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[PATCH v3 3/4] cat-file --textconv/--filters: allow specifying the path separately

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Sep 9, 2016, 10:10 UTC
Message-ID
<9e01395c0732b47b382d2363a2ef6f4bf361666e.1473415827.git.johannes.schindelin@gmx.de>
In-Reply-To
<cover.1473415827.git.johannes.schindelin@gmx.de>

There are circumstances when it is relatively easy to figure out the object name for a given path, but not the name of the containing tree. For example, when looking at a diff generated by Git, the object names are recorded, but not the revision. As a matter of fact, the revisions from which the diff was generated may not even exist locally.

In such a case, the user would have to generate a fake revision just to be able to use --textconv or --filters.

Let's simplify this dramatically, because we do not really need that revision at all: all we care about is that we know the path. In the scenario described above, we do know the path, and we just want to specify it separately from the object name.

Example usage:
	git cat-file --textconv --path=main.c 0f1937fd
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Documentation/git-cat-file.txt |  7 ++++++-
 builtin/cat-file.c             | 26 +++++++++++++++++++++-----
 t/t8010-cat-file-filters.sh    | 20 ++++++++++++++++++++
 3 files changed, 47 insertions(+), 6 deletions(-)
diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 537d02c..4fa9041 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -9,7 +9,7 @@ git-cat-file - Provide content or type and size information for repository objec
 SYNOPSIS
 --------
 [verse]
-'git cat-file' (-t [--allow-unknown-type]| -s [--allow-unknown-type]| -e | -p | <type> | --textconv | --filters ) <object>
+'git cat-file' (-t [--allow-unknown-type]| -s [--allow-unknown-type]| -e | -p | <type> | --textconv | --filters ) [--path=<path>] <object>
 'git cat-file' (--batch | --batch-check) [--follow-symlinks]
 
 DESCRIPTION
@@ -64,6 +64,11 @@ OPTIONS
 	end-of-line conversion, etc). In this case, <object> has to be of
 	the form <tree-ish>:<path>, or :<path>.
 
+--path=<path>::
+	For use with --textconv or --filters, to allow specifying an object
+	name and a path separately, e.g. when it is difficult to figure out
+	the revision from which the blob came.
+
 --batch::
 --batch=<format>::
 	Print object information and contents for each object provided
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 0b74afa..b648056 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -20,6 +20,8 @@ struct batch_options {
 	const char *format;
 };
 
+static const char *force_path;
+
 static int filter_object(const char *path, unsigned mode,
 			 const unsigned char *sha1,
 			 char **buf, unsigned long *size)
@@ -58,6 +60,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	struct object_info oi = {NULL};
 	struct strbuf sb = STRBUF_INIT;
 	unsigned flags = LOOKUP_REPLACE_OBJECT;
+	const char *path = force_path;
 
 	if (unknown_type)
 		flags |= LOOKUP_UNKNOWN_OBJECT;
@@ -65,6 +68,11 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	if (get_sha1_with_context(obj_name, 0, sha1, &obj_context))
 		die("Not a valid object name %s", obj_name);
 
+	if (!path)
+		path = obj_context.path;
+	if (obj_context.mode == S_IFINVALID)
+		obj_context.mode = 0100644;
+
 	buf = NULL;
 	switch (opt) {
 	case 't':
@@ -89,21 +97,22 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		return !has_sha1_file(sha1);
 
 	case 'w':
-		if (!obj_context.path[0])
+		if (!path[0])
 			die("git cat-file --filters %s: <object> must be "
 			    "<sha1:path>", obj_name);
 
-		if (filter_object(obj_context.path, obj_context.mode,
+		if (filter_object(path, obj_context.mode,
 				  sha1, &buf, &size))
 			return -1;
 		break;
 
 	case 'c':
-		if (!obj_context.path[0])
+		if (!path[0])
 			die("git cat-file --textconv %s: <object> must be <sha1:path>",
 			    obj_name);
 
-		if (textconv_object(obj_context.path, obj_context.mode, sha1, 1, &buf, &size))
+		if (textconv_object(path, obj_context.mode,
+				    sha1, 1, &buf, &size))
 			break;
 
 	case 'p':
@@ -477,7 +486,7 @@ static int batch_objects(struct batch_options *opt)
 }
 
 static const char * const cat_file_usage[] = {
-	N_("git cat-file (-t [--allow-unknown-type]|-s [--allow-unknown-type]|-e|-p|<type>|--textconv|--filters) <object>"),
+	N_("git cat-file (-t [--allow-unknown-type]|-s [--allow-unknown-type]|-e|-p|<type>|--textconv|--filters) [--path=<path>] <object>"),
 	N_("git cat-file (--batch | --batch-check) [--follow-symlinks]"),
 	NULL
 };
@@ -525,6 +534,8 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 			    N_("for blob objects, run textconv on object's content"), 'c'),
 		OPT_CMDMODE(0, "filters", &opt,
 			    N_("for blob objects, run filters on object's content"), 'w'),
+		OPT_STRING(0, "path", &force_path, N_("blob"),
+			   N_("use a specific path for --textconv/--filters")),
 		OPT_BOOL(0, "allow-unknown-type", &unknown_type,
 			  N_("allow -s and -t to work with broken/corrupt objects")),
 		OPT_BOOL(0, "buffer", &batch.buffer_output, N_("buffer --batch output")),
@@ -567,6 +578,11 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 		usage_with_options(cat_file_usage, options);
 	}
 
+	if (force_path && opt != 'c' && opt != 'w') {
+		error("--path=<path> needs --textconv or --filters");
+		usage_with_options(cat_file_usage, options);
+	}
+
 	if (batch.buffer_output < 0)
 		batch.buffer_output = batch.all_objects;
 
diff --git a/t/t8010-cat-file-filters.sh b/t/t8010-cat-file-filters.sh
index e466634..0d5c33e 100755
--- a/t/t8010-cat-file-filters.sh
+++ b/t/t8010-cat-file-filters.sh
@@ -31,4 +31,24 @@ test_expect_success 'cat-file --filters converts to worktree version' '
 	has_cr actual
 '
 
+test_expect_success 'cat-file --filters --path=<path> works' '
+	sha1=$(git rev-parse -q --verify HEAD:world.txt) &&
+	git cat-file --filters --path=world.txt $sha1 >actual &&
+	has_cr actual
+'
+
+test_expect_success 'cat-file --textconv --path=<path> works' '
+	sha1=$(git rev-parse -q --verify HEAD:world.txt) &&
+	test_config diff.txt.textconv "tr A-Za-z N-ZA-Mn-za-m <" &&
+	git cat-file --textconv --path=hello.txt $sha1 >rot13 &&
+	test uryyb = "$(cat rot13 | remove_cr)"
+'
+
+test_expect_success '----path=<path> complains without --textconv/--filters' '
+	sha1=$(git rev-parse -q --verify HEAD:world.txt) &&
+	test_must_fail git cat-file --path=hello.txt blob $sha1 >actual 2>err &&
+	test ! -s actual &&
+	grep "path.*needs.*filters" err
+'
+
 test_done

-- 
2.10.0.windows.1.10.g803177d
Previous: Johannes SchindelinNext: Junio C Hamano
Message 55 of 66 in “cat-file: optionally convert to worktree version”
  1. 0/4 cat-file: optionally convert to worktree versionJohannes Schindelin, Aug 18, 2016
  2. 3/4 cat-file --textconv/--filters: allow specifying the path separatelyJohannes Schindelin, Aug 18, 2016
  3. Junio C HamanoAug 18, 2016
  4. Johannes SchindelinAug 19, 2016
  5. Junio C HamanoAug 19, 2016
  6. Johannes SchindelinAug 24, 2016
  7. 2/4 cat-file: introduce the --filters optionJohannes Schindelin, Aug 18, 2016
  8. Junio C HamanoAug 18, 2016
  9. Johannes SchindelinAug 19, 2016
  10. Torsten BögershausenAug 18, 2016
  11. Johannes SchindelinAug 19, 2016
  12. Junio C HamanoAug 19, 2016
  13. Torsten BögershausenAug 19, 2016
  14. Johannes SchindelinAug 19, 2016
  15. Junio C HamanoAug 19, 2016
  16. Torsten BögershausenAug 22, 2016
  17. Johannes SchindelinAug 24, 2016
  18. 4/4 cat-file: support --textconv/--filters in batch modeJohannes Schindelin, Aug 18, 2016
  19. Junio C HamanoAug 18, 2016
  20. Johannes SchindelinAug 19, 2016
  21. Jeff KingAug 19, 2016
  22. Jeff KingAug 18, 2016
  23. Junio C HamanoAug 18, 2016
  24. Johannes SchindelinAug 19, 2016
  25. Johannes SchindelinAug 19, 2016
  26. Jeff KingAug 19, 2016
  27. Torsten BögershausenAug 18, 2016
  28. Johannes SchindelinAug 19, 2016
  29. Jeff KingAug 19, 2016
  30. Junio C HamanoAug 19, 2016
  31. 1/4 cat-file: fix a grammo in the man pageJohannes Schindelin, Aug 18, 2016
  32. Junio C HamanoAug 18, 2016
  33. 0/4 cat-file: optionally convert to worktree versionJohannes Schindelin, Aug 24, 2016
  34. 4/4 cat-file: support --textconv/--filters in batch modeJohannes Schindelin, Aug 24, 2016
  35. 2/4 cat-file: introduce the --filters optionJohannes Schindelin, Aug 24, 2016
  36. Junio C HamanoAug 24, 2016
  37. Junio C HamanoAug 24, 2016
  38. Johannes SchindelinAug 31, 2016
  39. Junio C HamanoAug 31, 2016
  40. 1/4 cat-file: fix a grammo in the man pageJohannes Schindelin, Aug 24, 2016
  41. 3/4 cat-file --textconv/--filters: allow specifying the path separatelyJohannes Schindelin, Aug 24, 2016
  42. Junio C HamanoAug 24, 2016
  43. Junio C HamanoAug 24, 2016
  44. Johannes SchindelinAug 31, 2016
  45. Junio C HamanoAug 31, 2016
  46. Junio C HamanoAug 24, 2016
  47. Jeff KingAug 24, 2016
  48. Junio C HamanoAug 24, 2016
  49. Jeff KingAug 24, 2016
  50. Junio C HamanoAug 24, 2016
  51. Junio C HamanoAug 29, 2016
  52. Johannes SchindelinAug 31, 2016
  53. 0/4 cat-file: optionally convert to worktree versionJohannes Schindelin, Sep 9, 2016
  54. 1/4 cat-file: fix a grammo in the man pageJohannes Schindelin, Sep 9, 2016
  55. 3/4 cat-file --textconv/--filters: allow specifying the path separatelyJohannes Schindelin, Sep 9, 2016
  56. Junio C HamanoSep 9, 2016
  57. Johannes SchindelinSep 10, 2016
  58. 4/4 cat-file: support --textconv/--filters in batch modeJohannes Schindelin, Sep 9, 2016
  59. 2/4 cat-file: introduce the --filters optionJohannes Schindelin, Sep 9, 2016
  60. Junio C HamanoSep 9, 2016
  61. Johannes SchindelinSep 9, 2016
  62. Junio C HamanoSep 9, 2016
  63. Junio C HamanoSep 9, 2016
  64. Junio C HamanoSep 9, 2016
  65. Johannes SchindelinSep 10, 2016
  66. Junio C HamanoSep 11, 2016

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