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 <ran@unusedvar.com>
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 402784f40e3e1fa72aba7a64ab69acfc8892f301..a181f8b7601d1a17f0cd54600ebef2f18bdb5b31 100644 (file)
--- a/src/interfaces/libpq/fe-trace.c
+++ b/src/interfaces/libpq/fe-trace.c
@@ -112,7 +112,7 @@ 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;
@@ -200,7 +200,7 @@ pqTraceOutputNchar(FILE *pfdebug, int len, const char *data, int *cursor)
        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;
        }
    }