Imbus/xv6-riscv-kernel
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believe it or not, this was working

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the macro expansion of "char *cp;" turned into
char *(curproc[cpu()]);  which declares a dynamically
sized array of char* called curproc.

so then &cp == &(curproc[cpu()]) was actually a
stack variable as "expected".  it was one past the
end of the array, but the implicit alloca allocated
more than was necessary.

do not tell me that making cp a #define was a bad idea.
there are worse problems to fix.  more on that later.
This commit is contained in:
rsc 2007-09-27 05:13:10 +00:00
parent 90d975e9c8
commit 666f58c711
3 changed files with 14 additions and 10 deletions
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12
sysfile.c
View file

@ -49,11 +49,11 @@ sys_read(void)
{
struct file *f;
int n;
char *cp;
char *p;
if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0)
return -1;
return fileread(f, cp, n);
return fileread(f, p, n);
}
int
@ -61,11 +61,11 @@ sys_write(void)
{
struct file *f;
int n;
char *cp;
char *p;
if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0)
return -1;
return filewrite(f, cp, n);
return filewrite(f, p, n);
}
int