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mirror of https://git.tartarus.org/simon/putty.git synced 2025-01-09 17:38:00 +00:00
putty-source/utils/dup_wc_to_mb.c
Simon Tatham 4f756d2a4d Rework Unicode conversion APIs to use a BinarySink.
The previous mb_to_wc and wc_to_mb had horrible and also buggy APIs.
This commit introduces a fresh pair of functions to replace them,
which generate output by writing to a BinarySink. So it's now up to
the caller to decide whether it wants the output written to a
fixed-size buffer with overflow checking (via buffer_sink), or
dynamically allocated, or even written directly to some other output
channel.

Nothing uses the new functions yet. I plan to migrate things over in
upcoming commits.

What was wrong with the old APIs: they had that awkward undocumented
Windows-specific 'flags' parameter that I described in the previous
commit and took out of the dup_X_to_Y wrappers. But much worse, the
semantics for buffer overflow were not just undocumented but actually
inconsistent. dup_wc_to_mb() in utils assumed that the underlying
wc_to_mb would fill the buffer nearly full and return the size of data
it wrote. In fact, this was untrue in the case where wc_to_mb called
WideCharToMultiByte: that returns straight-up failure, setting the
Windows error code to ERROR_INSUFFICIENT_BUFFER. It _does_ partially
fill the output buffer, but doesn't tell you how much it wrote!

What's wrong with the new API: it's a bit awkward to write a sequence
of wchar_t in native byte order to a byte-oriented BinarySink, so
people using put_mb_to_wc directly have to do some annoying pointer
casting. But I think that's less horrible than the previous APIs.

Another change: in the new API for wc_to_mb, defchr can be "", but not
NULL.
2024-09-26 11:30:07 +01:00

29 lines
788 B
C

/*
* dup_wc_to_mb: memory-allocating wrapper on wc_to_mb.
*
* Also dup_wc_to_mb_c: same but you already know the length of the
* wide string, and you get told the length of the returned string.
* (But it's still NUL-terminated, for convenience.).
*/
#include <wchar.h>
#include "putty.h"
#include "misc.h"
char *dup_wc_to_mb_c(int codepage, const wchar_t *string,
size_t inlen, const char *defchr, size_t *outlen_p)
{
strbuf *sb = strbuf_new();
put_wc_to_mb(sb, codepage, string, inlen, defchr);
if (outlen_p)
*outlen_p = sb->len;
return strbuf_to_str(sb);
}
char *dup_wc_to_mb(int codepage, const wchar_t *string,
const char *defchr)
{
return dup_wc_to_mb_c(codepage, string, wcslen(string), defchr, NULL);
}