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author | Michael Haggerty <mhagger@alum.mit.edu> | 2015-05-11 17:25:04 +0200 |
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committer | Junio C Hamano <gitster@pobox.com> | 2015-05-11 11:50:17 -0700 |
commit | 49e818762aaf08791504d4de2076027e7d275844 (patch) | |
tree | 21c98c5470dc52b426969749343377d2901f0079 /refs.c | |
parent | 433efcad9d3c0c0b30f01b3de2cfa51a854befb3 (diff) | |
download | git-49e818762aaf08791504d4de2076027e7d275844.tar.gz git-49e818762aaf08791504d4de2076027e7d275844.tar.xz |
is_refname_available(): revamp the comments
Change the comments to a running example of running the function with
refname set to "refs/foo/bar". Add some more explanation of the logic.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Diffstat (limited to 'refs.c')
-rw-r--r-- | refs.c | 69 |
1 files changed, 47 insertions, 22 deletions
@@ -876,9 +876,9 @@ static void report_refname_conflict(struct ref_entry *entry, * operation). * * Two reference names conflict if one of them exactly matches the - * leading components of the other; e.g., "foo/bar" conflicts with - * both "foo" and with "foo/bar/baz" but not with "foo/bar" or - * "foo/barbados". + * leading components of the other; e.g., "refs/foo/bar" conflicts + * with both "refs/foo" and with "refs/foo/bar/baz" but not with + * "refs/foo/bar" or "refs/foo/barbados". * * skip must be sorted. */ @@ -891,19 +891,39 @@ static int is_refname_available(const char *refname, int pos; char *dirname; + /* + * For the sake of comments in this function, suppose that + * refname is "refs/foo/bar". + */ + for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) { /* - * We are still at a leading dir of the refname; we are - * looking for a conflict with a leaf entry. - * - * If we find one, we still must make sure it is - * not in "skip". + * We are still at a leading dir of the refname (e.g., + * "refs/foo"; if there is a reference with that name, + * it is a conflict, *unless* it is in skip. */ pos = search_ref_dir(dir, refname, slash - refname); if (pos >= 0) { + /* + * We found a reference whose name is a proper + * prefix of refname; e.g., "refs/foo". + */ struct ref_entry *entry = dir->entries[pos]; - if (entry_matches(entry, skip)) + if (entry_matches(entry, skip)) { + /* + * The reference we just found, e.g., + * "refs/foo", is also in skip, so it + * is not considered a conflict. + * Moreover, the fact that "refs/foo" + * exists means that there cannot be + * any references anywhere under the + * "refs/foo/" namespace (because they + * would have conflicted with + * "refs/foo"). So we can stop looking + * now and return true. + */ return 1; + } report_refname_conflict(entry, refname); return 0; } @@ -911,19 +931,29 @@ static int is_refname_available(const char *refname, /* * Otherwise, we can try to continue our search with - * the next component; if we come up empty, we know - * there is nothing under this whole prefix. + * the next component. So try to look up the + * directory, e.g., "refs/foo/". */ pos = search_ref_dir(dir, refname, slash + 1 - refname); - if (pos < 0) + if (pos < 0) { + /* + * There was no directory "refs/foo/", so + * there is nothing under this whole prefix, + * and we are OK. + */ return 1; + } dir = get_ref_dir(dir->entries[pos]); } /* - * We are at the leaf of our refname; we want to - * make sure there are no directories which match it. + * We are at the leaf of our refname (e.g., "refs/foo/bar"). + * There is no point in searching for a reference with that + * name, because a refname isn't considered to conflict with + * itself. But we still need to check for references whose + * names are in the "refs/foo/bar/" namespace, because they + * *do* conflict. */ len = strlen(refname); dirname = xmallocz(len + 1); @@ -933,9 +963,9 @@ static int is_refname_available(const char *refname, if (pos >= 0) { /* - * We found a directory named "refname". It is a - * problem iff it contains any ref that is not - * in "skip". + * We found a directory named "$refname/" (e.g., + * "refs/foo/bar/"). It is a problem iff it contains + * any ref that is not in "skip". */ struct ref_entry *entry = dir->entries[pos]; struct ref_dir *dir = get_ref_dir(entry); @@ -950,11 +980,6 @@ static int is_refname_available(const char *refname, return 0; } - /* - * There is no point in searching for another leaf - * node which matches it; such an entry would be the - * ref we are looking for, not a conflict. - */ return 1; } |