[PATCH v2 0/1] git-clone: fix relative path problem in the alternates

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Revision v2 of 2 in this series.

2 messages, 1 author, 2016-06-15 · open the first message on its own page

[PATCH v2 0/1] git-clone: fix relative path problem in the alternates

From: Hui Wang <hidden>
Date: 2016-06-15 22:51:51

Hi Junio,

In the V2 version, i use strbuf_xxxx() to help to parse alternates file
and change relative paths to absolute paths according to your suggestion,
now the strbuf operations are safer.

When updating new content to the lockfile, i choose to write whole content at
one time instead of update it line by line. The reason is:

1. we will conditionally update the lockfile, if original alternates doesn't
include relative path, we don't need to update the lockfile. This logic can't
easily be handled line by line.
2. current git system only provides add_to_alternates_file()in the sha1_file.c
to update lockfile, this function can add a line to lockfile but can't empty
and write lockfile, we need to add a similar function to empty and write to
lockfile, and we must guarantee the first line update will call this function,
then remaining update line call add_to_alternates_file(), this logic is a
little complicated comparing to update whole content at one time.
3. current existing add_to_alternates_file() will unconditionally append
"/objects" at each new added line, that need us to parse and  remove
"/objects" from each line read out from source alternates, this is a little
bit complicated.

If we choose update lockfile at one time, we can add a new function to
implement this requirement and overcome all above complexity.


Hui Wang (1):
      clone: replace relative paths in the alternates

 builtin/clone.c |   47 ++++++++++++++++++++++++++++++++++++++++++++++-
 cache.h         |    1 +
 sha1_file.c     |   11 +++++++++++

[PATCH v2 1/1] clone: replace relative paths in the alternates

From: Hui Wang <hidden>
Date: 2016-06-15 22:51:51

When we clone a local source repository to a new local destination
repository without "--shared" option, if source repository has
relative path in the alternates, the clone will fail.

The root cause is when cloning local source repository to local
destination repository, the alternates of the source repository
will be copied to the destination repository, the relative path in
the alternates is source repository to base repository rather than
destination repository to base repository, so the destination
repository get a wrong relative path in the alternates, this will
cause errors when refer to base repository in the destination
repository.

To fix it, adding a function update_alt_rel_path() to replace all
relative paths to absolute paths in the alternates of the destination
repository before destination repository use those paths to look for
the base repository.

Signed-off-by: Hui Wang <redacted>
---
 builtin/clone.c |   47 ++++++++++++++++++++++++++++++++++++++++++++++-
 cache.h         |    1 +
 sha1_file.c     |   11 +++++++++++
 3 files changed, 58 insertions(+), 1 deletions(-)
diff --git a/builtin/clone.c b/builtin/clone.c
index 7663bc2..7b5e603 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -286,6 +286,50 @@ static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest)
 	closedir(dir);
 }
 
+/*
+ * This function is called by clone_local() of clone.c
+ * If alternates in the src_repo (source repository) has relative path,
+ * call this function will replace the relative path to absolute path
+ * in the des_repo (destination repository) alternates.
+ */
+static void update_alt_rel_path(const char *src_repo)
+{
+	int need_update = 0;
+	FILE *ifp;
+	struct strbuf istr = STRBUF_INIT;
+	struct strbuf ostr = STRBUF_INIT;
+
+	ifp = fopen(git_path("objects/info/alternates"), "r");
+	if (!ifp)
+		return;
+
+	while (strbuf_getline(&istr, ifp, '\n') != EOF) {
+		/* comment line, empty line or absolute path line */
+		if (istr.buf[0] == '#' || istr.len == 0 || is_absolute_path(istr.buf)) {
+			strbuf_add(&ostr, istr.buf, istr.len);
+			strbuf_add(&ostr, "\n", 1);
+		} else {
+			char *abs_path, abs_buf[PATH_MAX];
+			int len;
+
+			abs_path = mkpath("%s/objects/%s", src_repo, istr.buf);
+			normalize_path_copy(abs_buf, abs_path);
+			len = strlen(abs_buf);
+			strbuf_add(&ostr, abs_buf, len);
+			strbuf_add(&ostr, "\n", 1);
+			need_update = 1;
+		}
+	}
+
+	fclose(ifp);
+
+	if (need_update)
+		update_alternates_file_content(ostr.buf);
+
+	strbuf_release(&istr);
+	strbuf_release(&ostr);
+}
+
 static const struct ref *clone_local(const char *src_repo,
 				     const char *dest_repo)
 {
@@ -303,8 +347,9 @@ static const struct ref *clone_local(const char *src_repo,
 		copy_or_link_directory(&src, &dest);
 		strbuf_release(&src);
 		strbuf_release(&dest);
-	}
 
+		update_alt_rel_path(src_repo);
+	}
 	remote = remote_get(src_repo);
 	transport = transport_get(remote, src_repo);
 	ret = transport_get_remote_refs(transport);
diff --git a/cache.h b/cache.h
index fcf4501..d81c0f0 100644
--- a/cache.h
+++ b/cache.h
@@ -913,6 +913,7 @@ extern struct alternate_object_database {
 } *alt_odb_list;
 extern void prepare_alt_odb(void);
 extern void add_to_alternates_file(const char *reference);
+extern void update_alternates_file_content(const char *content);
 typedef int alt_odb_fn(struct alternate_object_database *, void *);
 extern void foreach_alt_odb(alt_odb_fn, void*);
 
diff --git a/sha1_file.c b/sha1_file.c
index d5616dc..dae7bf6 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -388,6 +388,17 @@ void add_to_alternates_file(const char *reference)
 		link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
 }
 
+void update_alternates_file_content(const char *content)
+{
+	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
+	int fd = hold_lock_file_for_update(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
+	write_or_die(fd, content, strlen(content));
+	if (commit_lock_file(lock))
+		die("could not close alternates file");
+	if (alt_odb_tail)
+		link_alt_odb_entries(content, content + strlen(content), '\n', NULL, 0);
+}
+
 void foreach_alt_odb(alt_odb_fn fn, void *cb)
 {
 	struct alternate_object_database *ent;
-- 
1.7.6
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