common : add getpwuid fallback for HF cache when HOME is not set (#21035)

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

Author: angt

common/hf-cache.cpp

@@ -26,6 +26,8 @@ namespace nl = nlohmann;
 #include <windows.h>
 #else
 #define HOME_DIR "HOME"
+#include <unistd.h>
+#include <pwd.h>
 #endif
 
 namespace hf_cache {
@@ -51,6 +53,13 @@ static fs::path get_cache_directory() {
                 return entry.path.empty() ? base : base / entry.path;
             }
         }
+#ifndef _WIN32
+        const struct passwd * pw = getpwuid(getuid());
+
+        if (pw->pw_dir && *pw->pw_dir) {
+            return fs::path(pw->pw_dir) / ".cache" / "huggingface" / "hub";
+        }
+#endif
         throw std::runtime_error("Failed to determine HF cache directory");
     }();