@matheusbsbs / matheus-bagliano / commits / 98d9b23e90

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

index bd24d913f9..03c4538ec8 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -484,16 +484,16 @@ int mingw_open (const char *filename, int oflags, ...) return -1; } - if (filename && !strcmp(filename, "/dev/null")) - filename = "nul"; - if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename)) open_fn = mingw_open_append; else open_fn = _wopen; - if (xutftowcs_path(wfilename, filename) < 0) + if (filename && !strcmp(filename, "/dev/null")) + wcscpy(wfilename, L"nul"); + else if (xutftowcs_path(wfilename, filename) < 0) return -1; + fd = open_fn(wfilename, oflags, mode); if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) { @@ -556,10 +556,13 @@ FILE *mingw_fopen (const char *filename, const char *otype) return NULL; } if (filename && !strcmp(filename, "/dev/null")) - filename = "nul"; - if (xutftowcs_path(wfilename, filename) < 0 || - xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) + wcscpy(wfilename, L"nul"); + else if (xutftowcs_path(wfilename, filename) < 0) return NULL; + + if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) + return NULL; + if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) { error("could not unhide %s", filename); return NULL; @@ -583,10 +586,13 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream) return NULL; } if (filename && !strcmp(filename, "/dev/null")) - filename = "nul"; - if (xutftowcs_path(wfilename, filename) < 0 || - xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) + wcscpy(wfilename, L"nul"); + else if (xutftowcs_path(wfilename, filename) < 0) return NULL; + + if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) + return NULL; + if (hide && !access(filename, F_OK) && set_hidden_flag(wfilename, 0)) { error("could not unhide %s", filename); return NULL;