Get rid of custom implementation of Utils::PathName (p4lang#4721)

* Get rid of custom implementation of Utils::PathName.
  - Switch to std::filesystem::path
  - Simplify and cleanup code aroung
  - Get rid of (some) cstrings around paths

* Get rid of Util::PathName alias

* Resolve a fixme

backends/bmv2/common/options.h

@@ -28,7 +28,7 @@ class BMV2Options : public CompilerOptions {
     /// Generate externs.
     bool emitExterns = false;
     /// File to output to.
-    cstring outputFile = nullptr;
+    std::filesystem::path outputFile;
     /// Read from json.
     bool loadIRFromJson = false;
 
@@ -44,15 +44,15 @@ class BMV2Options : public CompilerOptions {
         registerOption(
             "-o", "outfile",
             [this](const char *arg) {
-                outputFile = cstring(arg);
+                outputFile = arg;
                 return true;
             },
             "Write output to outfile");
         registerOption(
             "--fromJSON", "file",
             [this](const char *arg) {
                 loadIRFromJson = true;
-                file = cstring(arg);
+                file = arg;
                 return true;
             },
             "Use IR representation from JsonFile dumped previously,"

backends/bmv2/psa_switch/main.cpp

@@ -98,7 +98,7 @@ int main(int argc, char *const argv[]) {
     try {
         toplevel = midEnd.process(program);
         if (::errorCount() > 1 || toplevel == nullptr || toplevel->getMain() == nullptr) return 1;
-        if (options.dumpJsonFile)
+        if (!options.dumpJsonFile.empty())
             JSONGenerator(*openFile(options.dumpJsonFile, true), true) << program << std::endl;
     } catch (const std::exception &bug) {
         std::cerr << bug.what() << std::endl;
@@ -119,7 +119,7 @@ int main(int argc, char *const argv[]) {
     }
     if (::errorCount() > 0) return 1;
 
-    if (!options.outputFile.isNullOrEmpty()) {
+    if (!options.outputFile.empty()) {
         std::ostream *out = openFile(options.outputFile, false);
         if (out != nullptr) {
             backend->serialize(*out);

backends/bmv2/psa_switch/psaSwitch.cpp

@@ -314,7 +314,7 @@ void PsaSwitchBackend::convert(const IR::ToplevelBlock *tlb) {
         }
     }
     program->apply(toJson);
-    json->add_program_info(options.file);
+    json->add_program_info(cstring(options.file));
     json->add_meta_info();
 }
 

backends/bmv2/simple_switch/main.cpp

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 #include <cstdio>
+#include <fstream>
 #include <iostream>
 #include <string>
 
@@ -27,7 +28,6 @@ limitations under the License.
 #include "frontends/common/applyOptionsPragmas.h"
 #include "frontends/common/parseInput.h"
 #include "frontends/p4/frontend.h"
-#include "fstream"
 #include "ir/ir.h"
 #include "ir/json_generator.h"
 #include "ir/json_loader.h"
@@ -99,7 +99,7 @@ int main(int argc, char *const argv[]) {
     try {
         toplevel = midEnd.process(program);
         if (::errorCount() > 1 || toplevel == nullptr || toplevel->getMain() == nullptr) return 1;
-        if (options.dumpJsonFile && !options.loadIRFromJson)
+        if (!options.dumpJsonFile.empty() && !options.loadIRFromJson)
             JSONGenerator(*openFile(options.dumpJsonFile, true), true) << program << std::endl;
     } catch (const std::exception &bug) {
         std::cerr << bug.what() << std::endl;
@@ -120,7 +120,7 @@ int main(int argc, char *const argv[]) {
     }
     if (::errorCount() > 0) return 1;
 
-    if (!options.outputFile.isNullOrEmpty()) {
+    if (!options.outputFile.empty()) {
         std::ostream *out = openFile(options.outputFile, false);
         if (out != nullptr) {
             backend->serialize(*out);

backends/bmv2/simple_switch/simpleSwitch.cpp

@@ -1207,7 +1207,7 @@ void SimpleSwitchBackend::convert(const IR::ToplevelBlock *tlb) {
     // called (e.g. resubmit or generate_digest)
     BMV2::nextId("field_lists"_cs);
     BMV2::nextId("learn_lists"_cs);
-    json->add_program_info(options.file);
+    json->add_program_info(cstring(options.file));
     json->add_meta_info();
 
     // convert all enums to json

backends/dpdk/backend.cpp

@@ -116,12 +116,12 @@ void DpdkBackend::convert(const IR::ToplevelBlock *tlb) {
         new DpdkArchLast(),
         new VisitFunctor([this, genContextJson] {
             // Serialize context json object into user specified file
-            if (!options.ctxtFile.isNullOrEmpty()) {
-                std::ostream *out = openFile(options.ctxtFile, false);
-                if (out != nullptr) {
+            if (!options.ctxtFile.empty()) {
+                if (std::ostream *out = openFile(options.ctxtFile, false)) {
                     genContextJson->serializeContextJson(out);
-                }
-                out->flush();
+                    out->flush();
+                } else
+                    ::error(ErrorType::ERR_IO, "Could not open file: %1%", options.ctxtFile);
             }
         }),
         new ReplaceHdrMetaField(),

backends/dpdk/control-plane/bfruntime_ext.cpp

@@ -221,14 +221,7 @@ const Util::JsonObject *BFRuntimeSchemaGenerator::genSchema() const {
     auto *json = new Util::JsonObject();
 
     if (isTDI) {
-        cstring progName = options.file;
-        auto fileName = progName.findlast('/');
-        // Handle the case when input file is in the current working directory.
-        // fileName would be null in that case, hence progName should remain unchanged.
-        if (fileName) progName = cstring(fileName);
-        auto fileext = cstring(progName.find("."));
-        progName = cstring(progName.replace(fileext, cstring::empty));
-        progName = progName.trim("/\t\n\r");
+        auto progName = options.file.stem();
         json->emplace("program_name"_cs, progName);
         json->emplace("build_date"_cs, cstring(options.getBuildDate()));
         json->emplace("compile_command"_cs, cstring(options.getCompileCommand()));

backends/dpdk/dpdkContext.cpp

@@ -23,10 +23,9 @@ limitations under the License.
 namespace DPDK {
 
 cstring DpdkContextGenerator::removePipePrefix(cstring tableName) {
-    if (!options.bfRtSchema.isNullOrEmpty() || !options.tdiFile.isNullOrEmpty()) {
+    if (!options.bfRtSchema.empty() || !options.tdiFile.empty()) {
         cstring tablename = cstring(tableName.find('.'));
-        tablename = tablename.trim(".\t\n\r");
-        return tablename;
+        return tablename.trim(".\t\n\r");
     }
     return tableName;
 }

backends/dpdk/dpdkContext.h

@@ -82,21 +82,14 @@ struct externAttributes {
 
 /// Program level information for context json.
 struct TopLevelCtxt {
-    cstring progName;
+    std::string progName;
     cstring buildDate;
     cstring compileCommand;
     cstring compilerVersion;
     void initTopLevelCtxt(DpdkOptions &options) {
         buildDate = options.getBuildDate();
         compileCommand = options.getCompileCommand();
-        progName = options.file;
-        auto fileName = progName.findlast('/');
-        // Handle the case when input file is in the current working directory.
-        // fileName would be null in that case, hence progName should remain unchanged.
-        if (fileName) progName = cstring(fileName);
-        auto fileext = progName.find(".");
-        progName = progName.replace(cstring(fileext), cstring::empty);
-        progName = progName.trim("/\t\n\r");
+        progName = options.file.stem();
         compilerVersion = options.compilerVersion;
     }
 };

backends/dpdk/main.cpp

@@ -52,7 +52,7 @@ void generateTDIBfrtJson(bool isTDI, const IR::P4Program *program, DPDK::DpdkOpt
             "pna"_cs, new P4::ControlPlaneAPI::Standard::PNAArchHandlerBuilderForDPDK());
     auto p4Runtime = P4::generateP4Runtime(program, options.arch);
 
-    cstring filename = isTDI ? options.tdiFile : options.bfRtSchema;
+    std::filesystem::path filename = isTDI ? options.tdiFile : options.bfRtSchema;
     auto p4rt = new P4::BFRT::BFRuntimeSchemaGenerator(*p4Runtime.p4Info, isTDI, options);
     std::ostream *out = openFile(filename, false);
     if (!out) {
@@ -115,14 +115,14 @@ int main(int argc, char *const argv[]) {
     P4::serializeP4RuntimeIfRequired(program, options);
     if (::errorCount() > 0) return 1;
 
-    if (!options.tdiBuilderConf.isNullOrEmpty()) {
+    if (!options.tdiBuilderConf.empty()) {
         DPDK::TdiBfrtConf::generate(program, options);
     }
 
-    if (!options.bfRtSchema.isNullOrEmpty()) {
+    if (!options.bfRtSchema.empty()) {
         generateTDIBfrtJson(false, program, options);
     }
-    if (!options.tdiFile.isNullOrEmpty()) {
+    if (!options.tdiFile.empty()) {
         generateTDIBfrtJson(true, program, options);
     }
 
@@ -133,7 +133,7 @@ int main(int argc, char *const argv[]) {
     try {
         toplevel = midEnd.process(program);
         if (::errorCount() > 1 || toplevel == nullptr || toplevel->getMain() == nullptr) return 1;
-        if (options.dumpJsonFile)
+        if (!options.dumpJsonFile.empty())
             JSONGenerator(*openFile(options.dumpJsonFile, true), true) << program << std::endl;
     } catch (const std::exception &bug) {
         std::cerr << bug.what() << std::endl;
@@ -146,7 +146,7 @@ int main(int argc, char *const argv[]) {
     backend->convert(toplevel);
     if (::errorCount() > 0) return 1;
 
-    if (!options.outputFile.isNullOrEmpty()) {
+    if (!options.outputFile.empty()) {
         std::ostream *out = openFile(options.outputFile, false);
         if (out != nullptr) {
             backend->codegen(*out);

backends/dpdk/options.h

@@ -23,15 +23,15 @@ namespace DPDK {
 
 class DpdkOptions : public CompilerOptions {
  public:
-    cstring bfRtSchema = cstring::empty;
+    std::filesystem::path bfRtSchema;
     /// File to output to.
-    cstring outputFile = nullptr;
+    std::filesystem::path outputFile;
     /// File to output TDI JSON to.
-    cstring tdiFile = cstring::empty;
+    std::filesystem::path tdiFile;
     /// File to output context JSON to.
-    cstring ctxtFile = cstring::empty;
+    std::filesystem::path ctxtFile;
     /// File to output the TDI builder configuration to.
-    cstring tdiBuilderConf = cstring::empty;
+    std::filesystem::path tdiBuilderConf;
     /// Read from JSON.
     bool loadIRFromJson = false;
     /// Enable/disable Egress pipeline in PSA.
@@ -58,43 +58,43 @@ class DpdkOptions : public CompilerOptions {
         registerOption(
             "--bf-rt-schema", "file",
             [this](const char *arg) {
-                bfRtSchema = cstring(arg);
+                bfRtSchema = arg;
                 return true;
             },
             "Generate and write BF-RT JSON schema to the specified file");
         registerOption(
             "-o", "outfile",
             [this](const char *arg) {
-                outputFile = cstring(arg);
+                outputFile = arg;
                 return true;
             },
             "Write output to outfile");
         registerOption(
             "--tdi-builder-conf", "file",
             [this](const char *arg) {
-                tdiBuilderConf = cstring(arg);
+                tdiBuilderConf = arg;
                 return true;
             },
             "Generate and write the TDI builder configuration to the specified file");
         registerOption(
             "--tdi", "file",
             [this](const char *arg) {
-                tdiFile = cstring(arg);
+                tdiFile = arg;
                 return true;
             },
             "Generate and write TDI JSON to the specified file");
         registerOption(
             "--context", "file",
             [this](const char *arg) {
-                ctxtFile = cstring(arg);
+                ctxtFile = arg;
                 return true;
             },
             "Generate and write context JSON to the specified file");
         registerOption(
             "--fromJSON", "file",
             [this](const char *arg) {
                 loadIRFromJson = true;
-                file = cstring(arg);
+                file = arg;
                 return true;
             },
             "Use IR representation from JsonFile dumped previously,"

backends/dpdk/tdiConf.cpp

@@ -68,33 +68,33 @@ std::optional<cstring> TdiBfrtConf::findPipeName(const IR::P4Program *prog,
 }
 
 void TdiBfrtConf::generate(const IR::P4Program *prog, DPDK::DpdkOptions &options) {
-    if (options.outputFile.isNullOrEmpty()) {
+    if (options.outputFile.empty()) {
         ::error(ErrorType::ERR_UNEXPECTED,
                 "No output file provided. Unable to generate correct TDI builder config file.");
         return;
     }
-    auto inputFile = std::filesystem::absolute(options.file.c_str());
-    auto outFile = std::filesystem::absolute(options.outputFile.c_str());
+    auto inputFile = std::filesystem::absolute(options.file);
+    auto outFile = std::filesystem::absolute(options.outputFile);
     auto outDir = outFile.parent_path();
-    auto tdiFile = std::filesystem::absolute(options.tdiBuilderConf.c_str());
+    auto tdiFile = std::filesystem::absolute(options.tdiBuilderConf);
     auto programName = inputFile.stem();
 
-    if (options.bfRtSchema.isNullOrEmpty()) {
-        options.bfRtSchema = cstring((outDir / programName).replace_filename("json").c_str());
+    if (options.bfRtSchema.empty()) {
+        options.bfRtSchema = (outDir / programName).replace_filename("json");
         ::warning(
             "BF-Runtime Schema file name not provided, but is required for the TDI builder "
             "configuration. Generating file %1%",
             options.bfRtSchema);
     }
-    if (options.ctxtFile.isNullOrEmpty()) {
-        options.ctxtFile = cstring((outDir / "context.json").c_str());
+    if (options.ctxtFile.empty()) {
+        options.ctxtFile = outDir / "context.json";
         ::warning(
             "DPDK context file name not provided, but is required for the TDI builder "
             "configuration. Generating file %1%",
             options.ctxtFile);
     }
 
-    auto contextFile = std::filesystem::absolute(options.ctxtFile.c_str());
+    auto contextFile = std::filesystem::absolute(options.ctxtFile);
     auto bfRtSchema = std::filesystem::absolute(options.bfRtSchema.c_str());
 
     auto pipeName = findPipeName(prog, options);
@@ -103,6 +103,7 @@ void TdiBfrtConf::generate(const IR::P4Program *prog, DPDK::DpdkOptions &options
     }
     // TODO: Ideally, this should be a template. We could use Inja, but this adds another
     // dependency.
+    // FIXME: Just use absl::StrSubstitute
     std::stringstream ss;
     ss << R"""({
     "chip_list": [
@@ -149,7 +150,7 @@ void TdiBfrtConf::generate(const IR::P4Program *prog, DPDK::DpdkOptions &options
     if (out.is_open()) {
         out << ss;
     } else {
-        ::error(ErrorType::ERR_IO, "Could not open file: %1%", tdiFile.c_str());
+        ::error(ErrorType::ERR_IO, "Could not open file: %1%", tdiFile);
         return;
     }
     out.close();

backends/ebpf/ebpfBackend.cpp

@@ -37,19 +37,14 @@ void emitFilterModel(const EbpfOptions &options, Target *target, const IR::Tople
     auto ebpfprog = new EBPFProgram(options, toplevel->getProgram(), refMap, typeMap, toplevel);
     if (!ebpfprog->build()) return;
 
-    if (options.outputFile.isNullOrEmpty()) return;
+    if (options.outputFile.empty()) return;
 
-    cstring cfile = options.outputFile;
-    auto cstream = openFile(cfile, false);
+    auto *cstream = openFile(options.outputFile, false);
     if (cstream == nullptr) return;
 
-    cstring hfile;
-    const char *dot = cfile.findlast('.');
-    if (dot == nullptr)
-        hfile = cfile + ".h";
-    else
-        hfile = cfile.before(dot) + ".h";
-    auto hstream = openFile(hfile, false);
+    std::filesystem::path hfile = options.outputFile;
+    hfile.replace_extension(".h");
+    auto *hstream = openFile(hfile, false);
     if (hstream == nullptr) return;
 
     ebpfprog->emitH(&h, hfile);
@@ -96,10 +91,9 @@ void run_ebpf_backend(const EbpfOptions &options, const IR::ToplevelBlock *tople
         auto backend = new EBPF::PSASwitchBackend(options, target, refMap, typeMap);
         backend->convert(toplevel);
 
-        if (options.outputFile.isNullOrEmpty()) return;
+        if (options.outputFile.empty()) return;
 
-        cstring cfile = options.outputFile;
-        auto cstream = openFile(cfile, false);
+        auto cstream = openFile(options.outputFile, false);
         if (cstream == nullptr) return;
 
         backend->codegen(*cstream);

backends/ebpf/ebpfOptions.cpp

@@ -23,7 +23,7 @@ EbpfOptions::EbpfOptions() {
     registerOption(
         "-o", "outfile",
         [this](const char *arg) {
-            outputFile = cstring(arg);
+            outputFile = arg;
             return true;
         },
         "Write output to outfile");
@@ -42,7 +42,7 @@ EbpfOptions::EbpfOptions() {
         "--fromJSON", "file",
         [this](const char *arg) {
             loadIRFromJson = true;
-            file = cstring(arg);
+            file = arg;
             return true;
         },
         "Use IR representation from JsonFile dumped previously,"