Libc-1044.1.2.tar.gz

[apple/libc.git] / stdio / FreeBSD / fwrite.c

diff --git a/stdio/FreeBSD/fwrite.c b/stdio/FreeBSD/fwrite.c
index 0c40b93f17f0c5b41240742e3cc5fa048bf1810e..09eae8374dd6520429b3b2c04c39e7b78690222f 100644 (file)
--- a/stdio/FreeBSD/fwrite.c
+++ b/stdio/FreeBSD/fwrite.c
@@ -43,6 +43,13 @@ __FBSDID("$FreeBSD: src/lib/libc/stdio/fwrite.c,v 1.13 2009/07/12 13:09:43 ed Ex
 #include "fvwrite.h"
 #include "libc_private.h"
 
+/*
+ * The maximum amount to write to avoid integer overflow (especially for
+ * uio_resid in struct __suio).  INT_MAX is odd, so it make sense to make it
+ * even.  We subtract (BUFSIZ - 1) to get a whole number of BUFSIZ chunks.
+ */
+#define MAXWRITE       (INT_MAX - (BUFSIZ - 1))
+
 /*
  * Write `count' objects (each size `size') from memory to the given file.
  * Return the number of whole objects written.
@@ -53,31 +60,40 @@ fwrite(buf, size, count, fp)
        size_t size, count;
        FILE * __restrict fp;
 {
-       size_t n;
+       size_t n, resid;
        struct __suio uio;
        struct __siov iov;
+       int s;
 
        /*
         * ANSI and SUSv2 require a return value of 0 if size or count are 0.
         */
        n = count * size;
+#if __DARWIN_UNIX03
        if (n == 0)
                return (0);
-
-       iov.iov_base = (void *)buf;
-       uio.uio_resid = iov.iov_len = n;
+#endif
        uio.uio_iov = &iov;
        uio.uio_iovcnt = 1;
 
        FLOCKFILE(fp);
        ORIENT(fp, -1);
-       /*
-        * The usual case is success (__sfvwrite returns 0);
-        * skip the divide if this happens, since divides are
-        * generally slow and since this occurs whenever size==0.
-        */
-       if (__sfvwrite(fp, &uio) != 0)
-           count = (n - uio.uio_resid) / size;
+
+       for (resid = n; resid > 0; buf += s, resid -= s) {
+               s = resid > INT_MAX ? MAXWRITE : (int)resid;
+               iov.iov_base = (void *)buf;
+               uio.uio_resid = iov.iov_len = s;
+
+               /*
+                * The usual case is success (__sfvwrite returns 0);
+                * skip the divide if this happens, since divides are
+                * generally slow and since this occurs whenever size==0.
+                */
+               if (__sfvwrite(fp, &uio) != 0) {
+                       count = (n - resid + s - uio.uio_resid) / size;
+                       break;
+               }
+       }
        FUNLOCKFILE(fp);
        return (count);
 }