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A few uncommitted fixes

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This commit is contained in:
Suzanne Soy 2021-05-28 21:01:21 +01:00
parent 92ef4bb690
commit 94649bd5ed
3 changed files with 31 additions and 22 deletions
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5
git-tutorial.css
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@ -10,7 +10,10 @@ article#git-tutorial { max-width: 63rem; position: absolute; right:18.4em; top:0
/* td.cell-path { } */
#git-tutorial td.cell-contents { font-family: monospace; width: 36em; }
#git-tutorial td { padding-left: 0.3em; padding-right: 0.3em; }
@media (max-width: 72em) {
#git-tutorial td { padding-left: 0; padding-right: 0; }
#git-tutorial td.cell-contents { width: 34em; }
article#git-tutorial { right: 7em; }
#git-tutorial #toc { right: -11em; }
@ -18,6 +21,7 @@ article#git-tutorial { max-width: 63rem; position: absolute; right:18.4em; top:0
}
@media (max-width: 63em) {
#git-tutorial td { padding-left: 0; padding-right: 0; }
#git-tutorial td.cell-contents { width: 30em; }
article#git-tutorial { right:6em; }
#git-tutorial #toc { right: -12em; }
@ -38,6 +42,7 @@ article#git-tutorial { max-width: 63rem; position: absolute; right:18.4em; top:0
#git-tutorial .object-hash.hilite-dest { background: lightyellow; border-color: red; }
#git-tutorial .object-hash { border: thin solid transparent; }
#git-tutorial .space { text-decoration: underline; color: brown; opacity: 0.5; white-space: pre; }
#git-tutorial .deflate-toggle { cursor: pointer; }
#git-tutorial .deflated { color: red; }
#git-tutorial .directory { color: darkcyan; }
#git-tutorial .error { color: orangered; }

4
git-tutorial.js
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@ -138,7 +138,7 @@ function ___hilite(src, dest) {
var p3 = { left: x, top: yb };
var p4 = { left: xb, top: yb };
var thickness = 2;
var thickness = 3;
// line 1
l1.style.width = p2.left-p1.left;
@ -281,7 +281,7 @@ function ___specialchars_and_colour_and_hex_and_zlib(s) {
}
if (inflated) {
var id=___global_unique_id++;
return '<span onClick="___deflated_click('+id+')">'
return '<span class="deflate-toggle" onClick="___deflated_click('+id+')">'
+ '<span id="deflated'+id+'-pretty">'
+ '<span class="deflated">deflated:</span>'
+ ___specialchars_and_colour_and_hex(___uint8ArrayToString(inflated))

44
index.html
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@ -140,16 +140,17 @@ stored under a unique name. The unique name is obtained by hashing the
contents of the file.</p>
<textarea id="in5">
function hash_object(must_write, type, is_data, path_or_data) {
var data = is_data ? path_or_data : read(current_directory + "/" + path_or_data);
var data = is_data ? path_or_data : read(join_paths(current_directory, path_or_data));
object_contents = type + ' ' + data.length + '\0' + data;
var hash = sha1(object_contents)
var hash = sha1(object_contents);
if (must_write) {
mkdir(join_paths(current_directory, '.git/objects'));
mkdir(join_paths(current_directory, '.git/objects/' + hash.slice(0,2)));
var object_path = join_paths(current_directory, '.git/objects/' + hash.slice(0,2) + '/' + hash.slice(2));
mkdir(join_paths(current_directory, '.git/objects/' + hash.substr(0,2)));
var object_path = join_paths(current_directory, '.git/objects/' + hash.substr(0,2) + '/' + hash.substr(2));
// deflate() compresses using zlib
write(object_path, deflate(object_contents));
}
@ -171,9 +172,9 @@ hash_object(true, 'blob', false, 'README');
</textarea>
<p>The objects stored in the GIT database are compressed with zlib
(using the "deflate" compression method). The filesystem view shows
the <span class="deflated">deflated:</span> followed by the uncompressed
data. Click on the file contents to toggle between this pretty-printed
view and the raw compressed data.
the marker <span class="deflated">deflated:</span> followed by the
uncompressed data. Click on the file contents to toggle between this
pretty-printed view and the raw compressed data.
</p>
<p>You will notice that the database does not contain the name of the
@ -189,7 +190,7 @@ hash_object(true, 'blob', false, 'src/main.scm');
<section id="zlib-compression-note">
<h1><code>zlib</code> compression</h1>
<p>The real implementation of GIT compresses objects with zlib. To
<p>GIT compresses objects with zlib. To
view a zlib-compressed object in your terminal, simply write this
declaration in your shell, and then call e.g. <code>unzlib
.git/objects/95/d318ae78cee607a77c453ead4db344fc1221b7</code></p>
@ -211,7 +212,7 @@ files, but it would be nice to also store the filenames.
This is done by creating a <em>tree</em> object</p>
<p>A tree object can contain files (by associating the file's blob to its name), or directories (by associating the hash of other subtrees to their name).
The mode (<code>100644</code> for the file and <code>40000</code>) incidates the permissions, and is given in octal using <a href="https://unix.stackexchange.com/a/145118/19059">the values used by *nix</a></p>
The mode (<code>100644</code> for the file and <code>40000</code> for the folder) incidates the permissions, and is given in octal using <a href="https://unix.stackexchange.com/a/145118/19059">the values used by *nix</a></p>
<textarea id="in8">
// base_directory is a string
@ -219,7 +220,9 @@ This is done by creating a <em>tree</em> object</p>
// subtrees is a list of {name, hash} objects.
function store_tree(base_directory, filenames, subtrees) {
function get_file_hash(filename) {
return from_hex(hash_object(true, 'blob', false, join_paths(base_directory, filename)));
var path = join_paths(base_directory, filename);
var hash = hash_object(true, 'blob', false, path)
return hex_to_bin(hash);
}
var blobs = filenames.map(function (filename) {
@ -227,19 +230,20 @@ function store_tree(base_directory, filenames, subtrees) {
});
var trees = subtrees.map(function (subtree) {
return "40000 " + subtree.name + "\0" + from_hex(subtree.hash);
return "40000 " + subtree.name + "\0" + hex_to_bin(subtree.hash);
});
tree_contents = blobs.join('') + trees.join('');
// blobs are listed before subtrees
var tree_content = blobs.join('') + trees.join('');
// cat tree_contents | git hash-object -w -t tree --stdin
return hash_object(true, 'tree', true, tree_contents);
// cat tree_content | git hash-object -w -t tree --stdin
return hash_object(true, 'tree', true, tree_content);
}
</textarea>
<p>This function needs a small utility to convert hashes encoded in hexadecimal to a binary form.</p>
<textarea id="in9">
function from_hex(hex) {
function hex_to_bin(hex) {
var hex = String(hex);
var str = ""
for (var i = 0; i < hex.length; i+=2) {
@ -252,8 +256,8 @@ function from_hex(hex) {
<section id="store-tree-example">
<h1>Example use of store_tree</h1>
<textarea id="in10">
//hash_src_tree = store_tree("src/", ["main.scm"], []);
//hash_root_tree = store_tree("", ["README"], [{name:"src", hash:hash_src_tree}]);
//hash_src_tree = store_tree("src", ["main.scm"], []);
//hash_root_tree = store_tree("", ["README"], [{name:"src", hash:hash_src_tree}]);
</textarea>
</section>
@ -756,7 +760,7 @@ function git_init() {
for a more in-depth study of the index.</p>
<textarea id="index-binary-utils">
function binary(val, bytes) {
return from_hex(left_pad(val.toString(16), '0', bytes*2));
return hex_to_bin(left_pad(val.toString(16), '0', bytes*2));
}
function binary16(val) { return binary(val, 2); }
@ -783,7 +787,7 @@ function store_index(paths) {
var uid = binary32(0);
var gid = binary32(0);
var size = binary32(read(join_paths(current_directory, paths[i])).length);
var hash = from_hex(hash_object(true, 'blob', false, paths[i]));
var hash = hex_to_bin(hash_object(true, 'blob', false, paths[i]));
// for this simple index, the flags (the 4 higher bits) are 0.
assert(paths[i].length < 0xfff)
var flags_and_file_path_length = binary16(paths[i].length)
@ -798,7 +802,7 @@ function store_index(paths) {
index += entry;
}
index += from_hex(sha1(index));
index += hex_to_bin(sha1(index));
write(join_paths(current_directory, '.git/index'), index)
}