[PATCH v2 15/17] [GSOC] cat-file: re-implement --textconv, --filters options

["ZheNing Hu via GitGitGadget" <gitgitgadget@gmail.com>]

From: ZheNing Hu <adlternative@gmail.com>

After cat-file reuses the ref-filter logic, we re-implement the
functions of --textconv and --filters options.

Add members `cat_file_cmdmode` to struct `ref_array_item`,
so that struct `batch_option` member `cmdmode` will be passed
to ref-filter, and then ref-filter will take use of it to filter
the content of the object in get_object().

Use `actual_oi` to record the real expand_data: it may point to the
original `oi` or the `act_oi` processed by `textconv_object()` or
`convert_to_working_tree()`. `grab_values()` will grab the contents
of `actual_oi` and `grab_common_values()` to grab the contents of origin
`oi`, this ensures that `%(objectsize)` still uses the size of the
unfiltered data.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Hariom Verma <hariom18599@gmail.com>
Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
 builtin/cat-file.c |  2 +-
 ref-filter.c       | 35 +++++++++++++++++++++++++++++++++--
 ref-filter.h       |  1 +
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index dc604a9879d..3a6153e778f 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -217,7 +217,7 @@ static void batch_object_write(const char *obj_name,
 			       struct expand_data *data)
 {
 	int ret;
-	struct ref_array_item item = { data->oid, data->rest };
+	struct ref_array_item item = { data->oid, data->rest, opt->cmdmode };
 
 	strbuf_reset(scratch);
 	strbuf_reset(err);
diff --git a/ref-filter.c b/ref-filter.c
index b4f41fec871..91e26c9aba3 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1,3 +1,4 @@
+#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "builtin.h"
 #include "cache.h"
 #include "parse-options.h"
@@ -1755,6 +1756,9 @@ static int get_object(struct ref_array_item *ref, int deref, struct object **obj
 {
 	/* parse_object_buffer() will set eaten to 0 if free() will be needed */
 	int eaten = 1;
+	struct expand_data *actual_oi = oi;
+	struct expand_data act_oi = {0};
+
 	if (oi->info.contentp) {
 		/* We need to know that to use parse_object_buffer properly */
 		oi->info.sizep = &oi->size;
@@ -1768,19 +1772,45 @@ static int get_object(struct ref_array_item *ref, int deref, struct object **obj
 		BUG("Object size is less than zero.");
 
 	if (oi->info.contentp) {
-		*obj = parse_object_buffer(the_repository, &oi->oid, oi->type, oi->size, oi->content, &eaten);
+		if ((ref->cat_file_cmdmode == 'c' || ref->cat_file_cmdmode == 'w') && !ref->rest)
+			return strbuf_addf_ret(err, -1, _("missing path for '%s'"),
+					       oid_to_hex(&act_oi.oid));
+		if (oi->type == OBJ_BLOB) {
+			if (ref->cat_file_cmdmode == 'c') {
+				act_oi = *oi;
+				if (textconv_object(the_repository,
+						    ref->rest, 0100644, &act_oi.oid,
+						    1, (char **)(&act_oi.content), &act_oi.size))
+					actual_oi = &act_oi;
+			} else if (ref->cat_file_cmdmode == 'w') {
+				struct strbuf strbuf = STRBUF_INIT;
+				struct checkout_metadata meta;
+				act_oi = *oi;
+
+				init_checkout_metadata(&meta, NULL, NULL, &act_oi.oid);
+				if (!convert_to_working_tree(&the_index, ref->rest, act_oi.content, act_oi.size, &strbuf, &meta))
+					die("could not convert '%s' %s",
+					    oid_to_hex(&oi->oid), ref->rest);
+				act_oi.size = strbuf.len;
+				act_oi.content = strbuf_detach(&strbuf, NULL);
+				actual_oi = &act_oi;
+			}
+		}
+		*obj = parse_object_buffer(the_repository, &actual_oi->oid, actual_oi->type, actual_oi->size, actual_oi->content, &eaten);
 		if (!*obj) {
 			if (!eaten)
 				free(oi->content);
 			return strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"),
 					       oid_to_hex(&oi->oid), ref->refname);
 		}
-		grab_values(ref->value, deref, *obj, oi);
+		grab_values(ref->value, deref, *obj, actual_oi);
 	}
 
 	grab_common_values(ref->value, deref, oi);
 	if (!eaten)
 		free(oi->content);
+	if (actual_oi != oi)
+		free(actual_oi->content);
 	return 0;
 }
 
@@ -2189,6 +2219,7 @@ static struct ref_array_item *new_ref_array_item(const char *refname,
 	FLEX_ALLOC_STR(ref, refname, refname);
 	oidcpy(&ref->objectname, oid);
 	ref->rest = NULL;
+	ref->cat_file_cmdmode = 0;
 
 	return ref;
 }
diff --git a/ref-filter.h b/ref-filter.h
index 053980a6a42..a93d5e4dd61 100644
--- a/ref-filter.h
+++ b/ref-filter.h
@@ -39,6 +39,7 @@ struct ref_sorting {
 struct ref_array_item {
 	struct object_id objectname;
 	const char *rest;
+	int cat_file_cmdmode;
 	int flag;
 	unsigned int kind;
 	const char *symref;
-- 
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