cosmopolitan/libc/calls/finddebugbinary.c
Justine Tunney 6ffed14b9c
Rewrite memory manager
Actually Portable Executable now supports Android. Cosmo's old mmap code
required a 47 bit address space. The new implementation is very agnostic
and supports both smaller address spaces (e.g. embedded) and even modern
56-bit PML5T paging for x86 which finally came true on Zen4 Threadripper

Cosmopolitan no longer requires UNIX systems to observe the Windows 64kb
granularity; i.e. sysconf(_SC_PAGE_SIZE) will now report the host native
page size. This fixes a longstanding POSIX conformance issue, concerning
file mappings that overlap the end of file. Other aspects of conformance
have been improved too, such as the subtleties of address assignment and
and the various subtleties surrounding MAP_FIXED and MAP_FIXED_NOREPLACE

On Windows, mappings larger than 100 megabytes won't be broken down into
thousands of independent 64kb mappings. Support for MAP_STACK is removed
by this change; please use NewCosmoStack() instead.

Stack overflow avoidance is now being implemented using the POSIX thread
APIs. Please use GetStackBottom() and GetStackAddr(), instead of the old
error-prone GetStackAddr() and HaveStackMemory() APIs which are removed.
2024-06-22 05:45:11 -07:00

131 lines
4.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "ape/sections.internal.h"
#include "libc/atomic.h"
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/cosmo.h"
#include "libc/dce.h"
#include "libc/elf/def.h"
#include "libc/elf/tinyelf.internal.h"
#include "libc/errno.h"
#include "libc/intrin/directmap.internal.h"
#include "libc/nt/memory.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/runtime.h"
#include "libc/serialize.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
static struct {
atomic_uint once;
const char *res;
char buf[PATH_MAX];
} g_comdbg;
static const char *kDbgExts[] = {
".dbg",
".com.dbg",
#ifdef __aarch64__
".aarch64.elf",
#elif defined(__powerpc64__)
".ppc64.elf",
#endif
};
static int GetElfMachine(void) {
#ifdef __x86_64__
return EM_NEXGEN32E;
#elif defined(__aarch64__)
return EM_AARCH64;
#elif defined(__powerpc64__)
return EM_PPC64;
#elif defined(__riscv)
return EM_RISCV;
#elif defined(__s390x__)
return EM_S390;
#else
#error "unsupported architecture"
#endif
}
static bool IsMyDebugBinary(const char *path) {
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)) {
res = !_etext || value == (uintptr_t)_etext;
}
if (!IsWindows()) {
sys_munmap(dm.addr, size);
} else {
CloseHandle(dm.maphandle);
UnmapViewOfFile(dm.addr);
}
}
close(fd);
}
ALLOW_CANCELATION;
errno = e;
return res;
}
static void FindDebugBinaryInit(void) {
const char *comdbg;
if ((comdbg = getenv("COMDBG")) && IsMyDebugBinary(comdbg)) {
g_comdbg.res = comdbg;
return;
}
char *prog = GetProgramExecutableName();
for (int i = 0; i < ARRAYLEN(kDbgExts); ++i) {
strlcpy(g_comdbg.buf, prog, sizeof(g_comdbg.buf));
strlcat(g_comdbg.buf, kDbgExts[i], sizeof(g_comdbg.buf));
if (IsMyDebugBinary(g_comdbg.buf)) {
g_comdbg.res = g_comdbg.buf;
return;
}
}
g_comdbg.res = prog;
}
/**
* Returns path of binary with the debug information, or null.
*
* @return path to debug binary, or NULL
*/
const char *FindDebugBinary(void) {
cosmo_once(&g_comdbg.once, FindDebugBinaryInit);
return g_comdbg.res;
}