stricter options for SET command

Issue: #2157
As the SET command is parsed, it remembers which options are already set
and if a duplicate option is found, raises an error because it is
essentially an invalid syntax.

It still allows mutually exclusive options like EX and PX because taking
an option over another (precedence) is not essentially a syntactic
error.

1 files changed, 8 insertions, 4 deletions

diff --git a/src/t_string.c b/src/t_string.c
index 74c05793c..0bbefcaad 100644
--- a/src/t_string.c
+++ b/src/t_string.c
@@ -61,6 +61,8 @@ static int checkStringLength(redisClient *c, long long size) {
 #define REDIS_SET_NO_FLAGS 0
 #define REDIS_SET_NX (1<<0)     /* Set if key not exists. */
 #define REDIS_SET_XX (1<<1)     /* Set if key exists. */
+#define REDIS_SET_EX (1<<2)     /* Set if time in seconds is given */
+#define REDIS_SET_PX (1<<3)     /* Set if time in ms in given */
 
 void setGenericCommand(redisClient *c, int flags, robj *key, robj *val, robj *expire, int unit, robj *ok_reply, robj *abort_reply) {
     long long milliseconds = 0; /* initialized to avoid any harmness warning */
@@ -101,19 +103,21 @@ void setCommand(redisClient *c) {
         char *a = c->argv[j]->ptr;
         robj *next = (j == c->argc-1) ? NULL : c->argv[j+1];
 
-        if ((a[0] == 'n' || a[0] == 'N') &&
+        if (!(flags & REDIS_SET_NX) && (a[0] == 'n' || a[0] == 'N') &&
             (a[1] == 'x' || a[1] == 'X') && a[2] == '\0') {
             flags |= REDIS_SET_NX;
-        } else if ((a[0] == 'x' || a[0] == 'X') &&
+        } else if (!(flags & REDIS_SET_XX) && (a[0] == 'x' || a[0] == 'X') &&
                    (a[1] == 'x' || a[1] == 'X') && a[2] == '\0') {
             flags |= REDIS_SET_XX;
-        } else if ((a[0] == 'e' || a[0] == 'E') &&
+        } else if (!(flags & REDIS_SET_EX) && (a[0] == 'e' || a[0] == 'E') &&
                    (a[1] == 'x' || a[1] == 'X') && a[2] == '\0' && next) {
+            flags |= REDIS_SET_EX;
             unit = UNIT_SECONDS;
             expire = next;
             j++;
-        } else if ((a[0] == 'p' || a[0] == 'P') &&
+        } else if (!(flags & REDIS_SET_PX) && (a[0] == 'p' || a[0] == 'P') &&
                    (a[1] == 'x' || a[1] == 'X') && a[2] == '\0' && next) {
+            flags |= REDIS_SET_PX;
             unit = UNIT_MILLISECONDS;
             expire = next;
             j++;