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ww: preserve compiler sink outputs

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This commit is contained in:
Hojun-Cho
2026-08-14 19:10:36 +09:00
parent 763bbc8f25
commit 25da54936d
3 changed files with 84 additions and 16 deletions
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48
cmd/w6c/main.c
View File

@@ -13,6 +13,7 @@ struct publication {
char *backup;
int had_old;
int installed;
int passthrough;
};
static char *
@@ -30,9 +31,37 @@ publish_path(const char *dst, const char *kind)
return p;
}
static int
copy_stream(FILE *src, FILE *out)
{
int bad = fflush(src) != 0 || fseek(src, 0, SEEK_SET) != 0;
unsigned char buf[65536];
while (!bad) {
size_t n = fread(buf, 1, sizeof buf, src);
if (n != 0 && fwrite(buf, 1, n, out) != n) bad = 1;
if (n < sizeof buf) {
if (ferror(src)) bad = 1;
break;
}
}
return bad ? -1 : 0;
}
static int
materialize_stream(FILE *src, struct publication *p)
{
struct stat st;
if (lstat(p->dst, &st) == 0 && S_ISCHR(st.st_mode)) {
FILE *out = fopen(p->dst, "wb");
int bad = out == NULL || copy_stream(src, out) < 0;
if (out != NULL && fclose(out) != 0) bad = 1;
if (bad) {
fprintf(stderr, "w6c: cannot write %s\n", p->dst);
return -1;
}
p->passthrough = 1;
return 0;
}
p->stage = publish_path(p->dst, "new");
p->backup = publish_path(p->dst, "old");
if (p->stage == NULL || p->backup == NULL) {
@@ -50,16 +79,7 @@ materialize_stream(FILE *src, struct publication *p)
unlink(p->stage);
return -1;
}
int bad = fflush(src) != 0 || fseek(src, 0, SEEK_SET) != 0;
unsigned char buf[65536];
while (!bad) {
size_t n = fread(buf, 1, sizeof buf, src);
if (n != 0 && fwrite(buf, 1, n, out) != n) bad = 1;
if (n < sizeof buf) {
if (ferror(src)) bad = 1;
break;
}
}
int bad = copy_stream(src, out) < 0;
if (fclose(out) != 0) bad = 1;
if (bad) {
unlink(p->stage);
@@ -100,6 +120,7 @@ static int
publish_all(struct publication *p, int n)
{
for (int i = 0; i < n; i++) {
if (p[i].passthrough) continue;
if (!path_is_regular_nofollow(p[i].stage)) {
fprintf(stderr, "w6c: publication stage is not a regular file for %s\n",
p[i].dst);
@@ -120,6 +141,7 @@ publish_all(struct publication *p, int n)
}
}
for (int i = 0; i < n; i++) {
if (p[i].passthrough) continue;
int exists = path_exists_nofollow(p[i].backup);
if (exists != 0) {
if (exists < 0)
@@ -132,6 +154,7 @@ publish_all(struct publication *p, int n)
}
}
for (int i = 0; i < n; i++) {
if (p[i].passthrough) continue;
if (rename(p[i].dst, p[i].backup) == 0)
p[i].had_old = 1;
else if (errno != ENOENT) {
@@ -140,6 +163,7 @@ publish_all(struct publication *p, int n)
}
}
for (int i = 0; i < n; i++) {
if (p[i].passthrough) continue;
if (rename(p[i].stage, p[i].dst) != 0) {
fprintf(stderr, "w6c: cannot publish %s\n", p[i].dst);
goto rollback;
@@ -149,13 +173,15 @@ publish_all(struct publication *p, int n)
/* Installation is the commit point. Backup cleanup cannot truthfully
* turn a completely installed pair into a rejected compilation. */
for (int i = 0; i < n; i++)
if (p[i].had_old && unlink(p[i].backup) != 0) {
if (!p[i].passthrough && p[i].had_old
&& unlink(p[i].backup) != 0) {
fprintf(stderr, "w6c: cannot remove backup for %s\n", p[i].dst);
}
return 0;
rollback:
for (int i = n - 1; i >= 0; i--) {
if (p[i].passthrough) continue;
if (p[i].installed) (void)unlink(p[i].dst);
if (p[i].had_old) (void)rename(p[i].backup, p[i].dst);
if (p[i].stage != NULL) (void)unlink(p[i].stage);

10
docs/build-system.md
View File

@@ -5147,10 +5147,12 @@ and is never followed or removed. A committed dispatcher voucher must itself
be a regular file before it can authorize reuse. Compiler assembly and
interface bytes are first generated through anonymous files with checked full
writes and then published as their own rollback group. A non-regular compiler
destination is rejected before preservation, and installation—not cleanup of
a recoverable old backup—is the commit point. Cold rejection removes the exact
request-owned scratch tree. Stale init code, stale closure metadata, and mixed
committed generations therefore cannot be reused.
destination is rejected before preservation, except that an already existing
character-device sink such as `/dev/null` receives a checked passthrough and is
never renamed or treated as a persistent artifact. Installation—not cleanup
of a recoverable old backup—is the commit point. Cold rejection removes the
exact request-owned scratch tree. Stale init code, stale closure metadata, and
mixed committed generations therefore cannot be reused.
#### Stage and observer ownership

42
selfhost/cmd/w6c/main.ww
View File

@@ -14,6 +14,7 @@ type publication = struct {
backup: str,
hadold: bool,
installed: bool,
passthrough: bool,
};
fn publicationpath(dst: *u8, kind: str) str = {
@@ -21,6 +22,17 @@ fn publicationpath(dst: *u8, kind: str) str = {
strconv.i32tos(os.getpid(), strconv.base.DEC), ".", kind);
};
fn pathischardevice(path: *u8) bool = {
let fi: os.filestat;
match (os.lstat(&fi, pathstr(path))) {
case void => {
return (((fi.mode: u32) & 61440u32) == (os.mode.CHR: u32));
};
case let e: os.oserror => return false;
};
return false;
};
// Open a destination-adjacent file and immediately unlink its name. Cgen's
// fatal exit then leaves only a kernel-owned fd, never a partial destination
// or named staging artifact.
@@ -28,6 +40,12 @@ fn anonymousfd(dst: *u8, kind: str) i32 = {
let path: str = publicationpath(dst, kind);
let fd: i32 = os.open(path,
os.flag.RDWR | os.flag.CREATE | os.flag.EXCL, 384i32);
if (fd < 0 && pathischardevice(dst)) {
path = strings.concat("/tmp/ww-w6c.",
strconv.i32tos(os.getpid(), strconv.base.DEC), ".", kind);
fd = os.open(path,
os.flag.RDWR | os.flag.CREATE | os.flag.EXCL, 384i32);
};
if (fd < 0) {
os.write(2, "w6c: cannot create anonymous output\n".ptr,
"w6c: cannot create anonymous output\n".len: u64);
@@ -60,6 +78,21 @@ fn copystream(src: i32, dst: i32) bool = {
fn materializestream(src: i32, dst: *u8, p: *publication) bool = {
p.dst = dst;
p.passthrough = false;
let fi: os.filestat;
match (os.lstat(&fi, pathstr(dst))) {
case void => {
if (((fi.mode: u32) & 61440u32) == (os.mode.CHR: u32)) {
let sink: i32 = os.open(pathstr(dst), os.flag.WRONLY, 0i32);
if (sink < 0) { return false; };
let sinkok: bool = copystream(src, sink);
if (os.close(sink) != 0) { sinkok = false; };
if (sinkok) { p.passthrough = true; };
return sinkok;
};
};
case let e: os.oserror => void;
};
p.stage = publicationpath(dst, "new");
p.backup = publicationpath(dst, "old");
p.hadold = false;
@@ -110,6 +143,7 @@ fn publishall(p: *publication, n: i32) bool = {
let i: i32 = 0;
let ok: bool = true;
for (i < n) {
if (p[i].passthrough) { i += 1; continue; };
if (!pathisregularnofollow(p[i].stage)) {
publishdiag("w6c: publication stage is not a regular file for ",
p[i].dst);
@@ -140,6 +174,7 @@ fn publishall(p: *publication, n: i32) bool = {
if (ok) {
i = 0;
for (i < n) {
if (p[i].passthrough) { i += 1; continue; };
let exists: i32 = pathexistsnofollow(p[i].backup);
if (exists != 0) {
if (exists < 0) {
@@ -157,6 +192,7 @@ fn publishall(p: *publication, n: i32) bool = {
if (ok) {
i = 0;
for (i < n) {
if (p[i].passthrough) { i += 1; continue; };
let rc: i32 = os.rename(pathstr(p[i].dst), p[i].backup);
if (rc == 0) { p[i].hadold = true; }
else { if (rc != -2) {
@@ -170,6 +206,7 @@ fn publishall(p: *publication, n: i32) bool = {
if (ok) {
i = 0;
for (i < n) {
if (p[i].passthrough) { i += 1; continue; };
if (os.rename(p[i].stage, pathstr(p[i].dst)) != 0) {
publishdiag("w6c: cannot publish ", p[i].dst);
ok = false;
@@ -183,7 +220,8 @@ fn publishall(p: *publication, n: i32) bool = {
// truthfully turn a completely installed pair into rejection.
i = 0;
for (i < n) {
if (p[i].hadold && os.remove(p[i].backup) != 0) {
if (!p[i].passthrough && p[i].hadold
&& os.remove(p[i].backup) != 0) {
publishdiag("w6c: cannot remove backup for ", p[i].dst);
};
i += 1;
@@ -193,6 +231,7 @@ fn publishall(p: *publication, n: i32) bool = {
};
i = n - 1;
for (i >= 0) {
if (p[i].passthrough) { i -= 1; continue; };
if (p[i].installed) { os.remove(pathstr(p[i].dst)); };
if (p[i].hadold) { os.rename(p[i].backup, pathstr(p[i].dst)); };
if (p[i].stage.len != 0) { os.remove(p[i].stage); };
@@ -882,6 +921,7 @@ export fn main(argc: i32, argv: **u8) i32 = {
pubs[pi].backup = "";
pubs[pi].hadold = false;
pubs[pi].installed = false;
pubs[pi].passthrough = false;
pi += 1;
};
let npub: i32 = 0;