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ucm: implement ${sys:sysfs/path} substitution

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Example:

Condition {
	Type String
	String1 "${sys:class/dmi/id/board_vendor}"
	String2 "LENOVO"
}

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2019-11-20 13:43:39 +01:00
parent 1d848ab739
commit cb84b02702
1 changed files with 53 additions and 0 deletions
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53
src/ucm/ucm_subs.c
View file

@ -25,6 +25,8 @@
*/
#include "ucm_local.h"
#include <sys/stat.h>
#include <limits.h>
static char *rval_conf_name(snd_use_case_mgr_t *uc_mgr)
{
@ -83,6 +85,56 @@ static char *rval_env(snd_use_case_mgr_t *uc_mgr ATTRIBUTE_UNUSED, const char *i
return NULL;
}
static char *rval_sysfs(snd_use_case_mgr_t *uc_mgr ATTRIBUTE_UNUSED, const char *id)
{
char path[PATH_MAX], link[PATH_MAX + 1];
struct stat sb;
ssize_t len;
char *e;
int fd;
e = getenv("SYSFS_PATH");
if (e == NULL)
e = "/sys";
if (id[0] == '/')
id++;
snprintf(path, sizeof(path), "%s/%s", e, id);
if (lstat(path, &sb) != 0)
return NULL;
if (S_ISLNK(sb.st_mode)) {
len = readlink(path, link, sizeof(link) - 1);
if (len <= 0) {
uc_error("sysfs: cannot read link '%s' (%d)", path, errno);
return NULL;
}
link[len] = '\0';
e = strrchr(link, '/');
if (e)
return strdup(e + 1);
return NULL;
}
if (S_ISDIR(sb.st_mode))
return NULL;
if ((sb.st_mode & S_IRUSR) == 0)
return NULL;
fd = open(path, O_RDONLY);
if (fd < 0) {
uc_error("sysfs open failed for '%s' (%d)", path, errno);
return NULL;
}
len = read(fd, path, sizeof(path)-1);
close(fd);
if (len < 0) {
uc_error("sysfs unable to read value '%s' (%d)", path, errno);
return NULL;
}
while (len > 0 && path[len-1] == '\n')
len--;
path[len] = '\0';
return strdup(path);
}
#define MATCH_VARIABLE(name, id, fcn) \
if (strncmp((name), (id), sizeof(id) - 1) == 0) { \
rval = fcn(uc_mgr); \
@ -133,6 +185,7 @@ int uc_mgr_get_substituted_value(snd_use_case_mgr_t *uc_mgr,
MATCH_VARIABLE(value, "${CardLongName}", rval_card_longname);
MATCH_VARIABLE(value, "${CardComponents}", rval_card_components);
MATCH_VARIABLE2(value, "${env:", rval_env);
MATCH_VARIABLE2(value, "${sys:", rval_sysfs);
err = -EINVAL;
tmp = strchr(value, '}');
if (tmp) {