forked from KolibriOS/kolibrios
100 lines
3.1 KiB
Markdown
100 lines
3.1 KiB
Markdown
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# microtar
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A lightweight tar library written in ANSI C
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## Basic Usage
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The library consists of `microtar.c` and `microtar.h`. These two files can be
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dropped into an existing project and compiled along with it.
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#### Reading
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```c
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mtar_t tar;
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mtar_header_t h;
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char *p;
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/* Open archive for reading */
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mtar_open(&tar, "test.tar", "r");
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/* Print all file names and sizes */
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while ( (mtar_read_header(&tar, &h)) != MTAR_ENULLRECORD ) {
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printf("%s (%d bytes)\n", h.name, h.size);
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mtar_next(&tar);
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}
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/* Load and print contents of file "test.txt" */
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mtar_find(&tar, "test.txt", &h);
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p = calloc(1, h.size + 1);
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mtar_read_data(&tar, p, h.size);
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printf("%s", p);
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free(p);
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/* Close archive */
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mtar_close(&tar);
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```
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#### Writing
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```c
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mtar_t tar;
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const char *str1 = "Hello world";
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const char *str2 = "Goodbye world";
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/* Open archive for writing */
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mtar_open(&tar, "test.tar", "w");
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/* Write strings to files `test1.txt` and `test2.txt` */
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mtar_write_file_header(&tar, "test1.txt", strlen(str1));
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mtar_write_data(&tar, str1, strlen(str1));
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mtar_write_file_header(&tar, "test2.txt", strlen(str2));
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mtar_write_data(&tar, str2, strlen(str2));
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/* Finalize -- this needs to be the last thing done before closing */
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mtar_finalize(&tar);
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/* Close archive */
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mtar_close(&tar);
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```
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## Error handling
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All functions which return an `int` will return `MTAR_ESUCCESS` if the operation
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is successful. If an error occurs an error value less-than-zero will be
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returned; this value can be passed to the function `mtar_strerror()` to get its
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corresponding error string.
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## Wrapping a stream
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If you want to read or write from something other than a file, the `mtar_t`
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struct can be manually initialized with your own callback functions and a
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`stream` pointer.
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All callback functions are passed a pointer to the `mtar_t` struct as their
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first argument. They should return `MTAR_ESUCCESS` if the operation succeeds
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without an error, or an integer below zero if an error occurs.
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After the `stream` field has been set, all required callbacks have been set and
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all unused fields have been zeroset the `mtar_t` struct can be safely used with
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the microtar functions. `mtar_open` *should not* be called if the `mtar_t`
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struct was initialized manually.
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#### Reading
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The following callbacks should be set for reading an archive from a stream:
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Name | Arguments | Description
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--------|------------------------------------------|---------------------------
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`read` | `mtar_t *tar, void *data, unsigned size` | Read data from the stream
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`seek` | `mtar_t *tar, unsigned pos` | Set the position indicator
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`close` | `mtar_t *tar` | Close the stream
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#### Writing
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The following callbacks should be set for writing an archive to a stream:
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Name | Arguments | Description
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--------|------------------------------------------------|---------------------
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`write` | `mtar_t *tar, const void *data, unsigned size` | Write data to the stream
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## License
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This library is free software; you can redistribute it and/or modify it under
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the terms of the MIT license. See [LICENSE](LICENSE) for details.
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