonPressed)
e |= 2; // right
}
OutputXtermMouseEvent:
*p++ = 033;
*p++ = '[';
@ -489,9 +481,8 @@ static textwindows bool EraseKeystroke(void) {
if ((k->buf[i] & 0300) == 0200)
continue; // utf-8 cont
EraseCharacter();
if (!(__ttyconf.magic & kTtyEchoRaw) && IsCtl(k->buf[i])) {
if (!(__ttyconf.magic & kTtyEchoRaw) && IsCtl(k->buf[i]))
EraseCharacter();
}
}
return true;
} else {
@ -504,9 +495,8 @@ static textwindows void IngestConsoleInputRecord(struct NtInputRecord *r) {
// convert win32 console event into ansi
int len;
char buf[23];
if (!(len = ConvertConsoleInputToAnsi(r, buf))) {
if (!(len = ConvertConsoleInputToAnsi(r, buf)))
return;
}
// handle backspace in canonical mode
if (len == 1 && buf[0] && //
@ -532,9 +522,8 @@ static textwindows void IngestConsoleInputRecord(struct NtInputRecord *r) {
// echo input if it was successfully recorded
// assuming the win32 console isn't doing it already
if (!(__ttyconf.magic & kTtySilence)) {
if (!(__ttyconf.magic & kTtySilence))
EchoTty(buf, len);
}
// save keystroke to appropriate list
if (__ttyconf.magic & kTtyUncanon) {
@ -597,12 +586,10 @@ textwindows int CountConsoleInputBytes(void) {
InitConsole();
LockKeystrokes();
IngestConsoleInput();
for (e = dll_first(__keystroke.list); e; e = dll_next(__keystroke.list, e)) {
for (e = dll_first(__keystroke.list); e; e = dll_next(__keystroke.list, e))
count += KEYSTROKE_CONTAINER(e)->buflen;
}
if (!count && __keystroke.end_of_file) {
if (!count && __keystroke.end_of_file)
count = -1;
}
UnlockKeystrokes();
ALLOW_SIGNALS;
return count;
@ -702,9 +689,8 @@ static textwindows bool DigestConsoleInput(char *data, size_t size, int *rc) {
} else {
FreeKeystroke(&__keystroke.list, e);
}
if ((__ttyconf.magic & kTtyUncanon) && toto >= __ttyconf.vmin) {
if ((__ttyconf.magic & kTtyUncanon) && toto >= __ttyconf.vmin)
break;
}
}
// return result
@ -731,9 +717,8 @@ static textwindows int WaitForConsole(struct Fd *f, sigset_t waitmask) {
return -1;
if (f->flags & _O_NONBLOCK)
return eagain();
if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask)))
goto DeliverSignal;
}
struct PosixThread *pt = _pthread_self();
pt->pt_blkmask = waitmask;
pt->pt_semaphore = sem = CreateSemaphore(0, 0, 1, 0);
@ -781,17 +766,14 @@ textwindows ssize_t ReadBuffer(int fd, void *data, size_t size, int64_t offset,
// switch to terminal polyfill if reading from win32 console
struct Fd *f = g_fds.p + fd;
if (f->kind == kFdDevNull) {
if (f->kind == kFdDevNull)
return 0;
}
if (f->kind == kFdDevRandom) {
if (f->kind == kFdDevRandom)
return ProcessPrng(data, size) ? size : __winerr();
}
if (f->kind == kFdConsole) {
if (f->kind == kFdConsole)
return ReadFromConsole(f, data, size, waitmask);
}
// perform heavy lifting
ssize_t rc;

12
libc/calls/readlinkat-nt.c
View file

@ -120,7 +120,17 @@ static textwindows ssize_t sys_readlinkat_nt_impl(int dirfd, const char *path,
}
rc = j;
} else {
NTTRACE("sys_readlinkat_nt() should have kNtIoReparseTagSymlink");
// e.g. 0xA000001D means IO_REPARSE_TAG_LX_SYMLINK
//
// "WSL symlinks can't be opened from Windows, only from
// within WSL, so if we identify them as fs.ModeSymlink,
// then functions like filepath.Walk would fail when trying
// to follow the link."
//
// —Quoth Quim Muntal (dev on Go team at Microsoft)
//
// See also MSDN Learn § 2.1.2.1 Reparse Tags
NTTRACE("reparse tag %#x != kNtIoReparseTagSymlink", rdb->ReparseTag);
rc = einval();
}
} else {