[libvirt] [PATCH] util: distinguish get{pw|gr}nam_r error from the "not found" cases

[Guannan Ren]

manpage:
"If no matching record was found, these functions return 0 and
store NULL in *result.  In case of error, an error number is returned,
and NULL is stored in *result."

So we can distinguish function error from "no found" cases based on
the return value.
---
 src/util/virutil.c | 46 ++++++++++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/src/util/virutil.c b/src/util/virutil.c
index 4605c78..9a4682e 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -2532,6 +2532,7 @@ virGetUserIDByName(const char *name, uid_t *uid)
         goto cleanup;
     }
 
+    errno = 0;
     while ((rc = getpwnam_r(name, &pwbuf, strbuf, strbuflen, &pw)) == ERANGE) {
         if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0) {
             virReportOOMError();
@@ -2540,16 +2541,11 @@ virGetUserIDByName(const char *name, uid_t *uid)
     }
 
     if (!pw) {
-        if (rc != 0) {
-            char buf[1024];
-            /* log the possible error from getpwnam_r. Unfortunately error
-             * reporting from this function is bad and we can't really
-             * rely on it, so we just report that the user wasn't found */
-            VIR_WARN("User record for user '%s' was not found: %s",
-                     name, virStrerror(rc, buf, sizeof(buf)));
-        }
-
-        ret = 1;
+        if (rc == 0)
+            ret = 1;
+        else
+            virReportSystemError(errno = rc,
+                                 _("cannot getpwnam_r(%s)"), name);
         goto cleanup;
     }
 
@@ -2577,8 +2573,13 @@ virGetUserID(const char *user, uid_t *uid)
         user++;
     } else {
         int rc = virGetUserIDByName(user, uid);
-        if (rc <= 0)
+        if (rc > 0) {
+            virReportError(VIR_ERR_INVALID_ARG,
+                           _("User '%s' was not found"), user);
+            return -1;
+        } else {
             return rc;
+        }
     }
 
     if (virStrToLong_ui(user, NULL, 10, &uint_uid) < 0 ||
@@ -2616,6 +2617,7 @@ virGetGroupIDByName(const char *name, gid_t *gid)
         goto cleanup;
     }
 
+    errno = 0;
     while ((rc = getgrnam_r(name, &grbuf, strbuf, strbuflen, &gr)) == ERANGE) {
         if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0) {
             virReportOOMError();
@@ -2624,16 +2626,11 @@ virGetGroupIDByName(const char *name, gid_t *gid)
     }
 
     if (!gr) {
-        if (rc != 0) {
-            char buf[1024];
-            /* log the possible error from getgrnam_r. Unfortunately error
-             * reporting from this function is bad and we can't really
-             * rely on it, so we just report that the user wasn't found */
-            VIR_WARN("Group record for user '%s' was not found: %s",
-                     name, virStrerror(rc, buf, sizeof(buf)));
-        }
-
-        ret = 1;
+        if (rc == 0)
+            ret = 1;
+        else
+            virReportSystemError(errno = rc,
+                                 _("cannot getgrnam_r(%s)"), name);
         goto cleanup;
     }
 
@@ -2661,8 +2658,13 @@ virGetGroupID(const char *group, gid_t *gid)
         group++;
     } else {
         int rc = virGetGroupIDByName(group, gid);
-        if (rc <= 0)
+        if (rc > 0) {
+            virReportError(VIR_ERR_INVALID_ARG,
+                           _("Group '%s' was not found"), group);
+            return -1;
+        } else {
             return rc;
+        }
     }
 
     if (virStrToLong_ui(group, NULL, 10, &uint_gid) < 0 ||
-- 
1.7.11.2