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19de4c3a8c
Explain in the documentation that conversion errors should never happen.
432 lines
12 KiB
C
432 lines
12 KiB
C
#include "Python.h"
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#ifdef MS_WINDOWS
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# include <windows.h>
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#endif
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#ifdef HAVE_STAT
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/* Decode a byte string from the locale encoding with the
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surrogateescape error handler (undecodable bytes are decoded as characters
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in range U+DC80..U+DCFF). If a byte sequence can be decoded as a surrogate
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character, escape the bytes using the surrogateescape error handler instead
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of decoding them.
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Use _Py_wchar2char() to encode the character string back to a byte string.
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Return a pointer to a newly allocated wide character string (use
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PyMem_Free() to free the memory) and write the number of written wide
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characters excluding the null character into *size if size is not NULL, or
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NULL on error (conversion or memory allocation error).
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Conversion errors should never happen, unless there is a bug in the C
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library. */
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wchar_t*
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_Py_char2wchar(const char* arg, size_t *size)
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{
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wchar_t *res;
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#ifdef HAVE_BROKEN_MBSTOWCS
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/* Some platforms have a broken implementation of
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* mbstowcs which does not count the characters that
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* would result from conversion. Use an upper bound.
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*/
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size_t argsize = strlen(arg);
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#else
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size_t argsize = mbstowcs(NULL, arg, 0);
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#endif
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size_t count;
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unsigned char *in;
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wchar_t *out;
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#ifdef HAVE_MBRTOWC
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mbstate_t mbs;
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#endif
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if (argsize != (size_t)-1) {
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res = (wchar_t *)PyMem_Malloc((argsize+1)*sizeof(wchar_t));
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if (!res)
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goto oom;
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count = mbstowcs(res, arg, argsize+1);
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if (count != (size_t)-1) {
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wchar_t *tmp;
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/* Only use the result if it contains no
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surrogate characters. */
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for (tmp = res; *tmp != 0 &&
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(*tmp < 0xd800 || *tmp > 0xdfff); tmp++)
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;
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if (*tmp == 0) {
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if (size != NULL)
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*size = count;
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return res;
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}
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}
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PyMem_Free(res);
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}
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/* Conversion failed. Fall back to escaping with surrogateescape. */
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#ifdef HAVE_MBRTOWC
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/* Try conversion with mbrtwoc (C99), and escape non-decodable bytes. */
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/* Overallocate; as multi-byte characters are in the argument, the
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actual output could use less memory. */
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argsize = strlen(arg) + 1;
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res = (wchar_t*)PyMem_Malloc(argsize*sizeof(wchar_t));
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if (!res)
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goto oom;
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in = (unsigned char*)arg;
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out = res;
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memset(&mbs, 0, sizeof mbs);
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while (argsize) {
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size_t converted = mbrtowc(out, (char*)in, argsize, &mbs);
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if (converted == 0)
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/* Reached end of string; null char stored. */
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break;
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if (converted == (size_t)-2) {
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/* Incomplete character. This should never happen,
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since we provide everything that we have -
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unless there is a bug in the C library, or I
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misunderstood how mbrtowc works. */
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fprintf(stderr, "unexpected mbrtowc result -2\n");
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PyMem_Free(res);
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return NULL;
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}
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if (converted == (size_t)-1) {
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/* Conversion error. Escape as UTF-8b, and start over
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in the initial shift state. */
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*out++ = 0xdc00 + *in++;
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argsize--;
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memset(&mbs, 0, sizeof mbs);
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continue;
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}
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if (*out >= 0xd800 && *out <= 0xdfff) {
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/* Surrogate character. Escape the original
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byte sequence with surrogateescape. */
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argsize -= converted;
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while (converted--)
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*out++ = 0xdc00 + *in++;
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continue;
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}
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/* successfully converted some bytes */
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in += converted;
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argsize -= converted;
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out++;
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}
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#else
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/* Cannot use C locale for escaping; manually escape as if charset
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is ASCII (i.e. escape all bytes > 128. This will still roundtrip
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correctly in the locale's charset, which must be an ASCII superset. */
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res = PyMem_Malloc((strlen(arg)+1)*sizeof(wchar_t));
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if (!res) goto oom;
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in = (unsigned char*)arg;
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out = res;
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while(*in)
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if(*in < 128)
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*out++ = *in++;
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else
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*out++ = 0xdc00 + *in++;
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*out = 0;
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#endif
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if (size != NULL)
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*size = out - res;
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return res;
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oom:
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fprintf(stderr, "out of memory\n");
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return NULL;
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}
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/* Encode a (wide) character string to the locale encoding with the
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surrogateescape error handler (characters in range U+DC80..U+DCFF are
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converted to bytes 0x80..0xFF).
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This function is the reverse of _Py_char2wchar().
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Return a pointer to a newly allocated byte string (use PyMem_Free() to free
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the memory), or NULL on conversion or memory allocation error.
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If error_pos is not NULL: *error_pos is the index of the invalid character
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on conversion error, or (size_t)-1 otherwise. */
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char*
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_Py_wchar2char(const wchar_t *text, size_t *error_pos)
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{
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const size_t len = wcslen(text);
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char *result = NULL, *bytes = NULL;
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size_t i, size, converted;
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wchar_t c, buf[2];
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if (error_pos != NULL)
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*error_pos = (size_t)-1;
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/* The function works in two steps:
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1. compute the length of the output buffer in bytes (size)
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2. outputs the bytes */
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size = 0;
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buf[1] = 0;
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while (1) {
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for (i=0; i < len; i++) {
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c = text[i];
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if (c >= 0xdc80 && c <= 0xdcff) {
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/* UTF-8b surrogate */
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if (bytes != NULL) {
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*bytes++ = c - 0xdc00;
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size--;
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}
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else
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size++;
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continue;
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}
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else {
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buf[0] = c;
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if (bytes != NULL)
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converted = wcstombs(bytes, buf, size);
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else
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converted = wcstombs(NULL, buf, 0);
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if (converted == (size_t)-1) {
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if (result != NULL)
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PyMem_Free(result);
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if (error_pos != NULL)
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*error_pos = i;
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return NULL;
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}
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if (bytes != NULL) {
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bytes += converted;
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size -= converted;
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}
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else
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size += converted;
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}
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}
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if (result != NULL) {
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*bytes = 0;
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break;
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}
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size += 1; /* nul byte at the end */
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result = PyMem_Malloc(size);
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if (result == NULL)
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return NULL;
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bytes = result;
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}
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return result;
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}
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/* In principle, this should use HAVE__WSTAT, and _wstat
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should be detected by autoconf. However, no current
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POSIX system provides that function, so testing for
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it is pointless.
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Not sure whether the MS_WINDOWS guards are necessary:
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perhaps for cygwin/mingw builds?
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*/
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#if defined(HAVE_STAT) && !defined(MS_WINDOWS)
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/* Get file status. Encode the path to the locale encoding. */
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int
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_Py_wstat(const wchar_t* path, struct stat *buf)
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{
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int err;
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char *fname;
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fname = _Py_wchar2char(path, NULL);
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if (fname == NULL) {
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errno = EINVAL;
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return -1;
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}
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err = stat(fname, buf);
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PyMem_Free(fname);
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return err;
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}
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#endif
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/* Call _wstat() on Windows, or encode the path to the filesystem encoding and
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call stat() otherwise. Only fill st_mode attribute on Windows.
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Return 0 on success, -1 on _wstat() / stat() error or (if PyErr_Occurred())
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unicode error. */
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int
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_Py_stat(PyObject *path, struct stat *statbuf)
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{
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#ifdef MS_WINDOWS
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int err;
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struct _stat wstatbuf;
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err = _wstat(PyUnicode_AS_UNICODE(path), &wstatbuf);
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if (!err)
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statbuf->st_mode = wstatbuf.st_mode;
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return err;
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#else
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int ret;
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PyObject *bytes = PyUnicode_EncodeFSDefault(path);
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if (bytes == NULL)
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return -1;
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ret = stat(PyBytes_AS_STRING(bytes), statbuf);
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Py_DECREF(bytes);
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return ret;
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#endif
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}
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/* Open a file. Use _wfopen() on Windows, encode the path to the locale
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encoding and use fopen() otherwise. */
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FILE *
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_Py_wfopen(const wchar_t *path, const wchar_t *mode)
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{
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#ifndef MS_WINDOWS
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FILE *f;
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char *cpath;
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char cmode[10];
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size_t r;
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r = wcstombs(cmode, mode, 10);
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if (r == (size_t)-1 || r >= 10) {
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errno = EINVAL;
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return NULL;
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}
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cpath = _Py_wchar2char(path, NULL);
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if (cpath == NULL)
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return NULL;
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f = fopen(cpath, cmode);
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PyMem_Free(cpath);
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return f;
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#else
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return _wfopen(path, mode);
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#endif
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}
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/* Call _wfopen() on Windows, or encode the path to the filesystem encoding and
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call fopen() otherwise.
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Return the new file object on success, or NULL if the file cannot be open or
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(if PyErr_Occurred()) on unicode error */
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FILE*
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_Py_fopen(PyObject *path, const char *mode)
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{
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#ifdef MS_WINDOWS
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wchar_t wmode[10];
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int usize;
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usize = MultiByteToWideChar(CP_ACP, 0, mode, -1, wmode, sizeof(wmode));
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if (usize == 0)
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return NULL;
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return _wfopen(PyUnicode_AS_UNICODE(path), wmode);
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#else
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FILE *f;
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PyObject *bytes = PyUnicode_EncodeFSDefault(path);
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if (bytes == NULL)
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return NULL;
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f = fopen(PyBytes_AS_STRING(bytes), mode);
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Py_DECREF(bytes);
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return f;
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#endif
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}
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#ifdef HAVE_READLINK
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/* Read value of symbolic link. Encode the path to the locale encoding, decode
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the result from the locale encoding. */
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int
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_Py_wreadlink(const wchar_t *path, wchar_t *buf, size_t bufsiz)
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{
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char *cpath;
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char cbuf[PATH_MAX];
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wchar_t *wbuf;
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int res;
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size_t r1;
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cpath = _Py_wchar2char(path, NULL);
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if (cpath == NULL) {
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errno = EINVAL;
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return -1;
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}
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res = (int)readlink(cpath, cbuf, PATH_MAX);
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PyMem_Free(cpath);
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if (res == -1)
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return -1;
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if (res == PATH_MAX) {
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errno = EINVAL;
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return -1;
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}
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cbuf[res] = '\0'; /* buf will be null terminated */
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wbuf = _Py_char2wchar(cbuf, &r1);
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if (wbuf == NULL) {
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errno = EINVAL;
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return -1;
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}
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if (bufsiz <= r1) {
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PyMem_Free(wbuf);
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errno = EINVAL;
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return -1;
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}
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wcsncpy(buf, wbuf, bufsiz);
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PyMem_Free(wbuf);
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return (int)r1;
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}
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#endif
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#ifdef HAVE_REALPATH
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/* Return the canonicalized absolute pathname. Encode path to the locale
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encoding, decode the result from the locale encoding. */
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wchar_t*
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_Py_wrealpath(const wchar_t *path,
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wchar_t *resolved_path, size_t resolved_path_size)
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{
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char *cpath;
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char cresolved_path[PATH_MAX];
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wchar_t *wresolved_path;
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char *res;
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size_t r;
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cpath = _Py_wchar2char(path, NULL);
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if (cpath == NULL) {
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errno = EINVAL;
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return NULL;
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}
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res = realpath(cpath, cresolved_path);
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PyMem_Free(cpath);
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if (res == NULL)
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return NULL;
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wresolved_path = _Py_char2wchar(cresolved_path, &r);
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if (wresolved_path == NULL) {
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errno = EINVAL;
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return NULL;
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}
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if (resolved_path_size <= r) {
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PyMem_Free(wresolved_path);
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errno = EINVAL;
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return NULL;
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}
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wcsncpy(resolved_path, wresolved_path, resolved_path_size);
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PyMem_Free(wresolved_path);
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return resolved_path;
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}
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#endif
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/* Get the current directory. size is the buffer size in wide characters
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including the null character. Decode the path from the locale encoding. */
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wchar_t*
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_Py_wgetcwd(wchar_t *buf, size_t size)
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{
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#ifdef MS_WINDOWS
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return _wgetcwd(buf, size);
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#else
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char fname[PATH_MAX];
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wchar_t *wname;
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size_t len;
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if (getcwd(fname, PATH_MAX) == NULL)
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return NULL;
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wname = _Py_char2wchar(fname, &len);
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if (wname == NULL)
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return NULL;
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if (size <= len) {
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PyMem_Free(wname);
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return NULL;
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}
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wcsncpy(buf, wname, size);
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PyMem_Free(wname);
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return buf;
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#endif
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}
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#endif
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