From 9ded880a0221f4d1256845fc4ab957ffd377c760 Mon Sep 17 00:00:00 2001
From: Jia Tan <jiat0218@gmail.com>
Date: Fri, 6 Jan 2023 00:02:29 +0800
Subject: [PATCH] xz: Add --filters option to CLI.

The --filters option uses the new lzma_str_to_filters() function
to convert a string into a full filter chain. Using this option
will reset all previous filters set by --preset, --[filter], or
--filters.
---
 src/xz/args.c  |  9 +++++++--
 src/xz/coder.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 src/xz/coder.h |  3 +++
 3 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/src/xz/args.c b/src/xz/args.c
index b831946f..e21aee93 100644
--- a/src/xz/args.c
+++ b/src/xz/args.c
@@ -136,7 +136,8 @@ static void
 parse_real(args_info *args, int argc, char **argv)
 {
 	enum {
-		OPT_X86 = INT_MIN,
+		OPT_FILTERS = INT_MIN,
+		OPT_X86,
 		OPT_POWERPC,
 		OPT_IA64,
 		OPT_ARM,
@@ -206,6 +207,7 @@ parse_real(args_info *args, int argc, char **argv)
 		{ "best",         no_argument,       NULL,  '9' },
 
 		// Filters
+		{ "filters",      optional_argument, NULL,  OPT_FILTERS},
 		{ "lzma1",        optional_argument, NULL,  OPT_LZMA1 },
 		{ "lzma2",        optional_argument, NULL,  OPT_LZMA2 },
 		{ "x86",          optional_argument, NULL,  OPT_X86 },
@@ -372,7 +374,10 @@ parse_real(args_info *args, int argc, char **argv)
 			opt_mode = MODE_COMPRESS;
 			break;
 
-		// Filter setup
+		// --filters
+		case OPT_FILTERS:
+			coder_add_filters_from_str(optarg);
+			break;
 
 		case OPT_X86:
 			coder_add_filter(LZMA_FILTER_X86,
diff --git a/src/xz/coder.c b/src/xz/coder.c
index 05f22888..b998cb2b 100644
--- a/src/xz/coder.c
+++ b/src/xz/coder.c
@@ -45,6 +45,11 @@ static uint32_t filters_count = 0;
 /// Number of the preset (0-9)
 static uint32_t preset_number = LZMA_PRESET_DEFAULT;
 
+/// True if the current filter chain was set using the --filters option.
+/// The filter chain is reset if a preset option (like -9) or an old-style
+/// filter option (like --lzma2) is used after a --filters option.
+static bool string_to_filter_used = false;
+
 /// Integrity check type
 static lzma_check check;
 
@@ -77,14 +82,15 @@ coder_set_check(lzma_check new_check)
 static void
 forget_filter_chain(void)
 {
-	// Setting a preset makes us forget a possibly defined custom
-	// filter chain.
+	// Setting a preset or using --filters makes us forget
+	// the earlier custom filter chain (if any).
 	while (filters_count > 0) {
 		--filters_count;
 		free(filters[filters_count].options);
 		filters[filters_count].options = NULL;
 	}
 
+	string_to_filter_used = false;
 	return;
 }
 
@@ -114,6 +120,9 @@ coder_add_filter(lzma_vli id, void *options)
 	if (filters_count == LZMA_FILTERS_MAX)
 		message_fatal(_("Maximum number of filters is four"));
 
+	if (string_to_filter_used)
+		forget_filter_chain();
+
 	filters[filters_count].id = id;
 	filters[filters_count].options = options;
 	++filters_count;
@@ -128,6 +137,43 @@ coder_add_filter(lzma_vli id, void *options)
 }
 
 
+extern void
+coder_add_filters_from_str(const char *filter_str)
+{
+	// Forget presets and previously defined filter chain. See
+	// coder_add_filter() above for why preset_number must be reset too.
+	forget_filter_chain();
+	preset_number = LZMA_PRESET_DEFAULT;
+
+	string_to_filter_used = true;
+
+	// Include LZMA_STR_ALL_FILTERS so this can be used with --format=raw.
+	int error_pos;
+	const char *err = lzma_str_to_filters(filter_str, &error_pos,
+			filters, LZMA_STR_ALL_FILTERS, NULL);
+
+	if (err != NULL) {
+		// FIXME? The message in err isn't translated.
+		// Including the translations in the xz translations is
+		// slightly ugly but possible. Creating a new domain for
+		// liblzma might not be worth it especially since on some
+		// OSes it adds extra dependencies to translation libraries.
+		message(V_ERROR, _("Error in --filters=FILTERS option:"));
+		message(V_ERROR, "%s", filter_str);
+		message(V_ERROR, "%*s^", error_pos, "");
+		message_fatal("%s", err);
+	}
+
+	// Set the filters_count to be the number of filters converted from
+	// the string.
+	for (filters_count = 0; filters[filters_count].id != LZMA_VLI_UNKNOWN;
+			++filters_count) ;
+
+	assert(filters_count > 0);
+	return;
+}
+
+
 static void lzma_attribute((__noreturn__))
 memlimit_too_small(uint64_t memory_usage)
 {
diff --git a/src/xz/coder.h b/src/xz/coder.h
index b4f43a2b..997d2586 100644
--- a/src/xz/coder.h
+++ b/src/xz/coder.h
@@ -77,3 +77,6 @@ extern void coder_run(const char *filename);
 /// Free the memory allocated for the coder and kill the worker threads.
 extern void coder_free(void);
 #endif
+
+/// Create filter chain from string
+extern void coder_add_filters_from_str(const char *filter_str);