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/* proc.c -- process control system calls ($Revision: 1.2 $) */
#include "es.h"
/* TODO: the rusage code for the time builtin really needs to be cleaned up */
#if HAVE_WAIT3
#include <sys/time.h>
#include <sys/resource.h>
#endif
Boolean hasforked = FALSE;
typedef struct Proc Proc;
struct Proc {
int pid;
int status;
Boolean alive, background;
Proc *next, *prev;
#if HAVE_WAIT3
struct rusage rusage;
#endif
};
static Proc *proclist = NULL;
/* mkproc -- create a Proc structure */
extern Proc *mkproc(int pid, Boolean background) {
Proc *proc;
for (proc = proclist; proc != NULL; proc = proc->next)
if (proc->pid == pid) { /* are we recycling pids? */
assert(!proc->alive); /* if false, violates unix semantics */
break;
}
if (proc == NULL) {
proc = ealloc(sizeof (Proc));
proc->next = proclist;
}
proc->pid = pid;
proc->alive = TRUE;
proc->background = background;
proc->prev = NULL;
return proc;
}
/* efork -- fork (if necessary) and clean up as appropriate */
extern int efork(Boolean parent, Boolean background) {
if (parent) {
int pid = fork();
switch (pid) {
default: { /* parent */
Proc *proc = mkproc(pid, background);
if (proclist != NULL)
proclist->prev = proc;
proclist = proc;
return pid;
}
case 0: /* child */
proclist = NULL;
hasforked = TRUE;
break;
case -1:
fail("es:efork", "fork: %s", esstrerror(errno));
}
}
closefds();
setsigdefaults();
newchildcatcher();
return 0;
}
#if HAVE_WAIT3
static struct rusage wait_rusage;
#endif
/* dowait -- a wait wrapper that interfaces with signals */
static int dowait(int *statusp) {
int n;
interrupted = FALSE;
if (!setjmp(slowlabel)) {
slow = TRUE;
n = interrupted ? -2 :
#if HAVE_WAIT3
wait3((void *) statusp, 0, &wait_rusage);
#else
wait((void *) statusp);
#endif
} else
n = -2;
slow = FALSE;
if (n == -2) {
errno = EINTR;
n = -1;
}
return n;
}
/* reap -- mark a process as dead and attach its exit status */
static void reap(int pid, int status) {
Proc *proc;
for (proc = proclist; proc != NULL; proc = proc->next)
if (proc->pid == pid) {
assert(proc->alive);
proc->alive = FALSE;
proc->status = status;
#if HAVE_WAIT3
proc->rusage = wait_rusage;
#endif
return;
}
}
/* ewait -- wait for a specific process to die, or any process if pid == 0 */
extern int ewait(int pid, Boolean interruptible, void *rusage) {
Proc *proc;
top:
for (proc = proclist; proc != NULL; proc = proc->next)
if (proc->pid == pid || (pid == 0 && !proc->alive)) {
int status;
if (proc->alive) {
int deadpid;
while ((deadpid = dowait(&proc->status)) != pid)
if (deadpid != -1)
reap(deadpid, proc->status);
else if (errno != EINTR)
fail("es:ewait", "wait: %s", esstrerror(errno));
else if (interruptible)
SIGCHK();
proc->alive = FALSE;
#if HAVE_WAIT3
proc->rusage = wait_rusage;
#endif
}
if (proc->next != NULL)
proc->next->prev = proc->prev;
if (proc->prev != NULL)
proc->prev->next = proc->next;
else
proclist = proc->next;
status = proc->status;
if (proc->background)
printstatus(proc->pid, status);
efree(proc);
#if HAVE_WAIT3
if (rusage != NULL)
memcpy(rusage, &proc->rusage, sizeof (struct rusage));
#else
assert(rusage == NULL);
#endif
return status;
}
if (pid == 0) {
int status;
while ((pid = dowait(&status)) == -1) {
if (errno != EINTR)
fail("es:ewait", "wait: %s", esstrerror(errno));
if (interruptible)
SIGCHK();
}
reap(pid, status);
goto top;
}
fail("es:ewait", "wait: %d is not a child of this shell", pid);
NOTREACHED;
}
#include "prim.h"
PRIM(apids) {
Proc *p;
Ref(List *, lp, NULL);
for (p = proclist; p != NULL; p = p->next)
if (p->background && p->alive) {
Term *t = mkstr(str("%d", p->pid));
lp = mklist(t, lp);
}
/* TODO: sort the return value, but by number? */
RefReturn(lp);
}
PRIM(wait) {
int pid;
if (list == NULL)
pid = 0;
else if (list->next == NULL) {
pid = atoi(getstr(list->term));
if (pid <= 0) {
fail("$&wait", "wait: %d: bad pid", pid);
NOTREACHED;
}
} else {
fail("$&wait", "usage: wait [pid]");
NOTREACHED;
}
return mklist(mkstr(mkstatus(ewait(pid, TRUE, NULL))), NULL);
}
extern Dict *initprims_proc(Dict *primdict) {
X(apids);
X(wait);
return primdict;
}
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