Create file format for format version 1

This is in preparation of improving compression by concatenating files
together before compressing them to reduce the per-file overhead.

diff --git a/file_format.md b/file_format.md
index fb9c21035ebb80c86672c4a2b4f20454fa0c111c..2f4831e56f0ec78b7c81ca979cc16c0959298777 100644 (file)
--- a/file_format.md
+++ b/file_format.md
@@ -76,3 +76,105 @@ Following the file-count bytes, the following bytes are added for each file:
     1. 8 bytes 64-bit unsigned integer "size of filename in this archive file"
        in big-endian.
     2. X bytes file data (length defined by previous value).
+
+## Format Version 1
+
+File extension is "*.simplearchive" but this isn't really checked.
+
+First 18 bytes of file will be (in ascii):
+
+    SIMPLE_ARCHIVE_VER
+
+Next 2 bites is a 16-bit unsigned integer "version" in big-endian. It will be:
+
+    0x00 0x01
+
+Next 4 bytes are bit-flags.
+
+1. The first byte
+    1. The first bit is set if de/compressor is set for this archive.
+
+The remaining unused flags in the previous bit-flags bytes are reserved for
+future revisions and are currently ignored.
+
+If the previous "de/compressor is set" flag is enabled, then the next section is
+added:
+
+1. 2 bytes is 16-bit unsigned integer "compressor cmd+args" in big-endian. This
+   does not include the NULL at the end of the string.
+2. X bytes of "compressor cmd+args" (length defined by previous value). Is a
+   NULL-terminated string.
+3. 2 bytes is 16-bit unsigned integer "decompressor cmd+args" in big-endian.
+   This does not include the NULL at the end of the string.
+4. X bytes of "decompressor cmd+args" (length defined by previous value). Is a
+   NULL-terminated string.
+
+The next 4 bytes is a 32-bit unsigned integer "link count" in big-endian which
+will indicate the number of symbolic links in this archive.
+
+Following the link-count bytes, the following bytes are added for each symlink:
+
+1. 2 bytes bit-flags:
+    1. The first byte.
+        1. The first bit is UNSET if relative links are preferred, and is SET if
+           absolute links are preferred.
+    2. The second byte.
+        1. Currently unused.
+2. 2 bytes is 16-bit unsigned integer "link target absolute path" in
+   big-endian. This does not include the NULL at the end of the string.
+3. X bytes of link-target-absolute-path (length defined by previous value).
+   Is a NULL-terminated string. If the previous "size" value is 0, then
+   this entry does not exist and should be skipped.
+4. 2 bytes is 16-bit unsigned integer "link target relative path" in
+   big-endian. This does not include the NULL at the end of the string.
+5. X bytes of link-target-relative-path (length defined by previous value).
+   Is a NULL-terminated string. If the previous "size" value is 0, then
+   this entry does not exist and should be skipped.
+
+After the symlink related data, the next 4 bytes is a 32-bit unsigned integer
+"chunk count" in big-endian which will indicate the number of chunks in this
+archive.
+
+Following the chunk-count bytes, the following bytes are added for each chunk:
+
+1. 2 bytes that are a 16-bit unsigned integer "file count" in big-endian.
+
+The following bytes are added for each file within each chunk:
+
+1. 2 bytes that are a 16-bit unsigned integer "filename length" in big-endian.
+   This does not include the NULL at the end of the string.
+2. X bytes of filename (length defined by previous value). Is a NULL-terminated
+   string.
+3. 4 bytes bit-flags.
+    1. The first byte.
+        1. The first bit is "user read permission".
+        2. The second bit is "user write permission".
+        3. The third bit is "user execute permission".
+        4. The fourth bit is "group read permission".
+        5. The fifth bit is "group write permission".
+        6. The sixth bit is "group execute permission".
+        7. The seventh bit is "other read permission".
+        8. The eighth bit is "other write permission".
+    2. The second byte.
+        1. The first bit is "other execute permission".
+    3. The third byte.
+        1. Currently unused.
+    4. The fourth byte.
+        1. Currently unused.
+4. Two 4-byte unsigned integers in big-endian for UID and GID.
+    1. A 32-bit unsigned integer in big endian that specifies the UID of the
+       file. Note that during extraction, if the user is not root, then this
+       value will be ignored.
+    2. A 32-bit unsigned integer in big endian that specifies the GID of the
+       file. Note that during extraction, if the user is not root, then this
+       value will be ignored.
+5. A 64-bit unsigned integer in big endian for the "size of file".
+
+After the files' metadata are the current chunk's data:
+
+1. A 64-bit unsigned integer in big endian for the "size of chunk".
+2. X bytes of data for the current chunk of the previously specified size. If
+   not using de/compressor, this section is the previously mentioned files
+   concatenated with each other. If using de/compressor, this section is the
+   previously mentioned files concatenated and compressed into a single blob of
+   data.