53 lines
2.9 KiB
Markdown
53 lines
2.9 KiB
Markdown
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---
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title: "file_descriptor.h"
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summary: "Processes have no direct access to the VFS, instead they have file descriptors"
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---
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File descriptors are numbers that represent files.
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They are mostly used in file related syscalls.
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# `FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE` - macro
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The amount of file descriptors a `file_descriptor_array_chunk_T` (reference needed) can hold.
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# `file_descriptor_t` - typedef
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This is a typedef of `ìnt32_t` and represents a file descriptor.
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# `std_file_descriptors_E` - enum
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These are reserved file descriptors.
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* `FILE_DESCRIPTOR_INVALID` - This represents an invalid file descriptor, just like NULL is an invalid pointer.
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# `file_descriptor_array_chunk_T` - struct
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| Name | Type | Description |
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|--------|------------------------------------------------|----------------------------------------------------------------------------------------|
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| prev | file_descriptor_array_chunk_T* | The previous chunk |
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| next | file_descriptor_array_chunk_T* | The next chunk |
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| lookup | vfs_node_T* [FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE] | The array of file pointers, that the file descriptors reference |
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| bitmap | bitmap_T | This bitmap indicates which file descriptors of this chunk are free nad which are used |
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| amount | uint32_t | The amount of file descriptors which the chunk actually holds |
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# `file_descriptor_array_T` - struct
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| Name | Type | Description |
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|------------|--------------------------------|------------------------------|
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| base_chunk | file_descriptor_array_chunk_T* | The first chunk in the array |
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# `file_descriptor_request(fd_array, node)` - function (file_descriptor_t)
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Requests and returns new file descriptor, which will be linked with _**node**_.
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# `file_descriptor_resolve(fd_array, fd)` - function (vfs_node_T*)
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Returns the VFS node, with which _**fd**_ is linked.
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# `file_descriptor_free(fd_array, fd)` - function (void)
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Frees _**fd**_ and marks it as reclaimable.
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# `file_descriptor_array_alloc()` - function (file_descriptor_array_T*)
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Allocates a new chunked file descriptor array.
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# `file_descriptor_array_destruct(fd_array)` - function (void)
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Destructs _**fd_array**_ and all its resources, like e.g. chunks.
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# `file_descriptor_array_chunk_alloc(prev)` - function (file_descriptor_array_chunk_T*)
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Allocates a new chunk for a file descriptor array.
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_**prev**_ has to be the last chunk of an array or NULL when the chunk is the base chunk for a fresh file descriptor array.
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# `file_descriptor_array_chunk_destruct(chunk)` - function (void)
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Destructs _**chunk**_ and all its resources.
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