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dict: Handle ENOSYS from getentropy gracefully

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Also add some comments.

Should fix #854.
This commit is contained in:
Nick Wellnhofer 2025-02-02 13:13:20 +01:00
parent bc43786822
commit cd491ac07d
1 changed files with 35 additions and 6 deletions
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41
dict.c
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@ -929,10 +929,13 @@ xmlDictQLookup(xmlDictPtr dict, const xmlChar *prefix, const xmlChar *name) {
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <bcrypt.h>
#elif HAVE_DECL_GETENTROPY
#include <unistd.h>
#include <sys/random.h>
#else
#if HAVE_DECL_GETENTROPY
/* POSIX 2024 */
#include <unistd.h>
/* Older platforms */
#include <sys/random.h>
#endif
#include <time.h>
#endif
@ -954,24 +957,50 @@ xmlInitRandom(void) {
#ifdef _WIN32
NTSTATUS status;
/*
* You can find many (recent as of 2025) discussions how
* to get a pseudo-random seed on Windows in projects like
* Golang, Rust, Chromium and Firefox.
*
* TODO: Support ProcessPrng available since Windows 10.
*/
status = BCryptGenRandom(NULL, (unsigned char *) globalRngState,
sizeof(globalRngState),
BCRYPT_USE_SYSTEM_PREFERRED_RNG);
if (!BCRYPT_SUCCESS(status))
xmlAbort("libxml2: BCryptGenRandom failed with error code %lu\n",
GetLastError());
#elif HAVE_DECL_GETENTROPY
#else
int var;
#if HAVE_DECL_GETENTROPY
while (1) {
if (getentropy(globalRngState, sizeof(globalRngState)) == 0)
return;
/*
* This most likely means that libxml2 was compiled on
* a system supporting certain system calls and is running
* on a system that doesn't support these calls, as can
* be the case on Linux.
*/
if (errno == ENOSYS)
break;
/*
* We really don't want to fallback to the unsafe PRNG
* for possibly accidental reasons, so we abort on any
* unknown error.
*/
if (errno != EINTR)
xmlAbort("libxml2: getentropy failed with error code %d\n",
errno);
}
#else
int var;
#endif
/*
* TODO: Fallback to /dev/urandom for older POSIX systems.
*/
globalRngState[0] =
(unsigned) time(NULL) ^
HASH_ROL((unsigned) ((size_t) &xmlInitRandom & 0xFFFFFFFF), 8);