From: Nadav Har'El <n...@scylladb.com>
Committer: Nadav Har'El <n...@scylladb.com>
Branch: master
libc: fix build error (and potential bug) in __year_to_secs
Musl's __year_to_secs() has this strange code:
int *is_leap;
...
if (!is_leap) is_leap = &(int){0};
The motivation is to set the pointer, if unset, to point to our own integer.
But nothing in the C standard guarantees that this temporary integer will
actually live as long as the "is_leap" variable lives... Since C++03
there is such a guarantee for *const* *reference*, but this is not C++,
not const, and not a reference :-)
Gcc 12.1.1 started to complain about this, calling it a "dangling pointer
to an unnamed temporary". Unfortunately to fix it we need to make a copy
of this musl source file and change it:
15,19c15
< int our_is_leap;
< if (!is_leap) {
< our_is_leap = 0;
< is_leap = &our_is_leap;
< }
---
> if (!is_leap) is_leap = &(int){0};
Signed-off-by: Nadav Har'El <n...@scylladb.com>
---
diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -1812,7 +1812,7 @@ musl += time/__secs_to_tm.o
musl += time/__tm_to_secs.o
libc += time/__tz.o
$(out)/libc/time/__tz.o: pre-include-api = -isystem
include/api/internal_musl_headers -isystem musl/src/include
-musl += time/__year_to_secs.o
+libc += time/__year_to_secs.o
musl += time/asctime.o
musl += time/asctime_r.o
musl += time/ctime.o
diff --git a/libc/time/__year_to_secs.c b/libc/time/__year_to_secs.c
--- a/libc/time/__year_to_secs.c
+++ b/libc/time/__year_to_secs.c
@@ -0,0 +1,51 @@
+long long __year_to_secs(long long year, int *is_leap)
+{
+ if (year-2ULL <= 136) {
+ int y = year;
+ int leaps = (y-68)>>2;
+ if (!((y-68)&3)) {
+ leaps--;
+ if (is_leap) *is_leap = 1;
+ } else if (is_leap) *is_leap = 0;
+ return 31536000*(y-70) + 86400*leaps;
+ }
+
+ int cycles, centuries, leaps, rem;
+
+ int our_is_leap;
+ if (!is_leap) {
+ our_is_leap = 0;
+ is_leap = &our_is_leap;
+ }
+ cycles = (year-100) / 400;
+ rem = (year-100) % 400;
+ if (rem < 0) {
+ cycles--;
+ rem += 400;
+ }
+ if (!rem) {
+ *is_leap = 1;
+ centuries = 0;
+ leaps = 0;
+ } else {
+ if (rem >= 200) {
+ if (rem >= 300) centuries = 3, rem -= 300;
+ else centuries = 2, rem -= 200;
+ } else {
+ if (rem >= 100) centuries = 1, rem -= 100;
+ else centuries = 0;
+ }
+ if (!rem) {
+ *is_leap = 0;
+ leaps = 0;
+ } else {
+ leaps = rem / 4U;
+ rem %= 4U;
+ *is_leap = !rem;
+ }
+ }
+
+ leaps += 97*cycles + 24*centuries - *is_leap;
+
+ return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
+}
--
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