[Minor] Allow to map files at some offset

diff --git a/src/libserver/hyperscan_tools.cxx b/src/libserver/hyperscan_tools.cxx
index ff566b9be4581f6a3173d74ca9af9fdb9d4adfcd..89cc4e23bccda539a10037d6af5f48286cbb598b 100644 (file)
--- a/src/libserver/hyperscan_tools.cxx
+++ b/src/libserver/hyperscan_tools.cxx
@@ -268,7 +268,7 @@ hs_shared_from_serialized(raii_mmaped_file &&map) -> tl::expected<hs_shared_data
        return tl::expected<hs_shared_database, error>{tl::in_place, target};
 }
 
-auto load_cached_hs_file(const char *fname) -> tl::expected<hs_shared_database, error>
+auto load_cached_hs_file(const char *fname, std::int64_t offset = 0) -> tl::expected<hs_shared_database, error>
 {
        auto &hs_cache = hs_known_files_cache::get();
        const auto *log_func = RSPAMD_LOG_FUNC;

diff --git a/src/libutil/cxx/file_util.cxx b/src/libutil/cxx/file_util.cxx
index 1993ff666d0e2e2490724270e42478719d3b2366..f457a4cd78b99ecfacbe936cd58bf72b0d6db448 100644 (file)
--- a/src/libutil/cxx/file_util.cxx
+++ b/src/libutil/cxx/file_util.cxx
@@ -181,31 +181,36 @@ auto raii_locked_file::unlock() -> raii_file {
        return raii_file{static_cast<raii_file&&>(std::move(*this))};
 }
 
-raii_mmaped_file::raii_mmaped_file(raii_file &&_file, void *_map)
-               : file(std::move(_file)), map(_map)
+raii_mmaped_file::raii_mmaped_file(raii_file &&file, void *map, std::size_t sz)
+               : file(std::move(file)), map(map), map_size(sz)
 {
 }
 
 auto raii_mmaped_file::mmap_shared(raii_file &&file,
-                                                                  int flags) -> tl::expected<raii_mmaped_file, error>
+                                                                  int flags, std::int64_t offset) -> tl::expected<raii_mmaped_file, error>
 {
        void *map;
 
+       if (file.get_stat().st_size < offset || offset < 0) {
+               return tl::make_unexpected(error {
+                       fmt::format("cannot mmap file {} due to incorrect offset; offset={}, size={}",
+                               file.get_name(), offset, file.get_size()), EINVAL});
+       }
        /* Update stat on file to ensure it is up-to-date */
        file.update_stat();
-       map = mmap(NULL, file.get_stat().st_size, flags, MAP_SHARED, file.get_fd(), 0);
+       map = mmap(nullptr, file.get_size() - offset, flags, MAP_SHARED, file.get_fd(), offset);
 
        if (map == MAP_FAILED) {
-               return tl::make_unexpected(error { fmt::format("cannot mmap file at fd: {}: {}",
-                               file.get_fd(), ::strerror(errno)), errno });
+               return tl::make_unexpected(error { fmt::format("cannot mmap file {}: {}",
+                               file.get_name(), ::strerror(errno)), errno });
 
        }
 
-       return raii_mmaped_file{std::move(file), map};
+       return raii_mmaped_file{std::move(file), map,  file.get_size() - offset};
 }
 
 auto raii_mmaped_file::mmap_shared(const char *fname, int open_flags,
-                                                                  int mmap_flags) -> tl::expected<raii_mmaped_file, error>
+                                                                  int mmap_flags, std::int64_t offset) -> tl::expected<raii_mmaped_file, error>
 {
        auto file = raii_file::open(fname, open_flags);
 
@@ -213,13 +218,13 @@ auto raii_mmaped_file::mmap_shared(const char *fname, int open_flags,
                return tl::make_unexpected(file.error());
        }
 
-       return raii_mmaped_file::mmap_shared(std::move(file.value()), mmap_flags);
+       return raii_mmaped_file::mmap_shared(std::move(file.value()), mmap_flags, offset);
 }
 
 raii_mmaped_file::~raii_mmaped_file()
 {
        if (map != nullptr) {
-               munmap(map, file.get_stat().st_size);
+               munmap(map, map_size);
        }
 }
 
@@ -227,6 +232,7 @@ raii_mmaped_file::raii_mmaped_file(raii_mmaped_file &&other) noexcept
                : file(std::move(other.file))
 {
        std::swap(map, other.map);
+       std::swap(map_size, other.map_size);
 }
 
 auto raii_file_sink::create(const char *fname, int flags, int perms,

diff --git a/src/libutil/cxx/file_util.hxx b/src/libutil/cxx/file_util.hxx
index 9fbcda540197c20c7342059196312269e1dc0cda..06073dbab824fa1baa943ce7aab4251598d1a16d 100644 (file)
--- a/src/libutil/cxx/file_util.hxx
+++ b/src/libutil/cxx/file_util.hxx
@@ -196,14 +196,14 @@ private:
  */
 struct raii_mmaped_file final {
        ~raii_mmaped_file();
-       static auto mmap_shared(raii_file &&file, int flags) -> tl::expected<raii_mmaped_file, error>;
-       static auto mmap_shared(const char *fname, int open_flags, int mmap_flags) -> tl::expected<raii_mmaped_file, error>;
+       static auto mmap_shared(raii_file &&file, int flags, std::int64_t offset = 0) -> tl::expected<raii_mmaped_file, error>;
+       static auto mmap_shared(const char *fname, int open_flags, int mmap_flags, std::int64_t offset = 0) -> tl::expected<raii_mmaped_file, error>;
        // Returns a constant pointer to the underlying map
        auto get_map() const -> void* {return map;}
        auto get_file() const -> const raii_file& { return file; }
        // Passes the ownership of the mmaped memory to the callee
        auto steal_map() -> std::tuple<void *, std::size_t> {
-               auto ret = std::make_tuple(this->map, file.get_stat().st_size);
+               auto ret = std::make_tuple(this->map, map_size);
                this->map = nullptr;
                return ret;
        }
@@ -212,6 +212,7 @@ struct raii_mmaped_file final {
 
        raii_mmaped_file& operator=(raii_mmaped_file &&other) noexcept {
                std::swap(map, other.map);
+               std::swap(map_size, other.map_size);
                file = std::move(other.file);
 
                return *this;
@@ -225,9 +226,10 @@ struct raii_mmaped_file final {
        raii_mmaped_file(const raii_mmaped_file &other) = delete;
 private:
        /* Is intended to be used with map_shared */
-       explicit raii_mmaped_file(raii_file &&_file, void *_map);
+       explicit raii_mmaped_file(raii_file &&_file, void *_map, std::size_t sz);
        raii_file file;
        void *map = nullptr;
+       std::size_t map_size;
 };
 
 /**