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diff --git a/c_src/exile.c b/c_src/exile.c
index b1e2812..a5ea734 100644
--- a/c_src/exile.c
+++ b/c_src/exile.c
@@ -1,600 +1,625 @@
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200809L
#endif
#include "erl_nif.h"
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#ifdef ERTS_DIRTY_SCHEDULERS
#define USE_DIRTY_IO ERL_NIF_DIRTY_JOB_IO_BOUND
#else
#define USE_DIRTY_IO 0
#endif
//#define DEBUG
#ifdef DEBUG
#define debug(...) \
do { \
enif_fprintf(stderr, __VA_ARGS__); \
enif_fprintf(stderr, "\n"); \
} while (0)
#define start_timing() ErlNifTime __start = enif_monotonic_time(ERL_NIF_USEC)
#define elapsed_microseconds() (enif_monotonic_time(ERL_NIF_USEC) - __start)
#else
#define debug(...)
#define start_timing()
#define elapsed_microseconds() 0
#endif
#define error(...) \
do { \
enif_fprintf(stderr, __VA_ARGS__); \
enif_fprintf(stderr, "\n"); \
} while (0)
#define GET_CTX(env, arg, ctx) \
do { \
ExilePriv *data = enif_priv_data(env); \
if (enif_get_resource(env, arg, data->rt, (void **)&ctx) == false) { \
return make_error(env, ATOM_INVALID_CTX); \
} \
} while (0);
static const int PIPE_READ = 0;
static const int PIPE_WRITE = 1;
static const int PIPE_CLOSED = -1;
static const int CMD_EXIT = -1;
static const int MAX_ARGUMENTS = 20;
static const int MAX_ARGUMENT_LEN = 1024;
/* We are choosing an exit code which is not reserved see:
* https://www.tldp.org/LDP/abs/html/exitcodes.html. */
static const int FORK_EXEC_FAILURE = 125;
static ERL_NIF_TERM ATOM_TRUE;
static ERL_NIF_TERM ATOM_FALSE;
static ERL_NIF_TERM ATOM_OK;
static ERL_NIF_TERM ATOM_ERROR;
static ERL_NIF_TERM ATOM_UNDEFINED;
static ERL_NIF_TERM ATOM_INVALID_CTX;
static ERL_NIF_TERM ATOM_PIPE_CLOSED;
static ERL_NIF_TERM ATOM_EAGAIN;
/* command exit types */
static ERL_NIF_TERM ATOM_EXIT;
static ERL_NIF_TERM ATOM_SIGNALED;
static ERL_NIF_TERM ATOM_STOPPED;
enum exec_status {
SUCCESS,
PIPE_CREATE_ERROR,
PIPE_FLAG_ERROR,
FORK_ERROR,
PIPE_DUP_ERROR,
NULL_DEV_OPEN_ERROR,
};
enum exit_type { NORMAL_EXIT, SIGNALED, STOPPED };
typedef struct ExilePriv {
ErlNifResourceType *rt;
} ExilePriv;
typedef struct ExecContext {
int cmd_input_fd;
int cmd_output_fd;
int exit_status; // can be exit status or signal number depending on exit_type
enum exit_type exit_type;
pid_t pid;
} ExecContext;
typedef struct StartProcessResult {
bool success;
int err;
ExecContext context;
} StartProcessResult;
/* TODO: assert if the external process is exit (?) */
static void rt_dtor(ErlNifEnv *env, void *obj) {
debug("Exile rt_dtor called\n");
}
static void rt_stop(ErlNifEnv *env, void *obj, int fd, int is_direct_call) {
debug("Exile rt_stop called\n");
}
static void rt_down(ErlNifEnv *env, void *obj, ErlNifPid *pid,
ErlNifMonitor *monitor) {
debug("Exile rt_down called\n");
}
static ErlNifResourceTypeInit rt_init = {rt_dtor, rt_stop, rt_down};
static inline ERL_NIF_TERM make_ok(ErlNifEnv *env, ERL_NIF_TERM term) {
return enif_make_tuple2(env, ATOM_OK, term);
}
static inline ERL_NIF_TERM make_error(ErlNifEnv *env, ERL_NIF_TERM term) {
return enif_make_tuple2(env, ATOM_ERROR, term);
}
static int set_flag(int fd, int flags) {
return fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | flags);
}
static void close_all(int pipes[2][2]) {
for (int i = 0; i < 2; i++) {
if (pipes[i][PIPE_READ] > 0)
close(pipes[i][PIPE_READ]);
if (pipes[i][PIPE_WRITE] > 0)
close(pipes[i][PIPE_WRITE]);
}
}
+/* time is assumed to be in microseconds */
+static void notify_consumed_timeslice(ErlNifEnv *env, ErlNifTime start, ErlNifTime stop) {
+ ErlNifTime pct;
+
+ pct = (ErlNifTime)((stop - start) / 10);
+ if (pct > 100)
+ pct = 100;
+ else if (pct == 0)
+ pct = 1;
+ enif_consume_timeslice(env, pct);
+}
+
/* This is not ideal, but as of now there is no portable way to do this */
static void close_all_fds() {
int fd_limit = (int)sysconf(_SC_OPEN_MAX);
for (int i = STDERR_FILENO + 1; i < fd_limit; i++)
close(i);
}
static StartProcessResult start_proccess(char *args[], bool stderr_to_console) {
StartProcessResult result = {.success = false};
pid_t pid;
int pipes[2][2] = {{0, 0}, {0, 0}};
if (pipe(pipes[STDIN_FILENO]) == -1 || pipe(pipes[STDOUT_FILENO]) == -1) {
result.err = errno;
perror("[exile] failed to create pipes");
close_all(pipes);
return result;
}
const int r_cmdin = pipes[STDIN_FILENO][PIPE_READ];
const int w_cmdin = pipes[STDIN_FILENO][PIPE_WRITE];
const int r_cmdout = pipes[STDOUT_FILENO][PIPE_READ];
const int w_cmdout = pipes[STDOUT_FILENO][PIPE_WRITE];
if (set_flag(r_cmdin, O_CLOEXEC) < 0 || set_flag(w_cmdout, O_CLOEXEC) < 0 ||
set_flag(w_cmdin, O_CLOEXEC | O_NONBLOCK) < 0 ||
set_flag(r_cmdout, O_CLOEXEC | O_NONBLOCK) < 0) {
result.err = errno;
perror("[exile] failed to set flags for pipes");
close_all(pipes);
return result;
}
- /* TODO: fork() can be expensive. especially in mac os. we should report
- * correct reduction cost for this to avoid potential scheduler collapse */
switch (pid = fork()) {
case -1:
result.err = errno;
perror("[exile] failed to fork");
close_all(pipes);
return result;
case 0: // child
close(STDIN_FILENO);
close(STDOUT_FILENO);
if (dup2(r_cmdin, STDIN_FILENO) < 0) {
perror("[exile] failed to dup to stdin");
/* We are assuming FORK_EXEC_FAILURE exit code wont be used by the command
* we are running. Technically we can not assume any exit code here. The
* parent can not differentiate between exit before `exec` and the normal
* command exit.
* One correct way to solve this might be to have a separate
* pipe shared between child and parent and signaling the parent by
* closing it or writing to it. */
_exit(FORK_EXEC_FAILURE);
}
if (dup2(w_cmdout, STDOUT_FILENO) < 0) {
perror("[exile] failed to dup to stdout");
_exit(FORK_EXEC_FAILURE);
}
if (stderr_to_console != true) {
close(STDERR_FILENO);
int dev_null = open("/dev/null", O_WRONLY);
if (dev_null == -1) {
perror("[exile] failed to open /dev/null");
_exit(FORK_EXEC_FAILURE);
}
if (dup2(dev_null, STDERR_FILENO) < 0) {
perror("[exile] failed to dup stderr");
_exit(FORK_EXEC_FAILURE);
}
close(dev_null);
}
close_all_fds();
execvp(args[0], args);
perror("[exile] execvp(): failed");
_exit(FORK_EXEC_FAILURE);
default: // parent
/* close file descriptors used by child */
close(r_cmdin);
close(w_cmdout);
result.success = true;
result.context.pid = pid;
result.context.cmd_input_fd = w_cmdin;
result.context.cmd_output_fd = r_cmdout;
return result;
}
}
/* TODO: return appropriate error instead returning generic "badarg" error */
static ERL_NIF_TERM exec_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
char tmp[MAX_ARGUMENTS][MAX_ARGUMENT_LEN + 1];
char *exec_args[MAX_ARGUMENTS + 1];
-
+ ErlNifTime start;
unsigned int args_len;
+
+ start = enif_monotonic_time(ERL_NIF_USEC);
+
if (enif_get_list_length(env, argv[0], &args_len) != true)
return enif_make_badarg(env);
if (args_len > MAX_ARGUMENTS)
return enif_make_badarg(env);
ERL_NIF_TERM head, tail, list = argv[0];
for (unsigned int i = 0; i < args_len; i++) {
if (enif_get_list_cell(env, list, &head, &tail) != true)
return enif_make_badarg(env);
if (enif_get_string(env, head, tmp[i], MAX_ARGUMENT_LEN, ERL_NIF_LATIN1) <
1)
return enif_make_badarg(env);
exec_args[i] = tmp[i];
list = tail;
}
exec_args[args_len] = NULL;
bool stderr_to_console = true;
int tmp_int;
if (enif_get_int(env, argv[1], &tmp_int) != true)
return enif_make_badarg(env);
stderr_to_console = tmp_int == 1 ? true : false;
struct ExilePriv *data = enif_priv_data(env);
StartProcessResult result = start_proccess(exec_args, stderr_to_console);
ExecContext *ctx = NULL;
ERL_NIF_TERM term;
if (result.success) {
ctx = enif_alloc_resource(data->rt, sizeof(ExecContext));
ctx->cmd_input_fd = result.context.cmd_input_fd;
ctx->cmd_output_fd = result.context.cmd_output_fd;
ctx->pid = result.context.pid;
debug("pid: %d cmd_in_fd: %d cmd_out_fd: %d", ctx->pid, ctx->cmd_input_fd,
ctx->cmd_output_fd);
term = enif_make_resource(env, ctx);
/* resource should be collected beam GC when there are no more references */
enif_release_resource(ctx);
+ notify_consumed_timeslice(env, start, enif_monotonic_time(ERL_NIF_USEC));
+
return make_ok(env, term);
} else {
return make_error(env, enif_make_int(env, result.err));
}
}
static int select_write(ErlNifEnv *env, ExecContext *ctx) {
int retval = enif_select(env, ctx->cmd_input_fd, ERL_NIF_SELECT_WRITE, ctx,
NULL, ATOM_UNDEFINED);
if (retval != 0)
perror("select_write()");
return retval;
}
static ERL_NIF_TERM write_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
if (argc != 2)
enif_make_badarg(env);
+ ErlNifTime start;
+ start = enif_monotonic_time(ERL_NIF_USEC);
+
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->cmd_input_fd == PIPE_CLOSED)
return make_error(env, ATOM_PIPE_CLOSED);
ErlNifBinary bin;
/* TODO: should not use enif_inspect_binary */
if (enif_inspect_binary(env, argv[1], &bin) != true)
return enif_make_badarg(env);
unsigned int result = write(ctx->cmd_input_fd, bin.data, bin.size);
+ notify_consumed_timeslice(env, start, enif_monotonic_time(ERL_NIF_USEC));
+
/* TODO: branching is ugly, cleanup required */
if (result >= bin.size) { // request completely satisfied
return make_ok(env, enif_make_int(env, result));
} else if (result >= 0) { // request partially satisfied
int retval = select_write(env, ctx);
if (retval != 0)
return make_error(env, enif_make_int(env, retval));
return make_ok(env, enif_make_int(env, result));
} else if (errno == EAGAIN) { // busy
int retval = select_write(env, ctx);
if (retval != 0)
return make_error(env, enif_make_int(env, retval));
return make_error(env, ATOM_EAGAIN);
} else { // Error
perror("write()");
return make_error(env, enif_make_int(env, errno));
}
}
static ERL_NIF_TERM close_pipe(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
int kind;
enif_get_int(env, argv[1], &kind);
int result;
switch (kind) {
case 0:
if (ctx->cmd_input_fd == PIPE_CLOSED) {
return ATOM_OK;
} else {
result = close(ctx->cmd_input_fd);
if (result == 0) {
ctx->cmd_input_fd = PIPE_CLOSED;
return ATOM_OK;
} else {
perror("cmd_input_fd close()");
return make_error(env, enif_make_int(env, errno));
}
}
case 1:
if (ctx->cmd_output_fd == PIPE_CLOSED) {
return ATOM_OK;
} else {
result = close(ctx->cmd_output_fd);
if (result == 0) {
ctx->cmd_output_fd = PIPE_CLOSED;
return ATOM_OK;
} else {
perror("cmd_output_fd close()");
return make_error(env, enif_make_int(env, errno));
}
}
default:
debug("invalid file descriptor type");
return enif_make_badarg(env);
}
}
static int select_read(ErlNifEnv *env, ExecContext *ctx) {
int retval = enif_select(env, ctx->cmd_output_fd, ERL_NIF_SELECT_READ, ctx,
NULL, ATOM_UNDEFINED);
if (retval != 0)
perror("select_read()");
return retval;
}
static ERL_NIF_TERM read_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
if (argc != 2)
enif_make_badarg(env);
+ ErlNifTime start;
+ start = enif_monotonic_time(ERL_NIF_USEC);
+
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->cmd_output_fd == PIPE_CLOSED)
return make_error(env, ATOM_PIPE_CLOSED);
bool is_buffered = true;
int size;
enif_get_int(env, argv[1], &size);
if (size == -1) {
size = 65535;
is_buffered = false;
} else if (size > 65535 || size < 1) {
enif_make_badarg(env);
}
unsigned char buf[size];
int result = read(ctx->cmd_output_fd, buf, sizeof(buf));
ERL_NIF_TERM bin_term = 0;
if (result >= 0) {
ErlNifBinary bin;
enif_alloc_binary(result, &bin);
/* TODO: we should use the erl binary for `read` itself instead of
* allocating again */
memcpy(bin.data, buf, result);
bin_term = enif_make_binary(env, &bin);
}
+ notify_consumed_timeslice(env, start, enif_monotonic_time(ERL_NIF_USEC));
+
/* TODO: branching is ugly, cleanup required */
if (result >= size ||
(is_buffered == false && result >= 0)) { // request completely satisfied
return make_ok(env, bin_term);
} else if (result > 0) { // request partially satisfied
int retval = select_read(env, ctx);
if (retval != 0)
return make_error(env, enif_make_int(env, retval));
return make_ok(env, bin_term);
} else if (result == 0) { // EOF
return make_ok(env, bin_term);
} else if (errno == EAGAIN) { // busy
int retval = select_read(env, ctx);
if (retval != 0)
return make_error(env, enif_make_int(env, retval));
return make_error(env, ATOM_EAGAIN);
} else { // Error
perror("read()");
return make_error(env, enif_make_int(env, errno));
}
}
static ERL_NIF_TERM is_alive(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->pid == CMD_EXIT)
return ATOM_FALSE;
int result = kill(ctx->pid, 0);
if (result == 0) {
return ATOM_TRUE;
} else {
return ATOM_FALSE;
}
}
static ERL_NIF_TERM terminate_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->pid == CMD_EXIT)
return make_ok(env, enif_make_int(env, 0));
return make_ok(env, enif_make_int(env, kill(ctx->pid, SIGTERM)));
}
static ERL_NIF_TERM kill_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->pid == CMD_EXIT)
return make_ok(env, enif_make_int(env, 0));
return make_ok(env, enif_make_int(env, kill(ctx->pid, SIGKILL)));
}
static ERL_NIF_TERM make_exit_term(ErlNifEnv *env, ExecContext *ctx) {
switch (ctx->exit_type) {
case NORMAL_EXIT:
return make_ok(env, enif_make_tuple2(env, ATOM_EXIT,
enif_make_int(env, ctx->exit_status)));
case SIGNALED:
/* exit_status here points to signal number */
return make_ok(env, enif_make_tuple2(env, ATOM_SIGNALED,
enif_make_int(env, ctx->exit_status)));
case STOPPED:
return make_ok(env, enif_make_tuple2(env, ATOM_STOPPED,
enif_make_int(env, ctx->exit_status)));
default:
error("Invalid wait status");
return make_error(env, ATOM_UNDEFINED);
}
}
static ERL_NIF_TERM wait_proc(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->pid == CMD_EXIT)
return make_exit_term(env, ctx);
int status;
int wpid = waitpid(ctx->pid, &status, WNOHANG);
if (wpid == ctx->pid) {
ctx->pid = CMD_EXIT;
if (WIFEXITED(status)) {
ctx->exit_type = NORMAL_EXIT;
ctx->exit_status = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
ctx->exit_type = SIGNALED;
ctx->exit_status = WTERMSIG(status);
} else if (WIFSTOPPED(status)) {
ctx->exit_type = STOPPED;
ctx->exit_status = 0;
}
return make_exit_term(env, ctx);
} else if (wpid != 0) {
perror("waitpid()");
}
ERL_NIF_TERM term = enif_make_tuple2(env, enif_make_int(env, wpid),
enif_make_int(env, status));
return make_error(env, term);
}
static ERL_NIF_TERM os_pid(ErlNifEnv *env, int argc,
const ERL_NIF_TERM argv[]) {
ExecContext *ctx = NULL;
GET_CTX(env, argv[0], ctx);
if (ctx->pid == CMD_EXIT)
return make_ok(env, enif_make_int(env, 0));
return make_ok(env, enif_make_int(env, ctx->pid));
}
static int on_load(ErlNifEnv *env, void **priv, ERL_NIF_TERM load_info) {
struct ExilePriv *data = enif_alloc(sizeof(struct ExilePriv));
if (!data)
return 1;
data->rt =
enif_open_resource_type_x(env, "exile_resource", &rt_init,
ERL_NIF_RT_CREATE | ERL_NIF_RT_TAKEOVER, NULL);
ATOM_TRUE = enif_make_atom(env, "true");
ATOM_FALSE = enif_make_atom(env, "false");
ATOM_OK = enif_make_atom(env, "ok");
ATOM_ERROR = enif_make_atom(env, "error");
ATOM_UNDEFINED = enif_make_atom(env, "undefined");
ATOM_INVALID_CTX = enif_make_atom(env, "invalid_exile_exec_ctx");
ATOM_PIPE_CLOSED = enif_make_atom(env, "closed_pipe");
ATOM_EXIT = enif_make_atom(env, "exit");
ATOM_SIGNALED = enif_make_atom(env, "signaled");
ATOM_STOPPED = enif_make_atom(env, "stopped");
ATOM_EAGAIN = enif_make_atom(env, "eagain");
*priv = (void *)data;
return 0;
}
static void on_unload(ErlNifEnv *env, void *priv) {
debug("exile unload");
enif_free(priv);
}
static ErlNifFunc nif_funcs[] = {
{"exec_proc", 2, exec_proc, USE_DIRTY_IO},
{"write_proc", 2, write_proc, USE_DIRTY_IO},
{"read_proc", 2, read_proc, USE_DIRTY_IO},
{"close_pipe", 2, close_pipe, USE_DIRTY_IO},
{"terminate_proc", 1, terminate_proc, USE_DIRTY_IO},
{"wait_proc", 1, wait_proc, USE_DIRTY_IO},
{"kill_proc", 1, kill_proc, USE_DIRTY_IO},
{"is_alive", 1, is_alive, USE_DIRTY_IO},
{"os_pid", 1, os_pid, USE_DIRTY_IO},
};
ERL_NIF_INIT(Elixir.Exile.ProcessNif, nif_funcs, &on_load, NULL, NULL,
&on_unload)

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