[ruby/prism] Stat file first to check directory

https://github.com/ruby/prism/commit/4ed7de537b

prism/util/pm_string.c

@@ -254,38 +254,45 @@ pm_string_file_init(pm_string_t *string, const char *filepath) {
     *string = (pm_string_t) { .type = PM_STRING_OWNED, .source = source, .length = (size_t) file_size };
     return PM_STRING_INIT_SUCCESS;
 #elif defined(PRISM_HAS_FILESYSTEM)
-    FILE *file = fopen(filepath, "rb");
-    if (file == NULL) {
+    // Open the file for reading
+    int fd = open(filepath, O_RDONLY);
+    if (fd == -1) {
         return PM_STRING_INIT_ERROR_GENERIC;
     }
 
-    fseek(file, 0, SEEK_END);
-    long file_size = ftell(file);
-
-    if (file_size == -1) {
-        fclose(file);
+    // Stat the file to get the file size
+    struct stat sb;
+    if (fstat(fd, &sb) == -1) {
+        close(fd);
         return PM_STRING_INIT_ERROR_GENERIC;
     }
 
-    if (file_size == 0) {
-        fclose(file);
+    // Ensure it is a file and not a directory
+    if (S_ISDIR(sb.st_mode)) {
+        close(fd);
+        return PM_STRING_INIT_ERROR_DIRECTORY;
+    }
+
+    // Check the size to see if it's empty
+    size_t size = (size_t) sb.st_size;
+    if (size == 0) {
+        close(fd);
         const uint8_t source[] = "";
         *string = (pm_string_t) { .type = PM_STRING_CONSTANT, .source = source, .length = 0 };
         return PM_STRING_INIT_SUCCESS;
     }
 
-    size_t length = (size_t) file_size;
+    size_t length = (size_t) size;
     uint8_t *source = xmalloc(length);
     if (source == NULL) {
-        fclose(file);
+        close(fd);
         return PM_STRING_INIT_ERROR_GENERIC;
     }
 
-    fseek(file, 0, SEEK_SET);
-    size_t bytes_read = fread(source, length, 1, file);
-    fclose(file);
+    long bytes_read = (long) read(fd, source, length);
+    close(fd);
 
-    if (bytes_read != 1) {
+    if (bytes_read == -1) {
         xfree(source);
         return PM_STRING_INIT_ERROR_GENERIC;
     }

prism/util/pm_string.h

@@ -22,6 +22,9 @@
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
+#elif defined(PRISM_HAS_FILESYSTEM)
+#include <fcntl.h>
+#include <sys/stat.h>
 #endif
 
 /**

test/prism/api/parse_test.rb

@@ -87,7 +87,6 @@ module Prism
       rescue SystemCallError => error
       end
 
-      return if error.nil? || error.is_a?(Errno::ENOMEM)
       assert_kind_of Errno::EISDIR, error
     end