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Share file offset across execve() on Windows

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This is a breaking change. It defines the new environment variable named
_COSMO_FDS_V2 which is used for inheriting non-stdio file descriptors on
execve() or posix_spawn(). No effort has been spent thus far integrating
with the older variable. If a new binary launches the older ones or vice
versa they'll only be able to pass stdin / stdout / stderr to each other
therefore it's important that you upgrade all your cosmo binaries if you
depend on this functionality. You'll be glad you did because inheritance
of file descriptors is more aligned with the POSIX standard than before.
This commit is contained in:
Justine Tunney 2024-08-03 17:48:00 -07:00
parent 761c6ad615
commit 3f26dfbb31
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
29 changed files with 572 additions and 249 deletions
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37
libc/proc/describefds.c
View file

@ -18,8 +18,10 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/fds.h"
#include "libc/intrin/maps.h"
#include "libc/intrin/strace.h"
#include "libc/mem/mem.h"
#include "libc/nt/files.h"
@ -27,7 +29,7 @@
#include "libc/nt/struct/startupinfo.h"
#include "libc/sysv/consts/o.h"
#define FDS_VAR "_COSMO_FDS="
#define FDS_VAR "_COSMO_FDS_V2="
#define MAX_ENTRY_BYTES 256
@ -99,6 +101,8 @@ textwindows char *__describe_fds(const struct Fd *fds, size_t fdslen,
if (__is_cloexec(f))
continue;
++handlecount;
if (f->cursor)
++handlecount;
}
if (!(handles = calloc(handlecount, sizeof(*handles)))) {
OnFailure:
@ -116,17 +120,31 @@ textwindows char *__describe_fds(const struct Fd *fds, size_t fdslen,
// make inheritable version of handle exist in creator process
if (!DuplicateHandle(GetCurrentProcess(), f->handle, hCreatorProcess,
&handle, 0, true, kNtDuplicateSameAccess)) {
STRACE("__describe_fds() DuplicateHandle() failed w/ %d", GetLastError());
__winerr();
goto OnFailure;
}
for (uint32_t i = 0; i < 3; ++i) {
if (lpStartupInfo->stdiofds[i] == f->handle) {
for (uint32_t i = 0; i < 3; ++i)
if (lpStartupInfo->stdiofds[i] == f->handle)
lpStartupInfo->stdiofds[i] = handle;
}
}
handles[hi++] = handle;
// get shared memory handle for the file offset pointer
intptr_t shand = 0;
if (f->cursor) {
struct Map *map;
if (!(map = __maps_floor((const char *)f->cursor->shared)) ||
map->addr != (const char *)f->cursor->shared) {
errno = EFAULT;
goto OnFailure;
}
if (!DuplicateHandle(GetCurrentProcess(), map->hand, hCreatorProcess,
&shand, 0, true, kNtDuplicateSameAccess)) {
__winerr();
goto OnFailure;
}
handles[hi++] = shand;
}
// ensure output string has enough space for new entry
if (sb.i + MAX_ENTRY_BYTES > sb.n) {
char *p2;
@ -151,12 +169,7 @@ textwindows char *__describe_fds(const struct Fd *fds, size_t fdslen,
*p++ = '_';
p = FormatInt64(p, f->mode);
*p++ = '_';
//
// - v1 abi: This field was originally the file pointer.
//
// - v2 abi: This field is the negated shared memory address.
//
p = FormatInt64(p, -(uintptr_t)f->shared);
p = FormatInt64(p, shand);
*p++ = '_';
p = FormatInt64(p, f->type);
*p++ = '_';

2
libc/proc/describefds.internal.h
View file

@ -4,6 +4,8 @@
#include "libc/nt/struct/startupinfo.h"
COSMOPOLITAN_C_START_
#define CURSOR_ADDRESS_FLAG 0x4000000000000000
bool __is_cloexec(const struct Fd *) libcesque;
void __undescribe_fds(int64_t, int64_t *, uint32_t) libcesque;
char *__describe_fds(const struct Fd *, size_t, struct NtStartupInfo *, int64_t,