In my previous report I suggesting building one of the example modules from the
ksh source distribution (open.c) - that is still a worthwhile test
case but I have another that may be simpler to work with:
This example, when run, takes two arguments, a variable name, and a value, and
assigns the value to the variable. It's useful as a test case because
it's simple, more so than open.c. It's a bit limited as a test case because it
doesn't include any stdio calls - which is currently where I'm stuck in
terms of getting things working.
Interestingly enough, I discovered that some of the build files in the ksh
source distribution do appear to conditionally add -Wl,--export-dynamic to
the linker flags, but for whatever reason that doesn't seem to be taking effect
in the actual build.
/* setvar:
*
* A loadable Korn Shell "builtin" that provides a simple test of the process of creating builtins
*/
#include <ast.h>
#include <error.h>
#include <defs.h>
#include <variables.h>
#include <builtins.h>
#include <nval.h>
#include "stdio.h"
/* b_setvar() is ksh's entry point to the module
Shbltin_t is a starting point for accessing ksh data structures.
It is defined in src/lib/libast/include/shcmd.h in the ksh source tree. */
int b_setvar(int argc, char *argv[], Shbltin_t *context)
{
Shell_t* shp = context->shp;
Namval_t* var;
char* var_name = 0;
char* var_value = 0;
if (argc == 3)
{
var_name = argv[1];
var_value = argv[2];
}
else
{
return -1;
}
var = nv_open(var_name, shp->var_tree, (NV_ASSIGN | NV_IDENT | NV_VARNAME));
/* I think nv_open will actually print our error and exit out for us if we get a bad var name
But just in case... */
if (!var)
{
return -2;
}
nv_putval(var, var_value, 0);
nv_close(var);
return 0;
}
SHLIB(setvar);
INCLUDES=-I /home/tetsujin/src/ksh-93u+20120801/arch/linux.i386-64/include/ast/ -I /home/tetsujin/src/ksh-93u+20120801/src/cmd/ksh93/include/ -I /home/tetsujin/src/ksh-93u+20120801/arch/linux.i386-64/src/cmd/ksh93/
CCFLAGS=-fPIC -g $(INCLUDES)
LDFLAGS=-shared -L/home/tetsujin/src/ksh-93u+20120801/arch/linux.i386-64/lib -last
all: setvar.so
.c.o:
gcc -c $(CCFLAGS) -c -o $@ $<
setvar.so: setvar.o
gcc $(LDFLAGS) -Wl,-soname,setvar.so -o setvar.so setvar.o
