gri3-wm/i3bar/src/child.c

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/*
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* vim:ts=4:sw=4:expandtab
*
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* i3bar - an xcb-based status- and ws-bar for i3
* © 2010-2012 Axel Wagner and contributors (see also: LICENSE)
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*
* child.c: Getting Input for the statusline
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*
*/
#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>
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#include <err.h>
#include <ev.h>
#include <yajl/yajl_common.h>
#include <yajl/yajl_parse.h>
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#include <yajl/yajl_version.h>
#include "common.h"
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/* Global variables for child_*() */
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i3bar_child child = { 0 };
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/* stdin- and sigchild-watchers */
ev_io *stdin_io;
ev_child *child_sig;
/* JSON parser for stdin */
yajl_callbacks callbacks;
yajl_handle parser;
typedef struct parser_ctx {
/* True if one of the parsed blocks was urgent */
bool has_urgent;
/* A copy of the last JSON map key. */
char *last_map_key;
/* The current block. Will be filled, then copied and put into the list of
* blocks. */
struct status_block block;
} parser_ctx;
parser_ctx parser_context;
/* The buffer statusline points to */
struct statusline_head statusline_head = TAILQ_HEAD_INITIALIZER(statusline_head);
char *statusline_buffer = NULL;
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/*
* Stop and free() the stdin- and sigchild-watchers
*
*/
void cleanup(void) {
if (stdin_io != NULL) {
ev_io_stop(main_loop, stdin_io);
FREE(stdin_io);
FREE(statusline_buffer);
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/* 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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memset(&child, 0, sizeof(i3bar_child));
}
/*
* The start of a new array is the start of a new status line, so we clear all
* previous entries.
*
*/
static int stdin_start_array(void *context) {
struct status_block *first;
while (!TAILQ_EMPTY(&statusline_head)) {
first = TAILQ_FIRST(&statusline_head);
I3STRING_FREE(first->full_text);
FREE(first->color);
TAILQ_REMOVE(&statusline_head, first, blocks);
free(first);
}
return 1;
}
/*
* The start of a map is the start of a single block of the status line.
*
*/
static int stdin_start_map(void *context) {
parser_ctx *ctx = context;
memset(&(ctx->block), '\0', sizeof(struct status_block));
return 1;
}
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#if YAJL_MAJOR >= 2
static int stdin_map_key(void *context, const unsigned char *key, size_t len) {
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#else
static int stdin_map_key(void *context, const unsigned char *key, unsigned int len) {
#endif
parser_ctx *ctx = context;
FREE(ctx->last_map_key);
sasprintf(&(ctx->last_map_key), "%.*s", len, key);
return 1;
}
static int stdin_boolean(void *context, int val) {
parser_ctx *ctx = context;
if (strcasecmp(ctx->last_map_key, "urgent") == 0) {
ctx->block.urgent = val;
}
return 1;
}
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#if YAJL_MAJOR >= 2
static int stdin_string(void *context, const unsigned char *val, size_t len) {
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#else
static int stdin_string(void *context, const unsigned char *val, unsigned int len) {
#endif
parser_ctx *ctx = context;
if (strcasecmp(ctx->last_map_key, "full_text") == 0) {
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ctx->block.full_text = i3string_from_utf8_with_length((const char *)val, len);
}
if (strcasecmp(ctx->last_map_key, "color") == 0) {
sasprintf(&(ctx->block.color), "%.*s", len, val);
}
return 1;
}
static int stdin_end_map(void *context) {
parser_ctx *ctx = context;
struct status_block *new_block = smalloc(sizeof(struct status_block));
memcpy(new_block, &(ctx->block), sizeof(struct status_block));
/* Ensure we have a full_text set, so that when it is missing (or null),
* i3bar doesnt crash and the user gets an annoying message. */
if (!new_block->full_text)
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new_block->full_text = i3string_from_utf8("SPEC VIOLATION (null)");
if (new_block->urgent)
ctx->has_urgent = true;
TAILQ_INSERT_TAIL(&statusline_head, new_block, blocks);
return 1;
}
static int stdin_end_array(void *context) {
DLOG("dumping statusline:\n");
struct status_block *current;
TAILQ_FOREACH(current, &statusline_head, blocks) {
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DLOG("full_text = %s\n", i3string_as_utf8(current->full_text));
DLOG("color = %s\n", current->color);
}
DLOG("end of dump\n");
return 1;
}
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/*
* Helper function to read stdin
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*
*/
static unsigned char *get_buffer(ev_io *watcher, int *ret_buffer_len) {
int fd = watcher->fd;
int n = 0;
int rec = 0;
int buffer_len = STDIN_CHUNK_SIZE;
unsigned char *buffer = smalloc(buffer_len+1);
buffer[0] = '\0';
while(1) {
n = read(fd, buffer + rec, buffer_len - rec);
if (n == -1) {
if (errno == EAGAIN) {
/* finish up */
break;
}
ELOG("read() failed!: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (n == 0) {
/* end of file, kill the watcher */
ELOG("stdin: received EOF\n");
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cleanup();
draw_bars(false);
*ret_buffer_len = -1;
return NULL;
}
rec += n;
if (rec == buffer_len) {
buffer_len += STDIN_CHUNK_SIZE;
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buffer = srealloc(buffer, buffer_len);
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}
}
if (*buffer == '\0') {
FREE(buffer);
rec = -1;
}
*ret_buffer_len = rec;
return buffer;
}
static void read_flat_input(char *buffer, int length) {
struct status_block *first = TAILQ_FIRST(&statusline_head);
/* Clear the old buffer if any. */
I3STRING_FREE(first->full_text);
/* Remove the trailing newline and terminate the string at the same
* time. */
if (buffer[length-1] == '\n' || buffer[length-1] == '\r')
buffer[length-1] = '\0';
else buffer[length] = '\0';
first->full_text = i3string_from_utf8(buffer);
}
static bool read_json_input(unsigned char *input, int length) {
yajl_status status = yajl_parse(parser, input, length);
bool has_urgent = false;
#if YAJL_MAJOR >= 2
if (status != yajl_status_ok) {
#else
if (status != yajl_status_ok && status != yajl_status_insufficient_data) {
#endif
fprintf(stderr, "[i3bar] Could not parse JSON input (code %d): %.*s\n",
status, length, input);
} else if (parser_context.has_urgent) {
has_urgent = true;
}
return has_urgent;
}
/*
* Callbalk for stdin. We read a line from stdin and store the result
* in statusline
*
*/
void stdin_io_cb(struct ev_loop *loop, ev_io *watcher, int revents) {
int rec;
unsigned char *buffer = get_buffer(watcher, &rec);
if (buffer == NULL)
return;
bool has_urgent = false;
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if (child.version > 0) {
has_urgent = read_json_input(buffer, rec);
} else {
read_flat_input((char*)buffer, rec);
}
free(buffer);
draw_bars(has_urgent);
}
/*
* Callbalk for stdin first line. We read the first line to detect
* whether this is JSON or plain text
*
*/
void stdin_io_first_line_cb(struct ev_loop *loop, ev_io *watcher, int revents) {
int rec;
unsigned char *buffer = get_buffer(watcher, &rec);
if (buffer == NULL)
return;
DLOG("Detecting input type based on buffer *%.*s*\n", rec, buffer);
/* Detect whether this is JSON or plain text. */
unsigned int consumed = 0;
/* At the moment, we dont care for the version. This might change
* in the future, but for now, we just discard it. */
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parse_json_header(&child, buffer, rec, &consumed);
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if (child.version > 0) {
/* 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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read_json_input(buffer + consumed, rec - consumed);
} else {
/* In case of plaintext, we just add a single block and change its
* full_text pointer later. */
struct status_block *new_block = scalloc(sizeof(struct status_block));
TAILQ_INSERT_TAIL(&statusline_head, new_block, blocks);
read_flat_input((char*)buffer, rec);
}
free(buffer);
ev_io_stop(main_loop, stdin_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 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,
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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) {
/* Allocate a yajl parser which will be used to parse stdin. */
memset(&callbacks, '\0', sizeof(yajl_callbacks));
callbacks.yajl_map_key = stdin_map_key;
callbacks.yajl_boolean = stdin_boolean;
callbacks.yajl_string = stdin_string;
callbacks.yajl_start_array = stdin_start_array;
callbacks.yajl_end_array = stdin_end_array;
callbacks.yajl_start_map = stdin_start_map;
callbacks.yajl_end_map = stdin_end_map;
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#if YAJL_MAJOR < 2
yajl_parser_config parse_conf = { 0, 0 };
parser = yajl_alloc(&callbacks, &parse_conf, NULL, (void*)&parser_context);
#else
parser = yajl_alloc(&callbacks, NULL, &parser_context);
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#endif
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if (command != NULL) {
int fd[2];
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if (pipe(fd) == -1)
err(EXIT_FAILURE, "pipe(fd)");
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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);
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 = smalloc(sizeof(ev_io));
ev_io_init(stdin_io, &stdin_io_first_line_cb, STDIN_FILENO, EV_READ);
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ev_io_start(main_loop, stdin_io);
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/* We must cleanup, if the child unexpectedly terminates */
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child_sig = smalloc(sizeof(ev_child));
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ev_child_init(child_sig, &child_sig_cb, child.pid, 0);
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ev_child_start(main_loop, child_sig);
atexit(kill_child_at_exit);
}
/*
* kill()s the child-process (if any). Called when exit()ing.
*
*/
void kill_child_at_exit(void) {
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if (child.pid > 0) {
if (child.cont_signal > 0 && child.stopped)
kill(child.pid, child.cont_signal);
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kill(child.pid, SIGTERM);
}
}
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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(void) {
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if (child.pid > 0) {
if (child.cont_signal > 0 && child.stopped)
kill(child.pid, child.cont_signal);
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kill(child.pid, SIGTERM);
int status;
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waitpid(child.pid, &status, 0);
cleanup();
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}
}
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/*
* Sends a SIGSTOP to the child-process (if existent)
*
*/
void stop_child(void) {
if (child.stop_signal > 0 && !child.stopped) {
child.stopped = true;
kill(child.pid, child.stop_signal);
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}
}
/*
* Sends a SIGCONT to the child-process (if existent)
*
*/
void cont_child(void) {
if (child.cont_signal > 0 && child.stopped) {
child.stopped = false;
kill(child.pid, child.cont_signal);
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}
}