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/*
* BSD Zero Clause License
*
* Copyright (c) 2022 Thomas Voss
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#define _POSIX_C_SOURCE 200809L
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include "lux.h"
#ifdef O_PATH
#define GETDIR_FLAGS O_PATH
#else
#define GETDIR_FLAGS (O_RDONLY | O_DIRECTORY)
#endif
static int intlen(int);
static int getdir(void);
static FILE *getbstream(int);
int
luxinit(struct luxdisp *disp)
{
/* Set the default values for the luxdisp struct. We want to be as lazy
* as possible, so we don't bother with __bstream and __max yet. We do
* need __dirfd though.
*/
*disp = (struct luxdisp) {
.__bstream = NULL,
.__max = -1,
.__dirfd = getdir()
};
return disp->__dirfd;
}
int
luxget(struct luxdisp *disp)
{
/* If we don't have an open stream with the brightness file yet then
* open one. If we do, we instead rewind to the start of the file so
* that we don't just read an EOF.
*/
if (disp->__bstream == NULL) {
if ((disp->__bstream = getbstream(disp->__dirfd)) == NULL)
return -1;
} else
rewind(disp->__bstream);
int n;
fscanf(disp->__bstream, "%d", &n);
return n;
}
int
luxset(struct luxdisp *disp, int n)
{
/* The same deal as in luxget() */
if (disp->__bstream == NULL) {
if ((disp->__bstream = getbstream(disp->__dirfd)) == NULL)
return -1;
} else
rewind(disp->__bstream);
/* After writing the new brightness value to the brightness file, we
* need to truncate it so that luxset(disp, 1234); luxset(disp, 9);
* gives us a final brightness of 2 and not 9234.
*/
fprintf(disp->__bstream, "%d", n);
ftruncate(fileno(disp->__bstream), intlen(n));
return n;
}
int
luxmax(struct luxdisp *disp)
{
/* The maximum brightness shouldn't change, so we can cache it in the
* struct.
*/
if (disp->__max != -1)
return disp->__max;
int fd = openat(disp->__dirfd, "max_brightness", O_RDONLY);
if (fd == -1)
return -1;
FILE *stream = fdopen(fd, "r");
if (stream == NULL) {
close(fd);
return -1;
}
fscanf(stream, "%d", &disp->__max);
fclose(stream);
return disp->__max;
}
void
luxfree(struct luxdisp *disp)
{
if (disp->__dirfd != -1)
close(disp->__dirfd);
if (disp->__bstream != NULL)
fclose(disp->__bstream);
}
int
intlen(int n)
{
return n < 10 ? 1
: n < 100 ? 2
: n < 1000 ? 3
: n < 10000 ? 4
: n < 100000 ? 5
: n < 1000000 ? 6
: n < 10000000 ? 7
: n < 100000000 ? 8
: n < 1000000000 ? 9
: 10;
}
int
getdir(void)
{
int fd, dfd;
struct dirent *dp;
DIR *dir;
/* To get the file descriptor for the directory where all the brightness
* files are located, we first need to open BACKLIGHT_DIR which is the
* directory where the backlight directories are located. Then we need
* to get a DIR* of that directory and get the 3rd entry. We need the
* third because the fist and second are the . and .. folders. Finally
* we open the folder so that we have a file descriptor we can return.
*/
if ((dfd = open(BACKLIGHT_DIR, O_RDONLY)) == -1
|| (dir = fdopendir(dfd)) == NULL
|| (dp = readdir(dir)) == NULL
|| (dp = readdir(dir)) == NULL
|| (dp = readdir(dir)) == NULL
|| (fd = openat(dfd, dp->d_name, GETDIR_FLAGS)) == -1)
return -1;
closedir(dir);
return fd;
}
FILE *
getbstream(int dirfd)
{
return fdopen(openat(dirfd, "brightness", O_RDWR), "r+");
}
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