1 files changed, 158 insertions, 0 deletions
diff --git a/lib/pwdutils.c b/lib/pwdutils.c
new file mode 100644
index 0000000..1c1f13e
--- /dev/null
+++ b/lib/pwdutils.c
@@ -0,0 +1,158 @@
+/*
+ * No copyright is claimed.  This code is in the public domain; do with
+ * it what you wish.
+ */
+#include <stdlib.h>
+#include <assert.h>
+
+#include "c.h"
+#include "pwdutils.h"
+#include "xalloc.h"
+
+/* Returns allocated passwd and allocated pwdbuf to store passwd strings
+ * fields. In case of error returns NULL and set errno, for unknown user set
+ * errno to EINVAL
+ */
+struct passwd *xgetpwnam(const char *username, char **pwdbuf)
+{
+	struct passwd *pwd = NULL, *res = NULL;
+	int rc;
+
+	assert(pwdbuf);
+	assert(username);
+
+	*pwdbuf = xmalloc(UL_GETPW_BUFSIZ);
+	pwd = xcalloc(1, sizeof(struct passwd));
+
+	errno = 0;
+	rc = getpwnam_r(username, pwd, *pwdbuf, UL_GETPW_BUFSIZ, &res);
+	if (rc != 0) {
+		errno = rc;
+		goto failed;
+	}
+	if (!res) {
+		errno = EINVAL;
+		goto failed;
+	}
+	return pwd;
+failed:
+	free(pwd);
+	free(*pwdbuf);
+	return NULL;
+}
+
+/* Returns allocated group and allocated grpbuf to store group strings
+ * fields. In case of error returns NULL and set errno, for unknown group set
+ * errno to EINVAL
+ */
+struct group *xgetgrnam(const char *groupname, char **grpbuf)
+{
+	struct group *grp = NULL, *res = NULL;
+	int rc;
+
+	assert(grpbuf);
+	assert(groupname);
+
+	*grpbuf = xmalloc(UL_GETPW_BUFSIZ);
+	grp = xcalloc(1, sizeof(struct group));
+
+	errno = 0;
+	rc = getgrnam_r(groupname, grp, *grpbuf, UL_GETPW_BUFSIZ, &res);
+	if (rc != 0) {
+		errno = rc;
+		goto failed;
+	}
+	if (!res) {
+		errno = EINVAL;
+		goto failed;
+	}
+	return grp;
+failed:
+	free(grp);
+	free(*grpbuf);
+	return NULL;
+}
+
+struct passwd *xgetpwuid(uid_t uid, char **pwdbuf)
+{
+	struct passwd *pwd = NULL, *res = NULL;
+	int rc;
+
+	assert(pwdbuf);
+
+	*pwdbuf = xmalloc(UL_GETPW_BUFSIZ);
+	pwd = xcalloc(1, sizeof(struct passwd));
+
+	errno = 0;
+	rc = getpwuid_r(uid, pwd, *pwdbuf, UL_GETPW_BUFSIZ, &res);
+	if (rc != 0) {
+		errno = rc;
+		goto failed;
+	}
+	if (!res) {
+		errno = EINVAL;
+		goto failed;
+	}
+	return pwd;
+failed:
+	free(pwd);
+	free(*pwdbuf);
+	return NULL;
+}
+
+char *xgetlogin(void)
+{
+	struct passwd *pw = NULL;
+	uid_t ruid;
+
+	/* GNU Hurd implementation has an extension where a process can exist in a
+	 * non-conforming environment, and thus be outside the realms of POSIX
+	 * process identifiers; on this platform, getuid() fails with a status of
+	 * (uid_t)(-1) and sets errno if a program is run from a non-conforming
+	 * environment.
+	 *
+	 * http://austingroupbugs.net/view.php?id=511
+	 *
+	 * The same implementation is useful for other systems, since getlogin(3)
+	 * shouldn't be used as actual identification.
+	 */
+	errno = 0;
+	ruid = getuid();
+
+	if (errno == 0)
+		pw = getpwuid(ruid);
+	if (pw && pw->pw_name && *pw->pw_name)
+		return xstrdup(pw->pw_name);
+
+	return NULL;
+}
+
+#ifdef TEST_PROGRAM
+int main(int argc, char *argv[])
+{
+	char *buf = NULL;
+	struct passwd *pwd = NULL;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <username>\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	pwd = xgetpwnam(argv[1], &buf);
+	if (!pwd)
+		err(EXIT_FAILURE, "failed to get %s pwd entry", argv[1]);
+
+	printf("Username: %s\n", pwd->pw_name);
+	printf("UID:      %d\n", pwd->pw_uid);
+	printf("HOME:     %s\n", pwd->pw_dir);
+	printf("GECO:     %s\n", pwd->pw_gecos);
+
+	free(pwd);
+	free(buf);
+
+	printf("Current:  %s\n", (buf = xgetlogin()));
+	free(buf);
+
+	return EXIT_SUCCESS;
+}
+#endif /* TEST_PROGRAM */