Kernel/LibC: remove PATH resoltion from kernel

I have no idea why I had made PATH environment variable parsing
to be part of the kernel. Now the shell does the parsing and
environment syscall is no longer needed.

kernel/include/kernel/Process.h

@@ -71,8 +71,6 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_sleep(int seconds);
 		BAN::ErrorOr<long> sys_nanosleep(const timespec* rqtp, timespec* rmtp);
 
-		BAN::ErrorOr<long> sys_setenvp(char** envp);
-
 		BAN::ErrorOr<long> sys_setpwd(const char* path);
 		BAN::ErrorOr<long> sys_getpwd(char* buffer, size_t size);
 
@@ -147,7 +145,7 @@ namespace Kernel
 		static void register_process(Process*);
 
 		// Load an elf file to virtual address space of the current page table
-		static BAN::ErrorOr<BAN::UniqPtr<LibELF::ELF>> load_elf_for_exec(const Credentials&, BAN::StringView file_path, const BAN::String& cwd, const BAN::Vector<BAN::StringView>& path_env);
+		static BAN::ErrorOr<BAN::UniqPtr<LibELF::ELF>> load_elf_for_exec(const Credentials&, BAN::StringView file_path, const BAN::String& cwd);
 		
 		// Copy an elf file from the current page table to the processes own
 		void load_elf_to_memory(LibELF::ELF&);

kernel/kernel/Process.cpp

@@ -99,7 +99,7 @@ namespace Kernel
 
 	BAN::ErrorOr<Process*> Process::create_userspace(const Credentials& credentials, BAN::StringView path)
 	{
-		auto elf = TRY(load_elf_for_exec(credentials, path, "/"sv, {}));
+		auto elf = TRY(load_elf_for_exec(credentials, path, "/"sv));
 
 		auto* process = create_process(credentials, 0);
 		MUST(process->m_working_directory.push_back('/'));
@@ -114,7 +114,6 @@ namespace Kernel
 		elf.clear();
 
 		char** argv = nullptr;
-		char** envp = nullptr;
 		{
 			PageTableScope _(process->page_table());
 
@@ -123,18 +122,11 @@ namespace Kernel
 			memcpy(argv[0], path.data(), path.size());
 			argv[0][path.size()] = '\0';
 			argv[1] = nullptr;
-
-			BAN::StringView env1 = "PATH=/bin:/usr/bin"sv;
-			envp = (char**)MUST(process->sys_alloc(sizeof(char**) * 2));
-			envp[0] = (char*)MUST(process->sys_alloc(env1.size() + 1));
-			memcpy(envp[0], env1.data(), env1.size());
-			envp[0][env1.size()] = '\0';
-			envp[1] = nullptr;
 		}
 
 		process->m_userspace_info.argc = 1;
 		process->m_userspace_info.argv = argv;
-		process->m_userspace_info.envp = envp;
+		process->m_userspace_info.envp = nullptr;
 
 		auto* thread = MUST(Thread::create_userspace(process));
 		process->add_thread(thread);
@@ -275,7 +267,7 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<BAN::UniqPtr<LibELF::ELF>> Process::load_elf_for_exec(const Credentials& credentials, BAN::StringView file_path, const BAN::String& cwd, const BAN::Vector<BAN::StringView>& path_env)
+	BAN::ErrorOr<BAN::UniqPtr<LibELF::ELF>> Process::load_elf_for_exec(const Credentials& credentials, BAN::StringView file_path, const BAN::String& cwd)
 	{
 		if (file_path.empty())
 			return BAN::Error::from_errno(ENOENT);
@@ -283,43 +275,12 @@ namespace Kernel
 		BAN::String absolute_path;
 
 		if (file_path.front() == '/')
-		{
-			// We have an absolute path
 			TRY(absolute_path.append(file_path));
-		}
-		else if (file_path.front() == '.' || file_path.contains('/'))
-		{
-			// We have a relative path
-			TRY(absolute_path.append(cwd));
-			TRY(absolute_path.push_back('/'));
-			TRY(absolute_path.append(file_path));
-		}
 		else
-		{
-			// We have neither relative or absolute path,
-			// search from PATH environment
-			for (auto path_part : path_env)
-			{
-				if (path_part.empty())
-					continue;
-
-				if (path_part.front() != '/')
 		{
 			TRY(absolute_path.append(cwd));
 			TRY(absolute_path.push_back('/'));
-				}
-				TRY(absolute_path.append(path_part));
-				TRY(absolute_path.push_back('/'));
 			TRY(absolute_path.append(file_path));
-
-				if (!VirtualFileSystem::get().file_from_absolute_path(credentials, absolute_path, O_EXEC).is_error())
-					break;
-
-				absolute_path.clear();
-			}
-
-			if (absolute_path.empty())
-				return BAN::Error::from_errno(ENOENT);
 		}
 
 		auto file = TRY(VirtualFileSystem::get().file_from_absolute_path(credentials, absolute_path, O_EXEC));
@@ -412,14 +373,9 @@ namespace Kernel
 			for (int i = 0; argv && argv[i]; i++)
 				TRY(str_argv.emplace_back(argv[i]));
 
-			BAN::Vector<BAN::StringView> path_env;
 			BAN::Vector<BAN::String> str_envp;
 			for (int i = 0; envp && envp[i]; i++)
-			{
 				TRY(str_envp.emplace_back(envp[i]));
-				if (strncmp(envp[i], "PATH=", 5) == 0)
-					path_env = TRY(BAN::StringView(envp[i]).substring(5).split(':'));
-			}
 
 			BAN::String working_directory;
 
@@ -428,7 +384,7 @@ namespace Kernel
 				TRY(working_directory.append(m_working_directory));
 			}
 
-			auto elf = TRY(load_elf_for_exec(m_credentials, path, working_directory, path_env));
+			auto elf = TRY(load_elf_for_exec(m_credentials, path, working_directory));
 
 			LockGuard lock_guard(m_lock);
 
@@ -547,13 +503,6 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<long> Process::sys_setenvp(char** envp)
-	{
-		LockGuard _(m_lock);
-		m_userspace_info.envp = envp;
-		return 0;
-	}
-
 	void Process::load_elf_to_memory(LibELF::ELF& elf)
 	{
 		ASSERT(elf.is_native());

kernel/kernel/Syscall.cpp

@@ -97,9 +97,6 @@ namespace Kernel
 		case SYS_FSTAT:
 			ret = Process::current().sys_fstat((int)arg1, (struct stat*)arg2);
 			break;
-		case SYS_SETENVP:
-			ret = Process::current().sys_setenvp((char**)arg1);
-			break;
 		case SYS_READ_DIR_ENTRIES:
 			ret = Process::current().sys_read_dir_entries((int)arg1, (API::DirectoryEntryList*)arg2, (size_t)arg3);
 			break;

libc/include/sys/syscall.h

@@ -21,7 +21,6 @@ __BEGIN_DECLS
 #define SYS_SLEEP 17
 #define SYS_WAIT 18
 #define SYS_FSTAT 19
-#define SYS_SETENVP 20
 #define SYS_READ_DIR_ENTRIES 21
 #define SYS_SET_UID 22
 #define SYS_SET_GID 23

libc/stdlib.cpp

@@ -124,6 +124,16 @@ int putenv(char* string)
 		return -1;
 	}
 
+	if (!environ)
+	{
+		environ = (char**)malloc(sizeof(char*) * 2);
+		if (!environ)
+			return -1;
+		environ[0] = string;
+		environ[1] = nullptr;
+		return 0;
+	}
+
 	int cnt = 0;
 	for (int i = 0; string[i]; i++)
 		if (string[i] == '=')
@@ -151,10 +161,7 @@ int putenv(char* string)
 
 	char** new_envp = (char**)malloc(sizeof(char*) * (env_count + 2));
 	if (new_envp == nullptr)
-	{
-		errno = ENOMEM;
 		return -1;
-	}
 
 	for (int i = 0; i < env_count; i++)
 		new_envp[i] = environ[i];
@@ -164,8 +171,6 @@ int putenv(char* string)
 	free(environ);
 	environ = new_envp;
 
-	if (syscall(SYS_SETENVP, environ) == -1)
-		return -1;
 	return 0;
 }
 

libc/unistd.cpp

@@ -14,8 +14,23 @@ char** environ;
 extern void init_malloc();
 extern "C" void _init_libc(char** _environ)
 {
-	environ = _environ;
 	init_malloc();
+
+	if (!_environ)
+		return;
+
+	size_t env_count = 0;
+	while (_environ[env_count])
+		env_count++;
+	
+	environ = (char**)malloc(sizeof(char*) * env_count + 1);
+	for (size_t i = 0; i < env_count; i++)
+	{
+		size_t bytes = strlen(_environ[i]) + 1;
+		environ[i] = (char*)malloc(bytes);
+		memcpy(environ[i], _environ[i], bytes);
+	}
+	environ[env_count] = nullptr;
 }
 
 void _exit(int status)

userspace/Shell/main.cpp

@@ -437,6 +437,40 @@ pid_t execute_command_no_wait(BAN::Vector<BAN::String>& args, int fd_in, int fd_
 		MUST(cmd_args.push_back((char*)arg.data()));
 	MUST(cmd_args.push_back(nullptr));
 
+	// do PATH resolution
+	BAN::String executable_file;
+	if (!args.front().empty() && args.front().front() != '.' && args.front().front() != '/')
+	{
+		char* path_env_cstr = getenv("PATH");
+		if (path_env_cstr)
+		{
+			auto path_env_list = MUST(BAN::StringView(path_env_cstr).split(':'));
+			for (auto path_env : path_env_list)
+			{
+				BAN::String test_file = path_env;
+				MUST(test_file.push_back('/'));
+				MUST(test_file.append(args.front()));
+
+				struct stat st;
+				if (stat(test_file.data(), &st) == 0)
+				{
+					executable_file = BAN::move(test_file);
+					break;
+				}
+			}
+
+			if (executable_file.empty())
+			{
+				fprintf(stderr, "command not found: %s\n", args.front().data());
+				return -1;
+			}
+		}
+	}
+	else
+	{
+		executable_file = args.front();
+	}
+
 	pid_t pid = fork();
 	if (pid == 0)
 	{
@@ -477,11 +511,14 @@ pid_t execute_command_no_wait(BAN::Vector<BAN::String>& args, int fd_in, int fd_
 			setpgid(0, pgrp);
 		}
 
-		execv(cmd_args.front(), cmd_args.data());
+		execv(executable_file.data(), cmd_args.data());
 		perror("execv");
 		exit(1);
 	}
 
+	if (pid == -1)
+		ERROR_RETURN("fork", -1);
+
 	return pid;
 }
 
@@ -489,7 +526,7 @@ int execute_command(BAN::Vector<BAN::String>& args, int fd_in, int fd_out)
 {
 	pid_t pid = execute_command_no_wait(args, fd_in, fd_out, 0);
 	if (pid == -1)
-		ERROR_RETURN("fork", 1);
+		return 1;
 
 	int status;
 	if (waitpid(pid, &status, 0) == -1)

userspace/init/main.cpp

@@ -74,6 +74,8 @@ int main()
 			if (setuid(pwd->pw_uid) == -1)
 				perror("setuid");
 
+			setenv("PATH", "/bin:/usr/bin", 0);
+
 			setenv("HOME", pwd->pw_dir, 1);
 			chdir(pwd->pw_dir);