/* See LICENSE file for copyright and license details. */
#include "common.h"
/**
* Test whether a file descriptor refers to a VT
*
* @param fd The file descriptor
* @return Whether the file descriptor refers to a VT
*/
static int
is_vt_proper(int fd)
{
char buf[32], digit0;
/* Get TTY */
if (ttyname_r(fd, buf, sizeof(buf) / sizeof(char)))
return 0;
/* Validate TTY path */
if (!strcmp(buf, "/dev/console"))
return 1;
if (strncmp(buf, "/dev/tty", sizeof("/dev/tty") - 1))
return 0;
/* Validate TTY name */
digit0 = buf[sizeof("/dev/tty") - 1];
return '1' <= digit0 && digit0 <= '9';
}
/**
* Test the availability of an adjustment method
*
* @param method The adjustment method
* @param operation Allowed values:
* 0: Pass if the environment suggests it will work but is not fake
* 1: Pass if the environment suggests it will work
* 2: Pass if real and not fake
* 3: Pass if real
* 4: Always pass
* Other values invoke undefined behaviour
* @return Whether the test passed
*/
static int
list_method_test(int method, int operation)
{
struct libgamma_method_capabilities caps;
int fd, r, saved_errno;
libgamma_method_capabilities(&caps, sizeof(caps), method);
switch (operation) {
case 0:
/* Methods that the environment suggests will work, excluding fake */
if (caps.fake)
return 0;
/* fall through */
case 1:
/* Methods that the environment suggests will work, including fake */
if (!caps.real)
return 0;
#ifdef HAVE_LIBGAMMA_METHOD_LINUX_DRM
if (method == LIBGAMMA_METHOD_LINUX_DRM) {
saved_errno = errno;
if (is_vt_proper(STDIN_FILENO)) {
r = 1;
} else if (is_vt_proper(STDOUT_FILENO)) {
r = 1;
} else if (is_vt_proper(STDERR_FILENO)) {
r = 1;
} else {
r = 0;
fd = open("/dev/tty", O_RDONLY);
if (fd >= 0) {
r = is_vt_proper(fd);
close(fd);
}
}
errno = saved_errno;
return r;
}
#endif
#ifdef HAVE_LIBGAMMA_METHOD_DUMMY
if (method == LIBGAMMA_METHOD_DUMMY)
return 0;
#endif
return caps.default_site_known;
case 2:
/* All real non-fake methods */
return caps.real && !caps.fake;
case 3:
/* All real methods */
return caps.real;
default:
/* All methods */
return 1;
}
}
/**
* List available adjustment methods by their order of preference based on the environment
*
* @param methods Output array of methods, should be able to hold `LIBGAMMA_METHOD_COUNT` elements
* @param buf_size The number of elements that fits in `methods`, it should be `LIBGAMMA_METHOD_COUNT`,
* This is used to avoid writing outside the output buffer if this library adds new
* adjustment methods without the users of the library recompiling
* @param operation Allowed values:
* 0: Methods that the environment suggests will work, excluding fake
* 1: Methods that the environment suggests will work, including fake
* 2: All real non-fake methods
* 3: All real methods
* 4: All methods
* Other values invoke undefined behaviour
* @return The number of element that have been stored in `methods`, or should
* have been stored if the buffer was large enough
*/
size_t
libgamma_list_methods(int *restrict methods, size_t buf_size, int operation)
{
size_t n = 0;
#define X(CONST, ...)\
if (list_method_test(CONST, operation) && n++ < buf_size)\
methods[n - 1] = CONST;
LIST_AVAILABLE_METHODS(X)
#undef X
return n;
}
