From fa26bccbf67636b5c225ab25cb1f2729c0993b81 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@suse.de>
Date: Wed, 3 May 2006 10:23:31 +0200
Subject: [PATCH] [PATCH]: vmsplice2 update

---
 vmsplice2.c | 117 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 85 insertions(+), 32 deletions(-)

diff --git a/vmsplice2.c b/vmsplice2.c
index 448ba93..a273496 100644
--- a/vmsplice2.c
+++ b/vmsplice2.c
@@ -15,10 +15,12 @@
 
 #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;
+static int force_align;
+static int full_page;
+static int gift;
 
 int do_vmsplice(int fd, struct iovec *iov, unsigned long nr_vecs)
 {
@@ -34,7 +36,7 @@ int do_vmsplice(int fd, struct iovec *iov, unsigned long nr_vecs)
 		if (poll(&pfd, 1, -1) < 0)
 			return error("poll");
 
-		written = vmsplice(fd, iov, nr_vecs, 0);
+		written = vmsplice(fd, iov, nr_vecs, gift ? SPLICE_F_GIFT : 0);
 
 		if (written <= 0)
 			return error("vmsplice");
@@ -60,7 +62,7 @@ int do_vmsplice(int fd, struct iovec *iov, unsigned long nr_vecs)
 
 static int usage(char *name)
 {
-	fprintf(stderr, "%s [-s(tack)] [-c(ross page)]| ...\n", name);
+	fprintf(stderr, "%s [-s(tack)] [-c(ross page)] [-a(lign)] [-f(ull page)] [-g(ift)] | ...\n", name);
 	return 1;
 }
 
@@ -68,7 +70,7 @@ static int parse_options(int argc, char *argv[])
 {
 	int c, index = 1;
 
-	while ((c = getopt(argc, argv, "sc")) != -1) {
+	while ((c = getopt(argc, argv, "scafg")) != -1) {
 		switch (c) {
 		case 's':
 			alloc_stack = 1;
@@ -78,64 +80,115 @@ static int parse_options(int argc, char *argv[])
 			cross_page = 1;
 			index++;
 			break;
+		case 'a':
+			force_align = 1;
+			index++;
+			break;
+		case 'f':
+			full_page = 1;
+			index++;
+			break;
+		case 'g':
+			gift = 1;
+			index++;
+			break;
 		default:
 			return -1;
 		}
 	}
 
-	if (alloc_stack && cross_page)
-		fprintf(stderr, "Stack alloc and cross page are mutually exclusive\n");
+	if (cross_page && force_align) {
+		fprintf(stderr, "Can't get both aligning and cross page spanning\n");
+		return -1;
+	}
 
 	return index;
 }
 
+#define ASIZE	(3 * PAGE_SIZE)
 #define S1	"header header header header header header header header "
 #define S2	"body body body body body body body body body body body "
 #define S3	"footer footer footer footer footer footer footer footer"
 
+static void check_address(void *addr, void *start, void *end, int len,char *msg)
+{
+	if (addr < start || (addr + len - 1) > end)
+		fprintf(stderr, "%s: bad: %p < %p < %p false\n", msg, start, addr, end);
+}
+
 int main(int argc, char *argv[])
 {
 	struct iovec vecs[3];
+	char stack1[ASIZE], stack2[ASIZE], stack3[ASIZE];
+	char *h_s, *h_e, *b_s, *b_e, *f_s, *f_e;
 	char *h, *b, *f;
+	int i;
+
+	if (check_output_pipe())
+		return usage(argv[0]);
 
 	if (parse_options(argc, argv) < 0)
 		return usage(argv[0]);
 
 	if (alloc_stack) {
-		h = S1;
-		b = S2;
-		f = S3;
+		h = stack1;
+		b = stack2;
+		f = stack3;
 	} else {
+		h = malloc(ASIZE);
+		b = malloc(ASIZE);
+		f = malloc(ASIZE);
+	}
+
+	memset(h, 0, ASIZE);
+	memset(b, 0, ASIZE);
+	memset(f, 0, ASIZE);
+
+	h_s = h;
+	h_e = h_s + 2 * PAGE_SIZE - 1;
+	b_s = b;
+	b_e = b_s + 2 * PAGE_SIZE - 1;
+	f_s = f;
+	f_e = f_s + 2 * PAGE_SIZE - 1;
+
+	if (force_align || cross_page) {
+		/* align forward to start of 2nd page */
+		unsigned long off;
+
+		off = PAGE_SIZE - ((unsigned long) h & PAGE_MASK);
+		h += off;
+		off = PAGE_SIZE - ((unsigned long) b & PAGE_MASK);
+		b += off;
+		off = PAGE_SIZE - ((unsigned long) f & PAGE_MASK);
+		f += off;
 		if (cross_page) {
-			void *ptr;
-
-			ptr = ALIGN(malloc(3 * PAGE_SIZE));
-			h = ptr + PAGE_SIZE - (strlen(S1) / 2);
-			strcpy(h, S1);
-
-			ptr = ALIGN(malloc(3 * PAGE_SIZE));
-			b = ptr + PAGE_SIZE - (strlen(S2) / 2);
-			strcpy(b, S2);
-
-			ptr = ALIGN(malloc(3 * PAGE_SIZE));
-			f = ptr + PAGE_SIZE - (strlen(S3) / 2);
-			strcpy(f, S3);
-		} else {
-			h = strdup(S1);
-			b = strdup(S2);
-			f = strdup(S3);
+			/* this puts half the string in both pages */
+			h -= strlen(S1) / 2;
+			b -= strlen(S2) / 2;
+			f -= strlen(S3) / 2;
 		}
 	}
 
+	strcpy(h, S1);
+	strcpy(b, S2);
+	strcpy(f, S3);
+
 	vecs[0].iov_base = h;
 	vecs[1].iov_base = b;
 	vecs[2].iov_base = f;
-	vecs[0].iov_len = strlen(vecs[0].iov_base);
-	vecs[1].iov_len = strlen(vecs[1].iov_base);
-	vecs[2].iov_len = strlen(vecs[2].iov_base);
-		
-	if (check_output_pipe())
-		return usage(argv[0]);
+	if (!full_page) {
+		vecs[0].iov_len = strlen(vecs[0].iov_base);
+		vecs[1].iov_len = strlen(vecs[1].iov_base);
+		vecs[2].iov_len = strlen(vecs[2].iov_base);
+	} else {
+		vecs[0].iov_len = PAGE_SIZE;
+		vecs[1].iov_len = PAGE_SIZE;
+		vecs[2].iov_len = PAGE_SIZE;
+	}
+
+	check_address(h, h_s, h_e, vecs[0].iov_len, "header");
+	check_address(b, b_s, b_e, vecs[1].iov_len, "body");
+	check_address(f, f_s, f_e, vecs[2].iov_len, "footer");
 
 	return do_vmsplice(STDOUT_FILENO, vecs, 3);
 }
-- 
2.25.1