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#if 0
// simple example code
error
cd(Args args)
{
switch (args.len) {
case 0:
errorf("reached cd with no arguments!");
return 1;
case 1:
one:
errorf("sh: expected argument to command 'cd'");
return 1;
case 2:
if (args.a[1] == nil)
goto one;
break;
default:
errorf("sh: too many arguments to command 'cd'");
return 1;
}
if (chdir(args.a[1]))
errorf("cd fail: %s", strerror(errno));
return 0;
}
error
quit(Args args)
{
exit(0);
}
Builtin builtins[] = {
{ "cd", cd },
{ "exit", quit },
};
void
clear(Header *arr)
{
arr->len = 0;
}
int
readline(Code *code)
{
int n, b;
n = code->len;
getchar:
if (code->len >= code->cap) {
code->cap += 100;
code->s = realloc(code->s, code->cap);
}
/* TODO: unicode? */
switch ((b = getchar())) {
case EOF:
n = -1;
goto null;
case '\n':
n = code->len - n;
null:
code->s[code->len] = '\0';
break;
default:
code->s[code->len++] = b;
goto getchar;
}
return n;
}
/* TODO: unicode */
int
readargs(Code code, Args *args)
{
if (args->a)
clear(&args->hdr);
else {
args->cap += 20;
args->a = realloc(args->a, args->cap);
}
args->a[args->len++] = code.s;
while (*code.s) {
if (!isspace(*code.s++))
continue;
code.s[-1] = '\0';
/* consume all remaining space */
while (isspace(*code.s))
code.s++;
if (args->len >= args->cap-1) {
args->cap += 20;
args->a = realloc(args->a, args->cap);
}
args->a[args->len++] = code.s;
}
/* nil acts as a sentinel value */
args->a[args->len] = nil;
return args->len;
}
error
execute(Args args)
{
int i, status;
pid_t cid, wid;
for (i = 0; i < arrlen(builtins); i++) {
if (strcmp(args.a[0], builtins[i].cmd) == 0)
return builtins[i].func(args);
}
if ((cid = fork()) == 0) {
if (execvp(args.a[0], args.a) == -1)
errorf("exec failed: %s", strerror(errno));
exit(1);
} else if (cid > 0)
do
wid = waitpid(cid, &status, WUNTRACED);
while (!WIFEXITED(status) && !WIFSIGNALED(status));
else
errorf("fork failed: %s", strerror(errno));
return status;
}
static
void
flush(void)
{
io·flush(stdout);
}
static
void
prompt(void)
{
printf(";");
flush();
}
int
main(int argc, char *argv[])
{
int i, err, n;
Code code = {0};
Args args = {0};
ARGBEGIN {
} ARGEND;
do {
clear(&code.hdr);
prompt();
n = readline(&code);
readargs(code, &args);
err = execute(args);
} while (!err && n > 0);
}
#endif
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