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cpython/Python/fileutils.c

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#include "Python.h"
#ifdef MS_WINDOWS
# include <windows.h>
#endif
#ifdef __APPLE__
extern wchar_t* _Py_DecodeUTF8_surrogateescape(const char *s, Py_ssize_t size);
#endif
#ifdef HAVE_STAT
/* Decode a byte string from the locale encoding with the
surrogateescape error handler (undecodable bytes are decoded as characters
in range U+DC80..U+DCFF). If a byte sequence can be decoded as a surrogate
character, escape the bytes using the surrogateescape error handler instead
of decoding them.
Use _Py_wchar2char() to encode the character string back to a byte string.
Return a pointer to a newly allocated wide character string (use
PyMem_Free() to free the memory) and write the number of written wide
characters excluding the null character into *size if size is not NULL, or
NULL on error (conversion or memory allocation error).
Conversion errors should never happen, unless there is a bug in the C
library. */
wchar_t*
_Py_char2wchar(const char* arg, size_t *size)
{
#ifdef __APPLE__
wchar_t *wstr;
wstr = _Py_DecodeUTF8_surrogateescape(arg, strlen(arg));
if (size != NULL) {
if (wstr != NULL)
*size = wcslen(wstr);
else
*size = (size_t)-1;
}
return wstr;
#else
wchar_t *res;
#ifdef HAVE_BROKEN_MBSTOWCS
/* Some platforms have a broken implementation of
* mbstowcs which does not count the characters that
* would result from conversion. Use an upper bound.
*/
size_t argsize = strlen(arg);
#else
size_t argsize = mbstowcs(NULL, arg, 0);
#endif
size_t count;
unsigned char *in;
wchar_t *out;
#ifdef HAVE_MBRTOWC
mbstate_t mbs;
#endif
if (argsize != (size_t)-1) {
res = (wchar_t *)PyMem_Malloc((argsize+1)*sizeof(wchar_t));
if (!res)
goto oom;
count = mbstowcs(res, arg, argsize+1);
if (count != (size_t)-1) {
wchar_t *tmp;
/* Only use the result if it contains no
surrogate characters. */
for (tmp = res; *tmp != 0 &&
(*tmp < 0xd800 || *tmp > 0xdfff); tmp++)
;
if (*tmp == 0) {
if (size != NULL)
*size = count;
return res;
}
}
PyMem_Free(res);
}
/* Conversion failed. Fall back to escaping with surrogateescape. */
#ifdef HAVE_MBRTOWC
/* Try conversion with mbrtwoc (C99), and escape non-decodable bytes. */
/* Overallocate; as multi-byte characters are in the argument, the
actual output could use less memory. */
argsize = strlen(arg) + 1;
res = (wchar_t*)PyMem_Malloc(argsize*sizeof(wchar_t));
if (!res)
goto oom;
in = (unsigned char*)arg;
out = res;
memset(&mbs, 0, sizeof mbs);
while (argsize) {
size_t converted = mbrtowc(out, (char*)in, argsize, &mbs);
if (converted == 0)
/* Reached end of string; null char stored. */
break;
if (converted == (size_t)-2) {
/* Incomplete character. This should never happen,
since we provide everything that we have -
unless there is a bug in the C library, or I
misunderstood how mbrtowc works. */
fprintf(stderr, "unexpected mbrtowc result -2\n");
PyMem_Free(res);
return NULL;
}
if (converted == (size_t)-1) {
/* Conversion error. Escape as UTF-8b, and start over
in the initial shift state. */
*out++ = 0xdc00 + *in++;
argsize--;
memset(&mbs, 0, sizeof mbs);
continue;
}
if (*out >= 0xd800 && *out <= 0xdfff) {
/* Surrogate character. Escape the original
byte sequence with surrogateescape. */
argsize -= converted;
while (converted--)
*out++ = 0xdc00 + *in++;
continue;
}
/* successfully converted some bytes */
in += converted;
argsize -= converted;
out++;
}
#else /* HAVE_MBRTOWC */
/* Cannot use C locale for escaping; manually escape as if charset
is ASCII (i.e. escape all bytes > 128. This will still roundtrip
correctly in the locale's charset, which must be an ASCII superset. */
res = PyMem_Malloc((strlen(arg)+1)*sizeof(wchar_t));
if (!res) goto oom;
in = (unsigned char*)arg;
out = res;
while(*in)
if(*in < 128)
*out++ = *in++;
else
*out++ = 0xdc00 + *in++;
*out = 0;
#endif /* HAVE_MBRTOWC */
if (size != NULL)
*size = out - res;
return res;
oom:
fprintf(stderr, "out of memory\n");
return NULL;
#endif /* __APPLE__ */
}
/* Encode a (wide) character string to the locale encoding with the
surrogateescape error handler (characters in range U+DC80..U+DCFF are
converted to bytes 0x80..0xFF).
This function is the reverse of _Py_char2wchar().
Return a pointer to a newly allocated byte string (use PyMem_Free() to free
the memory), or NULL on conversion or memory allocation error.
If error_pos is not NULL: *error_pos is the index of the invalid character
on conversion error, or (size_t)-1 otherwise. */
char*
_Py_wchar2char(const wchar_t *text, size_t *error_pos)
{
#ifdef __APPLE__
Py_ssize_t len;
PyObject *unicode, *bytes = NULL;
char *cpath;
unicode = PyUnicode_FromWideChar(text, wcslen(text));
if (unicode == NULL)
return NULL;
bytes = PyUnicode_EncodeUTF8(PyUnicode_AS_UNICODE(unicode),
PyUnicode_GET_SIZE(unicode),
"surrogateescape");
Py_DECREF(unicode);
if (bytes == NULL) {
PyErr_Clear();
if (error_pos != NULL)
*error_pos = (size_t)-1;
return NULL;
}
len = PyBytes_GET_SIZE(bytes);
cpath = PyMem_Malloc(len+1);
if (cpath == NULL) {
PyErr_Clear();
Py_DECREF(bytes);
if (error_pos != NULL)
*error_pos = (size_t)-1;
return NULL;
}
memcpy(cpath, PyBytes_AsString(bytes), len + 1);
Py_DECREF(bytes);
return cpath;
#else /* __APPLE__ */
const size_t len = wcslen(text);
char *result = NULL, *bytes = NULL;
size_t i, size, converted;
wchar_t c, buf[2];
/* The function works in two steps:
1. compute the length of the output buffer in bytes (size)
2. outputs the bytes */
size = 0;
buf[1] = 0;
while (1) {
for (i=0; i < len; i++) {
c = text[i];
if (c >= 0xdc80 && c <= 0xdcff) {
/* UTF-8b surrogate */
if (bytes != NULL) {
*bytes++ = c - 0xdc00;
size--;
}
else
size++;
continue;
}
else {
buf[0] = c;
if (bytes != NULL)
converted = wcstombs(bytes, buf, size);
else
converted = wcstombs(NULL, buf, 0);
if (converted == (size_t)-1) {
if (result != NULL)
PyMem_Free(result);
if (error_pos != NULL)
*error_pos = i;
return NULL;
}
if (bytes != NULL) {
bytes += converted;
size -= converted;
}
else
size += converted;
}
}
if (result != NULL) {
*bytes = 0;
break;
}
size += 1; /* nul byte at the end */
result = PyMem_Malloc(size);
if (result == NULL) {
if (error_pos != NULL)
*error_pos = (size_t)-1;
return NULL;
}
bytes = result;
}
return result;
#endif /* __APPLE__ */
}
/* In principle, this should use HAVE__WSTAT, and _wstat
should be detected by autoconf. However, no current
POSIX system provides that function, so testing for
it is pointless.
Not sure whether the MS_WINDOWS guards are necessary:
perhaps for cygwin/mingw builds?
*/
#if defined(HAVE_STAT) && !defined(MS_WINDOWS)
/* Get file status. Encode the path to the locale encoding. */
int
_Py_wstat(const wchar_t* path, struct stat *buf)
{
int err;
char *fname;
fname = _Py_wchar2char(path, NULL);
if (fname == NULL) {
errno = EINVAL;
return -1;
}
err = stat(fname, buf);
PyMem_Free(fname);
return err;
}
#endif
/* Call _wstat() on Windows, or encode the path to the filesystem encoding and
call stat() otherwise. Only fill st_mode attribute on Windows.
Return 0 on success, -1 on _wstat() / stat() error or (if PyErr_Occurred())
unicode error. */
int
_Py_stat(PyObject *path, struct stat *statbuf)
{
#ifdef MS_WINDOWS
int err;
struct _stat wstatbuf;
err = _wstat(PyUnicode_AS_UNICODE(path), &wstatbuf);
if (!err)
statbuf->st_mode = wstatbuf.st_mode;
return err;
#else
int ret;
PyObject *bytes = PyUnicode_EncodeFSDefault(path);
if (bytes == NULL)
return -1;
ret = stat(PyBytes_AS_STRING(bytes), statbuf);
Py_DECREF(bytes);
return ret;
#endif
}
/* Open a file. Use _wfopen() on Windows, encode the path to the locale
encoding and use fopen() otherwise. */
FILE *
_Py_wfopen(const wchar_t *path, const wchar_t *mode)
{
#ifndef MS_WINDOWS
FILE *f;
char *cpath;
char cmode[10];
size_t r;
r = wcstombs(cmode, mode, 10);
if (r == (size_t)-1 || r >= 10) {
errno = EINVAL;
return NULL;
}
cpath = _Py_wchar2char(path, NULL);
if (cpath == NULL)
return NULL;
f = fopen(cpath, cmode);
PyMem_Free(cpath);
return f;
#else
return _wfopen(path, mode);
#endif
}
/* Call _wfopen() on Windows, or encode the path to the filesystem encoding and
call fopen() otherwise.
Return the new file object on success, or NULL if the file cannot be open or
(if PyErr_Occurred()) on unicode error */
FILE*
_Py_fopen(PyObject *path, const char *mode)
{
#ifdef MS_WINDOWS
wchar_t wmode[10];
int usize;
usize = MultiByteToWideChar(CP_ACP, 0, mode, -1, wmode, sizeof(wmode));
if (usize == 0)
return NULL;
return _wfopen(PyUnicode_AS_UNICODE(path), wmode);
#else
FILE *f;
PyObject *bytes = PyUnicode_EncodeFSDefault(path);
if (bytes == NULL)
return NULL;
f = fopen(PyBytes_AS_STRING(bytes), mode);
Py_DECREF(bytes);
return f;
#endif
}
#ifdef HAVE_READLINK
/* Read value of symbolic link. Encode the path to the locale encoding, decode
the result from the locale encoding. */
int
_Py_wreadlink(const wchar_t *path, wchar_t *buf, size_t bufsiz)
{
char *cpath;
char cbuf[PATH_MAX];
wchar_t *wbuf;
int res;
size_t r1;
cpath = _Py_wchar2char(path, NULL);
if (cpath == NULL) {
errno = EINVAL;
return -1;
}
res = (int)readlink(cpath, cbuf, PATH_MAX);
PyMem_Free(cpath);
if (res == -1)
return -1;
if (res == PATH_MAX) {
errno = EINVAL;
return -1;
}
cbuf[res] = '\0'; /* buf will be null terminated */
wbuf = _Py_char2wchar(cbuf, &r1);
if (wbuf == NULL) {
errno = EINVAL;
return -1;
}
if (bufsiz <= r1) {
PyMem_Free(wbuf);
errno = EINVAL;
return -1;
}
wcsncpy(buf, wbuf, bufsiz);
PyMem_Free(wbuf);
return (int)r1;
}
#endif
#ifdef HAVE_REALPATH
/* Return the canonicalized absolute pathname. Encode path to the locale
encoding, decode the result from the locale encoding. */
wchar_t*
_Py_wrealpath(const wchar_t *path,
wchar_t *resolved_path, size_t resolved_path_size)
{
char *cpath;
char cresolved_path[PATH_MAX];
wchar_t *wresolved_path;
char *res;
size_t r;
cpath = _Py_wchar2char(path, NULL);
if (cpath == NULL) {
errno = EINVAL;
return NULL;
}
res = realpath(cpath, cresolved_path);
PyMem_Free(cpath);
if (res == NULL)
return NULL;
wresolved_path = _Py_char2wchar(cresolved_path, &r);
if (wresolved_path == NULL) {
errno = EINVAL;
return NULL;
}
if (resolved_path_size <= r) {
PyMem_Free(wresolved_path);
errno = EINVAL;
return NULL;
}
wcsncpy(resolved_path, wresolved_path, resolved_path_size);
PyMem_Free(wresolved_path);
return resolved_path;
}
#endif
/* Get the current directory. size is the buffer size in wide characters
including the null character. Decode the path from the locale encoding. */
wchar_t*
_Py_wgetcwd(wchar_t *buf, size_t size)
{
#ifdef MS_WINDOWS
return _wgetcwd(buf, size);
#else
char fname[PATH_MAX];
wchar_t *wname;
size_t len;
if (getcwd(fname, PATH_MAX) == NULL)
return NULL;
wname = _Py_char2wchar(fname, &len);
if (wname == NULL)
return NULL;
if (size <= len) {
PyMem_Free(wname);
return NULL;
}
wcsncpy(buf, wname, size);
PyMem_Free(wname);
return buf;
#endif
}
#endif
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