95 lines
2.7 KiB
C
95 lines
2.7 KiB
C
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/*
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* Class for reading data from files, with base implementations
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* for reading local filesystem files and previous session files.
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*
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* TODO this is kept private for now, it can be useful to make that
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* public later.
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*/
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#ifndef FILE_SRC_H_
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#define FILE_SRC_H_
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#include <sys/types.h>
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struct data_source;
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struct iso_file_src {
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/**
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* Opens the file.
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* This should be called before any call to read_block().
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* @return 1 on success, <= 0 on error
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*/
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int (*open)(struct iso_file_src *src);
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/**
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* Close the file.
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* This should be called when the iso_file_src is no more needed.
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*/
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void (*close)(struct iso_file_src *src);
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/**
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* Read data from the file in 2048 bytes chunks.
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*
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* A pointer to the contents of the file will be updated, in such a way
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* that each time this function is called, new data is read to the buffer.
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* It behaves in the same way as usual read(2) call this way.
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*
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* This always reads 2048 bytes, unless an EOF is found, or we reach the
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* size previously returned by get_size(). In this case, the buffer is
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* completed with 0s.
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*
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* @param buffer Buffer where the data will be written. Its size must
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* be at least 2048 bytes.
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* @return
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* 1 if file contains more data. If we reach EOF before the expected
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* size, this keeps returning 1, and next blocks are filled with 0s.
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* 0 when we reach the expected size, that in normal usage is also EOF
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* on file.
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* < 0 on error. If such case, next calls to read_block will keep
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* returning < 0 until we reach the expected size, filling blocks with
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* 0s.
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*/
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int (*read_block)(struct iso_file_src *src, unsigned char *buffer);
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/**
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* Get the size in bytes of the file.
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*
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* This is set when the iso_file_src is created, and should not change. If
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* the actual file size changes, it will be truncated or padding with 0s
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* when the block is read
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*/
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off_t (*get_size)(struct iso_file_src *);
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/** Clean up the source specific data */
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void (*free_data)(struct iso_file_src *);
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/** Source specific data */
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void *data;
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};
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/**
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* Get a iso_file_src() for reading from a local filesystem file.
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*/
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struct iso_file_src* iso_file_src_from_path(const char *path);
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/**
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* Get a iso_file_src() for reading from a previous image file.
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* @param src data_source to read from previous image. It is not freed,
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* so you need to free it when no more needed.
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* @param block block on image where file begins
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* @param nblocks number of block of the file
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*/
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struct iso_file_src*
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iso_file_src_from_prev_img(struct data_source* src, int block, off_t size);
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/**
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* free a iso_file_src
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*/
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void iso_file_src_free(struct iso_file_src *src);
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#endif /*FILE_SRC_H_*/
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