4:42 p.m.
POSIX allows sysconf(_SC_GETPW_R_SIZE_MAX) to return -1 if there
is no fixed limit, and requires ERANGE errors to track real size.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwuid_r.html
Also, on error for get*_r functions, errno is undefined, and the
real error was the return value.
* src/util/util.c (virGetUserEnt, virGetUserID, virGetGroupID)
(virSetUIDGID): Cope with sysconf failure or too small buffer.
Reported by Matthias Bolte.
---
This pretty much copies the example implementation straight from POSIX
for getting a hint for initial size, then iterating until ERANGE no
longer occurs.
src/util/util.c | 74 +++++++++++++++++++++++++++++++++++++-----------------
1 files changed, 51 insertions(+), 23 deletions(-)
diff --git a/src/util/util.c b/src/util/util.c
index f169e54..240f776 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -603,7 +603,7 @@ virExecWithHook(const char *const*argv,
goto fork_error;
}
- openmax = sysconf (_SC_OPEN_MAX);
+ openmax = sysconf(_SC_OPEN_MAX);
for (i = 3; i < openmax; i++)
if (i != infd &&
i != null &&
@@ -2743,11 +2743,11 @@ static char *virGetUserEnt(uid_t uid,
struct passwd *pw = NULL;
long val = sysconf(_SC_GETPW_R_SIZE_MAX);
size_t strbuflen = val;
+ int rc;
- if (val < 0) {
- virReportSystemError(errno, "%s", _("sysconf failed"));
- return NULL;
- }
+ /* sysconf is a hint; if it fails, fall back to a reasonable size */
+ if (val < 0)
+ strbuflen = 1024;
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError();
@@ -2761,8 +2761,15 @@ static char *virGetUserEnt(uid_t uid,
* 0 or ENOENT or ESRCH or EBADF or EPERM or ...
* The given name or uid was not found.
*/
- if (getpwuid_r(uid, &pwbuf, strbuf, strbuflen, &pw) != 0 || pw == NULL) {
- virReportSystemError(errno,
+ while ((rc = getpwuid_r(uid, &pwbuf, strbuf, strbuflen, &pw)) == ERANGE) {
+ if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0) {
+ virReportOOMError();
+ VIR_FREE(strbuf);
+ return NULL;
+ }
+ }
+ if (rc != 0 || pw == NULL) {
+ virReportSystemError(rc,
_("Failed to find user record for uid
'%u'"),
(unsigned int) uid);
VIR_FREE(strbuf);
@@ -2800,11 +2807,11 @@ int virGetUserID(const char *name,
struct passwd *pw = NULL;
long val = sysconf(_SC_GETPW_R_SIZE_MAX);
size_t strbuflen = val;
+ int rc;
- if (val < 0) {
- virReportSystemError(errno, "%s", _("sysconf failed"));
- return -1;
- }
+ /* sysconf is a hint; if it fails, fall back to a reasonable size */
+ if (val < 0)
+ strbuflen = 1024;
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError();
@@ -2818,8 +2825,15 @@ int virGetUserID(const char *name,
* 0 or ENOENT or ESRCH or EBADF or EPERM or ...
* The given name or uid was not found.
*/
- if (getpwnam_r(name, &pwbuf, strbuf, strbuflen, &pw) != 0 || pw == NULL) {
- virReportSystemError(errno,
+ while ((rc = getpwnam_r(name, &pwbuf, strbuf, strbuflen, &pw)) == ERANGE) {
+ if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0) {
+ virReportOOMError();
+ VIR_FREE(strbuf);
+ return -1;
+ }
+ }
+ if (rc != 0 || pw == NULL) {
+ virReportSystemError(rc,
_("Failed to find user record for name
'%s'"),
name);
VIR_FREE(strbuf);
@@ -2842,11 +2856,11 @@ int virGetGroupID(const char *name,
struct group *gr = NULL;
long val = sysconf(_SC_GETGR_R_SIZE_MAX);
size_t strbuflen = val;
+ int rc;
- if (val < 0) {
- virReportSystemError(errno, "%s", _("sysconf failed"));
- return -1;
- }
+ /* sysconf is a hint; if it fails, fall back to a reasonable size */
+ if (val < 0)
+ strbuflen = 1024;
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError();
@@ -2860,8 +2874,15 @@ int virGetGroupID(const char *name,
* 0 or ENOENT or ESRCH or EBADF or EPERM or ...
* The given name or uid was not found.
*/
- if (getgrnam_r(name, &grbuf, strbuf, strbuflen, &gr) != 0 || gr == NULL) {
- virReportSystemError(errno,
+ while ((rc = getgrnam_r(name, &grbuf, strbuf, strbuflen, &gr)) == ERANGE) {
+ if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0) {
+ virReportOOMError();
+ VIR_FREE(strbuf);
+ return -1;
+ }
+ }
+ if (rc != 0 || gr == NULL) {
+ virReportSystemError(rc,
_("Failed to find group record for name
'%s'"),
name);
VIR_FREE(strbuf);
@@ -2897,6 +2918,7 @@ virSetUIDGID(uid_t uid, gid_t gid)
struct passwd pwd, *pwd_result;
char *buf = NULL;
size_t bufsize;
+ int rc;
bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
if (bufsize == -1)
@@ -2906,10 +2928,16 @@ virSetUIDGID(uid_t uid, gid_t gid)
virReportOOMError();
return -1;
}
- getpwuid_r(uid, &pwd, buf, bufsize, &pwd_result);
- if (!pwd_result) {
- virReportSystemError(errno,
- _("cannot getpwuid_r(%d)"),
+ while ((rc = getpwuid_r(uid, &pwd, buf, bufsize,
+ &pwd_result)) == ERANGE) {
+ if (VIR_RESIZE_N(buf, bufsize, bufsize, bufsize) < 0) {
+ virReportOOMError();
+ VIR_FREE(buf);
+ return -1;
+ }
+ }
+ if (rc || !pwd_result) {
+ virReportSystemError(rc, _("cannot getpwuid_r(%d)"),
(unsigned int) uid);
VIR_FREE(buf);
return -1;
--
1.7.4.4