[libvirt] [PATCHv3 1/3] util: improve user lookup helper
A future patch needs to look up pw_gid; but it is wasteful
to crawl through getpwuid_r twice for two separate pieces
of information, and annoying to copy that much boilerplate
code for doing the crawl. The current internal-only
virGetUserEnt is also a rather awkward interface; it's easier
to just design it to let callers request multiple pieces of
data as needed from one traversal.
And while at it, I noticed that virGetXDGDirectory could deref
NULL if the getpwuid_r lookup fails.
* src/util/virutil.c (virGetUserEnt): Alter signature.
(virGetUserDirectory, virGetXDGDirectory, virGetUserName): Adjust
callers.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
v3: fold in the changes proposed on-list.
I've gone ahead and pushed this, and the rest of the series, now.
Next, I'm working on backporting to at least v1.0.5-maint and
v0.10.2-maint, since those are active Fedora releases.
src/util/virutil.c | 53 ++++++++++++++++++++++++++++++++++-------------------
1 file changed, 34 insertions(+), 19 deletions(-)
diff --git a/src/util/virutil.c b/src/util/virutil.c
index 8f38fb1..d7e61db 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -647,28 +647,30 @@ cleanup:
}
#ifdef HAVE_GETPWUID_R
-enum {
- VIR_USER_ENT_DIRECTORY,
- VIR_USER_ENT_NAME,
-};
-
-static char *virGetUserEnt(uid_t uid,
- int field)
+/* Look up fields from the user database for the given user. On
+ * error, set errno, report the error, and return -1. */
+static int
+virGetUserEnt(uid_t uid, char **name, gid_t *group, char **dir)
{
char *strbuf;
- char *ret;
struct passwd pwbuf;
struct passwd *pw = NULL;
long val = sysconf(_SC_GETPW_R_SIZE_MAX);
size_t strbuflen = val;
int rc;
+ int ret = -1;
+
+ if (name)
+ *name = NULL;
+ if (dir)
+ *dir = 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)
- return NULL;
+ return -1;
/*
* From the manpage (terrifying but true):
@@ -679,19 +681,27 @@ static char *virGetUserEnt(uid_t uid,
*/
while ((rc = getpwuid_r(uid, &pwbuf, strbuf, strbuflen, &pw)) == ERANGE) {
if (VIR_RESIZE_N(strbuf, strbuflen, strbuflen, strbuflen) < 0)
- VIR_FREE(strbuf);
- return NULL;
+ goto cleanup;
}
if (rc != 0 || pw == NULL) {
virReportSystemError(rc,
_("Failed to find user record for uid
'%u'"),
(unsigned int) uid);
- VIR_FREE(strbuf);
- return NULL;
+ goto cleanup;
+ }
+
+ if (name && VIR_STRDUP(*name, pw->pw_name) < 0)
+ goto cleanup;
+ if (group)
+ *group = pw->pw_gid;
+ if (dir && VIR_STRDUP(*dir, pw->pw_dir) < 0) {
+ if (name)
+ VIR_FREE(*name);
+ goto cleanup;
}
- ignore_value(VIR_STRDUP(ret, field == VIR_USER_ENT_DIRECTORY ?
- pw->pw_dir : pw->pw_name));
+ ret = 0;
+cleanup:
VIR_FREE(strbuf);
return ret;
}
@@ -741,7 +751,9 @@ static char *virGetGroupEnt(gid_t gid)
char *virGetUserDirectory(void)
{
- return virGetUserEnt(geteuid(), VIR_USER_ENT_DIRECTORY);
+ char *ret;
+ virGetUserEnt(geteuid(), NULL, NULL, &ret);
+ return ret;
}
static char *virGetXDGDirectory(const char *xdgenvname, const char *xdgdefdir)
@@ -753,8 +765,9 @@ static char *virGetXDGDirectory(const char *xdgenvname, const char
*xdgdefdir)
if (path && path[0]) {
ignore_value(virAsprintf(&ret, "%s/libvirt", path));
} else {
- home = virGetUserEnt(geteuid(), VIR_USER_ENT_DIRECTORY);
- ignore_value(virAsprintf(&ret, "%s/%s/libvirt", home, xdgdefdir));
+ home = virGetUserDirectory();
+ if (home)
+ ignore_value(virAsprintf(&ret, "%s/%s/libvirt", home,
xdgdefdir));
}
VIR_FREE(home);
@@ -787,7 +800,9 @@ char *virGetUserRuntimeDirectory(void)
char *virGetUserName(uid_t uid)
{
- return virGetUserEnt(uid, VIR_USER_ENT_NAME);
+ char *ret;
+ virGetUserEnt(uid, &ret, NULL, NULL);
+ return ret;
}
char *virGetGroupName(gid_t gid)
--
1.8.1.4