59 lines
1.2 KiB
C
59 lines
1.2 KiB
C
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#include <stdio.h>
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#include <string.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#define DBG 0
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#if defined(__GNUC__) && (__GNUC__ > 3)
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__attribute__((format(printf, 1, 2), noreturn))
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#endif
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static void die(const char *format, ...)
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{
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if (DBG) {
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va_list args;
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va_start(args, format);
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vfprintf(stderr, format, args);
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va_end(args);
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}
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exit(1);
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}
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int main(int argc, char *argv[])
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{
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struct stat st;
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char buf[1024];
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int len, fd;
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if (argc != 2)
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die("Usage: xf86-video-intel-backlight-helper <iface>\n");
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if (strchr(argv[1], '/') != NULL)
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die("Invalid interface '%s': contains '/'\n", argv[1]);
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if (snprintf(buf, sizeof(buf),
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"/sys/class/backlight/%s/brightness",
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argv[1]) >= sizeof(buf))
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die("Invalid interface '%s': name too long\n", argv[1]);
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fd = open(buf, O_RDWR);
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if (fd < 0 || fstat(fd, &st) || major(st.st_dev))
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die("Invalid interface '%s': unknown backlight file\n", argv[1]);
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while (fgets(buf, sizeof(buf), stdin)) {
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len = strlen(buf);
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if (write(fd, buf, len) != len)
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die("Failed to update backlight interface '%s': errno=%d\n", argv[1], errno);
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}
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return 0;
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}
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