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refs: conditional ref updates

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Allow updating references if the old value matches the given one.
This commit is contained in:
Carlos Martín Nieto 2013-12-18 19:58:16 +01:00
parent 7369ea8075
commit 9b148098e6
6 changed files with 120 additions and 26 deletions
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49
include/git2/refs.h
View File

@ -143,6 +143,49 @@ GIT_EXTERN(int) git_reference_symbolic_create(git_reference **out, git_repositor
*/
GIT_EXTERN(int) git_reference_create(git_reference **out, git_repository *repo, const char *name, const git_oid *id, int force, const git_signature *signature, const char *log_message);
/**
* Conditionally create new direct reference
*
* A direct reference (also called an object id reference) refers directly
* to a specific object id (a.k.a. OID or SHA) in the repository. The id
* permanently refers to the object (although the reference itself can be
* moved). For example, in libgit2 the direct ref "refs/tags/v0.17.0"
* refers to OID 5b9fac39d8a76b9139667c26a63e6b3f204b3977.
*
* The direct reference will be created in the repository and written to
* the disk. The generated reference object must be freed by the user.
*
* Valid reference names must follow one of two patterns:
*
* 1. Top-level names must contain only capital letters and underscores,
* and must begin and end with a letter. (e.g. "HEAD", "ORIG_HEAD").
* 2. Names prefixed with "refs/" can be almost anything. You must avoid
* the characters '~', '^', ':', '\\', '?', '[', and '*', and the
* sequences ".." and "@{" which have special meaning to revparse.
*
* This function will return an error if a reference already exists with the
* given name unless `force` is true, in which case it will be overwritten.
*
* The signature and message for the reflog will be ignored if the
* reference does not belong in the standard set (HEAD, branches and
* remote-tracking branches) and and it does not have a reflog.
*
* It will also return an error if the reference's value at the time
* of updating does not match the one passed.
*
* @param out Pointer to the newly created reference
* @param repo Repository where that reference will live
* @param name The name of the reference
* @param id The object id pointed to by the reference.
* @param force Overwrite existing references
* @param force Overwrite existing references
* @param signature The identity that will used to populate the reflog entry
* @param log_message The one line long message to be appended to the reflog
* @param old_id The old value which the reference should have
* @return 0 on success, GIT_EEXISTS, GIT_EINVALIDSPEC or an error code
*/
GIT_EXTERN(int) git_reference_create_if(git_reference **out, git_repository *repo, const char *name, const git_oid *id, int force, const git_signature *signature, const char *log_message, const git_oid *old_id);
/**
* Get the OID pointed to by a direct reference.
*
@ -254,16 +297,12 @@ GIT_EXTERN(int) git_reference_symbolic_set_target(
const char *log_message);
/**
* Create a new reference with the same name as the given reference but a
* Conditionally create a new reference with the same name as the given reference but a
* different OID target. The reference must be a direct reference, otherwise
* this will fail.
*
* The new reference will be written to disk, overwriting the given reference.
*
* The signature and message for the reflog will be ignored if the
* reference does not belong in the standard set (HEAD, branches and
* remote-tracking branches) and and it does not have a reflog.
*
* @param out Pointer to the newly created reference
* @param ref The reference
* @param id The new target OID for the reference

3
include/git2/sys/refdb_backend.h
View File

@ -94,7 +94,8 @@ struct git_refdb_backend {
*/
int (*write)(git_refdb_backend *backend,
const git_reference *ref, int force,
const git_signature *who, const char *message);
const git_signature *who, const char *message,
const git_oid *old);
int (*rename)(
git_reference **out, git_refdb_backend *backend,

4
src/refdb.c
View File

@ -167,14 +167,14 @@ void git_refdb_iterator_free(git_reference_iterator *iter)
iter->free(iter);
}
int git_refdb_write(git_refdb *db, git_reference *ref, int force, const git_signature *who, const char *message)
int git_refdb_write(git_refdb *db, git_reference *ref, int force, const git_signature *who, const char *message, const git_oid *old)
{
assert(db && db->backend);
GIT_REFCOUNT_INC(db);
ref->db = db;
return db->backend->write(db->backend, ref, force, who, message);
return db->backend->write(db->backend, ref, force, who, message, old);
}
int git_refdb_rename(

2
src/refdb.h
View File

@ -42,7 +42,7 @@ int git_refdb_iterator_next(git_reference **out, git_reference_iterator *iter);
int git_refdb_iterator_next_name(const char **out, git_reference_iterator *iter);
void git_refdb_iterator_free(git_reference_iterator *iter);
int git_refdb_write(git_refdb *refdb, git_reference *ref, int force, const git_signature *who, const char *message);
int git_refdb_write(git_refdb *refdb, git_reference *ref, int force, const git_signature *who, const char *message, const git_oid *old);
int git_refdb_delete(git_refdb *refdb, const char *ref_name);
int git_refdb_reflog_read(git_reflog **out, git_refdb *db, const char *name);

41
src/refdb_fs.c
View File

@ -690,8 +690,11 @@ static int reference_path_available(
static int loose_lock(git_filebuf *file, refdb_fs_backend *backend, const git_reference *ref)
{
int error;
git_buf ref_path = GIT_BUF_INIT;
assert(file && backend && ref);
/* Remove a possibly existing empty directory hierarchy
* which name would collide with the reference name
*/
@ -701,17 +704,16 @@ static int loose_lock(git_filebuf *file, refdb_fs_backend *backend, const git_re
if (git_buf_joinpath(&ref_path, backend->path, ref->name) < 0)
return -1;
if (git_filebuf_open(file, ref_path.ptr, GIT_FILEBUF_FORCE, GIT_REFS_FILE_MODE) < 0) {
git_buf_free(&ref_path);
return -1;
}
error = git_filebuf_open(file, ref_path.ptr, GIT_FILEBUF_FORCE, GIT_REFS_FILE_MODE);
git_buf_free(&ref_path);
return 0;
return error;
}
static int loose_commit(git_filebuf *file, const git_reference *ref)
{
assert(file && ref);
if (ref->type == GIT_REF_OID) {
char oid[GIT_OID_HEXSZ + 1];
git_oid_nfmt(oid, sizeof(oid), &ref->target.oid);
@ -933,10 +935,12 @@ static int refdb_fs_backend__write(
const git_reference *ref,
int force,
const git_signature *who,
const char *message)
const char *message,
const git_oid *old_id)
{
refdb_fs_backend *backend = (refdb_fs_backend *)_backend;
git_filebuf file = GIT_FILEBUF_INIT;
git_reference *old_ref;
int error;
assert(backend);
@ -945,10 +949,28 @@ static int refdb_fs_backend__write(
if (error < 0)
return error;
/* We need to perform the reflog append under the ref's lock */
/* We need to perform the reflog append and old value check under the ref's lock */
if ((error = loose_lock(&file, backend, ref)) < 0)
return error;
if (old_id) {
if ((error = refdb_fs_backend__lookup(&old_ref, _backend, ref->name)) < 0) {
git_filebuf_cleanup(&file);
return error;
}
if (old_ref->type == GIT_REF_SYMBOLIC) {
giterr_set(GITERR_REFERENCE, "cannot compare id to symbolic reference target");
goto on_error;
}
/* Finally we can compare the ids */
if (git_oid_cmp(old_id, &old_ref->target.oid)) {
giterr_set(GITERR_REFERENCE, "old reference value does not match");
goto on_error;
}
}
if (should_write_reflog(backend->repo, ref->name) &&
(error = reflog_append(backend, ref, who, message)) < 0) {
git_filebuf_cleanup(&file);
@ -956,6 +978,11 @@ static int refdb_fs_backend__write(
}
return loose_commit(&file, ref);
on_error:
git_filebuf_cleanup(&file);
git_reference_free(old_ref);
return -1;
}
static int refdb_fs_backend__delete(

47
src/refs.c
View File

@ -331,7 +331,8 @@ static int reference__create(
const char *symbolic,
int force,
const git_signature *signature,
const char *log_message)
const char *log_message,
const git_oid *old_id)
{
char normalized[GIT_REFNAME_MAX];
git_refdb *refdb;
@ -380,7 +381,7 @@ static int reference__create(
GITERR_CHECK_ALLOC(ref);
if ((error = git_refdb_write(refdb, ref, force, signature, log_message)) < 0) {
if ((error = git_refdb_write(refdb, ref, force, signature, log_message, old_id)) < 0) {
git_reference_free(ref);
return error;
}
@ -410,15 +411,28 @@ int git_reference_create(
git_reference **ref_out,
git_repository *repo,
const char *name,
const git_oid *oid,
const git_oid *id,
int force,
const git_signature *signature,
const char *log_message)
{
return git_reference_create_if(ref_out, repo, name, id, force, signature, log_message, NULL);
}
int git_reference_create_if(
git_reference **ref_out,
git_repository *repo,
const char *name,
const git_oid *id,
int force,
const git_signature *signature,
const char *log_message,
const git_oid *old_id)
{
int error;
git_signature *who = NULL;
assert(oid);
assert(id);
if (!signature) {
if ((error = log_signature(&who, repo)) < 0)
@ -428,7 +442,7 @@ int git_reference_create(
}
error = reference__create(
ref_out, repo, name, oid, NULL, force, signature, log_message);
ref_out, repo, name, id, NULL, force, signature, log_message, old_id);
git_signature_free(who);
return error;
@ -456,7 +470,7 @@ int git_reference_symbolic_create(
}
error = reference__create(
ref_out, repo, name, NULL, target, force, signature, log_message);
ref_out, repo, name, NULL, target, force, signature, log_message, NULL);
git_signature_free(who);
return error;
@ -471,22 +485,25 @@ static int ensure_is_an_updatable_direct_reference(git_reference *ref)
return -1;
}
int git_reference_set_target(
int git_reference_set_target_if(
git_reference **out,
git_reference *ref,
const git_oid *id,
const git_signature *signature,
const char *log_message)
const char *log_message,
const git_oid *old_id)
{
int error;
git_repository *repo;
assert(out && ref && id);
repo = ref->db->repo;
if ((error = ensure_is_an_updatable_direct_reference(ref)) < 0)
return error;
return git_reference_create(
out, ref->db->repo, ref->name, id, 1, signature, log_message);
return git_reference_create_if(out, repo, ref->name, id, 1, signature, log_message, old_id);
}
static int ensure_is_an_updatable_symbolic_reference(git_reference *ref)
@ -498,6 +515,16 @@ static int ensure_is_an_updatable_symbolic_reference(git_reference *ref)
return -1;
}
int git_reference_set_target(
git_reference **out,
git_reference *ref,
const git_oid *id,
const git_signature *signature,
const char *log_message)
{
return git_reference_set_target_if(out, ref, id, signature, log_message, NULL);
}
int git_reference_symbolic_set_target(
git_reference **out,
git_reference *ref,