Warn user when value entered is greated than the amount supported

by the MBR for the given parameter and set that parameter to the
maximum value instead of just truncating the most significant part
silently.

Could happen for example if the capacity of the device is more
than 2TB, so that the number of sectors is greater than 2Mib.

MFC after:	1 month

1 files changed, 31 insertions, 20 deletions

diff --git a/sbin/fdisk/fdisk.c b/sbin/fdisk/fdisk.c
index 0495a69..bfe456d 100644
--- a/sbin/fdisk/fdisk.c
+++ b/sbin/fdisk/fdisk.c
@@ -62,7 +62,7 @@ static char lbuf[LBUF];
  *	Created.
  */
 
-#define Decimal(str, ans, tmp) if (decimal(str, &tmp, ans)) ans = tmp
+#define Decimal(str, ans, tmp, size) if (decimal(str, &tmp, ans, size)) ans = tmp
 
 #define RoundCyl(x) ((((x) + cylsecs - 1) / cylsecs) * cylsecs)
 
@@ -247,7 +247,7 @@ static int get_params(void);
 static int read_s0(void);
 static int write_s0(void);
 static int ok(const char *str);
-static int decimal(const char *str, int *num, int deflt);
+static int decimal(const char *str, int *num, int deflt, int size);
 static int read_config(char *config_file);
 static void reset_boot(void);
 static int sanitize_partition(struct dos_partition *);
@@ -572,9 +572,9 @@ change_part(int i)
 	}
 
 	do {
-		Decimal("sysid (165=FreeBSD)", partp->dp_typ, tmp);
-		Decimal("start", partp->dp_start, tmp);
-		Decimal("size", partp->dp_size, tmp);
+		Decimal("sysid (165=FreeBSD)", partp->dp_typ, tmp, sizeof(partp->dp_typ));
+		Decimal("start", partp->dp_start, tmp, sizeof(partp->dp_start));
+		Decimal("size", partp->dp_size, tmp, sizeof(partp->dp_size));
 		if (!sanitize_partition(partp)) {
 			warnx("ERROR: failed to adjust; setting sysid to 0");
 			partp->dp_typ = 0;
@@ -586,9 +586,9 @@ change_part(int i)
 			tcyl = DPCYL(partp->dp_scyl,partp->dp_ssect);
 			thd = partp->dp_shd;
 			tsec = DPSECT(partp->dp_ssect);
-			Decimal("beginning cylinder", tcyl, tmp);
-			Decimal("beginning head", thd, tmp);
-			Decimal("beginning sector", tsec, tmp);
+			Decimal("beginning cylinder", tcyl, tmp, sizeof(partp->dp_scyl));
+			Decimal("beginning head", thd, tmp, sizeof(partp->dp_shd));
+			Decimal("beginning sector", tsec, tmp, sizeof(partp->dp_ssect));
 			partp->dp_scyl = DOSCYL(tcyl);
 			partp->dp_ssect = DOSSECT(tsec,tcyl);
 			partp->dp_shd = thd;
@@ -596,9 +596,9 @@ change_part(int i)
 			tcyl = DPCYL(partp->dp_ecyl,partp->dp_esect);
 			thd = partp->dp_ehd;
 			tsec = DPSECT(partp->dp_esect);
-			Decimal("ending cylinder", tcyl, tmp);
-			Decimal("ending head", thd, tmp);
-			Decimal("ending sector", tsec, tmp);
+			Decimal("ending cylinder", tcyl, tmp, sizeof(partp->dp_ecyl));
+			Decimal("ending head", thd, tmp, sizeof(partp->dp_ehd));
+			Decimal("ending sector", tsec, tmp, sizeof(partp->dp_esect));
 			partp->dp_ecyl = DOSCYL(tcyl);
 			partp->dp_esect = DOSSECT(tsec,tcyl);
 			partp->dp_ehd = thd;
@@ -647,7 +647,7 @@ change_active(int which)
 setactive:
 	do {
 		new = active;
-		Decimal("active partition", new, tmp);
+		Decimal("active partition", new, tmp, 0);
 		if (new < 1 || new > 4) {
 			printf("Active partition number must be in range 1-4."
 					"  Try again.\n");
@@ -677,9 +677,9 @@ get_params_to_use()
 	{
 		do
 		{
-			Decimal("BIOS's idea of #cylinders", dos_cyls, tmp);
-			Decimal("BIOS's idea of #heads", dos_heads, tmp);
-			Decimal("BIOS's idea of #sectors", dos_sectors, tmp);
+			Decimal("BIOS's idea of #cylinders", dos_cyls, tmp, 0);
+			Decimal("BIOS's idea of #heads", dos_heads, tmp, 0);
+			Decimal("BIOS's idea of #sectors", dos_sectors, tmp, 0);
 			dos_cylsecs = dos_heads * dos_sectors;
 			print_params();
 		}
@@ -915,11 +915,16 @@ ok(const char *str)
 }
 
 static int
-decimal(const char *str, int *num, int deflt)
+decimal(const char *str, int *num, int deflt, int size)
 {
-	int acc = 0, c;
+	long long acc = 0, maxval;
+	int c;
 	char *cp;
 
+	if (size == 0) {
+		size = sizeof(*num);
+	}
+	maxval = (long long)1 << (size * 8);
 	while (1) {
 		printf("Supply a decimal value for \"%s\" [%d] ", str, deflt);
 		fflush(stdout);
@@ -935,14 +940,20 @@ decimal(const char *str, int *num, int deflt)
 		if (!c)
 			return 0;
 		while ((c = *cp++)) {
-			if (c <= '9' && c >= '0')
-				acc = acc * 10 + c - '0';
-			else
+			if (c <= '9' && c >= '0') {
+				if (acc < maxval)
+					acc = acc * 10 + c - '0';
+			} else
 				break;
 		}
 		if (c == ' ' || c == '\t')
 			while ((c = *cp) && (c == ' ' || c == '\t')) cp++;
 		if (!c) {
+			if (acc >= maxval) {
+				acc = maxval - 1;
+				printf("%s is too big, it will be truncated to %lld\n",
+				    lbuf, acc);
+			}
 			*num = acc;
 			return 1;
 		} else