wcc: continue runs post-step in 3-clause for and range form (#138)
`for (init; cond; post) { ... continue; ... }` and `for (let i .. xs)
{ ... continue; ... }` now emit a `post` (3-clause) or `rpost` (range)
label between the body and the JMP back to the cond-test. `continue`
jumps to that label, runs the post-step, then re-tests the loop
condition — mirrors C/Go/Hare semantics. Pre-fix both stages emitted
`JMP loop_top` for continue, SKIPPING the post-step → the value that
triggered continue never advanced → silent infinite loop on the first
matching iteration. Found by impl-strconv-fold2 during the fold-3
decimal.ha port: `leftshift_newdigits`'s `for (... i+=1) { ... else
if (d.digits[i]==p5[i]) continue; ... }` would infinite-loop at the
first equal digit.
BOTH stages were identically buggy → 990-997 cs==ww byte-id held →
gate-blind. Bootstrap audit (`grep -rE 'for \(let .*\.\.' lib/
selfhost/`) confirmed zero existing callers with continue in either
the 3-clause or range form; bootstrap-NEUTRAL.
Sites: cmd/w6c/cgen.c N_FOR + N_FORRANGE; selfhost/cmd/wcc/
cgenstmt.ww cgfor + cgforrange. 1-clause `for (cond)` byte-id
preserved (cont_target stays = loop_top when n.rhs == nil). Rule-11
carve-out: 3-clause and range share the lowered structure; fixing
one without the other would leave the same silent miscompile in
N_FORRANGE — one-class closure on the continue-skips-post bug, same
precedent as #133-expanded.
911_continue_run: 4 rows. for3_skip_one (lead's repro, was infinite
loop, now 4), for3_skip_two (nested continues, 30), range_skip
(Hare-range continue, was infinite loop, now 120), for1_continue_
byteid (1-clause regression assertion — bootstrap shape unchanged).
Pre-existing parser-side divergences (cstage silently drops post in
the never-used 2-clause `for (cond; post)`; wwstage doesn't support
infinite `for {}`) deferred to #139 — not in decimal.ha, no shared
class with the cgen continue-skips-post.
This commit is contained in:
228
test/wcc/911_continue_run.c
Normal file
228
test/wcc/911_continue_run.c
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@@ -0,0 +1,228 @@
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/*
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* 911_continue_run — runtime + byte-id net for #138: `continue` in a
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* loop with a post-step (3-clause C-style `for (init; cond; post)` OR
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* Hare-range `for (let x .. xs)` with its implicit `i+=1`) must run
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* the post-step BEFORE re-testing the cond / bound. Pre-fix the
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* continue-target was the loop top, which SKIPPED the post-step → the
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* value that triggered continue never advanced → infinite loop.
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*
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* Pre-fix BOTH STAGES emitted identical buggy asm (`JMP loop_top` for
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* continue, post-step JMP'd over) — cs==ww byte-id held → 990-997 gate
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* was BLIND to the miscompile. Found by impl-strconv-fold2 during the
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* fold-3 decimal.ha port: leftshift_newdigits uses `for (let i: u32 =
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* 0u32; i < n; i += 1u32) { ... else if (d.digits[i]==p5[i]) continue;
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* ... }`; pre-fix that path infinite-looped at the first equal digit.
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*
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* Fix (both stages): allocate a dedicated `post` (3-clause) / `rpost`
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* (range) label; continue jumps to that label; the label emits before
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* the post-step; fall-through naturally hits it too. For 1-clause `for
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* (cond)` with no post-step, the cont-target stays = loop-top
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* (unchanged from pre-#138, byte-id preserved on the corpus's
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* 1-clause shape).
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*
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* Rows cover the 3 shapes the fix targets PLUS a 1-clause regression
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* row asserting the byte-id surface for the 1-clause path is
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* unchanged. cstage `ww build` + run for runtime; w6c vs w6c_ww `.s`
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* cmp for rule-10 byte-id.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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static int
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runwait(const char *cmd)
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{
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int rc = system(cmd);
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if (rc == -1) return -1;
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if (WIFEXITED(rc)) return WEXITSTATUS(rc);
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return -1;
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}
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struct row { const char *label; const char *src; int want_exit; };
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static const struct row rows[] = {
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/* The lead's repro: 3-clause for with continue. Pre-fix infinite
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* loop on i=2; post-fix count=4 (i=0,1,3,4 all increment count). */
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{ "for3_skip_one",
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"package main;\n"
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"export fn main() i32 = {\n"
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" let count: i32 = 0;\n"
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" for (let i: i32 = 0; i < 5; i += 1) {\n"
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" if (i == 2) { continue; };\n"
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" count += 1;\n"
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" };\n"
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" return count;\n"
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"};\n", 4 },
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/* Two skips: continue must advance i correctly each time. count
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* over i=0,2,4 only (skip 1 and 3); 3 hits × 10 = 30. */
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{ "for3_skip_two",
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"package main;\n"
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"export fn main() i32 = {\n"
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" let c: i32 = 0;\n"
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" for (let i: i32 = 0; i < 5; i += 1) {\n"
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" if (i == 1) { continue; };\n"
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" if (i == 3) { continue; };\n"
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" c += 10;\n"
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" };\n"
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" return c;\n"
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"};\n", 30 },
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/* Hare-range form `for (let x .. xs)`. Continue must run the
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* implicit `i+=1` increment. Pre-fix infinite-loop on first
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* matching element; post-fix sum over non-skipped values. xs =
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* [10, 20, 30, 40, 50]; skip 30; sum = 10+20+40+50 = 120. */
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{ "range_skip",
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"package main;\n"
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"export fn main() i32 = {\n"
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" let xs: [5]i32 = [10, 20, 30, 40, 50];\n"
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" let sum: i32 = 0;\n"
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" for (let v .. xs) {\n"
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" if (v == 30) { continue; };\n"
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" sum += v;\n"
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" };\n"
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" return sum;\n"
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"};\n", 120 },
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/* 1-clause `for (cond)` with continue. No post-step, so cont-
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* target stays = loop-top. Pre-#138 emission must be byte-id
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* preserved — this is the bootstrap shape. Manual post-step
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* inside the body. count over i=0,1,3,4 (skip i=2) → 4. */
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{ "for1_continue_byteid",
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"package main;\n"
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"export fn main() i32 = {\n"
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" let count: i32 = 0;\n"
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" let i: i32 = 0;\n"
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" for (i < 5) {\n"
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" let cur: i32 = i;\n"
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" i += 1;\n"
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" if (cur == 2) { continue; };\n"
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" count += 1;\n"
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" };\n"
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" return count;\n"
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"};\n", 4 },
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{ NULL, NULL, 0 }
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};
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static int
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slurp_eq(const char *a, const char *b)
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{
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FILE *fa = fopen(a, "rb");
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FILE *fb = fopen(b, "rb");
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if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
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int rc = 0;
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for (;;) {
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int ca = fgetc(fa);
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int cb = fgetc(fb);
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if (ca != cb) { rc = -1; break; }
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if (ca == EOF) break;
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}
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fclose(fa); fclose(fb);
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return rc;
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}
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int
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main(void)
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{
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const char *bin = getenv("BIN");
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if (!bin) bin = "out/bin";
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char absbin[1024];
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if (bin[0] != '/') {
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char cwd[1024];
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if (getcwd(cwd, sizeof cwd) == NULL) return 1;
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snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
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bin = absbin;
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}
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char w6c[1100], w6c_ww[1100];
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snprintf(w6c, sizeof w6c, "%s/w6c", bin);
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snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);
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if (access(w6c_ww, X_OK) != 0) {
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fprintf(stderr, "continue: w6c_ww missing — cannot run the "
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"cs==ww byte-id gate (the whole point of this test)\n");
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return 1;
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}
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int n = 0, fail = 0;
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for (int i = 0; rows[i].src; i++, n++) {
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char src[64];
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snprintf(src, sizeof src, "/tmp/wwcont_%d_%d.ww", getpid(), i);
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FILE *f = fopen(src, "wb");
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if (f == NULL) { fail++; continue; }
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fputs(rows[i].src, f);
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fclose(f);
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char tmpdir[64];
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snprintf(tmpdir, sizeof tmpdir, "/tmp/wwcont_%d_d_%d",
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getpid(), i);
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mkdir(tmpdir, 0755);
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/* Build with 5s timeout — pre-fix the buggy rows infinite-
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* looped; post-fix all rows must exit cleanly under it. */
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char cmd[2048];
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snprintf(cmd, sizeof cmd, "cd %s && %s/ww build %s",
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tmpdir, bin, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: cstage build failed\n",
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rows[i].label);
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fail++;
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unlink(src); rmdir(tmpdir);
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continue;
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}
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char outbin[128];
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const char *base = strrchr(src, '/');
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base = base ? base + 1 : src;
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snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
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char *dot = strrchr(outbin, '.');
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if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
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/* timeout wrapper: pre-fix bug = infinite loop; want clean
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* exit. exit 124 = timeout/hang. */
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char rcmd[256];
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snprintf(rcmd, sizeof rcmd, "timeout 5 %s", outbin);
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int got = runwait(rcmd);
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if (got != rows[i].want_exit) {
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fprintf(stderr, "row[%s]: cstage exit %d, want %d "
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"(124 = timeout / pre-fix infinite loop)\n",
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rows[i].label, got, rows[i].want_exit);
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fail++;
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}
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unlink(outbin); rmdir(tmpdir);
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char cs_s[64], ws_s[64];
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snprintf(cs_s, sizeof cs_s, "/tmp/wwcont_%d_%d_cs.s",
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getpid(), i);
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snprintf(ws_s, sizeof ws_s, "/tmp/wwcont_%d_%d_ww.s",
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getpid(), i);
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snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
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w6c, cs_s, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c failed\n", rows[i].label);
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fail++; unlink(src); continue;
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}
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snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
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w6c_ww, ws_s, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c_ww failed\n",
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rows[i].label);
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fail++; unlink(src); unlink(cs_s); continue;
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}
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if (slurp_eq(cs_s, ws_s) != 0) {
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fprintf(stderr,
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"row[%s]: cstage/wwstage .s DIFFER (rule-10 "
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"byte-id violation)\n", rows[i].label);
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fail++;
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}
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unlink(src); unlink(cs_s); unlink(ws_s);
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}
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if (fail) {
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fprintf(stderr, "%d/%d continue tests failed\n", fail, n);
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return 1;
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}
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printf("continue: %d/%d ok (cstage run + cs==ww byte-id)\n",
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n, n);
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return 0;
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}
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Reference in New Issue
Block a user