gri3-wm/i3bar/src/child.c

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/*
* i3bar - an xcb-based status- and ws-bar for i3
*
* © 2010-2011 Axel Wagner and contributors
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*
* See file LICNSE for license information
*
* src/child.c: Getting Input for the statusline
*
*/
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <ev.h>
#include "common.h"
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/* Global variables for child_*() */
pid_t child_pid;
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/* stdin- and sigchild-watchers */
ev_io *stdin_io;
ev_child *child_sig;
/* The buffer statusline points to */
char *statusline_buffer = NULL;
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/*
* Stop and free() the stdin- and sigchild-watchers
*
*/
void cleanup() {
if (stdin_io != NULL) {
ev_io_stop(main_loop, stdin_io);
FREE(stdin_io);
FREE(statusline_buffer);
/* statusline pointed to memory within statusline_buffer */
statusline = NULL;
}
if (child_sig != NULL) {
ev_child_stop(main_loop, child_sig);
FREE(child_sig);
}
}
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/*
* Callbalk for stdin. We read a line from stdin and store the result
* in statusline
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*
*/
void stdin_io_cb(struct ev_loop *loop, ev_io *watcher, int revents) {
int fd = watcher->fd;
int n = 0;
int rec = 0;
int buffer_len = STDIN_CHUNK_SIZE;
char *buffer = malloc(buffer_len);
buffer[0] = '\0';
while(1) {
n = read(fd, buffer + rec, buffer_len - rec);
if (n == -1) {
if (errno == EAGAIN) {
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/* remove trailing newline and finish up */
buffer[rec-1] = '\0';
break;
}
ELOG("read() failed!: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (n == 0) {
if (rec != 0) {
/* remove trailing newline and finish up */
buffer[rec-1] = '\0';
}
/* end of file, kill the watcher */
ELOG("stdin: received EOF\n");
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cleanup();
draw_bars();
return;
}
rec += n;
if (rec == buffer_len) {
buffer_len += STDIN_CHUNK_SIZE;
buffer = realloc(buffer, buffer_len);
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}
}
if (*buffer == '\0') {
FREE(buffer);
return;
}
FREE(statusline_buffer);
statusline = statusline_buffer = buffer;
for (n = 0; buffer[n] != '\0'; ++n) {
if (buffer[n] == '\n')
statusline = &buffer[n + 1];
}
DLOG("%s\n", statusline);
draw_bars();
}
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/*
* We received a sigchild, meaning, that the child-process terminated.
* We simply free the respective data-structures and don't care for input
* anymore
*
*/
void child_sig_cb(struct ev_loop *loop, ev_child *watcher, int revents) {
ELOG("Child (pid: %d) unexpectedly exited with status %d\n",
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child_pid,
watcher->rstatus);
cleanup();
}
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/*
* Start a child-process with the specified command and reroute stdin.
* We actually start a $SHELL to execute the command so we don't have to care
* about arguments and such
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*
*/
void start_child(char *command) {
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child_pid = 0;
if (command != NULL) {
int fd[2];
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pipe(fd);
child_pid = fork();
switch (child_pid) {
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case -1:
ELOG("Couldn't fork(): %s\n", strerror(errno));
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exit(EXIT_FAILURE);
case 0:
/* Child-process. Reroute stdout and start shell */
close(fd[0]);
dup2(fd[1], STDOUT_FILENO);
static const char *shell = NULL;
if ((shell = getenv("SHELL")) == NULL)
shell = "/bin/sh";
execl(shell, shell, "-c", command, (char*) NULL);
return;
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default:
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/* Parent-process. Rerout stdin */
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close(fd[1]);
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dup2(fd[0], STDIN_FILENO);
/* If hide-on-modifier is set, we start of by sending the
* child a SIGSTOP, because the bars aren't mapped at start */
if (config.hide_on_modifier) {
stop_child();
}
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break;
}
}
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/* We set O_NONBLOCK because blocking is evil in event-driven software */
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fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
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stdin_io = malloc(sizeof(ev_io));
ev_io_init(stdin_io, &stdin_io_cb, STDIN_FILENO, EV_READ);
ev_io_start(main_loop, stdin_io);
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/* We must cleanup, if the child unexpectedly terminates */
child_sig = malloc(sizeof(ev_child));
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ev_child_init(child_sig, &child_sig_cb, child_pid, 0);
ev_child_start(main_loop, child_sig);
}
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/*
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* kill()s the child-process (if existent) and closes and
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* free()s the stdin- and sigchild-watchers
*
*/
void kill_child() {
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if (child_pid != 0) {
kill(child_pid, SIGCONT);
kill(child_pid, SIGTERM);
int status;
waitpid(child_pid, &status, 0);
child_pid = 0;
cleanup();
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}
}
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/*
* Sends a SIGSTOP to the child-process (if existent)
*
*/
void stop_child() {
if (child_pid != 0) {
kill(child_pid, SIGSTOP);
}
}
/*
* Sends a SIGCONT to the child-process (if existent)
*
*/
void cont_child() {
if (child_pid != 0) {
kill(child_pid, SIGCONT);
}
}