u-boot/include/exports.h
Wolfgang Denk 54841ab50c 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>
2010-07-04 23:55:42 +02:00

56 lines
1.3 KiB
C

#ifndef __EXPORTS_H__
#define __EXPORTS_H__
#ifndef __ASSEMBLY__
#include <common.h>
/* These are declarations of exported functions available in C code */
unsigned long get_version(void);
int getc(void);
int tstc(void);
void putc(const char);
void puts(const char*);
int printf(const char* fmt, ...);
void install_hdlr(int, interrupt_handler_t*, void*);
void free_hdlr(int);
void *malloc(size_t);
void free(void*);
void __udelay(unsigned long);
unsigned long get_timer(unsigned long);
int vprintf(const char *, va_list);
void do_reset (void);
unsigned long simple_strtoul(const char *cp,char **endp,unsigned int base);
char *getenv (char *name);
int setenv (char *varname, char *varvalue);
long simple_strtol(const char *cp,char **endp,unsigned int base);
int strcmp(const char * cs,const char * ct);
int ustrtoul(const char *cp, char **endp, unsigned int base);
#ifdef CONFIG_HAS_UID
void forceenv (char *varname, char *varvalue);
#endif
#if defined(CONFIG_CMD_I2C)
int i2c_write (uchar, uint, int , uchar* , int);
int i2c_read (uchar, uint, int , uchar* , int);
#endif
#include <spi.h>
void app_startup(char * const *);
#endif /* ifndef __ASSEMBLY__ */
enum {
#define EXPORT_FUNC(x) XF_ ## x ,
#include <_exports.h>
#undef EXPORT_FUNC
XF_MAX
};
#define XF_VERSION 6
#if defined(CONFIG_I386)
extern gd_t *global_data;
#endif
#endif /* __EXPORTS_H__ */