Fix read_entire_dir crash on empty path

Co-authored-by: Yaroslav Erohin <ysoftware@yandex.ru>

Author: rexim

nob.h

@@ -1923,7 +1923,7 @@ NOBDEF bool nob_dir_entry_open(const char *dir_path, Nob_Dir_Entry *dir)
     }
 #else
     dir->nob__private.posix_dir = opendir(dir_path);
-    if (dir == NULL) {
+    if (dir->nob__private.posix_dir == NULL) {
         nob_log(NOB_ERROR, "Could not open directory %s: %s", dir_path, strerror(errno));
         dir->error = true;
         return false;
@@ -2074,6 +2074,10 @@ NOBDEF bool nob_walk_dir_opt(const char *root, Nob_Walk_Func func, Nob_Walk_Dir_
 
 NOBDEF bool nob_read_entire_dir(const char *parent, Nob_File_Paths *children)
 {
+    if (strlen(parent) == 0) {
+        nob_log(NOB_ERROR, "Cannot read empty path");
+        return false;
+    }
     bool result = true;
     Nob_Dir_Entry dir = {0};
     if (!nob_dir_entry_open(parent, &dir)) nob_return_defer(false);
@@ -2910,6 +2914,7 @@ NOBDEF char *nob_temp_running_executable_path(void)
 /*
    Revision history:
 
+      3.2.2 (2026-02-06) Fix read_entire_dir crash on empty path (by @ysoftware)
       3.2.1 (2026-01-29) Fix the implicit declaration error when nob is included as a header (by @ysoftware)
       3.2.0 (2026-01-28) Introduce Chain API
                            - Nob_Chain

tests/read_entire_dir.c

@@ -1,5 +1,15 @@
 #include "shared.h"
 
+size_t error_counter = 0;
+
+void error_counting_log_handler(Nob_Log_Level level, const char *fmt, va_list args)
+{
+    UNUSED(level);
+    UNUSED(fmt);
+    UNUSED(args);
+    if (level == ERROR) error_counter++;
+}
+
 int compar_paths(const void *a, const void *b)
 {
     const char* const* ap = (const char* const*)a;
@@ -9,6 +19,17 @@ int compar_paths(const void *a, const void *b)
 
 int main(void)
 {
+    Nob_File_Paths empty = {0};
+
+    error_counter = 0;
+    nob_log_handler *saved_log_hander = get_log_handler();
+    set_log_handler(error_counting_log_handler);
+    {
+        bool ok = nob_read_entire_dir("", &empty);
+        printf("Reading empty dir: ok=%s, error_counter=%zu\n", ok ? "true" : "false", error_counter);
+    }
+    set_log_handler(saved_log_hander);
+
     if (!write_entire_file("foo.txt", NULL, 0)) return 1;
     if (!write_entire_file("bar.txt", NULL, 0)) return 1;
     if (!write_entire_file("baz.txt", NULL, 0)) return 1;

tests/read_entire_dir.stdout.txt

@@ -1,3 +1,4 @@
+Reading empty dir: ok=false, error_counter=1
 Tests:
     bar.txt
     baz.txt

tests/read_entire_dir.win32.stdout.txt

@@ -1,3 +1,4 @@
+Reading empty dir: ok=false, error_counter=1
 Tests:
     bar.txt
     baz.txt