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-rw-r--r--lib/xgetXXbyYY.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/lib/xgetXXbyYY.c b/lib/xgetXXbyYY.c
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+++ b/lib/xgetXXbyYY.c
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+/*
+ * 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);
+}
+