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AK: Do not keep an open FD in MmappedFile

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We only need an open FD while establishing the mapping,
and can close it immediately after mmap() call.
This commit is contained in:
Sergey Bugaev 2019-08-05 15:26:56 +03:00 committed by Andreas Kling
parent 837b476283
commit 55d7810fab
Notes: sideshowbarker 2024-07-19 12:52:31 +09:00 
Author: https://github.com/bugaevc
Commit: https://github.com/SerenityOS/serenity/commit/55d7810fab7
Pull-request: https://github.com/SerenityOS/serenity/pull/409
2 changed files with 15 additions and 18 deletions
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32
AK/MappedFile.cpp
View file

@ -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;
}

1
AK/MappedFile.h
View file

@ -24,7 +24,6 @@ public:
private:
size_t m_size { 0 };
int m_fd { -1 };
void* m_map { (void*)-1 };
};