core: Add thread-safe group info functions with dynamic buffers

Provides getgrgid, getgrnam, getpwuid & getpwnam replacements that are
thread safe (a la getgrgid_r() and friends) that internally
handle allocating big-enough buffers to avoid ERANGE errors
on large users or groups.

src/tests/usergroup-test.c

@@ -0,0 +1,161 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2009 Ted Percival
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <errno.h>
+
+#include <pulsecore/usergroup.h>
+
+static int load_reference_structs(struct group **gr, struct passwd **pw) {
+    setpwent();
+    *pw = getpwent();
+    endpwent();
+
+    setgrent();
+    *gr = getgrent();
+    endgrent();
+
+    return (*gr && *pw) ? 0 : 1;
+}
+
+static int compare_group(const struct group *a, const struct group *b) {
+    char **amem, **bmem;
+
+    if (strcmp(a->gr_name, b->gr_name)) {
+        fprintf(stderr, "Group name mismatch: [%s] [%s]\n",
+                a->gr_name, b->gr_name);
+        return 1;
+    }
+
+    if (strcmp(a->gr_passwd, b->gr_passwd)) {
+        fprintf(stderr, "Group password mismatch: [%s] [%s]\n",
+                a->gr_passwd, b->gr_passwd);
+        return 1;
+    }
+
+    if (a->gr_gid != b->gr_gid) {
+        fprintf(stderr, "Gid mismatch: [%lu] [%lu]\n",
+                (unsigned long) a->gr_gid, (unsigned long) b->gr_gid);
+        return 1;
+    }
+
+    /* XXX: Assuming the group ordering is identical. */
+    for (amem = a->gr_mem, bmem = b->gr_mem; *amem && *bmem; ++amem, ++bmem) {
+        if (strcmp(*amem, *bmem)) {
+            fprintf(stderr, "Group member mismatch: [%s] [%s]\n",
+                    *amem, *bmem);
+            return 1;
+        }
+    }
+
+    if (*amem || *bmem) {
+        fprintf(stderr, "Mismatched group count\n");
+        return 1;
+    }
+
+    return 0;
+}
+
+static int compare_passwd(const struct passwd *a, const struct passwd *b) {
+    if (strcmp(a->pw_name, b->pw_name)) {
+        fprintf(stderr, "pw_name mismatch: [%s] [%s]\n", a->pw_name, b->pw_name);
+        return 1;
+    }
+
+    if (strcmp(a->pw_passwd, b->pw_passwd)) {
+        fprintf(stderr, "pw_passwd mismatch: [%s] [%s]\n", a->pw_passwd, b->pw_passwd);
+        return 1;
+    }
+
+    if (a->pw_uid != b->pw_uid) {
+        fprintf(stderr, "pw_uid mismatch: [%lu] [%lu]\n",
+		(unsigned long) a->pw_uid, (unsigned long) b->pw_uid);
+        return 1;
+    }
+
+    if (a->pw_gid != b->pw_gid) {
+        fprintf(stderr, "pw_gid mismatch: [%lu] [%lu]\n",
+		(unsigned long) a->pw_gid, (unsigned long) b->pw_gid);
+        return 1;
+    }
+
+    if (strcmp(a->pw_gecos, b->pw_gecos)) {
+        fprintf(stderr, "pw_gecos mismatch: [%s] [%s]\n", a->pw_gecos, b->pw_gecos);
+        return 1;
+    }
+
+    if (strcmp(a->pw_dir, b->pw_dir)) {
+        fprintf(stderr, "pw_dir mismatch: [%s] [%s]\n", a->pw_dir, b->pw_dir);
+        return 1;
+    }
+
+    if (strcmp(a->pw_shell, b->pw_shell)) {
+        fprintf(stderr, "pw_shell mismatch: [%s] [%s]\n", a->pw_shell, b->pw_shell);
+        return 1;
+    }
+
+    return 0;
+}
+
+int main(int argc, char *argv[]) {
+    struct group *gr;
+    struct passwd *pw;
+    int err;
+    struct group *reference_group = NULL;
+    struct passwd *reference_passwd = NULL;
+
+    err = load_reference_structs(&reference_group, &reference_passwd);
+    if (err)
+        return 77;
+
+    errno = 0;
+    gr = pa_getgrgid_malloc(reference_group->gr_gid);
+    if (compare_group(reference_group, gr))
+        return 1;
+    pa_getgrgid_free(gr);
+
+    errno = 0;
+    gr = pa_getgrnam_malloc(reference_group->gr_name);
+    if (compare_group(reference_group, gr))
+        return 1;
+    pa_getgrnam_free(gr);
+
+    errno = 0;
+    pw = pa_getpwuid_malloc(reference_passwd->pw_uid);
+    if (compare_passwd(reference_passwd, pw))
+        return 1;
+    pa_getpwuid_free(pw);
+
+    errno = 0;
+    pw = pa_getpwnam_malloc(reference_passwd->pw_name);
+    if (compare_passwd(reference_passwd, pw))
+        return 1;
+    pa_getpwnam_free(pw);
+
+    return 0;
+}