1 files changed, 138 insertions, 0 deletions
diff --git a/libpam/pam_modutil_getgrgid.c b/libpam/pam_modutil_getgrgid.c
new file mode 100644
index 0000000..386d6f4
--- /dev/null
+++ b/libpam/pam_modutil_getgrgid.c
@@ -0,0 +1,138 @@
+/*
+ * $Id$
+ *
+ * This function provides a thread safer version of getgrgid() for use
+ * with PAM modules that care about this sort of thing.
+ *
+ * XXX - or at least it should provide a thread-safe alternative.
+ */
+
+#include "pam_modutil_private.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <grp.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int intlen(int number)
+{
+    int len = 2;
+    while (number != 0) {
+        number /= 10;
+	len++;
+    }
+    return len;
+}
+
+static int longlen(long number)
+{
+    int len = 2;
+    while (number != 0) {
+        number /= 10;
+	len++;
+    }
+    return len;
+}
+
+struct group *
+pam_modutil_getgrgid(pam_handle_t *pamh, gid_t gid)
+{
+#ifdef HAVE_GETGRGID_R
+
+    void *buffer=NULL;
+    size_t length = PWD_INITIAL_LENGTH;
+
+    do {
+	int status;
+	void *new_buffer;
+	struct group *result = NULL;
+
+	new_buffer = realloc(buffer, sizeof(struct group) + length);
+	if (new_buffer == NULL) {
+
+	    D(("out of memory"));
+
+	    /* no memory for the user - so delete the memory */
+	    if (buffer) {
+		free(buffer);
+	    }
+	    return NULL;
+	}
+	buffer = new_buffer;
+
+	/* make the re-entrant call to get the grp structure */
+	errno = 0;
+	status = getgrgid_r(gid, buffer,
+			    sizeof(struct group) + (char *) buffer,
+			    length, &result);
+	if (!status && (result == buffer)) {
+	    char *data_name;
+	    const void *ignore;
+	    int i;
+
+	    data_name = malloc(strlen("_pammodutil_getgrgid") + 1 +
+			       longlen((long)gid) + 1 + intlen(INT_MAX) + 1);
+	    if ((pamh != NULL) && (data_name == NULL)) {
+	        D(("was unable to register the data item [%s]",
+	           pam_strerror(pamh, status)));
+		free(buffer);
+		return NULL;
+	    }
+
+	    if (pamh != NULL) {
+	        for (i = 0; i < INT_MAX; i++) {
+	            sprintf(data_name, "_pammodutil_getgrgid_%ld_%d",
+			    (long) gid, i);
+		    status = PAM_NO_MODULE_DATA;
+	            if (pam_get_data(pamh, data_name, &ignore) != PAM_SUCCESS) {
+		        status = pam_set_data(pamh, data_name,
+					      result, pam_modutil_cleanup);
+		    }
+		    if (status == PAM_SUCCESS) {
+		        break;
+		    }
+		}
+	    } else {
+	        status = PAM_SUCCESS;
+	    }
+
+	    free(data_name);
+
+	    if (status == PAM_SUCCESS) {
+		D(("success"));
+		return result;
+	    }
+
+	    D(("was unable to register the data item [%s]",
+	       pam_strerror(pamh, status)));
+
+	    free(buffer);
+	    return NULL;
+
+	} else if (errno != ERANGE && errno != EINTR) {
+		/* no sense in repeating the call */
+		break;
+	}
+
+	length <<= PWD_LENGTH_SHIFT;
+
+    } while (length < PWD_ABSURD_PWD_LENGTH);
+
+    D(("grp structure took %u bytes or so of memory",
+       length+sizeof(struct group)));
+
+    free(buffer);
+    return NULL;
+
+#else /* ie. ifndef HAVE_GETGRGID_R */
+
+    /*
+     * Sorry, there does not appear to be a reentrant version of
+     * getgrgid(). So, we use the standard libc function.
+     */
+
+    return getgrgid(gid);
+
+#endif /* def HAVE_GETGRGID_R */
+}