sys/kern: quiet -Wwrite-strings

Quiet a variety of Wwrite-strings warnings in sys/kern at low-impact
sites.  This patch avoids addressing certain others which would need to
plumb const through structure definitions.

Reviewed by:	kib, markj
Differential Revision:	https://reviews.freebsd.org/D23798

sys/kern/kern_cons.c

@@ -98,7 +98,7 @@ static char *consbuf;			/* buffer used by `consmsgbuf' */
 static struct callout conscallout;	/* callout for outputting to constty */
 struct msgbuf consmsgbuf;		/* message buffer for console tty */
 static u_char console_pausing;		/* pause after each line during probe */
-static char *console_pausestr=
+static const char console_pausestr[] =
 "<pause; press any key to proceed to next line or '.' to end pause mode>";
 struct tty *constty;			/* pointer to console "window" tty */
 static struct mtx cnputs_mtx;		/* Mutex for cnputs(). */
@@ -510,7 +510,7 @@ cnputc(int c)
 {
 	struct cn_device *cnd;
 	struct consdev *cn;
-	char *cp;
+	const char *cp;
 
 #ifdef EARLY_PRINTF
 	if (early_putc != NULL) {
@@ -571,7 +571,7 @@ cnputsn(const char *p, size_t n)
 }
 
 void
-cnputs(char *p)
+cnputs(const char *p)
 {
 	cnputsn(p, strlen(p));
 }

sys/kern/kern_linker.c

@@ -1765,7 +1765,7 @@ SYSCTL_STRING(_kern, OID_AUTO, module_path, CTLFLAG_RWTUN, linker_path,
 
 TUNABLE_STR("module_path", linker_path, sizeof(linker_path));
 
-static char *linker_ext_list[] = {
+static const char * const linker_ext_list[] = {
 	"",
 	".ko",
 	NULL
@@ -1782,7 +1782,8 @@ linker_lookup_file(const char *path, int pathlen, const char *name,
 {
 	struct nameidata nd;
 	struct thread *td = curthread;	/* XXX */
-	char *result, **cpp, *sep;
+	const char * const *cpp, *sep;
+	char *result;
 	int error, len, extlen, reclen, flags;
 	enum vtype type;
 
@@ -1838,8 +1839,9 @@ linker_hints_lookup(const char *path, int pathlen, const char *modname,
 	struct ucred *cred = td ? td->td_ucred : NULL;
 	struct nameidata nd;
 	struct vattr vattr, mattr;
+	const char *best, *sep;
 	u_char *hints = NULL;
-	u_char *cp, *recptr, *bufend, *result, *best, *pathbuf, *sep;
+	u_char *cp, *recptr, *bufend, *result, *pathbuf;
 	int error, ival, bestver, *intp, found, flags, clen, blen;
 	ssize_t reclen;
 

sys/kern/kern_shutdown.c

@@ -1714,7 +1714,7 @@ dump_finish(struct dumperinfo *di, struct kerneldumpheader *kdh)
 
 void
 dump_init_header(const struct dumperinfo *di, struct kerneldumpheader *kdh,
-    char *magic, uint32_t archver, uint64_t dumplen)
+    const char *magic, uint32_t archver, uint64_t dumplen)
 {
 	size_t dstsize;
 

sys/kern/kern_sig.c

@@ -3181,7 +3181,7 @@ proc_wkilled(struct proc *p)
  * Kill the current process for stated reason.
  */
 void
-killproc(struct proc *p, char *why)
+killproc(struct proc *p, const char *why)
 {
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);

sys/kern/link_elf.c

@@ -405,7 +405,7 @@ link_elf_init(void* arg)
 	Elf_Size *ctors_sizep;
 	caddr_t modptr, baseptr, sizeptr;
 	elf_file_t ef;
-	char *modname;
+	const char *modname;
 
 	linker_add_class(&link_elf_class);
 

sys/sys/bufobj.h

@@ -78,7 +78,7 @@ typedef int b_sync_t(struct bufobj *, int waitfor);
 typedef void b_bdflush_t(struct bufobj *, struct buf *);
 
 struct buf_ops {
-	char		*bop_name;
+	const char	*bop_name;
 	b_write_t	*bop_write;
 	b_strategy_t	*bop_strategy;
 	b_sync_t	*bop_sync;

sys/sys/conf.h

@@ -374,7 +374,7 @@ int dump_append(struct dumperinfo *, void *, vm_offset_t, size_t);
 int dump_write(struct dumperinfo *, void *, vm_offset_t, off_t, size_t);
 int dump_finish(struct dumperinfo *di, struct kerneldumpheader *kdh);
 void dump_init_header(const struct dumperinfo *di, struct kerneldumpheader *kdh,
-    char *magic, uint32_t archver, uint64_t dumplen);
+    const char *magic, uint32_t archver, uint64_t dumplen);
 
 #endif /* _KERNEL */
 

sys/sys/cons.h

@@ -136,7 +136,7 @@ int	cncheckc(void);
 int	cngetc(void);
 void	cngets(char *, size_t, int);
 void	cnputc(int);
-void	cnputs(char *);
+void	cnputs(const char *);
 void	cnputsn(const char *, size_t);
 int	cnunavailable(void);
 void	constty_set(struct tty *tp);

sys/sys/signalvar.h

@@ -384,7 +384,7 @@ sigallowstop(int prev)
 int	cursig(struct thread *td);
 void	execsigs(struct proc *p);
 void	gsignal(int pgid, int sig, ksiginfo_t *ksi);
-void	killproc(struct proc *p, char *why);
+void	killproc(struct proc *p, const char *why);
 ksiginfo_t * ksiginfo_alloc(int wait);
 void	ksiginfo_free(ksiginfo_t *ksi);
 int	pksignal(struct proc *p, int sig, ksiginfo_t *ksi);