fix: resolve executable path when run via PATH

When clice is executed via PATH (e.g., 'clice' instead of '/path/to/clice'),
resolve_self_path() incorrectly resolves the path relative to current directory
instead of the actual executable location. This causes worker pool to fail
with 'no such file or directory' error.

Add search_in_path() function to search PATH environment variable when
argv[0] contains no path separators.

Fixes: worker pool fails to start when clice is in PATH

Author: tsurumi-yizhou

src/clice.cc

@@ -87,17 +87,77 @@ struct CliOptions {
     DECO_CFG_END();
 };
 
+auto search_in_path(std::string_view name) -> std::string {
+    const char* path_env = std::getenv("PATH");
+    if(!path_env || name.empty()) {
+        return std::string(name);
+    }
+
+#ifdef _WIN32
+    constexpr char path_sep = ';';
+    constexpr auto is_executable = [](const std::filesystem::path& p) {
+        return std::filesystem::exists(p) && !std::filesystem::is_directory(p);
+    };
+#else
+    constexpr char path_sep = ':';
+    constexpr auto is_executable = [](const std::filesystem::path& p) {
+        std::error_code ec;
+        auto status = std::filesystem::status(p, ec);
+        if(ec || !std::filesystem::exists(status) || std::filesystem::is_directory(status)) {
+            return false;
+        }
+        return (status.permissions() & (std::filesystem::perms::owner_exec | 
+                                        std::filesystem::perms::group_exec | 
+                                        std::filesystem::perms::others_exec)) != std::filesystem::perms::none;
+    };
+#endif
+
+    std::string_view path_view(path_env);
+    size_t start = 0;
+    while(start < path_view.size()) {
+        size_t end = path_view.find(path_sep, start);
+        if(end == std::string_view::npos) {
+            end = path_view.size();
+        }
+        
+        std::string_view dir = path_view.substr(start, end - start);
+        if(!dir.empty()) {
+            std::filesystem::path full_path = std::filesystem::path(dir) / name;
+            std::error_code ec;
+            auto canonical = std::filesystem::canonical(full_path, ec);
+            if(!ec && is_executable(canonical)) {
+                return canonical.string();
+            }
+        }
+        
+        start = end + 1;
+    }
+    
+    return std::string(name);
+}
+
 auto resolve_self_path(int argc, const char** argv) -> std::string {
     if(argc <= 0 || argv == nullptr || argv[0] == nullptr) {
         return "clice";
     }
 
+    std::string_view arg0(argv[0]);
     std::error_code ec;
-    auto absolute = std::filesystem::absolute(argv[0], ec);
-    if(ec) {
-        return std::string(argv[0]);
+
+    // If arg0 contains a path separator, treat it as a path (relative or absolute)
+    if(arg0.find('/') != std::string_view::npos || arg0.find('\\') != std::string_view::npos) {
+        auto absolute = std::filesystem::absolute(arg0, ec);
+        if(!ec) {
+            auto canonical = std::filesystem::weakly_canonical(absolute, ec);
+            if(!ec) {
+                return canonical.string();
+            }
+        }
+        return std::string(arg0);
     }
-    return absolute.string();
+
+    // No path separator - search in PATH
+    return search_in_path(arg0);
 }
 
 auto build_options(const CliOptions& cli_options, int argc, const char** argv)