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>
13 lines
419 B
C
13 lines
419 B
C
/* A little trick taken from the kernel asm-offsets.h where we convert
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* the C structures automatically into a bunch of defines for use in
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* the assembly files.
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*/
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#include <linux/stddef.h>
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#include <asm/mach-common/bits/bootrom.h>
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#define _DEFINE(sym, val) asm volatile("\n->" #sym " %0 " #val : : "i" (val))
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#define DEFINE(s, m) _DEFINE(offset_##s##_##m, offsetof(s, m))
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int main(int argc, char * const argv[])
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