On Mon, Feb 26, 2024 at 09:39:25PM +0000, Jeff Hostetler via GitGitGadget wrote:
> From: Jeff Hostetler <jeffhostetler@xxxxxxxxxx>
>
> Teach fsmonitor_refresh_callback() to handle case-insensitive
> lookups if case-sensitive lookups fail on case-insensitive systems.
> This can cause 'git status' to report stale status for files if there
> are case issues/errors in the worktree.
>
> The FSMonitor daemon sends FSEvents using the observed spelling
> of each pathname. On case-insensitive file systems this may be
> different than the expected case spelling.
>
> The existing code uses index_name_pos() to find the cache-entry for
> the pathname in the FSEvent and clear the CE_FSMONITOR_VALID bit so
> that the worktree scan/index refresh will revisit and revalidate the
> path.
>
> On a case-insensitive file system, the exact match lookup may fail
> to find the associated cache-entry. This causes status to think that
> the cached CE flags are correct and skip over the file.
>
> Update event handling to optionally use the name-hash and dir-name-hash
> if necessary.
>
> Also update t7527 to convert the "test_expect_failure" to "_success"
> now that we have fixed the bug.
>
> Signed-off-by: Jeff Hostetler <jeffhostetler@xxxxxxxxxx>
> ---
> fsmonitor.c | 121 +++++++++++++++++++++++++++++++++++
> t/t7527-builtin-fsmonitor.sh | 26 +++++---
> 2 files changed, 137 insertions(+), 10 deletions(-)
>
> diff --git a/fsmonitor.c b/fsmonitor.c
> index 3c87449be87..2b17d60bbbe 100644
> --- a/fsmonitor.c
> +++ b/fsmonitor.c
> @@ -5,6 +5,7 @@
> #include "ewah/ewok.h"
> #include "fsmonitor.h"
> #include "fsmonitor-ipc.h"
> +#include "name-hash.h"
> #include "run-command.h"
> #include "strbuf.h"
> #include "trace2.h"
> @@ -202,6 +203,113 @@ static void invalidate_ce_fsm(struct cache_entry *ce)
> static size_t handle_path_with_trailing_slash(
> struct index_state *istate, const char *name, int pos);
>
> +/*
> + * Use the name-hash to do a case-insensitive cache-entry lookup with
> + * the pathname and invalidate the cache-entry.
> + *
> + * Returns the number of cache-entries that we invalidated.
> + */
> +static size_t handle_using_name_hash_icase(
> + struct index_state *istate, const char *name)
> +{
> + struct cache_entry *ce = NULL;
> +
> + ce = index_file_exists(istate, name, strlen(name), 1);
> + if (!ce)
> + return 0;
> +
> + /*
> + * A case-insensitive search in the name-hash using the
> + * observed pathname found a cache-entry, so the observed path
> + * is case-incorrect. Invalidate the cache-entry and use the
> + * correct spelling from the cache-entry to invalidate the
> + * untracked-cache. Since we now have sparse-directories in
> + * the index, the observed pathname may represent a regular
> + * file or a sparse-index directory.
> + *
> + * Note that we should not have seen FSEvents for a
> + * sparse-index directory, but we handle it just in case.
> + *
> + * Either way, we know that there are not any cache-entries for
> + * children inside the cone of the directory, so we don't need to
> + * do the usual scan.
> + */
> + trace_printf_key(&trace_fsmonitor,
> + "fsmonitor_refresh_callback MAP: '%s' '%s'",
> + name, ce->name);
> +
> + /*
> + * NEEDSWORK: We used the name-hash to find the correct
> + * case-spelling of the pathname in the cache-entry[], so
> + * technically this is a tracked file or a sparse-directory.
> + * It should not have any entries in the untracked-cache, so
> + * we should not need to use the case-corrected spelling to
> + * invalidate the the untracked-cache. So we may not need to
> + * do this. For now, I'm going to be conservative and always
> + * do it; we can revisit this later.
> + */
> + untracked_cache_invalidate_trimmed_path(istate, ce->name, 0);
> +
> + invalidate_ce_fsm(ce);
> + return 1;
> +}
> +
> +/*
> + * Use the dir-name-hash to find the correct-case spelling of the
> + * directory. Use the canonical spelling to invalidate all of the
> + * cache-entries within the matching cone.
> + *
> + * Returns the number of cache-entries that we invalidated.
> + */
> +static size_t handle_using_dir_name_hash_icase(
> + struct index_state *istate, const char *name)
> +{
> + struct strbuf canonical_path = STRBUF_INIT;
> + int pos;
> + size_t len = strlen(name);
> + size_t nr_in_cone;
> +
> + if (name[len - 1] == '/')
> + len--;
Nit: this could use `strip_suffix()`.
> +
> + if (!index_dir_find(istate, name, len, &canonical_path))
> + return 0; /* name is untracked */
> +
> + if (!memcmp(name, canonical_path.buf, canonical_path.len)) {
> + strbuf_release(&canonical_path);
> + /*
> + * NEEDSWORK: Our caller already tried an exact match
> + * and failed to find one. They called us to do an
> + * ICASE match, so we should never get an exact match,
> + * so we could promote this to a BUG() here if we
> + * wanted to. It doesn't hurt anything to just return
Nit: this comment is stale as this has been promoted to a BUG already.
Patrick
> + * 0 and go on because we should never get here. Or we
> + * could just get rid of the memcmp() and this "if"
> + * clause completely.
> + */
> + BUG("handle_using_dir_name_hash_icase(%s) did not exact match",
> + name);
> + }
> +
> + trace_printf_key(&trace_fsmonitor,
> + "fsmonitor_refresh_callback MAP: '%s' '%s'",
> + name, canonical_path.buf);
> +
> + /*
> + * The dir-name-hash only tells us the corrected spelling of
> + * the prefix. We have to use this canonical path to do a
> + * lookup in the cache-entry array so that we repeat the
> + * original search using the case-corrected spelling.
> + */
> + strbuf_addch(&canonical_path, '/');
> + pos = index_name_pos(istate, canonical_path.buf,
> + canonical_path.len);
> + nr_in_cone = handle_path_with_trailing_slash(
> + istate, canonical_path.buf, pos);
> + strbuf_release(&canonical_path);
> + return nr_in_cone;
> +}
> +
> /*
> * The daemon sent an observed pathname without a trailing slash.
> * (This is the normal case.) We do not know if it is a tracked or
> @@ -335,6 +443,19 @@ static void fsmonitor_refresh_callback(struct index_state *istate, char *name)
> else
> nr_in_cone = handle_path_without_trailing_slash(istate, name, pos);
>
> + /*
> + * If we did not find an exact match for this pathname or any
> + * cache-entries with this directory prefix and we're on a
> + * case-insensitive file system, try again using the name-hash
> + * and dir-name-hash.
> + */
> + if (!nr_in_cone && ignore_case) {
> + nr_in_cone = handle_using_name_hash_icase(istate, name);
> + if (!nr_in_cone)
> + nr_in_cone = handle_using_dir_name_hash_icase(
> + istate, name);
> + }
> +
> if (nr_in_cone)
> trace_printf_key(&trace_fsmonitor,
> "fsmonitor_refresh_callback CNT: %d",
> diff --git a/t/t7527-builtin-fsmonitor.sh b/t/t7527-builtin-fsmonitor.sh
> index 830f2d9de33..730f3c7f810 100755
> --- a/t/t7527-builtin-fsmonitor.sh
> +++ b/t/t7527-builtin-fsmonitor.sh
> @@ -1051,7 +1051,7 @@ test_expect_success 'split-index and FSMonitor work well together' '
> #
> # The setup is a little contrived.
> #
> -test_expect_failure CASE_INSENSITIVE_FS 'fsmonitor subdir case wrong on disk' '
> +test_expect_success CASE_INSENSITIVE_FS 'fsmonitor subdir case wrong on disk' '
> test_when_finished "stop_daemon_delete_repo subdir_case_wrong" &&
>
> git init subdir_case_wrong &&
> @@ -1116,19 +1116,19 @@ test_expect_failure CASE_INSENSITIVE_FS 'fsmonitor subdir case wrong on disk' '
>
> grep -q "dir1/DIR2/dir3/file3.*pos -3" "$PWD/subdir_case_wrong.log1" &&
>
> + # Verify that we get a mapping event to correct the case.
> + grep -q "MAP:.*dir1/DIR2/dir3/file3.*dir1/dir2/dir3/file3" \
> + "$PWD/subdir_case_wrong.log1" &&
> +
> # The refresh-callbacks should have caused "git status" to clear
> # the CE_FSMONITOR_VALID bit on each of those files and caused
> # the worktree scan to visit them and mark them as modified.
> grep -q " M AAA" "$PWD/subdir_case_wrong.out" &&
> grep -q " M zzz" "$PWD/subdir_case_wrong.out" &&
> -
> - # Expect Breakage: with the case confusion, the "(pos -3)" causes
> - # the client to not clear the CE_FSMONITOR_VALID bit and therefore
> - # status will not rescan the file and therefore not report it as dirty.
> grep -q " M dir1/dir2/dir3/file3" "$PWD/subdir_case_wrong.out"
> '
>
> -test_expect_failure CASE_INSENSITIVE_FS 'fsmonitor file case wrong on disk' '
> +test_expect_success CASE_INSENSITIVE_FS 'fsmonitor file case wrong on disk' '
> test_when_finished "stop_daemon_delete_repo file_case_wrong" &&
>
> git init file_case_wrong &&
> @@ -1242,14 +1242,20 @@ test_expect_failure CASE_INSENSITIVE_FS 'fsmonitor file case wrong on disk' '
> GIT_TRACE_FSMONITOR="$PWD/file_case_wrong-try3.log" \
> git -C file_case_wrong --no-optional-locks status --short \
> >"$PWD/file_case_wrong-try3.out" &&
> +
> + # Verify that we get a mapping event to correct the case.
> + grep -q "fsmonitor_refresh_callback MAP:.*dir1/dir2/dir3/FILE-3-A.*dir1/dir2/dir3/file-3-a" \
> + "$PWD/file_case_wrong-try3.log" &&
> + grep -q "fsmonitor_refresh_callback MAP:.*dir1/dir2/dir4/file-4-a.*dir1/dir2/dir4/FILE-4-A" \
> + "$PWD/file_case_wrong-try3.log" &&
> +
> # FSEvents are in observed case.
> grep -q "fsmonitor_refresh_callback.*FILE-3-A.*pos -3" "$PWD/file_case_wrong-try3.log" &&
> grep -q "fsmonitor_refresh_callback.*file-4-a.*pos -9" "$PWD/file_case_wrong-try3.log" &&
>
> - # Expect Breakage: with the case confusion, the "(pos-3)" and
> - # "(pos -9)" causes the client to not clear the CE_FSMONITOR_VALID
> - # bit and therefore status will not rescan the files and therefore
> - # not report them as dirty.
> + # The refresh-callbacks should have caused "git status" to clear
> + # the CE_FSMONITOR_VALID bit on each of those files and caused
> + # the worktree scan to visit them and mark them as modified.
> grep -q " M dir1/dir2/dir3/file-3-a" "$PWD/file_case_wrong-try3.out" &&
> grep -q " M dir1/dir2/dir4/FILE-4-A" "$PWD/file_case_wrong-try3.out"
> '
> --
> gitgitgadget
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