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77 lines
2.4 KiB
77 lines
2.4 KiB
line_buffer API |
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=============== |
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The line_buffer library provides a convenient interface for |
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mostly-line-oriented input. |
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Each line is not permitted to exceed 10000 bytes. The provided |
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functions are not thread-safe or async-signal-safe, and like |
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`fgets()`, they generally do not function correctly if interrupted |
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by a signal without SA_RESTART set. |
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Calling sequence |
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---------------- |
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The calling program: |
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- initializes a `struct line_buffer` to LINE_BUFFER_INIT |
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- specifies a file to read with `buffer_init` |
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- processes input with `buffer_read_line`, `buffer_skip_bytes`, |
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and `buffer_copy_bytes` |
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- closes the file with `buffer_deinit`, perhaps to start over and |
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read another file. |
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When finished, the caller can use `buffer_reset` to deallocate |
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resources. |
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Using temporary files |
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--------------------- |
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Temporary files provide a place to store data that should not outlive |
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the calling program. A program |
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- initializes a `struct line_buffer` to LINE_BUFFER_INIT |
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- requests a temporary file with `buffer_tmpfile_init` |
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- acquires an output handle by calling `buffer_tmpfile_rewind` |
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- uses standard I/O functions like `fprintf` and `fwrite` to fill |
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the temporary file |
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- declares writing is over with `buffer_tmpfile_prepare_to_read` |
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- can re-read what was written with `buffer_read_line`, |
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`buffer_copy_bytes`, and so on |
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- can reuse the temporary file by calling `buffer_tmpfile_rewind` |
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again |
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- removes the temporary file with `buffer_deinit`, perhaps to |
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reuse the line_buffer for some other file. |
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When finished, the calling program can use `buffer_reset` to deallocate |
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resources. |
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Functions |
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--------- |
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`buffer_init`, `buffer_fdinit`:: |
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Open the named file or file descriptor for input. |
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buffer_init(buf, NULL) prepares to read from stdin. |
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On failure, returns -1 (with errno indicating the nature |
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of the failure). |
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`buffer_deinit`:: |
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Stop reading from the current file (closing it unless |
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it was stdin). Returns nonzero if `fclose` fails or |
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the error indicator was set. |
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`buffer_read_line`:: |
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Read a line and strip off the trailing newline. |
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On failure or end of file, returns NULL. |
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`buffer_copy_bytes`:: |
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Read `len` bytes of input and dump them to the standard output |
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stream. Returns early for error or end of file. |
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`buffer_skip_bytes`:: |
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Discards `len` bytes from the input stream (stopping early |
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if necessary because of an error or eof). Return value is |
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the number of bytes successfully read. |
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`buffer_reset`:: |
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Deallocates non-static buffers.
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