gvfs: ensure all filters and EOL conversions are blocked

Ensure all filters and EOL conversions are blocked when running under
GVFS so that our projected file sizes will match the actual file size
when it is hydrated on the local machine.

Signed-off-by: Ben Peart <Ben.Peart@microsoft.com>

Documentation/config/core.txt

@@ -634,6 +634,15 @@ core.gvfs::
 		since these will be downloaded on demand.  This flag will skip the
 		checks on the reachability of objects during a fetch as well as
 		the upload pack so that extraneous objects don't get downloaded.
+	GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS::
+		Bit value 64
+		With a virtual file system we only know the file size before any
+		CRLF or smudge/clean filters processing is done on the client.
+		To prevent file corruption due to truncation or expansion with
+		garbage at the end, these filters must not run when the file
+		is first accessed and brought down to the client. Git.exe can't
+		currently tell the first access vs subsequent accesses so this
+		flag just blocks them from occurring at all.
 --
 
 core.sparseCheckout::

convert.c

@@ -8,6 +8,7 @@
 #include "pkt-line.h"
 #include "sub-process.h"
 #include "utf8.h"
+#include "gvfs.h"
 
 /*
  * convert.c - convert a file when checking it out and checking it in.
@@ -564,6 +565,9 @@ static int crlf_to_git(const struct index_state *istate,
 	if (!buf)
 		return 1;
 
+	if (gvfs_config_is_set(GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS))
+		die("CRLF conversions not supported when running under GVFS");
+
 	/* only grow if not in place */
 	if (strbuf_avail(buf) + buf->len < len)
 		strbuf_grow(buf, len - buf->len);
@@ -603,6 +607,9 @@ static int crlf_to_worktree(const char *src, size_t len,
 	if (!will_convert_lf_to_crlf(&stats, crlf_action))
 		return 0;
 
+	if (gvfs_config_is_set(GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS))
+		die("CRLF conversions not supported when running under GVFS");
+
 	/* are we "faking" in place editing ? */
 	if (src == buf->buf)
 		to_free = strbuf_detach(buf, NULL);
@@ -717,6 +724,9 @@ static int apply_single_file_filter(const char *path, const char *src, size_t le
 	struct async async;
 	struct filter_params params;
 
+	if (gvfs_config_is_set(GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS))
+		die("Filter \"%s\" not supported when running under GVFS", cmd);
+
 	memset(&async, 0, sizeof(async));
 	async.proc = filter_buffer_or_fd;
 	async.data = &params;
@@ -1101,6 +1111,9 @@ static int ident_to_git(const char *src, size_t len,
 	if (!buf)
 		return 1;
 
+	if (gvfs_config_is_set(GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS))
+		die("ident conversions not supported when running under GVFS");
+
 	/* only grow if not in place */
 	if (strbuf_avail(buf) + buf->len < len)
 		strbuf_grow(buf, len - buf->len);
@@ -1148,6 +1161,9 @@ static int ident_to_worktree(const char *src, size_t len,
 	if (!cnt)
 		return 0;
 
+	if (gvfs_config_is_set(GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS))
+		die("ident conversions not supported when running under GVFS");
+
 	/* are we "faking" in place editing ? */
 	if (src == buf->buf)
 		to_free = strbuf_detach(buf, NULL);

gvfs.h

@@ -17,6 +17,7 @@
 #define GVFS_MISSING_OK                             (1 << 2)
 #define GVFS_NO_DELETE_OUTSIDE_SPARSECHECKOUT       (1 << 3)
 #define GVFS_FETCH_SKIP_REACHABILITY_AND_UPLOADPACK (1 << 4)
+#define GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS      (1 << 6)
 
 static inline int gvfs_config_is_set(int mask) {
 	return (core_gvfs & mask) == mask;

t/t0021-conversion.sh

@@ -314,6 +314,44 @@ test_expect_success "filter: smudge empty file" '
 	test_cmp expected filtered-empty-in-repo
 '
 
+test_expect_success "filter: clean filters blocked when under GVFS" '
+	test_config filter.empty-in-repo.clean "cat >/dev/null" &&
+	test_config filter.empty-in-repo.smudge "echo smudged && cat" &&
+	test_config core.gvfs 64 &&
+
+	echo dead data walking >empty-in-repo &&
+	test_must_fail git add empty-in-repo
+'
+
+test_expect_success "filter: smudge filters blocked when under GVFS" '
+	test_config filter.empty-in-repo.clean "cat >/dev/null" &&
+	test_config filter.empty-in-repo.smudge "echo smudged && cat" &&
+	test_config core.gvfs 64 &&
+
+	test_must_fail git checkout
+'
+
+test_expect_success "ident blocked on add when under GVFS" '
+	test_config core.gvfs 64 &&
+	test_config core.autocrlf false &&
+
+	echo "*.i ident" >.gitattributes &&
+	echo "\$Id\$" > ident.i &&
+
+	test_must_fail git add ident.i
+'
+
+test_expect_success "ident blocked when under GVFS" '
+	git add ident.i &&
+
+	git commit -m "added ident.i" &&
+	test_config core.gvfs 64 &&
+	rm ident.i &&
+	git checkout -- ident.i &&
+
+	test_must_fail git status
+'
+
 test_expect_success 'disable filter with empty override' '
 	test_config_global filter.disable.smudge false &&
 	test_config_global filter.disable.clean false &&

t/t0027-auto-crlf.sh

@@ -331,6 +331,18 @@ checkout_files () {
 	"
 }
 
+test_expect_success 'crlf conversions blocked when under GVFS' '
+	git checkout -b gvfs &&
+	test_commit initial &&
+	rm initial.t &&
+	test_config core.gvfs 64 &&
+	test_config core.autocrlf true &&
+	test_must_fail git read-tree --reset -u HEAD &&
+
+	git config core.autocrlf false &&
+	git read-tree --reset -u HEAD
+'
+
 # Test control characters
 # NUL SOH CR EOF==^Z
 test_expect_success 'ls-files --eol -o Text/Binary' '