Stephen Seo
c71f4f45c7
TODO:
Extract symlinks in new format (implemented but untested).
Extract compressed files in new format.
184 lines
7.8 KiB
Markdown
184 lines
7.8 KiB
Markdown
# File Format
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Note that any unused bytes/bits should be zeroed-out before being written.
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## Format Version 0
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File extension is "*.simplearchive"
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First 18 bytes of file will be:
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SIMPLE_ARCHIVE_VER
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Next 2 bytes is 16-bit unsigned integer "version" in big-endian. In this case,
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it will be zero.
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Next 4 bytes are bit-flags.
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1. The first byte
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1. The first bit is set if de/compressor is set for this archive.
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The remaining unused flags are reserved for future revisions and are currently
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ignored.
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If the previous "de/compressor is set" flag is enabled, then the next section is
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added:
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1. 2 bytes is 16-bit unsigned integer "compressor cmd+args" in big-endian. This
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does not include the NULL at the end of the string.
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2. X bytes of "compressor cmd+args" (length defined by previous value). Is a
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NULL-terminated string.
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3. 2 bytes is 16-bit unsigned integer "decompressor cmd+args" in big-endian.
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This does not include the NULL at the end of the string.
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4. X bytes of "decompressor cmd+args" (length defined by previous value). Is a
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NULL-terminated string.
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The next 4 bytes is 32-bit unsigned integer "file count" in big-endian which
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will indicate the number of files in this archive.
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Following the file-count bytes, the following bytes are added for each file:
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1. 2 bytes is 16-bit unsigned integer "filename length" in big-endian. This does
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not include the NULL at the end of the string.
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2. X bytes of filename (length defined by previous value). Is a NULL-terminated
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string.
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3. 4 bytes bit-flags
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1. The first byte
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1. The first bit is set if the file is a symbolic link.
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2. The second bit is "user read permission".
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3. The third bit is "user write permission".
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4. The fourth bit is "user execute permission".
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5. The fifth bit is "group read permission".
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6. The sixth bit is "group write permission".
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7. The seventh bit is "group execute permission".
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8. The eighth bit is "other read permission".
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2. The second byte.
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1. The first bit is "other write permission".
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2. The second bit is "other execute permission".
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3. The third bit is UNSET if relative links are preferred, and is SET
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if absolute links are preferred.
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3. The third byte.
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1. Currently unused.
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4. The fourth byte.
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1. Currently unused.
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4. If this file is a symbolic link:
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1. 2 bytes is 16-bit unsigned integer "link target absolute path" in
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big-endian. This does not include the NULL at the end of the string.
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2. X bytes of link-target-absolute-path (length defined by previous value).
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Is a NULL-terminated string. If the previous "size" value is 0, then
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this entry does not exist and should be skipped.
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3. 2 bytes is 16-bit unsigned integer "link target relative path" in
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big-endian. This does not include the NULL at the end of the string.
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4. X bytes of link-target-relative-path (length defined by previous value).
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Is a NULL-terminated string. If the previous "size" value is 0, then
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this entry does not exist and should be skipped.
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5. If this file is NOT a symbolic link:
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1. 8 bytes 64-bit unsigned integer "size of filename in this archive file"
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in big-endian.
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2. X bytes file data (length defined by previous value).
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## Format Version 1
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File extension is "*.simplearchive" but this isn't really checked.
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First 18 bytes of file will be (in ascii):
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SIMPLE_ARCHIVE_VER
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Next 2 bytes is a 16-bit unsigned integer "version" in big-endian. It will be:
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0x00 0x01
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Next 4 bytes are bit-flags.
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1. The first byte
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1. The first bit is set if de/compressor is set for this archive.
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The remaining unused flags in the previous bit-flags bytes are reserved for
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future revisions and are currently ignored.
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If the previous "de/compressor is set" flag is enabled, then the next section is
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added:
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1. 2 bytes is 16-bit unsigned integer "compressor cmd+args" in big-endian. This
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does not include the NULL at the end of the string.
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2. X bytes of "compressor cmd+args" (length defined by previous value). Is a
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NULL-terminated string.
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3. 2 bytes is 16-bit unsigned integer "decompressor cmd+args" in big-endian.
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This does not include the NULL at the end of the string.
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4. X bytes of "decompressor cmd+args" (length defined by previous value). Is a
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NULL-terminated string.
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The next 4 bytes is a 32-bit unsigned integer "link count" in big-endian which
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will indicate the number of symbolic links in this archive.
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Following the link-count bytes, the following bytes are added for each symlink:
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1. 2 bytes bit-flags:
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1. The first byte.
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1. The first bit is UNSET if relative links are preferred, and is SET if
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absolute links are preferred.
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2. The second byte.
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1. Currently unused.
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2. 2 bytes 16-bit unsigned integer "link name" in big-endian. This does not
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include the NULL at the end of the string. Must not be zero.
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3. X bytes of link-name (length defined by previous value). Is a NULL-terminated
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string.
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4. 2 bytes is 16-bit unsigned integer "link target absolute path" in
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big-endian. This does not include the NULL at the end of the string.
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5. X bytes of link-target-absolute-path (length defined by previous value).
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Is a NULL-terminated string. If the previous "size" value is 0, then
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this entry does not exist and should be skipped.
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6. 2 bytes is 16-bit unsigned integer "link target relative path" in
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big-endian. This does not include the NULL at the end of the string.
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7. X bytes of link-target-relative-path (length defined by previous value).
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Is a NULL-terminated string. If the previous "size" value is 0, then
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this entry does not exist and should be skipped.
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After the symlink related data, the next 4 bytes is a 32-bit unsigned integer
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"chunk count" in big-endian which will indicate the number of chunks in this
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archive.
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Following the chunk-count bytes, the following bytes are added for each chunk:
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1. 2 bytes that are a 16-bit unsigned integer "file count" in big-endian.
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The following bytes are added for each file within the current chunk:
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1. 2 bytes that are a 16-bit unsigned integer "filename length" in big-endian.
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This does not include the NULL at the end of the string.
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2. X bytes of filename (length defined by previous value). Is a NULL-terminated
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string.
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3. 4 bytes bit-flags.
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1. The first byte.
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1. The first bit is "user read permission".
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2. The second bit is "user write permission".
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3. The third bit is "user execute permission".
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4. The fourth bit is "group read permission".
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5. The fifth bit is "group write permission".
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6. The sixth bit is "group execute permission".
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7. The seventh bit is "other read permission".
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8. The eighth bit is "other write permission".
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2. The second byte.
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1. The first bit is "other execute permission".
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3. The third byte.
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1. Currently unused.
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4. The fourth byte.
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1. Currently unused.
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4. Two 4-byte unsigned integers in big-endian for UID and GID.
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1. A 32-bit unsigned integer in big endian that specifies the UID of the
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file. Note that during extraction, if the user is not root, then this
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value will be ignored.
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2. A 32-bit unsigned integer in big endian that specifies the GID of the
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file. Note that during extraction, if the user is not root, then this
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value will be ignored.
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5. A 64-bit unsigned integer in big endian for the "size of file".
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After the files' metadata are the current chunk's data:
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1. A 64-bit unsigned integer in big endian for the "size of chunk".
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2. X bytes of data for the current chunk of the previously specified size. If
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not using de/compressor, this section is the previously mentioned files
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concatenated with each other. If using de/compressor, this section is the
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previously mentioned files concatenated and compressed into a single blob of
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data.
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