Cleanup: Integrate similar code to cgroup_get_uid_gid_from_procfs().

CHANGELOG of v2.1:
================
* Rebase the patch for commit '340feae163c4797a6cb1247b3812c1ccdc52fa41'.

There are some similar functions for getting process's data (uid, gid) from
/proc/<pid>/status file, so this patch integrates these functions into one
cgroup_get_uid_gid_from_procfs().

Signed-off-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Reviewed-By: Jan Safranek <jsafrane@redhat.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>

6 files changed, 68 insertions, 140 deletions

diff --git a/src/api.c b/src/api.c
index 9a379d6..ccea89c 100644
--- a/src/api.c
+++ b/src/api.c
@@ -2473,3 +2473,58 @@ int cgroup_get_task_begin(char *cgroup, char *controller, void **handle,
 
 	return ret;
 }
+
+/**
+ * Get process data (euid and egid) from /proc/<pid>/status file.
+ * @param pid: The process id
+ * @param euid: The uid of param pid
+ * @param egid: The gid of param pid
+ * @return 0 on success, > 0 on error.
+ */
+int cgroup_get_uid_gid_from_procfs(pid_t pid, uid_t *euid, gid_t *egid)
+{
+	FILE *f;
+	char path[FILENAME_MAX];
+	char buf[4092];
+	uid_t ruid, suid, fsuid;
+	gid_t rgid, sgid, fsgid;
+	bool found_euid = false;
+	bool found_egid = false;
+
+	sprintf(path, "/proc/%d/status", pid);
+	f = fopen(path, "r");
+	if (!f)
+		return ECGROUPNOTEXIST;
+
+	while (fgets(buf, sizeof(buf), f)) {
+		if (!strncmp(buf, "Uid:", 4)) {
+			if (sscanf((buf + 5), "%d%d%d%d", &ruid, euid,
+					&suid, &fsuid) != 4)
+				break;
+			cgroup_dbg("Scanned proc values are %d %d %d %d\n",
+				ruid, *euid, suid, fsuid);
+			found_euid = true;
+		} else if (!strncmp(buf, "Gid:", 4)) {
+			if (sscanf((buf + 5), "%d%d%d%d", &rgid, egid,
+					&sgid, &fsgid) != 4)
+				break;
+			cgroup_dbg("Scanned proc values are %d %d %d %d\n",
+				rgid, *egid, sgid, fsgid);
+			found_egid = true;
+		}
+		if (found_euid && found_egid)
+			break;
+	}
+	fclose(f);
+	if (!found_euid || !found_egid) {
+		/*
+		 * This method doesn't match the file format of
+		 * /proc/<pid>/status. The format has been changed
+		 * and we should catch up the change.
+		 */
+		cgroup_dbg("The invlid file format of /proc/%d/status.\n", pid);
+		return ECGFAIL;
+	}
+	return 0;
+}
+
diff --git a/src/daemon/cgrulesengd.c b/src/daemon/cgrulesengd.c
index 1a7b321..4c71283 100644
--- a/src/daemon/cgrulesengd.c
+++ b/src/daemon/cgrulesengd.c
@@ -33,6 +33,7 @@
 
 #include "libcgroup.h"
 #include "cgrulesengd.h"
+#include "../libcgroup-internal.h"
 
 #include <errno.h>
 #include <stdarg.h>
@@ -140,52 +141,6 @@ void flog(int level, const char *format, ...)
 	}
 }
 
-static int cgre_get_euid_egid_from_status(pid_t pid, uid_t *euid, gid_t *egid)
-{
-	/* Handle for the /proc/PID/status file */
-	FILE *f;
-
-	/* Path for /proc/PID/status file */
-	char path[FILENAME_MAX];
-
-	/* Temporary buffer */
-	char buf[4092];
-
-	/* UID data */
-	uid_t ruid, suid, fsuid;
-
-	/* GID data */
-	gid_t rgid, sgid, fsgid;
-
-	/*
-	 * First, we need to open the /proc/PID/status file so that we can
-	 * get the effective UID and GID for the process that we're working
-	 * on.  This process is probably not us, so we can't just call
-	 * geteuid() or getegid().
-	 */
-	sprintf(path, "/proc/%d/status", pid);
-	f = fopen(path, "r");
-	if (!f) {
-		flog(LOG_WARNING, "Failed to open %s", path);
-		return 1;
-	}
-
-	/* Have the eUID, need to find the eGID. */
-	memset(buf, '\0', sizeof(buf));
-	while (fgets(buf, sizeof(buf), f)) {
-		if (!strncmp(buf, "Uid:", 4)) {
-			sscanf((buf + 5), "%d%d%d%d", &ruid, euid,
-				&suid, &fsuid);
-		} else if (!strncmp(buf, "Gid:", 4)) {
-			sscanf((buf + 5), "%d%d%d%d", &rgid, egid,
-				&sgid, &fsgid);
-		}
-		memset(buf, '\0', sizeof(buf));
-	}
-	fclose(f);
-	return 0;
-}
-
 struct parent_info {
 	__u64 timestamp;
 	pid_t pid;
@@ -325,10 +280,13 @@ int cgre_process_event(const struct proc_event *ev, const int type)
 	default:
 		break;
 	}
-	if (cgre_get_euid_egid_from_status(pid, &euid, &egid))
-		/* cgre_get_euid_egid_from_status() returns 1 if it fails to
-		 * open /proc/<pid>/status file and that is not a problem. */
+	ret = cgroup_get_uid_gid_from_procfs(pid, &euid, &egid);
+	if (ret == ECGROUPNOTEXIST)
+		/* cgroup_get_uid_gid_from_procfs() returns ECGROUPNOTEXIST
+		 * if a process finished and that is not a problem. */
 		return 0;
+	else if (ret)
+		return ret;
 
 	/*
 	 * Now that we have the UID, the GID, and the PID, we can make a call
diff --git a/src/daemon/cgrulesengd.h b/src/daemon/cgrulesengd.h
index 1840143..506cb5d 100644
--- a/src/daemon/cgrulesengd.h
+++ b/src/daemon/cgrulesengd.h
@@ -31,13 +31,6 @@ __BEGIN_DECLS
 #define __USE_GNU
 #endif
 
-/* A simple macro for printing messages only when CGROUP_DEBUG is defined. */
-#ifdef CGROUP_DEBUG
-  #define cgroup_dbg(a...) printf(a)
-#else
-  #define cgroup_dbg(a...) do {} while (0)
-#endif /* CGROUP_DEBUG */
-
 /* The following ten macros are all for the Netlink code. */
 #define SEND_MESSAGE_LEN (NLMSG_LENGTH(sizeof(struct cn_msg) + \
 	sizeof(enum proc_cn_mcast_op)))
diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
index 9e69f10..a80ae38 100644
--- a/src/libcgroup-internal.h
+++ b/src/libcgroup-internal.h
@@ -90,6 +90,8 @@ struct cgroup_rule_list {
 
 /* Internal API */
 char *cg_build_path(char *name, char *path, char *type);
+int cgroup_get_uid_gid_from_procfs(pid_t pid, uid_t *euid, gid_t *egid);
+
 
 /*
  * config related API
diff --git a/src/libcgroup.map b/src/libcgroup.map
index 539687f..8d330e6 100644
--- a/src/libcgroup.map
+++ b/src/libcgroup.map
@@ -63,4 +63,5 @@ global:
 	cgroup_read_stats_next;
 	cgroup_read_stats_end;
 	cgroup_get_controller;
+	cgroup_get_uid_gid_from_procfs;
 } CGROUP_0.33;
diff --git a/src/tools/cgclassify.c b/src/tools/cgclassify.c
index de10510..ceaca34 100644
--- a/src/tools/cgclassify.c
+++ b/src/tools/cgclassify.c
@@ -18,6 +18,7 @@
 #include <string.h>
 #include <errno.h>
 #include <libcgroup.h>
+#include <libcgroup-internal.h>
 #include <limits.h>
 #include <pwd.h>
 #include <unistd.h>
@@ -31,80 +32,6 @@
 #define TEMP_BUF	81
 
 /*
- * Go through /proc/<pid>/status file to determine the euid of the
- * process.
- * It returns 0 on success and negative values on failure.
- */
-
-int euid_of_pid(pid_t pid)
-{
-	FILE *fp;
-	char path[FILENAME_MAX];
-	char buf[TEMP_BUF];
-	uid_t ruid, euid, suid, fsuid;
-
-	sprintf(path, "/proc/%d/status", pid);
-	fp = fopen(path, "r");
-	if (!fp) {
-		cgroup_dbg("Error in opening file %s:%s\n", path,
-				strerror(errno));
-		return -1;
-	}
-
-	while (fgets(buf, TEMP_BUF, fp)) {
-		if (!strncmp(buf, "Uid:", 4)) {
-			sscanf((buf + 5), "%d%d%d%d", (int *)&ruid,
-				(int *)&euid, (int *)&suid, (int *)&fsuid);
-			cgroup_dbg("Scanned proc values are %d %d %d %d\n",
-				ruid, euid, suid, fsuid);
-			fclose(fp);
-			return euid;
-		}
-	}
-	fclose(fp);
-
-	/* If we are here, we could not find euid. Return error. */
-	return -1;
-}
-
-/*
- * Go through /proc/<pid>/status file to determine the egid of the
- * process.
- * It returns 0 on success and negative values on failure.
- */
-
-int egid_of_pid(pid_t pid)
-{
-	FILE *fp;
-	char path[FILENAME_MAX];
-	char buf[TEMP_BUF];
-	gid_t rgid, egid, sgid, fsgid;
-
-	sprintf(path, "/proc/%d/status", pid);
-	fp = fopen(path, "r");
-	if (!fp) {
-		cgroup_dbg("Error in opening file %s:%s\n", path,
-				strerror(errno));
-		return -1;
-	}
-
-	while (fgets(buf, TEMP_BUF, fp)) {
-		if (!strncmp(buf, "Gid:", 4)) {
-			sscanf((buf + 5), "%d%d%d%d", (int *)&rgid,
-				(int *)&egid, (int *)&sgid, (int *)&fsgid);
-			cgroup_dbg("Scanned proc values are %d %d %d %d\n",
-				rgid, egid, sgid, fsgid);
-			fclose(fp);
-			return egid;
-		}
-	}
-	fclose(fp);
-
-	/* If we are here, we could not find egid. Return error. */
-	return -1;
-}
-
-/*
  * Change process group as specified on command line.
  */
 int change_group_path(pid_t pid, struct cgroup_group_spec *cgroup_list[])
@@ -137,16 +64,8 @@ int change_group_uid_gid(pid_t pid)
 	int ret;
 
 	/* Put pid into right cgroup as per rules in /etc/cgrules.conf */
-	euid = euid_of_pid(pid);
-	if (euid == -1) {
-		fprintf(stderr, "Error in determining euid of"
-		" pid %d\n", pid);
-		return -1;
-	}
-
-	egid = egid_of_pid(pid);
-	if (egid == -1) {
-		fprintf(stderr, "Error in determining egid of"
+	if (cgroup_get_uid_gid_from_procfs(pid, &euid, &egid)) {
+		fprintf(stderr, "Error in determining euid/egid of"
 		" pid %d\n", pid);
 		return -1;
 	}