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 8660d27926e8bfa29073d00c4398572648273a91..27baec78730771c44905ae8c5d9f337ad362315f 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;
                }
        }