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Add crash proofing to ipv4.games server

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This commit is contained in:
Justine Tunney 2024-08-26 12:36:45 -07:00
parent e7b586e7f8
commit ebe1cbb1e3
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GPG key ID: BE714B4575D6E328
5 changed files with 256 additions and 33 deletions
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38
libc/calls/finddebugbinary.c
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@ -27,6 +27,7 @@
#include "libc/elf/tinyelf.internal.h"
#include "libc/errno.h"
#include "libc/intrin/directmap.h"
#include "libc/intrin/promises.h"
#include "libc/nt/memory.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/runtime.h"
@ -37,7 +38,6 @@
#include "libc/sysv/consts/prot.h"
static struct {
atomic_uint once;
const char *res;
char buf[PATH_MAX];
} g_comdbg;
@ -69,35 +69,26 @@ static int GetElfMachine(void) {
}
static bool IsMyDebugBinary(const char *path) {
void *addr;
int64_t size;
uintptr_t value;
bool res = false;
int fd, e = errno;
struct DirectMap dm;
BLOCK_CANCELATION;
if ((fd = open(path, O_RDONLY | O_CLOEXEC, 0)) != -1) {
// sanity test that this .com.dbg file (1) is an elf image, and (2)
// contains the same number of bytes of code as our .com executable
// which is currently running in memory.
if ((size = lseek(fd, 0, SEEK_END)) != -1 &&
(dm = sys_mmap((void *)0x12345000000, size, PROT_READ, MAP_SHARED, fd,
0))
.addr != MAP_FAILED) {
if (READ32LE((char *)dm.addr) == READ32LE("\177ELF") &&
((Elf64_Ehdr *)dm.addr)->e_machine == GetElfMachine() &&
GetElfSymbolValue(dm.addr, "_etext", &value)) {
(addr = mmap(0, size, PROT_READ, MAP_SHARED, fd, 0)) != MAP_FAILED) {
if (READ32LE((char *)addr) == READ32LE("\177ELF") &&
((Elf64_Ehdr *)addr)->e_machine == GetElfMachine() &&
GetElfSymbolValue(addr, "_etext", &value)) {
res = !_etext || value == (uintptr_t)_etext;
}
if (!IsWindows()) {
sys_munmap(dm.addr, size);
} else {
CloseHandle(dm.maphandle);
UnmapViewOfFile(dm.addr);
}
munmap(addr, size);
}
close(fd);
}
ALLOW_CANCELATION;
errno = e;
return res;
}
@ -106,7 +97,7 @@ static void FindDebugBinaryInit(void) {
const char *comdbg;
if (issetugid())
return;
if ((comdbg = getenv("COMDBG")) && IsMyDebugBinary(comdbg)) {
if ((comdbg = getenv("COMDBG"))) {
g_comdbg.res = comdbg;
return;
}
@ -125,9 +116,18 @@ static void FindDebugBinaryInit(void) {
/**
* Returns path of binary with the debug information, or null.
*
* @return path to debug binary, or NULL
* You can specify the COMDBG environment variable, with the path of the
* debug binary, in case the automatic heuristics fail. What we look for
* is GetProgramExecutableName() with ".dbg", ".com.dbg", etc. appended.
*
* @return path to debug binary, or NULL if we couldn't find it
* @asyncsignalsafe
*/
const char *FindDebugBinary(void) {
cosmo_once(&g_comdbg.once, FindDebugBinaryInit);
return g_comdbg.res;
}
// pay startup cost to make this signal safe from the user's perspective
__attribute__((__constructor__(10))) static void FindDebugBinaryCtor(void) {
FindDebugBinaryInit();
}