feat: add unique_file RAII wrapper for FILE* management

Add FileCloser functor and unique_file type alias (unique_ptr<FILE,
FileCloser>) to io.hpp, along with open_file() helper. Refactor
read_all() and write_all() to use RAII, eliminating manual fclose.
Update tee.cpp to use unique_file vector instead of raw FILE* with
manual cleanup loop.

Author: Charliechen114514

include/cfbox/io.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdio>
+#include <memory>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -9,20 +10,31 @@
 
 namespace cfbox::io {
 
-inline auto read_all(std::string_view path) -> base::Result<std::string> {
-    std::FILE* f = std::fopen(std::string{path}.c_str(), "rb");
+struct FileCloser {
+    void operator()(std::FILE* f) const noexcept {
+        if (f) std::fclose(f);
+    }
+};
+using unique_file = std::unique_ptr<std::FILE, FileCloser>;
+
+inline auto open_file(std::string_view path, const char* mode) -> base::Result<unique_file> {
+    auto* f = std::fopen(std::string{path}.c_str(), mode);
     if (!f) {
         return std::unexpected(base::Error{errno, "cannot open file: " + std::string{path}});
     }
+    return unique_file{f};
+}
 
-    std::fseek(f, 0, SEEK_END);
-    long size = std::ftell(f);
-    std::fseek(f, 0, SEEK_SET);
+inline auto read_all(std::string_view path) -> base::Result<std::string> {
+    CFBOX_TRY(f, open_file(path, "rb"));
+
+    std::fseek(f->get(), 0, SEEK_END);
+    long size = std::ftell(f->get());
+    std::fseek(f->get(), 0, SEEK_SET);
 
     std::string content(static_cast<std::size_t>(size), '\0');
-    auto nread = std::fread(content.data(), 1, content.size(), f);
+    auto nread = std::fread(content.data(), 1, content.size(), f->get());
     content.resize(nread);
-    std::fclose(f);
     return content;
 }
 
@@ -71,13 +83,8 @@ inline auto split_lines(const std::string& content) -> std::vector<std::string>
 }
 
 inline auto write_all(std::string_view path, std::string_view data) -> base::Result<void> {
-    std::FILE* f = std::fopen(std::string{path}.c_str(), "wb");
-    if (!f) {
-        return std::unexpected(
-            base::Error{errno, "cannot open file for writing: " + std::string{path}});
-    }
-    auto written = std::fwrite(data.data(), 1, data.size(), f);
-    std::fclose(f);
+    CFBOX_TRY(f, open_file(path, "wb"));
+    auto written = std::fwrite(data.data(), 1, data.size(), f->get());
     if (written != data.size()) {
         return std::unexpected(base::Error{errno, "write failed: " + std::string{path}});
     }

src/applets/tee.cpp

@@ -5,6 +5,7 @@
 
 #include <cfbox/args.hpp>
 #include <cfbox/help.hpp>
+#include <cfbox/io.hpp>
 
 namespace {
 constexpr cfbox::help::HelpEntry HELP = {
@@ -28,29 +29,26 @@ auto tee_main(int argc, char* argv[]) -> int {
     bool append = parsed.has('a');
     const auto& pos = parsed.positional();
 
-    std::vector<std::FILE*> files;
+    std::vector<cfbox::io::unique_file> files;
     for (auto p : pos) {
         auto* f = std::fopen(std::string{p}.c_str(), append ? "ab" : "wb");
         if (!f) {
             std::fprintf(stderr, "cfbox tee: %s: %s\n", std::string{p}.c_str(), std::strerror(errno));
         } else {
-            files.push_back(f);
+            files.emplace_back(f);
         }
     }
 
     char buf[4096];
     int rc = 0;
     while (auto n = std::fread(buf, 1, sizeof(buf), stdin)) {
         std::fwrite(buf, 1, n, stdout);
-        for (auto* f : files) {
-            if (std::fwrite(buf, 1, n, f) != n) {
+        for (auto& f : files) {
+            if (std::fwrite(buf, 1, n, f.get()) != n) {
                 rc = 1;
             }
         }
     }
 
-    for (auto* f : files) {
-        std::fclose(f);
-    }
     return rc;
 }