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commit 9ec0b001b87d32f1d39b038b72846a5c20417be3 (refs/remotes/origin/maint-5.16)
Author: Andy Dougherty <doughera@lafayette.edu>
Date: Wed Jan 16 12:30:43 2013 -0500
Avoid wraparound when casting unsigned size_t to signed ssize_t.
Practically, this only affects a perl compiled with 64-bit IVs on a 32-bit
system. In that instance a value of count >= 2**31 would turn negative
when cast to (ssize_t).
diff --git a/perlio.c b/perlio.c
index 7782728..cccfdcd 100644
--- a/perlio.c
+++ b/perlio.c
@@ -2164,7 +2164,7 @@ PerlIOBase_read(pTHX_ PerlIO *f, void *vbuf, Size_t count)
SSize_t avail = PerlIO_get_cnt(f);
SSize_t take = 0;
if (avail > 0)
- take = ((SSize_t)count < avail) ? (SSize_t)count : avail;
+ take = (((SSize_t) count >= 0) && ((SSize_t)count < avail)) ? (SSize_t)count : avail;
if (take > 0) {
STDCHAR *ptr = PerlIO_get_ptr(f);
Copy(ptr, buf, take, STDCHAR);
@@ -4098,7 +4098,7 @@ PerlIOBuf_unread(pTHX_ PerlIO *f, const void *vbuf, Size_t count)
*/
b->posn -= b->bufsiz;
}
- if (avail > (SSize_t) count) {
+ if ((SSize_t) count >= 0 && avail > (SSize_t) count) {
/*
* If we have space for more than count, just move count
*/
@@ -4148,7 +4148,7 @@ PerlIOBuf_write(pTHX_ PerlIO *f, const void *vbuf, Size_t count)
}
while (count > 0) {
SSize_t avail = b->bufsiz - (b->ptr - b->buf);
- if ((SSize_t) count < avail)
+ if ((SSize_t) count >= 0 && (SSize_t) count < avail)
avail = count;
if (flushptr > buf && flushptr <= buf + avail)
avail = flushptr - buf;
@@ -4423,7 +4423,7 @@ PerlIOPending_read(pTHX_ PerlIO *f, void *vbuf, Size_t count)
{
SSize_t avail = PerlIO_get_cnt(f);
SSize_t got = 0;
- if ((SSize_t)count < avail)
+ if ((SSize_t) count >= 0 && (SSize_t)count < avail)
avail = count;
if (avail > 0)
got = PerlIOBuf_read(aTHX_ f, vbuf, avail);
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