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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <poll.h>
#include <pwd.h>
#define FIFO_PATH "/tmp/brightnessd-fifo"
#define BRIGHT_FILE "/sys/class/backlight/radeon_bl0/brightness"
#define DELAY 5
#define STEP 1
#define BIG_STEP 10
#define USER "nobody"
#define BRIGHT_BUFFER_SIZE 4
#define DELAY_INFINITE (-1)
/**
* create and open fifo, using chmod since mkfifo is affected by umask
*/
int setup_fifo()
{
struct stat st;
if (stat(FIFO_PATH, &st) == 0)
{
if (remove(FIFO_PATH))
{
perror("remove("FIFO_PATH")");
return 1;
}
}
if (mkfifo(FIFO_PATH, 0666))
{
perror("mkfifo");
return 1;
}
if (chmod(FIFO_PATH, 0666))
{
perror("chmod");
return 1;
}
return 0;
}
int drop_priv()
{
struct passwd *p = NULL;
/* get group (and more) of USER */
p = getpwnam(USER);
if (p == NULL)
{
fprintf(stderr, "Failed to get uid and gid of user \""USER"\", bailing\n");
return 1;
}
if (setgid(p->pw_gid))
{
fprintf(stderr, "Failed to set gid to %d\n", p->pw_gid);
perror("setuid");
return 1;
}
if (setuid(p->pw_uid))
{
fprintf(stderr, "Failed to set uid to %d\n", p->pw_uid);
perror("setuid");
return 1;
}
if (!setuid(0) || !setgid(0))
{
fprintf(stderr, "Got uid 0 or gid 0 back after dropping, bailing\n");
return 1;
}
return 0;
}
int get_now(FILE *f)
{
char buffer[BRIGHT_BUFFER_SIZE]; /* FIXME: magic constant is icky */
/* FIXME: check return value for error */
fgets(buffer, sizeof(buffer), f);
return atoi(buffer);
}
int brightness_within_bounds(int bright, int lower, int upper)
{
/* FIXME: make a horrible but funny ternary statement */
if (bright < lower)
return lower;
if (bright > upper)
return upper;
return bright;
}
int main(int argc, char **argv)
{
int target = 0;
int now = 0;
FILE *f = NULL;
int fifo = 0;
struct pollfd fds;
int delay = 0;
int nread = 0;
char buffer[BRIGHT_BUFFER_SIZE];
/* Open brightness file */
if ((f = fopen(BRIGHT_FILE, "w+")) == NULL)
{
perror("fopen");
exit(EXIT_FAILURE);
}
if (setup_fifo())
{
fclose(f);
return 1;
}
if (drop_priv() != 0)
{
fclose(f);
return 1;
}
now = get_now(f);
target = now;
/* FIXME : check return val */
fifo = open(FIFO_PATH, O_RDWR);
fds.fd = fifo;
fds.events = POLLIN;
delay = DELAY_INFINITE;
while(1)
{
poll(&fds, 1, delay);
if (fds.revents & POLLIN)
{
delay = DELAY;
nread = read(fifo, buffer, sizeof(buffer));
if (nread == 0)
perror("read");
switch(buffer[0])
{
case '+':
target += BIG_STEP;
break;
case '-':
target -= BIG_STEP;
break;
default:
target = atoi(buffer);
break;
}
target = brightness_within_bounds(target, 1, 255);
}
if (now < target) {
now += STEP;
if (now > target)
now = target;
} else if (now > target) {
now -= STEP;
if (now < target)
now = target;
} else if (now == target) {
delay = DELAY_INFINITE;
}
fprintf(f, "%d\n", now);
rewind(f);
}
close(fifo);
remove(FIFO_PATH);
return 0;
}
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