From: Johannes Schindelin <johannes.schindelin@xxxxxx> There are a couple of reserved names that cannot be file names on Windows, such as `AUX`, `NUL`, etc. For an almost complete list, see https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file If one would try to create a directory named `NUL`, it would actually "succeed", i.e. the call would return success, but nothing would be created. Worse, even adding a file extension to the reserved name does not make it a valid file name. To understand the rationale behind that behavior, see https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42073 Let's just disallow them all. Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx> --- compat/mingw.c | 104 ++++++++++++++++++++++++++++++++++++------ compat/mingw.h | 11 ++++- t/t0060-path-utils.sh | 13 +++++- 3 files changed, 110 insertions(+), 18 deletions(-) diff --git a/compat/mingw.c b/compat/mingw.c index 03c4538ec8..f482ecd6da 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -393,7 +393,7 @@ int mingw_mkdir(const char *path, int mode) int ret; wchar_t wpath[MAX_PATH]; - if (!is_valid_win32_path(path)) { + if (!is_valid_win32_path(path, 0)) { errno = EINVAL; return -1; } @@ -479,7 +479,7 @@ int mingw_open (const char *filename, int oflags, ...) mode = va_arg(args, int); va_end(args); - if (!is_valid_win32_path(filename)) { + if (!is_valid_win32_path(filename, !create)) { errno = create ? EINVAL : ENOENT; return -1; } @@ -550,14 +550,13 @@ FILE *mingw_fopen (const char *filename, const char *otype) int hide = needs_hiding(filename); FILE *file; wchar_t wfilename[MAX_PATH], wotype[4]; - if (!is_valid_win32_path(filename)) { + if (filename && !strcmp(filename, "/dev/null")) + wcscpy(wfilename, L"nul"); + else if (!is_valid_win32_path(filename, 1)) { int create = otype && strchr(otype, 'w'); errno = create ? EINVAL : ENOENT; return NULL; - } - if (filename && !strcmp(filename, "/dev/null")) - wcscpy(wfilename, L"nul"); - else if (xutftowcs_path(wfilename, filename) < 0) + } else if (xutftowcs_path(wfilename, filename) < 0) return NULL; if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) @@ -580,14 +579,13 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream) int hide = needs_hiding(filename); FILE *file; wchar_t wfilename[MAX_PATH], wotype[4]; - if (!is_valid_win32_path(filename)) { + if (filename && !strcmp(filename, "/dev/null")) + wcscpy(wfilename, L"nul"); + else if (!is_valid_win32_path(filename, 1)) { int create = otype && strchr(otype, 'w'); errno = create ? EINVAL : ENOENT; return NULL; - } - if (filename && !strcmp(filename, "/dev/null")) - wcscpy(wfilename, L"nul"); - else if (xutftowcs_path(wfilename, filename) < 0) + } else if (xutftowcs_path(wfilename, filename) < 0) return NULL; if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) @@ -2412,14 +2410,16 @@ static void setup_windows_environment(void) } } -int is_valid_win32_path(const char *path) +int is_valid_win32_path(const char *path, int allow_literal_nul) { + const char *p = path; int preceding_space_or_period = 0, i = 0, periods = 0; if (!protect_ntfs) return 1; skip_dos_drive_prefix((char **)&path); + goto segment_start; for (;;) { char c = *(path++); @@ -2434,7 +2434,83 @@ int is_valid_win32_path(const char *path) return 1; i = periods = preceding_space_or_period = 0; - continue; + +segment_start: + switch (*path) { + case 'a': case 'A': /* AUX */ + if (((c = path[++i]) != 'u' && c != 'U') || + ((c = path[++i]) != 'x' && c != 'X')) { +not_a_reserved_name: + path += i; + continue; + } + break; + case 'c': case 'C': /* COM<N>, CON, CONIN$, CONOUT$ */ + if ((c = path[++i]) != 'o' && c != 'O') + goto not_a_reserved_name; + c = path[++i]; + if (c == 'm' || c == 'M') { /* COM<N> */ + if (!isdigit(path[++i])) + goto not_a_reserved_name; + } else if (c == 'n' || c == 'N') { /* CON */ + c = path[i + 1]; + if ((c == 'i' || c == 'I') && + ((c = path[i + 2]) == 'n' || + c == 'N') && + path[i + 3] == '$') + i += 3; /* CONIN$ */ + else if ((c == 'o' || c == 'O') && + ((c = path[i + 2]) == 'u' || + c == 'U') && + ((c = path[i + 3]) == 't' || + c == 'T') && + path[i + 4] == '$') + i += 4; /* CONOUT$ */ + } else + goto not_a_reserved_name; + break; + case 'l': case 'L': /* LPT<N> */ + if (((c = path[++i]) != 'p' && c != 'P') || + ((c = path[++i]) != 't' && c != 'T') || + !isdigit(path[++i])) + goto not_a_reserved_name; + break; + case 'n': case 'N': /* NUL */ + if (((c = path[++i]) != 'u' && c != 'U') || + ((c = path[++i]) != 'l' && c != 'L') || + (allow_literal_nul && + !path[i + 1] && p == path)) + goto not_a_reserved_name; + break; + case 'p': case 'P': /* PRN */ + if (((c = path[++i]) != 'r' && c != 'R') || + ((c = path[++i]) != 'n' && c != 'N')) + goto not_a_reserved_name; + break; + default: + continue; + } + + /* + * So far, this looks like a reserved name. Let's see + * whether it actually is one: trailing spaces, a file + * extension, or an NTFS Alternate Data Stream do not + * matter, the name is still reserved if any of those + * follow immediately after the actual name. + */ + i++; + if (path[i] == ' ') { + preceding_space_or_period = 1; + while (path[++i] == ' ') + ; /* skip all spaces */ + } + + c = path[i]; + if (c && c != '.' && c != ':' && c != '/' && c != '\\') + goto not_a_reserved_name; + + /* contains reserved name */ + return 0; case '.': periods++; /* fallthru */ diff --git a/compat/mingw.h b/compat/mingw.h index 04ca731a6b..ebc1e6a773 100644 --- a/compat/mingw.h +++ b/compat/mingw.h @@ -461,10 +461,17 @@ char *mingw_query_user_email(void); * * - contain any of the reserved characters, e.g. `:`, `;`, `*`, etc * + * - correspond to reserved names (such as `AUX`, `PRN`, etc) + * + * The `allow_literal_nul` parameter controls whether the path `NUL` should + * be considered valid (this makes sense e.g. before opening files, as it is + * perfectly legitimate to open `NUL` on Windows, just as it is to open + * `/dev/null` on Unix/Linux). + * * Returns 1 upon success, otherwise 0. */ -int is_valid_win32_path(const char *path); -#define is_valid_path(path) is_valid_win32_path(path) +int is_valid_win32_path(const char *path, int allow_literal_nul); +#define is_valid_path(path) is_valid_win32_path(path, 0) /** * Converts UTF-8 encoded string to UTF-16LE. diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh index b193ed4205..eaf3be94e3 100755 --- a/t/t0060-path-utils.sh +++ b/t/t0060-path-utils.sh @@ -465,11 +465,14 @@ test_expect_success 'match .gitmodules' ' ' test_expect_success MINGW 'is_valid_path() on Windows' ' - test-tool path-utils is_valid_path \ + test-tool path-utils is_valid_path \ win32 \ "win32 x" \ ../hello.txt \ C:\\git \ + comm \ + conout.c \ + lptN \ \ --not \ "win32 " \ @@ -477,7 +480,13 @@ test_expect_success MINGW 'is_valid_path() on Windows' ' "win32." \ "win32 . ." \ .../hello.txt \ - colon:test + colon:test \ + "AUX.c" \ + "abc/conOut\$ .xyz/test" \ + lpt8 \ + "lpt*" \ + Nul \ + "PRN./abc" ' test_done -- gitgitgadget
