Fix the handle locking in stdio
Fix the handle locking in stdio to use flockfile/funlockfile
internally when and where required. Macros in <stdio.h> are updated
to automatically call the underlying functions when the process is
threaded to obtain the necessary locking. A private mutex is added
to protect __sglue, the internal list of FILE handles, and another
to protect the one-time initialization. Some routines in libc that
use getc() change to use getc_unlocked() as they're either protected
by their own lock or aren't thread-safe routines anyway.
Based on OpenBSD change by guenther@openbsd.org
http://www.mail-archive.com/source-changes@cvs.openbsd.org/msg01015.html
Bug: 3446659
Change-Id: Ie82116e358c541718d6709ec45ca6796be5a007b
diff --git a/libc/stdio/fseek.c b/libc/stdio/fseek.c
index 8581b62..38697f5 100644
--- a/libc/stdio/fseek.c
+++ b/libc/stdio/fseek.c
@@ -70,6 +70,7 @@
* Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
* After this, whence is either SEEK_SET or SEEK_END.
*/
+ FLOCKFILE(fp);
switch (whence) {
case SEEK_CUR:
@@ -83,8 +84,10 @@
curoff = fp->_offset;
else {
curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
- if (curoff == (fpos_t)-1)
+ if (curoff == (fpos_t)-1) {
+ FUNLOCKFILE(fp);
return (EOF);
+ }
}
if (fp->_flags & __SRD) {
curoff -= fp->_r;
@@ -105,6 +108,7 @@
break;
default:
+ FUNLOCKFILE(fp);
errno = EINVAL;
return (EOF);
}
@@ -189,6 +193,7 @@
if (HASUB(fp))
FREEUB(fp);
fp->_flags &= ~__SEOF;
+ FUNLOCKFILE(fp);
return (0);
}
@@ -215,6 +220,7 @@
fp->_p += n;
fp->_r -= n;
}
+ FUNLOCKFILE(fp);
return (0);
/*
@@ -224,6 +230,7 @@
dumb:
if (__sflush(fp) ||
(*seekfn)(fp->_cookie, (fpos_t)offset, whence) == POS_ERR) {
+ FUNLOCKFILE(fp);
return (EOF);
}
/* success: clear EOF indicator and discard ungetc() data */
@@ -233,6 +240,7 @@
fp->_r = 0;
/* fp->_w = 0; */ /* unnecessary (I think...) */
fp->_flags &= ~__SEOF;
+ FUNLOCKFILE(fp);
return (0);
}