From 726f69e29ca9d4842f3acb20fffd2466fda62c09 Mon Sep 17 00:00:00 2001
From: Karel Zak
Date: Thu, 7 Dec 2006 00:25:33 +0100
Subject: Imported from util-linux-2.5 tarball.

---
 disk-utils/mkswap.c | 69 +++++++++++++++++++++++++++++------------------------
 1 file changed, 38 insertions(+), 31 deletions(-)

(limited to 'disk-utils/mkswap.c')

diff --git a/disk-utils/mkswap.c b/disk-utils/mkswap.c
index bb4e2249e..fe3f04c11 100644
--- a/disk-utils/mkswap.c
+++ b/disk-utils/mkswap.c
@@ -28,12 +28,8 @@
 
 #include <linux/mm.h>
 
-#ifndef __GNUC__
-#error "needs gcc for the bitop-__asm__'s"
-#endif
-
 #ifndef __linux__
-#define volatile
+# define volatile
 #endif
 
 #define TEST_BUFFER_PAGES 8
@@ -45,21 +41,29 @@ static long PAGES = 0;
 static int check = 0;
 static int badpages = 0;
 
-static char signature_page[PAGE_SIZE];
+static int signature_page[PAGE_SIZE/sizeof(int)];
 
-#define bitop(name,op) \
-static inline int name(char * addr,unsigned int nr) \
-{ \
-int __res; \
-__asm__ __volatile__("bt" op " %1,%2; adcl $0,%0" \
-:"=g" (__res) \
-:"r" (nr),"m" (*(addr)),"0" (0)); \
-return __res; \
+static long bit_test_and_set (unsigned int *addr, unsigned int nr)
+{
+	unsigned int r, m;
+
+	addr += nr / (8 * sizeof(int));
+	r = *addr;
+	m = 1 << (nr & (8 * sizeof(int) - 1));
+	*addr = r | m;
+	return (r & m) != 0;
 }
 
-bitop(bit,"")
-bitop(setbit,"s")
-bitop(clrbit,"r")
+static bit_test_and_clear (unsigned int *addr, unsigned int nr)
+{
+	unsigned int r, m;
+
+	addr += nr / (8 * sizeof(int));
+	r = *addr;
+	m = 1 << (nr & (8 * sizeof(int) - 1));
+	*addr = r & ~m;
+	return (r & m) != 0;
+}
 
 /*
  * Volatile to let gcc know that this doesn't return. When trying
@@ -84,18 +88,18 @@ void check_blocks(void)
 	current_page = 0;
 	while (current_page < PAGES) {
 		if (!check) {
-			setbit(signature_page,current_page++);
+			bit_test_and_set(signature_page,current_page++);
 			continue;
 		}
 		if (do_seek && lseek(DEV,current_page*PAGE_SIZE,SEEK_SET) !=
 		current_page*PAGE_SIZE)
 			die("seek failed in check_blocks");
 		if (do_seek = (PAGE_SIZE != read(DEV, buffer, PAGE_SIZE))) {
-			clrbit(signature_page,current_page++);
+			bit_test_and_clear(signature_page,current_page++);
 			badpages++;
 			continue;
 		}
-		setbit(signature_page,current_page++);
+		bit_test_and_set(signature_page,current_page++);
 	}
 	if (badpages)
 		printf("%d bad page%s\n",badpages,(badpages>1)?"s":"");
@@ -165,7 +169,7 @@ int main(int argc, char ** argv)
 		argv++;
 		if (argv[0][0] != '-')
 			if (device_name) {
-				PAGES = strtol(argv[0],&tmp,0)>>2;
+				PAGES = strtol(argv[0],&tmp,0)>>(PAGE_SHIFT-10);
 				if (*tmp)
 					usage();
 			} else
@@ -179,14 +183,17 @@ int main(int argc, char ** argv)
 	if (device_name && !PAGES) {
 		PAGES = get_size(device_name) / PAGE_SIZE;
 	}
-	if (!device_name || PAGES<10)
+	if (!device_name || PAGES<10) {
+		fprintf(stderr,
+			"%s: error: swap area needs to be at least %ldkB\n",
+			program_name, 10 * PAGE_SIZE / 1024);
 		usage();
-	if (PAGES > 32688) /* 130752 blocks */
-	        PAGES=32688;
-#if 0
-	if (PAGES > 32768)
-		PAGES=32768;
-#endif
+	}
+	if (PAGES > 8 * (PAGE_SIZE - 10)) {
+	        PAGES = 8 * (PAGE_SIZE - 10);
+		fprintf(stderr, "%s: warning: truncating swap area to %ldkB\n",
+			program_name, PAGES * PAGE_SIZE / 1024);
+	}
 	DEV = open(device_name,O_RDWR);
 	if (DEV < 0 || fstat(DEV, &statbuf) < 0) {
 		perror(device_name);
@@ -197,13 +204,13 @@ int main(int argc, char ** argv)
 	else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340)
 		die("Will not try to make swapdevice on '%s'");
 	check_blocks();
-	if (!clrbit(signature_page,0))
+	if (!bit_test_and_clear(signature_page,0))
 		die("fatal: first page unreadable");
 	goodpages = PAGES - badpages - 1;
-	if (!goodpages)
+	if (goodpages <= 0)
 		die("Unable to set up swap-space: unreadable");
 	printf("Setting up swapspace, size = %d bytes\n",goodpages*PAGE_SIZE);
-	strncpy(signature_page+PAGE_SIZE-10,"SWAP-SPACE",10);
+	strncpy((char*)signature_page+PAGE_SIZE-10,"SWAP-SPACE",10);
 	if (lseek(DEV, 0, SEEK_SET))
 		die("unable to rewind swap-device");
 	if (PAGE_SIZE != write(DEV, signature_page, PAGE_SIZE))
-- 
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