Allow paths to be created if they don't exist

A module can now declare a path parameter for a directory that does not
yet exist. If the directory does not exist, MaxScale will create the
directory with the requested permissions.

include/maxscale/modinfo.h

@@ -102,7 +102,8 @@ enum mxs_module_param_options
     MXS_MODULE_OPT_PATH_R_OK   = (1 << 2), /**< PATH: Read permission to path required */
     MXS_MODULE_OPT_PATH_W_OK   = (1 << 3), /**< PATH: Write permission to path required */
     MXS_MODULE_OPT_PATH_F_OK   = (1 << 4), /**< PATH: Path must exist */
-    MXS_MODULE_OPT_ENUM_UNIQUE = (1 << 5)  /**< ENUM: Only one value can be defined */
+    MXS_MODULE_OPT_PATH_CREAT  = (1 << 5), /**< PATH: Create path if it doesn't exist */
+    MXS_MODULE_OPT_ENUM_UNIQUE = (1 << 6)  /**< ENUM: Only one value can be defined */
 };
 
 /** String to enum value mappings */

server/core/config.cc

@@ -3276,18 +3276,21 @@ static bool check_path_parameter(const MXS_MODULE_PARAM *params, const char *val
         }
 
         int mode = F_OK;
+        int mask = X_OK;
 
         if (params->options & MXS_MODULE_OPT_PATH_W_OK)
         {
+            mask |= S_IWUSR;
             mode |= W_OK;
         }
         if (params->options & MXS_MODULE_OPT_PATH_R_OK)
         {
+            mask |= S_IRUSR;
             mode |= R_OK;
         }
         if (params->options & MXS_MODULE_OPT_PATH_X_OK)
         {
-            mode |= X_OK;
+            mask |= S_IXUSR;
         }
 
         if (access(buf, mode) == 0)
@@ -3296,8 +3299,30 @@ static bool check_path_parameter(const MXS_MODULE_PARAM *params, const char *val
         }
         else
         {
-            MXS_ERROR("Bad path parameter '%s' (absolute path '%s'): %d, %s", value,
+            /** Save errno as we do a second call to `accept` */
-                      buf, errno, mxs_strerror(errno));
+            int er = errno;
+
+            if (access(buf, F_OK) == 0 || (params->options & MXS_MODULE_OPT_PATH_CREAT) == 0)
+            {
+                /**
+                 * Path already exists and it doesn't have the requested access
+                 * right or the module doesn't want the directory to be created
+                 * if it doesn't exist.
+                 */
+                MXS_ERROR("Bad path parameter '%s' (absolute path '%s'): %d, %s",
+                          value, buf, er, mxs_strerror(er));
+            }
+            else if (mxs_mkdir_all(buf, mask))
+            {
+                /** Successfully created path */
+                valid = true;
+            }
+            else
+            {
+                /** Failed to create the directory, errno is set in `mxs_mkdir_all` */
+                MXS_ERROR("Can't create path '%s' (absolute path '%s'): %d, %s",
+                          value, buf, errno, mxs_strerror(errno));
+            }
         }
     }
     else

server/modules/routing/avrorouter/avro.c

@@ -181,13 +181,16 @@ MXS_MODULE* MXS_CREATE_MODULE()
                 "binlogdir",
                 MXS_MODULE_PARAM_PATH,
                 NULL,
-                MXS_MODULE_OPT_PATH_R_OK
+                MXS_MODULE_OPT_PATH_R_OK |
+                MXS_MODULE_OPT_PATH_CREAT
             },
             {
                 "avrodir",
                 MXS_MODULE_PARAM_PATH,
                 MXS_DEFAULT_DATADIR,
-                MXS_MODULE_OPT_PATH_W_OK
+                MXS_MODULE_OPT_PATH_R_OK |
+                MXS_MODULE_OPT_PATH_W_OK |
+                MXS_MODULE_OPT_PATH_CREAT
             },
             {"source", MXS_MODULE_PARAM_SERVICE},
             {"filestem", MXS_MODULE_PARAM_STRING, BINLOG_NAME_ROOT},

server/modules/routing/binlogrouter/blr.c

@@ -201,7 +201,14 @@ MXS_MODULE* MXS_CREATE_MODULE()
             {"burstsize", MXS_MODULE_PARAM_SIZE, DEF_BURST_SIZE},
             {"heartbeat", MXS_MODULE_PARAM_COUNT, BLR_HEARTBEAT_DEFAULT_INTERVAL},
             {"send_slave_heartbeat", MXS_MODULE_PARAM_BOOL, "false"},
-            {"binlogdir", MXS_MODULE_PARAM_PATH, NULL, MXS_MODULE_OPT_PATH_W_OK},
+            {
+                "binlogdir",
+                MXS_MODULE_PARAM_PATH,
+                NULL,
+                MXS_MODULE_OPT_PATH_R_OK |
+                MXS_MODULE_OPT_PATH_W_OK |
+                MXS_MODULE_OPT_PATH_CREAT
+            },
             {"ssl_cert_verification_depth", MXS_MODULE_PARAM_COUNT, "9"},
             {MXS_END_MODULE_PARAMS}
         }