[PATCH] vmsplice2: add option -c for each segment spanning a page

diff --git a/vmsplice2.c b/vmsplice2.c
index 2c489bb9d56b0f8d34db02d09a31d4377c5db075..5e18371898f4cec09516eb078e795d0cc9dd8d70 100644 (file)
--- a/vmsplice2.c
+++ b/vmsplice2.c
@@ -13,7 +13,12 @@
 
 #include "splice.h"
 
+#define PAGE_SIZE      4096
+#define PAGE_MASK      (PAGE_SIZE - 1)
+#define ALIGN(buf)     (void *) (((unsigned long) (buf) + PAGE_MASK) & ~PAGE_MASK)
+
 static int alloc_stack;
+static int cross_page;
 
 int do_vmsplice(int fd, struct iovec *iov, unsigned long nr_vecs)
 {
@@ -55,7 +60,7 @@ int do_vmsplice(int fd, struct iovec *iov, unsigned long nr_vecs)
 
 static int usage(char *name)
 {
-       fprintf(stderr, "%s [-s(tack)] | ...\n", name);
+       fprintf(stderr, "%s [-s(tack)] [-c(ross page)]| ...\n", name);
        return 1;
 }
 
@@ -63,17 +68,24 @@ static int parse_options(int argc, char *argv[])
 {
        int c, index = 1;
 
-       while ((c = getopt(argc, argv, "s")) != -1) {
+       while ((c = getopt(argc, argv, "sc")) != -1) {
                switch (c) {
                case 's':
                        alloc_stack = 1;
                        index++;
                        break;
+               case 'c':
+                       cross_page = 1;
+                       index++;
+                       break;
                default:
                        return -1;
                }
        }
 
+       if (alloc_stack && cross_page)
+               fprintf(stderr, "Stack alloc and cross page are mutually exclusive\n");
+
        return index;
 }
 
@@ -94,9 +106,25 @@ int main(int argc, char *argv[])
                b = S2;
                f = S3;
        } else {
-               h = strdup(S1);
-               b = strdup(S2);
-               f = strdup(S3);
+               if (cross_page) {
+                       void *ptr;
+
+                       ptr = ALIGN(malloc(2 * PAGE_SIZE));
+                       h = ptr - (strlen(S1) / 2);
+                       strcpy(h, S1);
+
+                       ptr = ALIGN(malloc(2 * PAGE_SIZE));
+                       b = ptr - (strlen(S2) / 2);
+                       strcpy(b, S2);
+
+                       ptr = ALIGN(malloc(2 * PAGE_SIZE));
+                       f = ptr - (strlen(S3) / 2);
+                       strcpy(f, S3);
+               } else {
+                       h = strdup(S1);
+                       b = strdup(S2);
+                       f = strdup(S3);
+               }
        }
 
        vecs[0].iov_base = h;