Commit b6735461d9148a91cfaf4633403843aa88db9001
2021-09-14T07:46:49
Merge pull request #6039 from lhchavez/avoid-mmap-in-git-indexer-append indexer: Avoid one `mmap(2)`/`munmap(2)` pair per `git_indexer_append` call
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diff --git a/src/indexer.c b/src/indexer.c
index d546888..ce77375 100644
--- a/src/indexer.c
+++ b/src/indexer.c
@@ -601,9 +601,10 @@ static void hash_partially(git_indexer *idx, const uint8_t *data, size_t size)
idx->inbuf_len += size - to_expell;
}
+#if defined(NO_MMAP) || !defined(GIT_WIN32)
+
static int write_at(git_indexer *idx, const void *data, off64_t offset, size_t size)
{
-#ifdef NO_MMAP
size_t remaining_size = size;
const char *ptr = (const char *)data;
@@ -619,7 +620,31 @@ static int write_at(git_indexer *idx, const void *data, off64_t offset, size_t s
offset += nb;
remaining_size -= nb;
}
+
+ return 0;
+}
+
+static int append_to_pack(git_indexer *idx, const void *data, size_t size)
+{
+ if (write_at(idx, data, idx->pack->mwf.size, size) < 0) {
+ git_error_set(GIT_ERROR_OS, "cannot extend packfile '%s'", idx->pack->pack_name);
+ return -1;
+ }
+
+ return 0;
+}
+
#else
+
+/*
+ * Windows may keep different views to a networked file for the mmap- and
+ * open-accessed versions of a file, so any writes done through
+ * `write(2)`/`pwrite(2)` may not be reflected on the data that `mmap(2)` is
+ * able to read.
+ */
+
+static int write_at(git_indexer *idx, const void *data, off64_t offset, size_t size)
+{
git_file fd = idx->pack->mwf.fd;
size_t mmap_alignment;
size_t page_offset;
@@ -644,7 +669,6 @@ static int write_at(git_indexer *idx, const void *data, off64_t offset, size_t s
map_data = (unsigned char *)map.data;
memcpy(map_data + page_offset, data, size);
p_munmap(&map);
-#endif
return 0;
}
@@ -680,6 +704,8 @@ static int append_to_pack(git_indexer *idx, const void *data, size_t size)
return write_at(idx, data, idx->pack->mwf.size, size);
}
+#endif
+
static int read_stream_object(git_indexer *idx, git_indexer_progress *stats)
{
git_packfile_stream *stream = &idx->stream;
@@ -1279,11 +1305,19 @@ int git_indexer_commit(git_indexer *idx, git_indexer_progress *stats)
if (git_mwindow_free_all(&idx->pack->mwf) < 0)
goto on_error;
- /* Truncate file to undo rounding up to next page_size in append_to_pack */
+#if !defined(NO_MMAP) && defined(GIT_WIN32)
+ /*
+ * Some non-Windows remote filesystems fail when truncating files if the
+ * file permissions change after opening the file (done by p_mkstemp).
+ *
+ * Truncation is only needed when mmap is used to undo rounding up to next
+ * page_size in append_to_pack.
+ */
if (p_ftruncate(idx->pack->mwf.fd, idx->pack->mwf.size) < 0) {
git_error_set(GIT_ERROR_OS, "failed to truncate pack file '%s'", idx->pack->pack_name);
return -1;
}
+#endif
if (idx->do_fsync && p_fsync(idx->pack->mwf.fd) < 0) {
git_error_set(GIT_ERROR_OS, "failed to fsync packfile");