fix broken thread list unlocking after fork

[musl] / src / internal / shgetc.c

diff --git a/src/internal/shgetc.c b/src/internal/shgetc.c
index 82e3a4f..7455d2f 100644 (file)
--- a/src/internal/shgetc.c
+++ b/src/internal/shgetc.c
@@ -1,9 +1,15 @@
 #include "shgetc.h"
 
+/* The shcnt field stores the number of bytes read so far, offset by
+ * the value of buf-rpos at the last function call (__shlim or __shgetc),
+ * so that between calls the inline shcnt macro can add rpos-buf to get
+ * the actual count. */
+
 void __shlim(FILE *f, off_t lim)
 {
        f->shlim = lim;
-       f->shcnt = f->rend - f->rpos;
+       f->shcnt = f->buf - f->rpos;
+       /* If lim is nonzero, rend must be a valid pointer. */
        if (lim && f->rend - f->rpos > lim)
                f->shend = f->rpos + lim;
        else
@@ -13,12 +19,19 @@ void __shlim(FILE *f, off_t lim)
 int __shgetc(FILE *f)
 {
        int c;
-       if (f->shcnt >= f->shlim) return EOF;
-       c = __uflow(f);
-       if (f->shlim && f->rend - f->rpos > f->shlim - f->shcnt - 1)
-               f->shend = f->rpos + (f->shlim - f->shcnt - 1);
+       off_t cnt = shcnt(f);
+       if (f->shlim && cnt >= f->shlim || (c=__uflow(f)) < 0) {
+               f->shcnt = f->buf - f->rpos + cnt;
+               f->shend = f->rpos;
+               f->shlim = -1;
+               return EOF;
+       }
+       cnt++;
+       if (f->shlim && f->rend - f->rpos > f->shlim - cnt)
+               f->shend = f->rpos + (f->shlim - cnt);
        else
                f->shend = f->rend;
-       if (f->rend) f->shcnt += f->rend - f->buf;
+       f->shcnt = f->buf - f->rpos + cnt;
+       if (f->rpos <= f->buf) f->rpos[-1] = c;
        return c;
 }