Make sure that argv[] argument pointers are not modified.

The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands.  Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".

This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:

int main (int argc, char **argv)
{
	while (--argc > 0 && **++argv == '-') {
/* ====> */	while (*++*argv) {
			switch (**argv) {
			case 'd':
				debug++;
				break;
			...
			default:
				usage ();
			}
		}
	}
	...
}

The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell.  With the modification, the compiler will prevent this with
an
	error: increment of read-only location '*argv'

N.B.: The code above can be trivially rewritten like this:

	while (--argc > 0 && **++argv == '-') {
		char *arg = *argv;
		while (*++arg) {
			switch (*arg) {
			...

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>

7 files changed, 11 insertions, 11 deletions

diff --git a/include/bedbug/type.h b/include/bedbug/type.h
index 38ee9de..b7b447b 100644
--- a/include/bedbug/type.h
+++ b/include/bedbug/type.h
@@ -15,7 +15,7 @@ typedef struct {
 	int current_bp;
 	struct pt_regs *regs;
 
-	void (*do_break) (cmd_tbl_t *, int, int, char *[]);
+	void (*do_break) (cmd_tbl_t *, int, int, char * const []);
 	void (*break_isr) (struct pt_regs *);
 	int (*find_empty) (void);
 	int (*set) (int, unsigned long);
diff --git a/include/command.h b/include/command.h
index 55caa6e..9144d69 100644
--- a/include/command.h
+++ b/include/command.h
@@ -48,14 +48,14 @@ struct cmd_tbl_s {
 	int		maxargs;	/* maximum number of arguments	*/
 	int		repeatable;	/* autorepeat allowed?		*/
 					/* Implementation function	*/
-	int		(*cmd)(struct cmd_tbl_s *, int, int, char *[]);
+	int		(*cmd)(struct cmd_tbl_s *, int, int, char * const []);
 	char		*usage;		/* Usage message	(short)	*/
 #ifdef	CONFIG_SYS_LONGHELP
 	char		*help;		/* Help  message	(long)	*/
 #endif
 #ifdef CONFIG_AUTO_COMPLETE
 	/* do auto completion on the arguments */
-	int		(*complete)(int argc, char *argv[], char last_char, int maxv, char *cmdv[]);
+	int		(*complete)(int argc, char * const argv[], char last_char, int maxv, char *cmdv[]);
 #endif
 };
 
@@ -67,7 +67,7 @@ extern cmd_tbl_t  __u_boot_cmd_end;
 
 /* common/command.c */
 int _do_help (cmd_tbl_t *cmd_start, int cmd_items, cmd_tbl_t * cmdtp, int
-	      flag, int argc, char *argv[]);
+	      flag, int argc, char * const argv[]);
 cmd_tbl_t *find_cmd(const char *cmd);
 cmd_tbl_t *find_cmd_tbl (const char *cmd, cmd_tbl_t *table, int table_len);
 
@@ -83,7 +83,7 @@ extern int cmd_auto_complete(const char *const prompt, char *buf, int *np, int *
  *
  * All commands use a common argument format:
  *
- * void function (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+ * void function (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
  */
 
 typedef	void	command_t (cmd_tbl_t *, int, int, char *[]);
diff --git a/include/common.h b/include/common.h
index 48f6a1a..eddec22 100644
--- a/include/common.h
+++ b/include/common.h
@@ -718,7 +718,7 @@ void show_boot_progress(int val);
 int cpu_status(int nr);
 int cpu_reset(int nr);
 int cpu_disable(int nr);
-int cpu_release(int nr, int argc, char *argv[]);
+int cpu_release(int nr, int argc, char * const argv[]);
 #endif
 
 #endif /* __ASSEMBLY__ */
diff --git a/include/exports.h b/include/exports.h
index 9588bc9..1d79a31 100644
--- a/include/exports.h
+++ b/include/exports.h
@@ -35,7 +35,7 @@ int i2c_read (uchar, uint, int , uchar* , int);
 #endif
 #include <spi.h>
 
-void app_startup(char **);
+void app_startup(char * const *);
 
 #endif    /* ifndef __ASSEMBLY__ */
 
diff --git a/include/image.h b/include/image.h
index 366b622..bcc08d1 100644
--- a/include/image.h
+++ b/include/image.h
@@ -328,12 +328,12 @@ int genimg_get_format (void *img_addr);
 int genimg_has_config (bootm_headers_t *images);
 ulong genimg_get_image (ulong img_addr);
 
-int boot_get_ramdisk (int argc, char *argv[], bootm_headers_t *images,
+int boot_get_ramdisk (int argc, char * const argv[], bootm_headers_t *images,
 		uint8_t arch, ulong *rd_start, ulong *rd_end);
 
 
 #ifdef CONFIG_OF_LIBFDT
-int boot_get_fdt (int flag, int argc, char *argv[], bootm_headers_t *images,
+int boot_get_fdt (int flag, int argc, char * const argv[], bootm_headers_t *images,
 		char **of_flat_tree, ulong *of_size);
 int boot_relocate_fdt (struct lmb *lmb, ulong bootmap_base,
 		char **of_flat_tree, ulong *of_size);
diff --git a/include/kgdb.h b/include/kgdb.h
index f543cd6..b6ba742 100644
--- a/include/kgdb.h
+++ b/include/kgdb.h
@@ -55,7 +55,7 @@ extern int kgdb_getregs(struct pt_regs *, char *, int);
 extern void kgdb_putreg(struct pt_regs *, int, char *, int);
 extern void kgdb_putregs(struct pt_regs *, char *, int);
 extern int kgdb_trap(struct pt_regs *);
-extern void kgdb_breakpoint(int argc, char *argv[]);
+extern void kgdb_breakpoint(int argc, char * const argv[]);
 
 /* these functions are provided by the platform serial driver */
 extern void kgdb_serial_init(void);
diff --git a/include/vxworks.h b/include/vxworks.h
index 1633904..917a9ff 100644
--- a/include/vxworks.h
+++ b/include/vxworks.h
@@ -24,7 +24,7 @@
 #ifndef _VXWORKS_H_
 #define _VXWORKS_H_
 
-int do_bootvx(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+int do_bootvx(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 
 /*
  * Use bootaddr to find the location in memory that VxWorks