cutils: sched_policy: Make getSchedulerGroup() play nicely with multiple control groups (503df207) · Commits · e / os / android_system_core

libcutils/sched_policy.c

+44 −20

Original line number	Diff line number	Diff line
		@@ -90,8 +90,9 @@ static inline void initialize()
		/*
		* Try to get the scheduler group.
		*
		* The data from /proc/<pid>/cgroup looks like:
		* The data from /proc/<pid>/cgroup looks (something) like:
		* 2:cpu:/bg_non_interactive
		* 1:cpuacct:/
		*
		* We return the part after the "/", which will be an empty string for
		* the default cgroup. If the string is longer than "bufLen", the string
		@@ -101,34 +102,57 @@ static int getSchedulerGroup(int tid, char* buf, size_t bufLen)
		{
		#ifdef HAVE_ANDROID_OS
		char pathBuf[32];
		char readBuf[256];
		ssize_t count;
		int fd;
		char lineBuf[256];
		FILE *fp;

		snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
		if ((fd = open(pathBuf, O_RDONLY)) < 0) {
		if (!(fp = fopen(pathBuf, "r"))) {
		return -1;
		}

		count = read(fd, readBuf, sizeof(readBuf));
		if (count <= 0) {
		close(fd);
		errno = ENODATA;
		return -1;
		while(fgets(lineBuf, sizeof(lineBuf) -1, fp)) {
		char *next = lineBuf;
		char *subsys;
		char *grp;
		size_t len;

		/* Junk the first field */
		if (!strsep(&next, ":")) {
		goto out_bad_data;
		}
		close(fd);

		readBuf[--count] = '\0'; /* remove the '\n', now count==strlen */
		if (!(subsys = strsep(&next, ":"))) {
		goto out_bad_data;
		}

		char* cp = strchr(readBuf, '/');
		if (cp == NULL) {
		readBuf[sizeof(readBuf)-1] = '\0';
		errno = ENODATA;
		return -1;
		if (strcmp(subsys, "cpu")) {
		/* Not the subsys we're looking for */
		continue;
		}

		memcpy(buf, cp+1, count); /* count-1 for cp+1, count+1 for NUL */
		if (!(grp = strsep(&next, ":"))) {
		goto out_bad_data;
		}
		grp++; /* Drop the leading '/' */
		len = strlen(grp);
		grp[len-1] = '\0'; /* Drop the trailing '\n' */

		if (bufLen <= len) {
		len = bufLen - 1;
		}
		strncpy(buf, grp, len);
		buf[len] = '\0';
		fclose(fp);
		return 0;
		}

		LOGE("Failed to find cpu subsys");
		fclose(fp);
		return -1;
		out_bad_data:
		LOGE("Bad cgroup data {%s}", lineBuf);
		fclose(fp);
		return -1;
		#else
		errno = ENOSYS;
		return -1;