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util: improve user lookup helper

Browse Source 
https://bugzilla.redhat.com/show_bug.cgi?id=964358

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@redhat.com>
(cherry picked from commit c1983ba4e3902308054e961fcae75cece73ef4ba)

Conflicts:
	src/util/virutil.c - oom reporting/strdup changes not backported
This commit is contained in:
Eric Blake 2013-07-09 17:57:48 -06:00
parent 27b2639f16
commit f468720661
1 changed files with 36 additions and 24 deletions
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60
src/util/util.c
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@ -2290,21 +2290,23 @@ check_and_return:
}
#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)
@ -2312,7 +2314,7 @@ static char *virGetUserEnt(uid_t uid,
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError();
return NULL;
return -1;
}
/*
@ -2325,28 +2327,33 @@ 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) {
virReportOOMError();
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 (field == VIR_USER_ENT_DIRECTORY)
ret = strdup(pw->pw_dir);
else
ret = strdup(pw->pw_name);
if (name && !(*name = strdup(pw->pw_name)))
goto no_memory;
if (group)
*group = pw->pw_gid;
if (dir && !(*dir = strdup(pw->pw_dir))) {
if (name)
VIR_FREE(*name);
goto no_memory;
}
ret = 0;
cleanup:
VIR_FREE(strbuf);
if (!ret)
virReportOOMError();
return ret;
no_memory:
virReportOOMError();
goto cleanup;
}
static char *virGetGroupEnt(gid_t gid)
@ -2401,20 +2408,23 @@ 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)
{
const char *path = getenv(xdgenvname);
char *ret = NULL;
char *home = virGetUserEnt(geteuid(), VIR_USER_ENT_DIRECTORY);
char *home = virGetUserDirectory();
if (path && path[0]) {
if (virAsprintf(&ret, "%s/libvirt", path) < 0)
goto no_memory;
} else {
if (virAsprintf(&ret, "%s/%s/libvirt", home, xdgdefdir) < 0)
if (home &&
virAsprintf(&ret, "%s/%s/libvirt", home, xdgdefdir) < 0)
goto no_memory;
}
@ -2456,7 +2466,9 @@ 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)