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libc: mmap: use VFS handle as reference for shared mappings
Fixes #4050
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446df00d0d
commit
3d432331b9
@ -76,12 +76,12 @@ class Libc::Vfs_plugin final : public Plugin
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struct Mmap_entry : Registry<Mmap_entry>::Element
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{
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void * const start;
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Libc::File_descriptor * const fd;
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Vfs::Vfs_handle * const reference_handle;
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Mmap_entry(Registry<Mmap_entry> ®istry, void *start,
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Libc::File_descriptor *fd)
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Vfs::Vfs_handle *reference_handle)
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: Registry<Mmap_entry>::Element(registry, *this), start(start),
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fd(fd) { }
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reference_handle(reference_handle) { }
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};
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Genode::Allocator &_alloc;
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@ -1946,11 +1946,19 @@ void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags
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} else if (flags & MAP_SHARED) {
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/* duplicate the file descriptor to keep the file open as long as the mapping exists */
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/* create another VFS handle to keep the file open as long as the mapping exists */
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Libc::File_descriptor *dup_fd = dup(fd);
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Vfs::Vfs_handle *reference_handle = nullptr;
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typedef Vfs::Directory_service::Open_result Result;
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Result vfs_open_result;
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monitor().monitor([&] {
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vfs_open_result = _root_fs.open(fd->fd_path, fd->flags,
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&reference_handle, _alloc);
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return Fn::COMPLETE;
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});
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if (!dup_fd) {
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if (vfs_open_result != Result::OPEN_OK) {
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error("mmap could not create reference VFS handle");
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errno = ENFILE;
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return MAP_FAILED;
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}
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@ -1964,7 +1972,10 @@ void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags
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if (!ds_cap.valid()) {
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Genode::error("mmap got invalid dataspace capability");
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close(dup_fd);
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monitor().monitor([&] {
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reference_handle->close();
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return Fn::COMPLETE;
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});
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errno = ENODEV;
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return MAP_FAILED;
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}
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@ -1972,12 +1983,15 @@ void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags
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try {
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addr = region_map().attach(ds_cap, length, offset);
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} catch (...) {
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close(dup_fd);
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monitor().monitor([&] {
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reference_handle->close();
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return Fn::COMPLETE;
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});
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errno = ENOMEM;
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return MAP_FAILED;
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}
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new (_alloc) Mmap_entry(_mmap_registry, addr, dup_fd);
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new (_alloc) Mmap_entry(_mmap_registry, addr, reference_handle);
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}
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return addr;
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@ -1994,20 +2008,23 @@ int Libc::Vfs_plugin::munmap(void *addr, ::size_t)
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/* shared mapping */
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Libc::File_descriptor *fd = nullptr;
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Vfs::Vfs_handle *reference_handle = nullptr;
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_mmap_registry.for_each([&] (Mmap_entry &entry) {
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if (entry.start == addr) {
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fd = entry.fd;
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reference_handle = entry.reference_handle;
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destroy(_alloc, &entry);
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region_map().detach(addr);
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}
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});
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if (!fd)
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if (!reference_handle)
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return Errno(EINVAL);
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close(fd);
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monitor().monitor([&] {
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reference_handle->close();
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return Fn::COMPLETE;
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});
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return 0;
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}
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