libpq: Fix PQtrace() format for non-printable characters

PQtrace() was generating its output for non-printable characters without
casting the characters printed with unsigned char, leading to some extra
"\xffffff" generated in the output due to the fact that char may be
signed.

Oversights introduced by commit 198b3716dba6, so backpatch down to v14.

Author: Ran Benita <[email protected]>
Discussion: https://postgr.es/m/a3383211-4539-459b-9d51-95c736ef08e0@app.fastmail.com
Backpatch-through: 14

diff --git a/src/interfaces/libpq/fe-trace.c b/src/interfaces/libpq/fe-trace.c
index a45f0d855871bea65a2cd9a9a0fe68d7b976a1a3..fae5b47e55161cf1936a5ac51f116f80e42d778e 100644 (file)
--- a/src/interfaces/libpq/fe-trace.c
+++ b/src/interfaces/libpq/fe-trace.c
@@ -113,7 +113,7 @@ pqTraceOutputByte1(FILE *pfdebug, const char *data, int *cursor)
     * that completes ErrorResponse and NoticeResponse messages.
     */
    if (!isprint((unsigned char) *v))
-       fprintf(pfdebug, " \\x%02x", *v);
+       fprintf(pfdebug, " \\x%02x", (unsigned char) *v);
    else
        fprintf(pfdebug, " %c", *v);
    *cursor += 1;
@@ -212,7 +212,7 @@ pqTraceOutputNchar(FILE *pfdebug, int len, const char *data, int *cursor, bool s
        else
        {
            fwrite(v + next, 1, i - next, pfdebug);
-           fprintf(pfdebug, "\\x%02x", v[i]);
+           fprintf(pfdebug, "\\x%02x", (unsigned char) v[i]);
            next = i + 1;
        }
    }