@matheusbsbs / matheus-bagliano / commits / 98d9b23e90

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mingw: short-circuit the conversion of `/dev/null` to UTF-16

In the next commit, we want to disallow accessing any path that contains any segment that is equivalent to `NUL`. In particular, we want to disallow accessing `NUL` (e.g. to prevent any repository from being checked out that contains a file called `NUL`, as that is not a valid file name on Windows). However, there are legitimate use cases within Git itself to write to the Null device. As Git is really a Linux project, it does not abstract that idea, though, but instead uses `/dev/null` to describe this intention. So let's side-step the validation _specifically_ in the case that we want to write to (or read from) `/dev/null`, via a dedicated short-cut in the code that skips the call to `validate_win32_path()`. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Johannes Schindelin committed Dec 21, 2019 at 22:05 UTC 98d9b23e90510c5acafa2ebc9463cc2293f40df0

1 file changed +16 -10

compat/mingw.c

+16 -10

@@ -484,16 +484,16 @@ int mingw_open (const char *filename, int oflags, ...)

484 return -1;

485 }

486

487 - if (filename && !strcmp(filename, "/dev/null"))

488 - filename = "nul";

489 -

487 if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename))

488 open_fn = mingw_open_append;

489 else

490 open_fn = _wopen;

491

495 - if (xutftowcs_path(wfilename, filename) < 0)

492 + if (filename && !strcmp(filename, "/dev/null"))

493 + wcscpy(wfilename, L"nul");

494 + else if (xutftowcs_path(wfilename, filename) < 0)

495 return -1;

496 +

497 fd = open_fn(wfilename, oflags, mode);

498

499 if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {

@@ -556,10 +556,13 @@ FILE *mingw_fopen (const char *filename, const char *otype)

556 return NULL;

557 }

558 if (filename && !strcmp(filename, "/dev/null"))

559 - filename = "nul";

560 - if (xutftowcs_path(wfilename, filename) < 0 ||

561 - xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)

559 + wcscpy(wfilename, L"nul");

560 + else if (xutftowcs_path(wfilename, filename) < 0)

561 return NULL;

562 +

563 + if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)

564 + return NULL;

565 +

566 if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) {

567 error("could not unhide %s", filename);

568 return NULL;

@@ -583,10 +586,13 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)

586 return NULL;

587 }

588 if (filename && !strcmp(filename, "/dev/null"))

586 - filename = "nul";

587 - if (xutftowcs_path(wfilename, filename) < 0 ||

588 - xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)

589 + wcscpy(wfilename, L"nul");

590 + else if (xutftowcs_path(wfilename, filename) < 0)

591 return NULL;

592 +

593 + if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)

594 + return NULL;

595 +

596 if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) {

597 error("could not unhide %s", filename);

598 return NULL;