[utils] adding a function for checking if files exists (yay C), or at least the closest agreed-upon method for it (may return false if the user doesn't have permissions, but that's ok for our purposes here)

src/crf_trainer.h

@@ -31,7 +31,6 @@ bool crf_trainer_hash_feature_to_id_exists(crf_trainer_t *self, char *feature, u
 bool crf_trainer_hash_prev_tag_feature_to_id(crf_trainer_t *self, char *feature, uint32_t *feature_id);
 bool crf_trainer_hash_prev_tag_feature_to_id_exists(crf_trainer_t *self, char *feature, uint32_t *feature_id, bool *exists);
 
-
 bool crf_trainer_get_feature_id(crf_trainer_t *self, char *feature, uint32_t *feature_id);
 bool crf_trainer_get_prev_tag_feature_id(crf_trainer_t *self, char *feature, uint32_t *feature_id);
 

src/file_utils.c

@@ -32,6 +32,13 @@ char *file_getline(FILE * f)
     return ret;
 }
 
+bool file_exists(char *filename) {
+    FILE *f = fopen(filename, "r");
+    bool exists = f != NULL;
+    if (exists) fclose(f);
+    return exists;
+}
+
 bool is_relative_path(struct dirent *ent) {
     return strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0;
 }

src/shuffle.c

@@ -47,11 +47,9 @@ bool shuffle_file_chunked(char *filename, size_t parts) {
     }
 
     // Make sure the input file exists
-    FILE *f = fopen(filename, "r");
-    if (f == NULL) {
+    if (!file_exists(filename)) {
         return false;
     }
-    fclose(f);
 
     // This is an in-place shuffle to keep the API simple
     char *outfile = filename;