mariadb-backup returns success after --galera-info loses the current binary log to EIO

#!/usr/bin/env bash

set -euo pipefail

IMAGE='mariadb@sha256:dd9b303aed4f4890ed09f766d8ca9ddfd176c0c6f6267feff53b3192ec65a979'

C="mdev-mcf203-$$"

OWNER="mdev-mcf203-$$"

TMP=$(mktemp -d)

cleanup() {

  if docker inspect --format '{{ index .Config.Labels "io.encryptiondbfuzz.owner" }}' \

       "$C" 2>/dev/null | grep -Fqx "$OWNER"; then

    docker rm -f "$C" >/dev/null 2>&1 || true

  fi

  rm -rf -- "$TMP"

}

trap cleanup EXIT

cat >"$TMP/fail.c" <<'EOF_C'

#define _GNU_SOURCE

#include <errno.h>

#include <fcntl.h>

#include <limits.h>

#include <stdio.h>

#include <string.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <unistd.h>

static int delivered;

static int target(int fd) {

  char p[64], v[PATH_MAX+1];

  snprintf(p,sizeof(p),"/proc/self/fd/%d",fd);

  ssize_t n=readlink(p,v,sizeof(v)-1); if(n<=0)return 0; v[n]=0;

  char *b=strrchr(v,'/'); b=b?b+1:v;

  return !strncmp(b,"mariadb-bin.",12) && strcmp(b,"mariadb-bin.index");

}

static void note(void) {

  const char s[]="injected EIO into current-binlog pread\n";

  int fd=open("/tmp/edbf-binlog-eio.log",O_WRONLY|O_CREAT|O_APPEND,0600);

  if(fd>=0){ssize_t n=write(fd,s,sizeof(s)-1);int rc=close(fd);(void)n;(void)rc;}

}

static ssize_t call(int fd,void *buf,size_t len,off_t off) {

  if(target(fd) && __sync_bool_compare_and_swap(&delivered,0,1)) {

    note(); errno=EIO; return -1;

  }

  return syscall(SYS_pread64,fd,buf,len,off);

}

ssize_t pread(int fd,void *buf,size_t len,off_t off){return call(fd,buf,len,off);}

ssize_t p64(int fd,void *buf,size_t len,off64_t off) __asm__("pread64");

ssize_t p64(int fd,void *buf,size_t len,off64_t off){return call(fd,buf,len,(off_t)off);}

EOF_C

gcc -shared -fPIC -O2 -Wall -Wextra -Werror \

  -o "$TMP/fail.so" "$TMP/fail.c"

chmod 755 "$TMP" && chmod 444 "$TMP/fail.so"

docker run --detach --name "$C" \

  --label "io.encryptiondbfuzz.owner=$OWNER" \

  --network none --read-only --cap-drop ALL \

  --security-opt no-new-privileges=true --pids-limit 224 \

  --memory 1700m --cpus 1 --user 999:999 \

  --tmpfs /var/lib/mysql:rw,nosuid,nodev,size=700m,uid=999,gid=999 \

  --tmpfs /run/mysqld:rw,nosuid,nodev,size=16m,uid=999,gid=999 \

  --tmpfs /tmp:rw,nosuid,nodev,size=700m,uid=999,gid=999 \

  --mount "type=bind,src=$TMP,dst=/edbf,readonly" \

  --env MARIADB_ALLOW_EMPTY_ROOT_PASSWORD=1 "$IMAGE" \

  --log-bin=mariadb-bin --binlog-format=ROW --server-id=1 \

  --gtid-strict-mode=ON --wsrep-on=ON \

  --wsrep-provider=/usr/lib/galera/libgalera_smm.so \

  --wsrep-cluster-address=gcomm:// --wsrep-new-cluster \

  --wsrep-node-address=127.0.0.1 --wsrep-node-name=edbf-node \

  --wsrep-provider-options=gmcast.listen_addr=tcp://127.0.0.1:4567 \

  --bind-address=127.0.0.1 >/dev/null

db() {

  docker exec --user 999:999 "$C" mariadb --protocol=socket \

    --socket=/run/mysqld/mysqld.sock -uroot --batch --skip-column-names "$@"

}

READY=0

for I in $(seq 1 120); do

  STATE=$(db -NBe "SELECT CONCAT(@@wsrep_on,'|',

    COALESCE((SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS

      WHERE VARIABLE_NAME='WSREP_READY'),''),'|',

    COALESCE((SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS

      WHERE VARIABLE_NAME='WSREP_LOCAL_STATE_COMMENT'),''))" 2>/dev/null || true)

  if [ "$STATE" = 'ON|ON|Synced' ]; then READY=1; break; fi

  sleep 1

done

test "$READY" -eq 1

db -e "CREATE DATABASE edbf; USE edbf;

  CREATE TABLE t(id INT PRIMARY KEY,pad VARCHAR(255)) ENGINE=InnoDB;

  INSERT INTO t VALUES(1,REPEAT('A',220)),(2,REPEAT('B',220)),(3,REPEAT('C',220));

  SELECT CONCAT('wsrep=',@@wsrep_on,', log_bin=',@@log_bin,

                ', gtid=',@@gtid_binlog_state,', rows=',COUNT(*)) FROM t;"

set +e

docker exec --user 999:999 \

  --env LD_PRELOAD=/edbf/fail.so "$C" timeout 170 mariadb-backup \

  --backup --galera-info --protocol=socket \

  --socket=/run/mysqld/mysqld.sock --user=root \

  --target-dir=/tmp/backup 2>&1 | tee "$TMP/backup.log"

RC=${PIPESTATUS[0]}

set -e

BINLOG=$(db -NBe 'SHOW MASTER STATUS' | cut -f1)

echo "backup_rc=$RC current_binlog=$BINLOG"

grep -E 'copy_file\(\) failed|Writing Galera info succeeded|completed OK' \

  "$TMP/backup.log"

docker exec --user 999:999 "$C" cat /tmp/edbf-binlog-eio.log

if docker exec --user 999:999 "$C" test -f "/tmp/backup/$BINLOG"; then

  echo 'backup_binlog=present'

else

  echo 'backup_binlog=MISSING'

fi

db -NBe "SELECT CONCAT('server_health_rows=',COUNT(*)) FROM edbf.t"

wsrep=ON, log_bin=ON, gtid=0-1-3, rows=3

Error: copy_file() failed.

Writing Galera info succeeded with <uuid>:4 0

completed OK!

backup_rc=0 current_binlog=mariadb-bin.000003

injected EIO into current-binlog pread

backup_binlog=MISSING

server_health_rows=3