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[RFC PATCH 12/22] builtin/init-db: add environment variable for new repo hash

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Jan 13, 2020, 12:47 UTC
Message-ID
<20200113124729.3684846-13-sandals@crustytoothpaste.net>
In-Reply-To
<20200113124729.3684846-1-sandals@crustytoothpaste.net>

For the foreseeable future, SHA-1 will be the default algorithm for Git. However, when running the testsuite, we want to be able to test an arbitrary algorithm. It would be quite burdensome and very untidy to have to specify the algorithm we'd like to test every time we initialized a new repository somewhere in the testsuite, so add an environment variable to allow us to specify the default hash algorithm for Git.

This has the benefit that we can set it once for the entire testsuite and not have to think about it. In the future, users can also use it to set the default for their repositories if they would like to do so.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 Documentation/git.txt | 6 ++++++
 builtin/init-db.c     | 9 +++++++++
 2 files changed, 15 insertions(+)
diff --git a/Documentation/git.txt b/Documentation/git.txt
index b1597ac002..d0e83fb7d7 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -479,6 +479,12 @@ double-quotes and respecting backslash escapes. E.g., the value
 	details. This variable has lower precedence than other path
 	variables such as GIT_INDEX_FILE, GIT_OBJECT_DIRECTORY...
 
+`GIT_DEFAULT_HASH_ALGORITHM`::
+	If this variable is set, the default hash algorithm for new
+	repositories will be set to this value. This value is currently
+	ignored when cloning; the setting of the remote repository
+	is used instead. The default is "sha1".
+
 Git Commits
 ~~~~~~~~~~~
 `GIT_AUTHOR_NAME`::
diff --git a/builtin/init-db.c b/builtin/init-db.c
index acb1fa1ad9..7b385aacfd 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -20,6 +20,8 @@
 #define TEST_FILEMODE 1
 #endif
 
+#define GIT_DEFAULT_HASH_ENVIRONMENT "GIT_DEFAULT_HASH"
+
 static int init_is_bare_repository = 0;
 static int init_shared_repository = -1;
 static const char *init_db_template_dir;
@@ -351,6 +353,7 @@ static void separate_git_dir(const char *git_dir, const char *git_link)
 
 static void validate_hash_algorithm(struct repository_format *repo_fmt, int hash)
 {
+	const char *env = getenv(GIT_DEFAULT_HASH_ENVIRONMENT);
 	/*
 	 * If we already have an initialized repo, don't allow the user to
 	 * specify a different algorithm, as that could cause corruption.
@@ -360,6 +363,12 @@ static void validate_hash_algorithm(struct repository_format *repo_fmt, int hash
 		die(_("attempt to reinitialize repository with different hash"));
 	else if (hash != GIT_HASH_UNKNOWN)
 		repo_fmt->hash_algo = hash;
+	else if (env) {
+		int env_algo = hash_algo_by_name(env);
+		if (env_algo == GIT_HASH_UNKNOWN)
+			die(_("unknown hash algorithm '%s'"), env);
+		repo_fmt->hash_algo = env_algo;
+	}
 }
 
 int init_db(const char *git_dir, const char *real_git_dir,
Previous: brian m. carlsonNext: brian m. carlson
Message 18 of 25 in “SHA-256 stage 4 implementation, part 1/3”
  1. 00/22 SHA-256 stage 4 implementation, part 1/3brian m. carlson, Jan 13, 2020
  2. 02/22 hex: add functions to parse hex object IDs in any algorithmbrian m. carlson, Jan 13, 2020
  3. Junio C HamanoJan 15, 2020
  4. brian m. carlsonJan 16, 2020
  5. 04/22 t: use hash-specific lookup tables to define test constantsbrian m. carlson, Jan 13, 2020
  6. 05/22 t6300: abstract away SHA-1-specific constantsbrian m. carlson, Jan 13, 2020
  7. 10/22 setup: allow check_repository_format to read repository formatbrian m. carlson, Jan 13, 2020
  8. 11/22 builtin/init-db: allow specifying hash algorithm on command linebrian m. carlson, Jan 13, 2020
  9. 17/22 tag: store SHA-256 signatures in a headerbrian m. carlson, Jan 13, 2020
  10. 19/22 fast-import: add helper function for inserting mark object entriesbrian m. carlson, Jan 13, 2020
  11. 16/22 gpg-interface: improve interface for parsing tagsbrian m. carlson, Jan 13, 2020
  12. 22/22 fast-import: add options for rewriting submodulesbrian m. carlson, Jan 13, 2020
  13. 18/22 fast-import: permit reading multiple marks filesbrian m. carlson, Jan 13, 2020
  14. 15/22 commit: use expected signature header for SHA-256brian m. carlson, Jan 13, 2020
  15. 20/22 fast-import: make find_marks work on any mark setbrian m. carlson, Jan 13, 2020
  16. 21/22 fast-import: add a generic function to iterate over marksbrian m. carlson, Jan 13, 2020
  17. 14/22 worktree: allow repository version 1brian m. carlson, Jan 13, 2020
  18. 12/22 builtin/init-db: add environment variable for new repo hashbrian m. carlson, Jan 13, 2020
  19. 13/22 init-db: move writing repo version into a functionbrian m. carlson, Jan 13, 2020
  20. 09/22 t/helper: make repository tests hash independentbrian m. carlson, Jan 13, 2020
  21. 03/22 repository: require a build flag to use SHA-256brian m. carlson, Jan 13, 2020
  22. 08/22 t/helper: initialize repository if necessarybrian m. carlson, Jan 13, 2020
  23. 07/22 t/helper/test-dump-split-index: initialize git repositorybrian m. carlson, Jan 13, 2020
  24. 01/22 hex: introduce parsing variants taking hash algorithmsbrian m. carlson, Jan 13, 2020
  25. 06/22 t6300: make hash algorithm independentbrian m. carlson, Jan 13, 2020

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