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util: improve user lookup helper

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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>
This commit is contained in:
Eric Blake 2013-07-09 17:57:48 -06:00
parent a5fcea5513
commit c1983ba4e3
1 changed files with 34 additions and 19 deletions
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53
src/util/virutil.c
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@ -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;
}
ignore_value(VIR_STRDUP(ret, field == VIR_USER_ENT_DIRECTORY ?
pw->pw_dir : pw->pw_name));
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;
}
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)