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Diffstat (limited to 'Documentation/user-manual.txt')
| -rw-r--r-- | Documentation/user-manual.txt | 42 |
1 files changed, 37 insertions, 5 deletions
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt index d8dbe6b..90a4189 100644 --- a/Documentation/user-manual.txt +++ b/Documentation/user-manual.txt @@ -1344,7 +1344,7 @@ $ git diff --theirs file.txt # same as the above. ------------------------------------------------- When using the 'ort' merge strategy (the default), before updating the working -tree with the result of the merge, Git writes a special ref named AUTO_MERGE +tree with the result of the merge, Git writes a ref named AUTO_MERGE reflecting the state of the tree it is about to write. Conflicted paths with textual conflicts that could not be automatically merged are written to this tree with conflict markers, just as in the working tree. AUTO_MERGE can thus be @@ -4093,15 +4093,46 @@ that not only specifies their type, but also provides size information about the data in the object. It's worth noting that the SHA-1 hash that is used to name the object is the hash of the original data plus this header, so `sha1sum` 'file' does not match the object name -for 'file'. +for 'file' (the earliest versions of Git hashed slightly differently +but the conclusion is still the same). + +The following is a short example that demonstrates how these hashes +can be generated manually: + +Let's assume a small text file with some simple content: + +------------------------------------------------- +$ echo "Hello world" >hello.txt +------------------------------------------------- + +We can now manually generate the hash Git would use for this file: + +- The object we want the hash for is of type "blob" and its size is + 12 bytes. + +- Prepend the object header to the file content and feed this to + `sha1sum`: + +------------------------------------------------- +$ { printf "blob 12\0"; cat hello.txt; } | sha1sum +802992c4220de19a90767f3000a79a31b98d0df7 - +------------------------------------------------- + +This manually constructed hash can be verified using `git hash-object` +which of course hides the addition of the header: + +------------------------------------------------- +$ git hash-object hello.txt +802992c4220de19a90767f3000a79a31b98d0df7 +------------------------------------------------- As a result, the general consistency of an object can always be tested independently of the contents or the type of the object: all objects can be validated by verifying that (a) their hashes match the content of the file and (b) the object successfully inflates to a stream of bytes that forms a sequence of -`<ascii type without space> + <space> + <ascii decimal size> + -<byte\0> + <binary object data>`. +`<ascii-type-without-space> + <space> + <ascii-decimal-size> + +<byte\0> + <binary-object-data>`. The structured objects can further have their structure and connectivity to other objects verified. This is generally done with @@ -4123,7 +4154,8 @@ $ git switch --detach e83c5163 ---------------------------------------------------- The initial revision lays the foundation for almost everything Git has -today, but is small enough to read in one sitting. +today (even though details may differ in a few places), but is small +enough to read in one sitting. Note that terminology has changed since that revision. For example, the README in that revision uses the word "changeset" to describe what we |