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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);
}
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