Format a command using an argument vector

hiredis.c

@@ -578,6 +578,42 @@ int redisFormatCommand(char **target, const char *format, ...) {
     return len;
 }
 
+/* Format a command according to the Redis protocol. This function takes the
+ * number of arguments, an array with arguments and an array with their
+ * lengths. If the latter is set to NULL, strlen will be used to compute the
+ * argument lengths.
+ */
+int redisFormatCommandArgv(char **target, int argc, const char **argv, const size_t *argvlen) {
+    char *cmd = NULL; /* final command */
+    int pos; /* position in final command */
+    size_t len;
+    int totlen, j;
+
+    /* Calculate number of bytes needed for the command */
+    totlen = 1+intlen(argc)+2;
+    for (j = 0; j < argc; j++) {
+        len = argvlen ? argvlen[j] : strlen(argv[j]);
+        totlen += 1+intlen(len)+2+len+2;
+    }
+
+    /* Build the command at protocol level */
+    cmd = malloc(totlen+1);
+    if (!cmd) redisOOM();
+    pos = sprintf(cmd,"*%d\r\n",argc);
+    for (j = 0; j < argc; j++) {
+        len = argvlen ? argvlen[j] : strlen(argv[j]);
+        pos += sprintf(cmd+pos,"$%zu\r\n",len);
+        memcpy(cmd+pos,argv[j],len);
+        pos += len;
+        cmd[pos++] = '\r';
+        cmd[pos++] = '\n';
+    }
+    assert(pos == totlen);
+    cmd[totlen] = '\0';
+    *target = cmd;
+    return totlen;
+}
+
 static int redisContextConnect(redisContext *c, const char *ip, int port) {
     char err[ANET_ERR_LEN];
     if (c->flags & REDIS_BLOCK) {

hiredis.h

@@ -125,6 +125,7 @@ int redisReplyReaderGetReply(void *reader, void **reply);
 /* Functions to format a command according to the protocol. */
 int redisvFormatCommand(char **target, const char *format, va_list ap);
 int redisFormatCommand(char **target, const char *format, ...);
+int redisFormatCommandArgv(char **target, int argc, const char **argv, const size_t *argvlen);
 
 redisContext *redisConnect(const char *ip, int port, redisReplyObjectFunctions *fn);
 redisContext *redisConnectNonBlock(const char *ip, int port, redisReplyObjectFunctions *fn);

test.c

@@ -28,6 +28,48 @@ static void __connect(redisContext **target) {
     }
 }
 
+static void test_format_commands() {
+    char *cmd;
+    int len;
+
+    test("Format command without interpolation: ");
+    len = redisFormatCommand(&cmd,"SET foo bar");
+    test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nbar\r\n",len) == 0 &&
+        len == 4+4+(3+2)+4+(3+2)+4+(3+2));
+    free(cmd);
+
+    test("Format command with %%s string interpolation: ");
+    len = redisFormatCommand(&cmd,"SET %s %s","foo","bar");
+    test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nbar\r\n",len) == 0 &&
+        len == 4+4+(3+2)+4+(3+2)+4+(3+2));
+    free(cmd);
+
+    test("Format command with %%b string interpolation: ");
+    len = redisFormatCommand(&cmd,"SET %b %b","foo",3,"b\0r",3);
+    test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nb\0r\r\n",len) == 0 &&
+        len == 4+4+(3+2)+4+(3+2)+4+(3+2));
+    free(cmd);
+
+    const char *argv[3];
+    argv[0] = "SET";
+    argv[1] = "foo";
+    argv[2] = "bar";
+    size_t lens[3] = { 3, 3, 3 };
+    int argc = 3;
+
+    test("Format command by passing argc/argv without lengths: ");
+    len = redisFormatCommandArgv(&cmd,argc,argv,NULL);
+    test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nbar\r\n",len) == 0 &&
+        len == 4+4+(3+2)+4+(3+2)+4+(3+2));
+    free(cmd);
+
+    test("Format command by passing argc/argv with lengths: ");
+    len = redisFormatCommandArgv(&cmd,argc,argv,lens);
+    test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nbar\r\n",len) == 0 &&
+        len == 4+4+(3+2)+4+(3+2)+4+(3+2));
+    free(cmd);
+}
+
 static void test_blocking_connection() {
     redisContext *c;
     redisReply *reply;
@@ -294,6 +336,7 @@ static void test_nonblocking_connection() {
 }
 
 int main(void) {
+    test_format_commands();
     test_blocking_connection();
     test_reply_reader();
     test_nonblocking_connection();