Slightly more paranoia and slightly better comments for use of

Windows-specific MultiByteToWideChar/WideCharToMultiByte calls.

diff --git a/src/backend/utils/adt/oracle_compat.c b/src/backend/utils/adt/oracle_compat.c
index b9ce723bc38c8785cc44326a819f19ca339cb5ab..feca491c920b38541c5c284a25efdd3044c5150e 100644 (file)
--- a/src/backend/utils/adt/oracle_compat.c
+++ b/src/backend/utils/adt/oracle_compat.c
@@ -187,7 +187,7 @@ win32_utf8_texttowcs(const text *txt)
                r = MultiByteToWideChar(CP_UTF8, 0, VARDATA_ANY(txt), nbytes,
                                                                result, nbytes);
 
-               if (!r)                                 /* assume it's NO_UNICODE_TRANSLATION */
+               if (r <= 0)                             /* assume it's NO_UNICODE_TRANSLATION */
                {
                        /* see notes above about error reporting */
                        pg_verifymbstr(VARDATA_ANY(txt), nbytes, false);
@@ -198,6 +198,7 @@ win32_utf8_texttowcs(const text *txt)
                }
        }
 
+       /* Append trailing null wchar (MultiByteToWideChar won't have) */
        Assert(r <= nbytes);
        result[r] = 0;
 
@@ -212,8 +213,9 @@ win32_utf8_wcstotext(const wchar_t *str)
        int                     nbytes;
        int                     r;
 
+       /* Compute size of output string (this *will* include trailing null) */
        nbytes = WideCharToMultiByte(CP_UTF8, 0, str, -1, NULL, 0, NULL, NULL);
-       if (nbytes == 0)                        /* shouldn't happen */
+       if (nbytes <= 0)                        /* shouldn't happen */
                ereport(ERROR,
                                (errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
                                 errmsg("UTF-16 to UTF-8 translation failed: %lu",
@@ -223,7 +225,7 @@ win32_utf8_wcstotext(const wchar_t *str)
 
        r = WideCharToMultiByte(CP_UTF8, 0, str, -1, VARDATA(result), nbytes,
                                                        NULL, NULL);
-       if (r == 0)                                     /* shouldn't happen */
+       if (r != nbytes)                        /* shouldn't happen */
                ereport(ERROR,
                                (errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
                                 errmsg("UTF-16 to UTF-8 translation failed: %lu",