From 0b96aa192317fd9d6a2d0090c1579525f3859d57 Mon Sep 17 00:00:00 2001
From: "Emil J. Tywoniak" <emil@tywoniak.eu>
Date: Fri, 3 Jan 2025 18:40:40 +0100
Subject: [PATCH] gzip: simplify uncompressed interface

---
 kernel/gzip.cc              | 21 ++++++++++++---------
 kernel/gzip.h               |  2 +-
 kernel/register.cc          |  8 +-------
 passes/techmap/dfflibmap.cc | 10 ++++------
 4 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/kernel/gzip.cc b/kernel/gzip.cc
index 900e33bf49d..0da53ff68c6 100644
--- a/kernel/gzip.cc
+++ b/kernel/gzip.cc
@@ -96,15 +96,17 @@ gzip_istream::ibuf::~ibuf() {
 
 // Takes a successfully opened ifstream. If it's gzipped, returns an istream. Otherwise,
 // returns the original ifstream, rewound to the start.
-std::istream* uncompressed(std::ifstream* f, const std::string filename) {
-	if (!f)
-		return nullptr;
+std::istream& uncompressed(const std::string filename, std::ios_base::openmode mode) {
+	std::ifstream& f = *new std::ifstream();
+	f.open(filename, mode);
+	if (f.fail())
+		return f;
 	// Check for gzip magic
 	unsigned char magic[3];
 	int n = 0;
 	while (n < 3)
 	{
-		int c = f->get();
+		int c = f.get();
 		if (c != EOF) {
 			magic[n] = (unsigned char) c;
 		}
@@ -116,15 +118,16 @@ std::istream* uncompressed(std::ifstream* f, const std::string filename) {
 		if (magic[2] != 8)
 			log_cmd_error("gzip file `%s' uses unsupported compression type %02x\n",
 				filename.c_str(), unsigned(magic[2]));
-		delete f;
-		gzip_istream* s = new gzip_istream();
-		return s->open(filename.c_str()) ? s : nullptr;
+		gzip_istream& s = *new gzip_istream();
+		delete &f;
+		s.open(filename.c_str());
+		return s;
 #else
 		log_cmd_error("File `%s' is a gzip file, but Yosys is compiled without zlib.\n", filename.c_str());
 #endif // YOSYS_ENABLE_ZLIB
 	} else {
-		f->clear();
-		f->seekg(0, std::ios::beg);
+		f.clear();
+		f.seekg(0, std::ios::beg);
 		return f;
 	}
 }
diff --git a/kernel/gzip.h b/kernel/gzip.h
index 22f5093a0bf..0201d2340bf 100644
--- a/kernel/gzip.h
+++ b/kernel/gzip.h
@@ -72,7 +72,7 @@ class gzip_istream final : public std::istream {
 
 #endif // YOSYS_ENABLE_ZLIB
 
-std::istream* uncompressed(std::ifstream* f, const std::string filename);
+std::istream& uncompressed(const std::string filename, std::ios_base::openmode mode = std::ios_base::in);
 
 YOSYS_NAMESPACE_END
 
diff --git a/kernel/register.cc b/kernel/register.cc
index a2e7cb5772a..040cc62076d 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -469,14 +469,8 @@ void Frontend::extra_args(std::istream *&f, std::string &filename, std::vector<s
 				next_args.insert(next_args.end(), args.begin(), args.begin()+argidx);
 				next_args.insert(next_args.end(), filenames.begin()+1, filenames.end());
 			}
-			std::ifstream *ff = new std::ifstream;
-			ff->open(filename.c_str(), bin_input ? std::ifstream::binary : std::ifstream::in);
 			yosys_input_files.insert(filename);
-			if (ff->fail()) {
-				delete ff;
-				ff = nullptr;
-			}
-			f = uncompressed(ff, filename);
+			f = &uncompressed(filename, bin_input ? std::ifstream::binary : std::ifstream::in);
 		}
 		if (f == NULL)
 			log_cmd_error("Can't open input file `%s' for reading: %s\n", filename.c_str(), strerror(errno));
diff --git a/passes/techmap/dfflibmap.cc b/passes/techmap/dfflibmap.cc
index fedcba1e1ce..df2bfa88f74 100644
--- a/passes/techmap/dfflibmap.cc
+++ b/passes/techmap/dfflibmap.cc
@@ -631,14 +631,12 @@ struct DfflibmapPass : public Pass {
 
 		LibertyMergedCells merged;
 		for (auto path : liberty_files) {
-			std::ifstream f;
-			f.open(path.c_str());
-			std::istream* ff = uncompressed(&f, path);
-			if (ff->fail())
+			std::istream& f = uncompressed(path);
+			if (f.fail())
 				log_cmd_error("Can't open liberty file `%s': %s\n", path.c_str(), strerror(errno));
-			LibertyParser p(*ff);
+			LibertyParser p(f);
 			merged.merge(p);
-			delete ff;
+			delete &f;
 		}
 
 		find_cell(merged.cells, ID($_DFF_N_), false, false, false, false, false, false, dont_use_cells);