1 files changed, 118 insertions, 0 deletions
diff --git a/lib/xgetXXbyYY.c b/lib/xgetXXbyYY.c
new file mode 100644
index 0000000..7d5e914
--- /dev/null
+++ b/lib/xgetXXbyYY.c
@@ -0,0 +1,118 @@
+/*
+ * SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * According to the Linux-PAM documentation:
+ *
+ *  4.1. Care about standard library calls
+ *
+ *  In general, writers of authorization-granting applications should
+ *  assume that each module is likely to call any or all 'libc' functions.
+ *  For 'libc' functions that return pointers to static/dynamically
+ *  allocated structures (ie.  the library allocates the memory and the
+ *  user is not expected to 'free()' it) any module call to this function
+ *  is likely to corrupt a pointer previously obtained by the application.
+ *  The application programmer should either re-call such a 'libc'
+ *  function after a call to the Linux-PAM library, or copy the structure
+ *  contents to some safe area of memory before passing control to the
+ *  Linux-PAM library.
+ *
+ *  Two important function classes that fall into this category are
+ *  getpwnam(3) and syslog(3).
+ *
+ * This file provides wrapper to the name or name_r functions.
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include "alloc.h"
+#include "prototypes.h"
+#include "shadowlog.h"
+
+#define XFUNCTION_NAME XPREFIX (FUNCTION_NAME)
+#define XPREFIX(name) XPREFIX1 (name)
+#define XPREFIX1(name) x##name
+#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
+#define APPEND_R(name) APPEND_R1 (name)
+#define APPEND_R1(name) name##_r
+#define STRINGIZE(name) STRINGIZE1 (name)
+#define STRINGIZE1(name) #name
+
+/*@null@*/ /*@only@*/LOOKUP_TYPE *XFUNCTION_NAME (ARG_TYPE ARG_NAME)
+{
+#if HAVE_FUNCTION_R
+	LOOKUP_TYPE *result=NULL;
+	char *buffer=NULL;
+	/* we have to start with something */
+	size_t length = 0x100;
+
+	result = MALLOC(1, LOOKUP_TYPE);
+	if (NULL == result) {
+		goto oom;
+	}
+
+	while (true) {
+		int status;
+		LOOKUP_TYPE *resbuf = NULL;
+		buffer = XREALLOC(buffer, length, char);
+		status = REENTRANT_NAME(ARG_NAME, result, buffer,
+		                        length, &resbuf);
+		if ((0 == status) && (resbuf == result)) {
+			/* Build a result structure that can be freed by
+			 * the shadow *_free functions. */
+			LOOKUP_TYPE *ret_result = DUP_FUNCTION(result);
+			if (NULL == ret_result) {
+				goto oom;
+			}
+			free(buffer);
+			free(result);
+			return ret_result;
+		}
+
+		if (ERANGE != status) {
+			break;
+		}
+
+		if (length == SIZE_MAX) {
+			break;
+		}
+
+		length = (length <= SIZE_MAX / 4) ? length * 4 : SIZE_MAX;
+	}
+
+	free(buffer);
+	free(result);
+	return NULL;
+
+#else /* !HAVE_FUNCTION_R */
+
+	/* No reentrant function.
+	 * Duplicate the structure to avoid other call to overwrite it.
+	 *
+	 * We should also restore the initial structure. But that would be
+	 * overkill.
+	 */
+	LOOKUP_TYPE *result = FUNCTION_NAME(ARG_NAME);
+
+	if (result) {
+		result = DUP_FUNCTION(result);
+		if (NULL == result) {
+			goto oom;
+		}
+	}
+
+	return result;
+#endif
+
+oom:
+	fprintf (log_get_logfd(), _("%s: out of memory\n"),
+		 "x" STRINGIZE(FUNCTION_NAME));
+	exit (13);
+}
+