From aff06436caf844877f99d32346b076a480e582a7 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 28 Oct 2020 14:35:53 -0400 Subject: [PATCH] Use mode "r" for popen() in psql's evaluate_backtick(). In almost all other places, we use plain "r" or "w" mode in popen() calls (the exceptions being for COPY data). This one has been overlooked (possibly because it's buried in a ".l" flex file?), but it's using PG_BINARY_R. Kensuke Okamura complained in bug #16688 that we fail to strip \r when stripping the trailing newline from a backtick result string. That's true enough, but we'd also fail to convert embedded \r\n cleanly, which also seems undesirable. Fixing the popen() mode seems like the best way to deal with this. It's been like this for a long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/16688-c649c7b69cd7e6f8@postgresql.org --- src/bin/psql/psqlscan.l | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/bin/psql/psqlscan.l b/src/bin/psql/psqlscan.l index a8f2bbe094a..03b785cd84d 100644 --- a/src/bin/psql/psqlscan.l +++ b/src/bin/psql/psqlscan.l @@ -1717,7 +1717,7 @@ evaluate_backtick(void) initPQExpBuffer(&cmd_output); - fd = popen(cmd, PG_BINARY_R); + fd = popen(cmd, "r"); if (!fd) { psql_error("%s: %s\n", cmd, strerror(errno)); @@ -1758,7 +1758,7 @@ evaluate_backtick(void) /* If no error, transfer result to output_buf */ if (!error) { - /* strip any trailing newline */ + /* strip any trailing newline (but only one) */ if (cmd_output.len > 0 && cmd_output.data[cmd_output.len - 1] == '\n') cmd_output.len--; -- 2.39.5