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/* This module should be dynamically loaded with enable -f
* which would create a new builtin named mypid. You'll need
* the source code for GNU bash to recompile this module.
*
* Then, from within bash, enable -f ./mypid enable_mypid, where ./mypid
* is the binary obtained from running make. Hereafter, `${MYPID}'
* is a shell builtin variable.
*
* This defines an unload hook function that is called when the builtin is
* deleted with enable -d that will unbind the MYPID variable so future
* references to it do not attempt to access memory that is no longer part
* of this process's address space.
*/
#include <config.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "builtins.h"
#include "shell.h"
#define INIT_DYNAMIC_VAR(var, val, gfunc, afunc) \
do \
{ SHELL_VAR *v = bind_variable (var, (val), 0); \
if (v) \
{ \
v->dynamic_value = gfunc; \
v->assign_func = afunc; \
} \
} \
while (0)
static SHELL_VAR *
assign_mypid (
SHELL_VAR *self,
char *value,
arrayind_t unused,
char *key )
{
return (self);
}
static SHELL_VAR *
get_mypid (SHELL_VAR *var)
{
int rv;
char *p;
rv = getpid();
p = itos (rv);
FREE (value_cell (var));
VSETATTR (var, att_integer);
var_setvalue (var, p);
return (var);
}
int
enable_mypid_builtin(WORD_LIST *list)
{
INIT_DYNAMIC_VAR ("MYPID", (char *)NULL, get_mypid, assign_mypid);
return 0;
}
void
enable_mypid_builtin_unload (char *s)
{
unbind_variable ("MYPID");
}
char const *enable_mypid_doc[] = {
"Enable $MYPID.",
"",
"Enables use of the ${MYPID} dynamic variable. ",
"It will yield the current pid of a subshell.",
(char *)0
};
struct builtin enable_mypid_struct = {
"enable_mypid",
enable_mypid_builtin,
BUILTIN_ENABLED,
(char**)(void*)enable_mypid_doc,
"enable_mypid N",
0
};
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