[PATCH 06/22] make sure partially read index is not changed

[Thomas Gummerer <t.gummerer@gmail.com>]

A partially read index file currently cannot be written to disk.  Make
sure that never happens, by re-reading the index file if the index file
wasn't read completely before changing the in-memory index.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 builtin/update-index.c | 4 ++++
 cache.h                | 4 +++-
 read-cache-v2.c        | 3 +++
 read-cache.c           | 8 ++++++++
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index 5c7762e..03f6426 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -49,6 +49,8 @@ static int mark_ce_flags(const char *path, int flag, int mark)
 	int namelen = strlen(path);
 	int pos = cache_name_pos(path, namelen);
 	if (0 <= pos) {
+		if (active_cache_partially_read)
+			cache_change_filter_opts(NULL);
 		if (mark)
 			active_cache[pos]->ce_flags |= flag;
 		else
@@ -253,6 +255,8 @@ static void chmod_path(int flip, const char *path)
 	pos = cache_name_pos(path, strlen(path));
 	if (pos < 0)
 		goto fail;
+	if (active_cache_partially_read)
+		cache_change_filter_opts(NULL);
 	ce = active_cache[pos];
 	mode = ce->ce_mode;
 	if (!S_ISREG(mode))
diff --git a/cache.h b/cache.h
index d38dfbd..f6c3407 100644
--- a/cache.h
+++ b/cache.h
@@ -293,7 +293,8 @@ struct index_state {
 	struct cache_tree *cache_tree;
 	struct cache_time timestamp;
 	unsigned name_hash_initialized : 1,
-		 initialized : 1;
+		 initialized : 1,
+		 partially_read : 1;
 	struct hash_table name_hash;
 	struct hash_table dir_hash;
 	struct index_ops *ops;
@@ -315,6 +316,7 @@ extern void free_name_hash(struct index_state *istate);
 #define active_alloc (the_index.cache_alloc)
 #define active_cache_changed (the_index.cache_changed)
 #define active_cache_tree (the_index.cache_tree)
+#define active_cache_partially_read (the_index.partially_read)
 
 #define read_cache() read_index(&the_index)
 #define read_cache_from(path) read_index_from(&the_index, (path))
diff --git a/read-cache-v2.c b/read-cache-v2.c
index 1ed640d..2cc792d 100644
--- a/read-cache-v2.c
+++ b/read-cache-v2.c
@@ -273,6 +273,7 @@ static int read_index_v2(struct index_state *istate, void *mmap,
 		src_offset += 8;
 		src_offset += extsize;
 	}
+	istate->partially_read = 0;
 	return 0;
 unmap:
 	munmap(mmap, mmap_size);
@@ -495,6 +496,8 @@ static int write_index_v2(struct index_state *istate, int newfd)
 	struct stat st;
 	struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
 
+	if (istate->partially_read)
+		die("BUG: index: cannot write a partially read index");
 	for (i = removed = extended = 0; i < entries; i++) {
 		if (cache[i]->ce_flags & CE_REMOVE)
 			removed++;
diff --git a/read-cache.c b/read-cache.c
index b30ee75..4529fab 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -30,6 +30,8 @@ static void replace_index_entry(struct index_state *istate, int nr, struct cache
 {
 	struct cache_entry *old = istate->cache[nr];
 
+	if (istate->partially_read)
+		index_change_filter_opts(istate, NULL);
 	remove_name_hash(istate, old);
 	set_index_entry(istate, nr, ce);
 	istate->cache_changed = 1;
@@ -467,6 +469,8 @@ int remove_index_entry_at(struct index_state *istate, int pos)
 {
 	struct cache_entry *ce = istate->cache[pos];
 
+	if (istate->partially_read)
+		index_change_filter_opts(istate, NULL);
 	record_resolve_undo(istate, ce);
 	remove_name_hash(istate, ce);
 	istate->cache_changed = 1;
@@ -978,6 +982,8 @@ int add_index_entry(struct index_state *istate, struct cache_entry *ce, int opti
 {
 	int pos;
 
+	if (istate->partially_read)
+		index_change_filter_opts(istate, NULL);
 	if (option & ADD_CACHE_JUST_APPEND)
 		pos = istate->cache_nr;
 	else {
@@ -1184,6 +1190,8 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
 				/* If we are doing --really-refresh that
 				 * means the index is not valid anymore.
 				 */
+				if (istate->partially_read)
+					index_change_filter_opts(istate, NULL);
 				ce->ce_flags &= ~CE_VALID;
 				istate->cache_changed = 1;
 			}
-- 
1.8.3.453.g1dfc63d