AK: Do not keep an open FD in MmappedFile

We only need an open FD while establishing the mapping,
and can close it immediately after mmap() call.

1 files changed, 15 insertions, 17 deletions

diff --git a/AK/MappedFile.cpp b/AK/MappedFile.cpp
index 83baecfaa4..73265c5a7f 100644
--- a/AK/MappedFile.cpp
+++ b/AK/MappedFile.cpp
@@ -13,21 +13,26 @@ namespace AK {
 MappedFile::MappedFile(const StringView& file_name)
 {
     m_size = PAGE_SIZE;
-    m_fd = open_with_path_length(file_name.characters_without_null_termination(), file_name.length(), O_RDONLY | O_CLOEXEC, 0);
+    int fd = open_with_path_length(file_name.characters_without_null_termination(), file_name.length(), O_RDONLY | O_CLOEXEC, 0);
 
-    if (m_fd != -1) {
-        struct stat st;
-        fstat(m_fd, &st);
-        m_size = st.st_size;
-        m_map = mmap(nullptr, m_size, PROT_READ, MAP_SHARED, m_fd, 0);
-
-        if (m_map == MAP_FAILED)
-            perror("");
+    if (fd == -1) {
+        perror("open");
+        return;
     }
 
+    struct stat st;
+    fstat(fd, &st);
+    m_size = st.st_size;
+    m_map = mmap(nullptr, m_size, PROT_READ, MAP_SHARED, fd, 0);
+
+    if (m_map == MAP_FAILED)
+        perror("mmap");
+
 #ifdef DEBUG_MAPPED_FILE
-    dbgprintf("MappedFile{%s} := { m_fd=%d, m_size=%u, m_map=%p }\n", file_name.characters(), m_fd, m_size, m_map);
+    dbgprintf("MappedFile{%s} := { fd=%d, m_size=%u, m_map=%p }\n", file_name.characters(), fd, m_size, m_map);
 #endif
+
+    close(fd);
 }
 
 MappedFile::~MappedFile()
@@ -39,23 +44,17 @@ void MappedFile::unmap()
 {
     if (!is_valid())
         return;
-    ASSERT(m_fd != -1);
     int rc = munmap(m_map, m_size);
     ASSERT(rc == 0);
-    rc = close(m_fd);
-    ASSERT(rc == 0);
     m_size = 0;
-    m_fd = -1;
     m_map = (void*)-1;
 }
 
 MappedFile::MappedFile(MappedFile&& other)
     : m_size(other.m_size)
-    , m_fd(other.m_fd)
     , m_map(other.m_map)
 {
     other.m_size = 0;
-    other.m_fd = -1;
     other.m_map = (void*)-1;
 }
 
@@ -65,7 +64,6 @@ MappedFile& MappedFile::operator=(MappedFile&& other)
         return *this;
     unmap();
     swap(m_size, other.m_size);
-    swap(m_fd, other.m_fd);
     swap(m_map, other.m_map);
     return *this;
 }