logging: create log directories when needed

Recursively create new log directories when needed. This makes it
possible to use date modifiers in the file path to create
directories based on date, e.g.:

  /var/log/suricata/2017/02/14/

src/util-logopenfile.c

@@ -188,6 +188,41 @@ static char *SCLogFilenameFromPattern(const char *pattern)
     return filename;
 }
 
+/** \brief recursively create missing log directories
+ *  \param path path to log file
+ *  \retval 0 on success
+ *  \retval -1 on error
+ */
+static int SCLogCreateDirectoryTree(const char *filepath)
+{
+    char pathbuf[PATH_MAX];
+    char *p;
+    size_t len = strlen(filepath);
+
+    if (len > PATH_MAX - 1) {
+        return -1;
+    }
+
+    strlcpy(pathbuf, filepath, len);
+
+    for (p = pathbuf + 1; *p; p++) {
+        if (*p == '/') {
+            /* Truncate, while creating directory */
+            *p = '\0';
+
+            if (mkdir(pathbuf, S_IRWXU | S_IRGRP | S_IXGRP) != 0) {
+                if (errno != EEXIST) {
+                    return -1;
+                }
+            }
+
+            *p = '/';
+        }
+    }
+
+    return 0;
+}
+
 static void SCLogFileClose(LogFileCtx *log_ctx)
 {
     if (log_ctx->fp)
@@ -211,6 +246,12 @@ SCLogOpenFileFp(const char *path, const char *append_setting, uint32_t mode)
         return NULL;
     }
 
+    int rc = SCLogCreateDirectoryTree(filename);
+    if (rc < 0) {
+        SCFree(filename);
+        return NULL;
+    }
+
     if (ConfValIsTrue(append_setting)) {
         ret = fopen(filename, "a");
     } else {