From 3d1333293ef48117060cd4e285e9c49a6d061e83 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Tue, 15 Dec 2015 12:25:56 +0100
Subject: [PATCH 63/84] login, mount: fix __SC_GETPW_R_SIZE_MAX usage

sysconf(_SC_GETPW_R_SIZE_MAX) returns initial suggested size for pwd
buffer (see getpwnam_r man page or POSIX). This is not large enough in
some cases.

Yes, this sysconf option is misnamed (should be _SC_GETPW_R_SIZE_MIN).

Upstream: http://github.com/karelzak/util-linux/commit/f7ac9e71b18fa7314151f2ab65ee0bdd2ea89c07
Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1290689
Signed-off-by: Karel Zak <kzak@redhat.com>
---
 include/c.h          |  7 +++++++
 libmount/src/utils.c | 25 ++++++-------------------
 login-utils/login.c  | 12 ++----------
 3 files changed, 15 insertions(+), 29 deletions(-)

diff --git a/include/c.h b/include/c.h
index a50e8a5..7b59ce8 100644
--- a/include/c.h
+++ b/include/c.h
@@ -300,4 +300,11 @@ static inline int usleep(useconds_t usec)
 # define SEEK_HOLE	4
 #endif
 
+/*
+ * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
+ * pwd buffer and in some cases it is not large enough. See POSIX and
+ * getpwnam_r man page for more details.
+ */
+#define UL_GETPW_BUFSIZ	(16 * 1024)
+
 #endif /* UTIL_LINUX_C_H */
diff --git a/libmount/src/utils.c b/libmount/src/utils.c
index 9305bb8..7c6f5b1 100644
--- a/libmount/src/utils.c
+++ b/libmount/src/utils.c
@@ -538,16 +538,6 @@ int mnt_get_filesystems(char ***filesystems, const char *pattern)
 	return rc;
 }
 
-static size_t get_pw_record_size(void)
-{
-#ifdef _SC_GETPW_R_SIZE_MAX
-	long sz = sysconf(_SC_GETPW_R_SIZE_MAX);
-	if (sz > 0)
-		return sz;
-#endif
-	return 16384;
-}
-
 /*
  * Returns allocated string with username or NULL.
  */
@@ -555,14 +545,13 @@ char *mnt_get_username(const uid_t uid)
 {
         struct passwd pwd;
 	struct passwd *res;
-	size_t sz = get_pw_record_size();
 	char *buf, *username = NULL;
 
-	buf = malloc(sz);
+	buf = malloc(UL_GETPW_BUFSIZ);
 	if (!buf)
 		return NULL;
 
-	if (!getpwuid_r(uid, &pwd, buf, sz, &res) && res)
+	if (!getpwuid_r(uid, &pwd, buf, UL_GETPW_BUFSIZ, &res) && res)
 		username = strdup(pwd.pw_name);
 
 	free(buf);
@@ -574,17 +563,16 @@ int mnt_get_uid(const char *username, uid_t *uid)
 	int rc = -1;
         struct passwd pwd;
 	struct passwd *pw;
-	size_t sz = get_pw_record_size();
 	char *buf;
 
 	if (!username || !uid)
 		return -EINVAL;
 
-	buf = malloc(sz);
+	buf = malloc(UL_GETPW_BUFSIZ);
 	if (!buf)
 		return -ENOMEM;
 
-	if (!getpwnam_r(username, &pwd, buf, sz, &pw) && pw) {
+	if (!getpwnam_r(username, &pwd, buf, UL_GETPW_BUFSIZ, &pw) && pw) {
 		*uid= pw->pw_uid;
 		rc = 0;
 	} else {
@@ -602,17 +590,16 @@ int mnt_get_gid(const char *groupname, gid_t *gid)
 	int rc = -1;
         struct group grp;
 	struct group *gr;
-	size_t sz = get_pw_record_size();
 	char *buf;
 
 	if (!groupname || !gid)
 		return -EINVAL;
 
-	buf = malloc(sz);
+	buf = malloc(UL_GETPW_BUFSIZ);
 	if (!buf)
 		return -ENOMEM;
 
-	if (!getgrnam_r(groupname, &grp, buf, sz, &gr) && gr) {
+	if (!getgrnam_r(groupname, &grp, buf, UL_GETPW_BUFSIZ, &gr) && gr) {
 		*gid= gr->gr_gid;
 		rc = 0;
 	} else {
diff --git a/login-utils/login.c b/login-utils/login.c
index a59dd3a..e0e960f 100644
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -671,22 +671,14 @@ static struct passwd *get_passwd_entry(const char *username,
 					 struct passwd *pwd)
 {
 	struct passwd *res = NULL;
-	size_t sz = 16384;
 	int x;
 
 	if (!pwdbuf || !username)
 		return NULL;
 
-#ifdef _SC_GETPW_R_SIZE_MAX
-	{
-		long xsz = sysconf(_SC_GETPW_R_SIZE_MAX);
-		if (xsz > 0)
-			sz = (size_t) xsz;
-	}
-#endif
-	*pwdbuf = xrealloc(*pwdbuf, sz);
+	*pwdbuf = xrealloc(*pwdbuf, UL_GETPW_BUFSIZ);
 
-	x = getpwnam_r(username, pwd, *pwdbuf, sz, &res);
+	x = getpwnam_r(username, pwd, *pwdbuf, UL_GETPW_BUFSIZ, &res);
 	if (!res) {
 		errno = x;
 		return NULL;
-- 
2.7.4