@matheusbsbs / matheus-bagliano / commits / cae70acf24

fsmonitor: de-duplicate BUG()s around dirty bits

The index has an fsmonitor_dirty bitmap that records which index entries are "dirty" based on the response from the FSMonitor. If this bitmap ever grows larger than the index, then there was an error in how it was constructed, and it was probably a developer's bug. There are several BUG() statements that are very similar, so replace these uses with a simpler assert_index_minimum(). Since there is one caller that uses a custom 'pos' value instead of the bit_size member, we cannot simplify it too much. However, the error string is identical in each, so this simplifies things. Be sure to add one when checking if a position if valid, since the minimum is a bound on the expected size. The end result is that the code is simpler to read while also preserving these assertions for developers in the FSMonitor space. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed Jan 23, 2021 at 19:58 UTC cae70acf2431f0c31e5c097b96fa5bd752526e6d
1 file changed +13 -14
fsmonitor.c
+13 -14
@@ -13,14 +13,19 @@
13
14 struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
15
16 +static void assert_index_minimum(struct index_state *istate, size_t pos)
17 +{
18 + if (pos > istate->cache_nr)
19 + BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
20 + (uintmax_t)pos, istate->cache_nr);
21 +}
22 +
23 static void fsmonitor_ewah_callback(size_t pos, void *is)
24 {
25 struct index_state *istate = (struct index_state *)is;
26 struct cache_entry *ce;
27
21 - if (pos >= istate->cache_nr)
22 - BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" >= %u)",
23 - (uintmax_t)pos, istate->cache_nr);
28 + assert_index_minimum(istate, pos + 1);
29
30 ce = istate->cache[pos];
31 ce->ce_flags &= ~CE_FSMONITOR_VALID;
@@ -82,10 +87,8 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data,
87 }
88 istate->fsmonitor_dirty = fsmonitor_dirty;
89
85 - if (!istate->split_index &&
86 - istate->fsmonitor_dirty->bit_size > istate->cache_nr)
87 - BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
88 - (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
90 + if (!istate->split_index)
91 + assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
92
93 trace_printf_key(&trace_fsmonitor, "read fsmonitor extension successful");
94 return 0;
@@ -110,10 +113,8 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
113 uint32_t ewah_size = 0;
114 int fixup = 0;
115
113 - if (!istate->split_index &&
114 - istate->fsmonitor_dirty->bit_size > istate->cache_nr)
115 - BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
116 - (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
116 + if (!istate->split_index)
117 + assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
118
119 put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
120 strbuf_add(sb, &hdr_version, sizeof(uint32_t));
@@ -335,9 +336,7 @@ void tweak_fsmonitor(struct index_state *istate)
336 }
337
338 /* Mark all previously saved entries as dirty */
338 - if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
339 - BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
340 - (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
339 + assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
340 ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
341
342 refresh_fsmonitor(istate);