diff --git a/os2.c b/os2.c
index 9356023..9fbcd24 100644
--- a/os2.c
+++ b/os2.c
@@ -38,17 +38,15 @@ static void add_temp(const char *);
 static void cleanup_temps(void);
 static void cleanup(void);
 
-#define RPUT(x) 													\
-	do {															\
-		if (new_argc >= new_alloc) {								\
-			new_alloc += 20;										\
-			new_argv = (const char **)realloc(new_argv,				\
-											  new_alloc * sizeof(char *));\
-			if (!new_argv)											\
-				goto exit_out_of_memory;							\
-		}															\
-		new_argv[new_argc++] = x;									\
-	} while (0)
+#define RPUT(x) do {					\
+	if (new_argc >= new_alloc) {			\
+		new_alloc += 20;			\
+		if (!(new_argv = realloc(new_argv,	\
+		    new_alloc * sizeof(char *))))	\
+			goto exit_out_of_memory;	\
+	}						\
+	new_argv[new_argc++] = (x);			\
+} while (/* CONSTCOND */ 0)
 
 #define KLIBC_ARG_RESPONSE_EXCLUDE	\
 	(__KLIBC_ARG_DQUOTE | __KLIBC_ARG_WILDCARD | __KLIBC_ARG_SHELL)
@@ -61,8 +59,8 @@ response(int *argcp, const char ***argvp)
 	char *line, *l, *p;
 	FILE *f;
 
-	old_argc = *argcp; old_argv = *argvp;
-
+	old_argc = *argcp;
+	old_argv = *argvp;
 	for (i = 1; i < old_argc; ++i)
 		if (old_argv[i] &&
 		    !(old_argv[i][-1] & KLIBC_ARG_RESPONSE_EXCLUDE) &&
@@ -70,9 +68,11 @@ response(int *argcp, const char ***argvp)
 			break;
 
 	if (i >= old_argc)
-		return; 					/* do nothing */
+		/* do nothing */
+		return;
 
-	new_argv = NULL; new_argc = 0;
+	new_argv = NULL;
+	new_argc = 0;
 	for (i = 0; i < old_argc; ++i) {
 		if (i == 0 || !old_argv[i] ||
 		    (old_argv[i][-1] & KLIBC_ARG_RESPONSE_EXCLUDE) ||
@@ -86,23 +86,28 @@ response(int *argcp, const char ***argvp)
 			filesize = ftell(f);
 			fseek(f, 0, SEEK_SET);
 
-			line = malloc(filesize + 1 + 1); /* 1 for type, 1 for NUL */
-			if (!line)
-				goto exit_out_of_memory;
+			line = malloc(filesize + /* type */ 1 + /* NUL */ 1);
+			if (!line) {
+ exit_out_of_memory:
+				fputs("Out of memory while reading response file\n", stderr);
+				exit(255);
+			}
 
 			line[0] = __KLIBC_ARG_NONZERO | __KLIBC_ARG_RESPONSE;
 			l = line + 1;
 			while (fgets(l, (filesize + 1) - (l - (line + 1)), f)) {
 				p = strchr(l, '\n');
 				if (p) {
-					/* if a line ends with '\',
-					 * then concatenate a next line
+					/*
+					 * if a line ends with a backslash,
+					 * concatenate with the next line
 					 */
 					if (p > l && p[-1] == '\\') {
 						char *p1;
 						int count = 0;
 
-						for (p1 = p - 1; p1 >= l && *p1 == '\\'; p1--)
+						for (p1 = p - 1; p1 >= l &&
+						    *p1 == '\\'; p1--)
 							count++;
 
 						if (count & 1) {
@@ -134,20 +139,22 @@ response(int *argcp, const char ***argvp)
 		}
 	}
 
-	RPUT(NULL); --new_argc;
+	RPUT(NULL);
+	--new_argc;
 
-	*argcp = new_argc; *argvp = new_argv;
-	return;
-
-exit_out_of_memory:
-	fputs("Out of memory while reading response file\n", stderr);
-	exit(255);
+	*argcp = new_argc;
+	*argvp = new_argv;
 }
 
 static void
 init_extlibpath(void)
 {
-	const char *vars[] = {"BEGINLIBPATH", "ENDLIBPATH", "LIBPATHSTRICT", NULL};
+	const char *vars[] = {
+		"BEGINLIBPATH",
+		"ENDLIBPATH",
+		"LIBPATHSTRICT",
+		NULL
+	};
 	char val[512];
 	int flag;
 
@@ -155,24 +162,29 @@ init_extlibpath(void)
 		DosQueryExtLIBPATH(val, flag + 1);
 		if (val[0])
 			setenv(vars[flag], val, 1);
-    }
+	}
 }
 
 /*
  * Convert backslashes of environmental variables to forward slahes.
- * A backslash may be used as an escaped character when do 'echo'. This leads
- * to an unexpected behavior.
+ * A backslash may be used as an escaped character when doing 'echo'.
+ * This leads to an unexpected behavior.
  */
 static void
 env_slashify(void)
 {
 	/*
-	 * PATH and TMPDIR are used by OS/2 as well. That is, they may have
-	 * backslashes as a directory separator.
+	 * PATH and TMPDIR are used by OS/2 as well. That is, they may
+	 * have backslashes as a directory separator.
 	 * BEGINLIBPATH and ENDLIBPATH are special variables on OS/2.
 	 */
-	const char *var_list[] = {"PATH", "TMPDIR",
-	                          "BEGINLIBPATH", "ENDLIBPATH", NULL};
+	const char *var_list[] = {
+		"PATH",
+		"TMPDIR",
+		"BEGINLIBPATH",
+		"ENDLIBPATH",
+		NULL
+	};
 	const char **var;
 	char *value;
 
@@ -184,7 +196,8 @@ env_slashify(void)
 	}
 }
 
-void os2_init(int *argcp, const char ***argvp)
+void
+os2_init(int *argcp, const char ***argvp)
 {
 	response(argcp, argvp);
 
@@ -201,10 +214,11 @@ void os2_init(int *argcp, const char ***argvp)
 	atexit(cleanup);
 }
 
-void setextlibpath(const char *name, const char *val)
+void
+setextlibpath(const char *name, const char *val)
 {
 	int flag;
-	char *p;
+	char *p, *cp;
 
 	if (!strcmp(name, "BEGINLIBPATH"))
 		flag = BEGIN_LIBPATH;
@@ -215,19 +229,19 @@ void setextlibpath(const char *name, const char *val)
 	else
 		return;
 
-	/* Convert slashes to backslashes. */
-	strdupx(p, val, ATEMP);
-	for (val = p; *p; p++) {
+	/* convert slashes to backslashes */
+	strdupx(cp, val, ATEMP);
+	for (p = cp; *p; p++) {
 		if (*p == '/')
 			*p = '\\';
 	}
 
-	DosSetExtLIBPATH(val, flag);
+	DosSetExtLIBPATH(cp, flag);
 
-	afree((char *)val, ATEMP);
+	afree(cp, ATEMP);
 }
 
-/* Remove trailing dots. */
+/* remove trailing dots */
 static char *
 remove_trailing_dots(char *name)
 {
@@ -239,45 +253,45 @@ remove_trailing_dots(char *name)
 	if (*p != '.' && *p != '/' && *p != '\\' && *p != ':')
 		p[1] = '\0';
 
-	return name;
+	return (name);
 }
 
 #define REMOVE_TRAILING_DOTS(name)	\
 	remove_trailing_dots(strcpy(alloca(strlen(name) + 1), name))
 
-/* Alias of stat() */
-int _std_stat(const char *, struct stat *);
+/* alias of stat() */
+extern int _std_stat(const char *, struct stat *);
 
-/* Replacement for stat() of kLIBC which fails if there are trailing dots */
+/* replacement for stat() of kLIBC which fails if there are trailing dots */
 int
 stat(const char *name, struct stat *buffer)
 {
-	return _std_stat(REMOVE_TRAILING_DOTS(name), buffer);
+	return (_std_stat(REMOVE_TRAILING_DOTS(name), buffer));
 }
 
-/* Alias of access() */
-int _std_access(const char *, int);
+/* alias of access() */
+extern int _std_access(const char *, int);
 
-/* Replacement for access() of kLIBC which fails if there are trailing dots */
+/* replacement for access() of kLIBC which fails if there are trailing dots */
 int
 access(const char *name, int mode)
 {
 	/*
-	 * On OS/2 kLIBC, X_OK is set only for executable files. This prevent
-	 * scripts from being executed.
+	 * On OS/2 kLIBC, X_OK is set only for executable files.
+	 * This prevents scripts from being executed.
 	 */
 	if (mode & X_OK)
 		mode = (mode & ~X_OK) | R_OK;
 
-	return _std_access(REMOVE_TRAILING_DOTS(name), mode);
+	return (_std_access(REMOVE_TRAILING_DOTS(name), mode));
 }
 
 #define MAX_X_SUFFIX_LEN	4
 
 static const char *x_suffix_list[] =
-	{"", ".ksh", ".exe", ".sh", ".cmd", ".com", ".bat", NULL};
+    { "", ".ksh", ".exe", ".sh", ".cmd", ".com", ".bat", NULL };
 
-/* Call fn() by appending executable extensions. */
+/* call fn() by appending executable extensions */
 static int
 access_stat_ex(int (*fn)(), const char *name, void *arg)
 {
@@ -285,7 +299,7 @@ access_stat_ex(int (*fn)(), const char *name, void *arg)
 	const char **x_suffix;
 	int rc = -1;
 
-	/* Otherwise, try to append executable suffixes */
+	/* otherwise, try to append executable suffixes */
 	x_name = alloc(strlen(name) + MAX_X_SUFFIX_LEN + 1, ATEMP);
 
 	for (x_suffix = x_suffix_list; rc && *x_suffix; x_suffix++) {
@@ -297,21 +311,21 @@ access_stat_ex(int (*fn)(), const char *name, void *arg)
 
 	afree(x_name, ATEMP);
 
-	return rc;
+	return (rc);
 }
 
 /* access()/search_access() version */
 int
 access_ex(int (*fn)(const char *, int), const char *name, int mode)
 {
-	return access_stat_ex(fn, name, (void *)mode);
+	return (access_stat_ex(fn, name, (void *)mode));
 }
 
 /* stat() version */
 int
 stat_ex(const char *name, struct stat *buffer)
 {
-	return access_stat_ex(stat, name, buffer);
+	return (access_stat_ex(stat, name, buffer));
 }
 
 static int
@@ -320,11 +334,11 @@ test_exec_exist(const char *name, char *real_name)
 	struct stat sb;
 
 	if (stat(name, &sb) < 0 || !S_ISREG(sb.st_mode))
-		return -1;
+		return (-1);
 
 	strcpy(real_name, name);
 
-	return 0;
+	return (0);
 }
 
 const char *
@@ -336,61 +350,60 @@ real_exec_name(const char *name)
 	if (access_stat_ex(test_exec_exist, real_name, x_name) != -1)
 		strdupx(real_name, x_name, ATEMP);
 
-	return real_name;
+	return (real_name);
 }
-
/* OS/2 can process a command line up to 32K. */
+
+/* OS/2 can process a command line up to 32 KiB */
 #define MAX_CMD_LINE_LEN 32768
 
-/* Make a response file to pass a very long command line. */
+/* make a response file to pass a very long command line */
 static char *
 make_response_file(char * const *argv)
 {
-	char  rsp_name_arg[] = "@mksh-rsp-XXXXXX";
+	char rsp_name_arg[] = "@mksh-rsp-XXXXXX";
 	char *rsp_name = &rsp_name_arg[1];
-	int   arg_len = 0;
-	int   i;
+	int arg_len = 0;
+	int i;
 
 	for (i = 0; argv[i]; i++)
 		arg_len += strlen(argv[i]) + 1;
 
 	/*
-	 * If a length of command line is longer than MAX_CMD_LINE_LEN, then use
-	 * a response file. OS/2 cannot process a command line longer than 32K.
-	 * Of course, a response file cannot be recognized by a normal OS/2
-	 * program, that is, neither non-EMX or non-kLIBC. But it cannot accept
-	 * a command line longer than 32K in itself. So using a response file
-	 * in this case, is an acceptable solution.
+	 * If a length of command line is longer than MAX_CMD_LINE_LEN, then
+	 * use a response file. OS/2 cannot process a command line longer
+	 * than 32K. Of course, a response file cannot be recognized by a
+	 * normal OS/2 program, that is, neither non-EMX or non-kLIBC. But
+	 * it cannot accept a command line longer than 32K in itself. So
+	 * using a response file in this case, is an acceptable solution.
 	 */
 	if (arg_len > MAX_CMD_LINE_LEN) {
 		int fd;
 		char *result;
 
 		if ((fd = mkstemp(rsp_name)) == -1)
-			return NULL;
+			return (NULL);
 
 		/* write all the arguments except a 0th program name */
 		for (i = 1; argv[i]; i++) {
 			write(fd, argv[i], strlen(argv[i]));
-			write(fd, "\n", 1 );
+			write(fd, "\n", 1);
 		}
 
 		close(fd);
-
 		add_temp(rsp_name);
-
 		strdupx(result, rsp_name_arg, ATEMP);
-
-		return result;
+		return (result);
 	}
 
-	return NULL;
+	return (NULL);
 }
 
-/* Alias of execve() */
-int _std_execve(const char *, char * const *, char * const *);
+/* alias of execve() */
+extern int _std_execve(const char *, char * const *, char * const *);
 
-/* Replacement for execve() of kLIBC */
-int execve(const char *name, char * const *argv, char * const *envp)
+/* replacement for execve() of kLIBC */
+int
+execve(const char *name, char * const *argv, char * const *envp)
 {
 	const char *exec_name;
 	FILE *fp;
@@ -409,16 +422,16 @@ int execve(const char *name, char * const *argv, char * const *envp)
 	exec_name = search_path(name, path, X_OK, NULL);
 	if (!exec_name) {
 		errno = ENOENT;
-		return -1;
+		return (-1);
 	}
 
-	/*
+	/*-
 	 * kLIBC execve() has problems when executing scripts.
 	 * 1. it fails to execute a script if a directory whose name
-	 * is same as an interpreter exists in a current directory.
+	 *    is same as an interpreter exists in a current directory.
 	 * 2. it fails to execute a script not starting with sharpbang.
 	 * 3. it fails to execute a batch file if COMSPEC is set to a shell
-	 * incompatible with cmd.exe, such as /bin/sh.
+	 *    incompatible with cmd.exe, such as /bin/sh.
 	 * And ksh process scripts more well, so let ksh process scripts.
 	 */
 	errno = 0;
@@ -438,7 +451,7 @@ int execve(const char *name, char * const *argv, char * const *envp)
 		errno = ENOEXEC;
 
 	if (errno == ENOEXEC)
-		return -1;
+		return (-1);
 
 	rsp_name_arg = make_response_file(argv);
 
@@ -452,16 +465,15 @@ int execve(const char *name, char * const *argv, char * const *envp)
 
 	pid = spawnve(P_NOWAIT, exec_name, argv, envp);
 
-	if (rsp_name_arg)
-		afree(rsp_name_arg, ATEMP);
+	afree(rsp_name_arg, ATEMP);
 
 	if (pid == -1) {
 		cleanup_temps();
 
-		return -1;
+		return (-1);
 	}
 
-	/* Close all opened handles */
+	/* close all opened handles */
 	for (fd = 0; fd < NUFILE; fd++) {
 		if (fcntl(fd, F_GETFD) == -1)
 			continue;
@@ -470,13 +482,13 @@ int execve(const char *name, char * const *argv, char * const *envp)
 	}
 
 	while ((rc = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
-		/* NOTHING */;
+		/* nothing */;
 
 	cleanup_temps();
 
-	/* Is this possible ? And is this right ? */
+	/* Is this possible? And is this right? */
 	if (rc == -1)
-		return -1;
+		return (-1);
 
 	if (WIFSIGNALED(status))
 		_exit(ksh_sigmask(WTERMSIG(status)));
@@ -486,7 +498,8 @@ int execve(const char *name, char * const *argv, char * const *envp)
 
 static struct temp *templist = NULL;
 
-static void add_temp(const char *name)
+static void
+add_temp(const char *name)
 {
 	struct temp *tp;
 
@@ -496,14 +509,15 @@ static void add_temp(const char *name)
 	templist = tp;
 }
 
-/* Alias of unlink() */
-int _std_unlink(const char *);
+/* alias of unlink() */
+extern int _std_unlink(const char *);
 
 /*
  * Replacement for unlink() of kLIBC not supporting to remove files used by
  * another processes.
  */
-int unlink(const char *name)
+int
+unlink(const char *name)
 {
 	int rc;
 
@@ -511,7 +525,7 @@ int unlink(const char *name)
 	if (rc == -1 && errno != ENOENT)
 		add_temp(name);
 
-	return rc;
+	return (rc);
 }
 
 static void