dd(1): Incorrect casting of arguments

dd(1) casts many of its numeric arguments from uintmax_t to intmax_t and
back again to detect whether or not the original arguments were negative.
This is not correct, and causes problems with boundary cases, for example
when count is SSIZE_MAX-1.

PR:		191263
Submitted by:	will@worrbase.com
Reviewed by:	pi, asomers
MFC after:	3 weeks

bin/dd/args.c

@@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 
+#include <ctype.h>
 #include <err.h>
 #include <errno.h>
 #include <inttypes.h>
@@ -184,7 +185,7 @@ f_bs(char *arg)
 
 	res = get_num(arg);
 	if (res < 1 || res > SSIZE_MAX)
-		errx(1, "bs must be between 1 and %jd", (intmax_t)SSIZE_MAX);
+		errx(1, "bs must be between 1 and %zd", SSIZE_MAX);
 	in.dbsz = out.dbsz = (size_t)res;
 }
 
@@ -195,22 +196,22 @@ f_cbs(char *arg)
 
 	res = get_num(arg);
 	if (res < 1 || res > SSIZE_MAX)
-		errx(1, "cbs must be between 1 and %jd", (intmax_t)SSIZE_MAX);
+		errx(1, "cbs must be between 1 and %zd", SSIZE_MAX);
 	cbsz = (size_t)res;
 }
 
 static void
 f_count(char *arg)
 {
-	intmax_t res;
+	uintmax_t res;
 
-	res = (intmax_t)get_num(arg);
-	if (res < 0)
-		errx(1, "count cannot be negative");
+	res = get_num(arg);
+	if (res == UINTMAX_MAX)
+		errc(1, ERANGE, "%s", oper);
 	if (res == 0)
-		cpy_cnt = (uintmax_t)-1;
+		cpy_cnt = UINTMAX_MAX;
 	else
-		cpy_cnt = (uintmax_t)res;
+		cpy_cnt = res;
 }
 
 static void
@@ -219,7 +220,7 @@ f_files(char *arg)
 
 	files_cnt = get_num(arg);
 	if (files_cnt < 1)
-		errx(1, "files must be between 1 and %jd", (uintmax_t)-1);
+		errx(1, "files must be between 1 and %zu", SIZE_MAX);
 }
 
 static void
@@ -240,8 +241,8 @@ f_ibs(char *arg)
 	if (!(ddflags & C_BS)) {
 		res = get_num(arg);
 		if (res < 1 || res > SSIZE_MAX)
-			errx(1, "ibs must be between 1 and %jd",
-			    (intmax_t)SSIZE_MAX);
+			errx(1, "ibs must be between 1 and %zd",
+			    SSIZE_MAX);
 		in.dbsz = (size_t)res;
 	}
 }
@@ -261,8 +262,8 @@ f_obs(char *arg)
 	if (!(ddflags & C_BS)) {
 		res = get_num(arg);
 		if (res < 1 || res > SSIZE_MAX)
-			errx(1, "obs must be between 1 and %jd",
-			    (intmax_t)SSIZE_MAX);
+			errx(1, "obs must be between 1 and %zd",
+			    SSIZE_MAX);
 		out.dbsz = (size_t)res;
 	}
 }

bin/dd/conv.c

@@ -133,7 +133,7 @@ block(void)
 	 */
 	ch = 0;
 	for (inp = in.dbp - in.dbcnt, outp = out.dbp; in.dbcnt;) {
-		maxlen = MIN(cbsz, in.dbcnt);
+		maxlen = MIN(cbsz, (size_t)in.dbcnt);
 		if ((t = ctab) != NULL)
 			for (cnt = 0; cnt < maxlen && (ch = *inp++) != '\n';
 			    ++cnt)
@@ -146,7 +146,7 @@ block(void)
 		 * Check for short record without a newline.  Reassemble the
 		 * input block.
 		 */
-		if (ch != '\n' && in.dbcnt < cbsz) {
+		if (ch != '\n' && (size_t)in.dbcnt < cbsz) {
 			(void)memmove(in.db, in.dbp - in.dbcnt, in.dbcnt);
 			break;
 		}
@@ -228,7 +228,7 @@ unblock(void)
 	 * translation has to already be done or we might not recognize the
 	 * spaces.
 	 */
-	for (inp = in.db; in.dbcnt >= cbsz; inp += cbsz, in.dbcnt -= cbsz) {
+	for (inp = in.db; (size_t)in.dbcnt >= cbsz; inp += cbsz, in.dbcnt -= cbsz) {
 		for (t = inp + cbsz - 1; t >= inp && *t == ' '; --t)
 			;
 		if (t >= inp) {

bin/dd/dd.c

@@ -204,10 +204,10 @@ setup(void)
 	 * record oriented I/O, only need a single buffer.
 	 */
 	if (!(ddflags & (C_BLOCK | C_UNBLOCK))) {
-		if ((in.db = malloc(out.dbsz + in.dbsz - 1)) == NULL)
+		if ((in.db = malloc((size_t)out.dbsz + in.dbsz - 1)) == NULL)
 			err(1, "input buffer");
 		out.db = in.db;
-	} else if ((in.db = malloc(MAX(in.dbsz, cbsz) + cbsz)) == NULL ||
+	} else if ((in.db = malloc(MAX((size_t)in.dbsz, cbsz) + cbsz)) == NULL ||
 	    (out.db = malloc(out.dbsz + cbsz)) == NULL)
 		err(1, "output buffer");
 
@@ -405,7 +405,7 @@ dd_in(void)
 			++st.in_full;
 
 		/* Handle full input blocks. */
-		} else if ((size_t)n == in.dbsz) {
+		} else if ((size_t)n == (size_t)in.dbsz) {
 			in.dbcnt += in.dbrcnt = n;
 			++st.in_full;
 
@@ -562,7 +562,7 @@ dd_out(int force)
 			outp += nw;
 			st.bytes += nw;
 
-			if ((size_t)nw == n && n == out.dbsz)
+			if ((size_t)nw == n && n == (size_t)out.dbsz)
 				++st.out_full;
 			else
 				++st.out_part;

bin/dd/dd.h

@@ -38,10 +38,9 @@
 typedef struct {
 	u_char		*db;		/* buffer address */
 	u_char		*dbp;		/* current buffer I/O address */
-	/* XXX ssize_t? */
-	size_t		dbcnt;		/* current buffer byte count */
-	size_t		dbrcnt;		/* last read byte count */
-	size_t		dbsz;		/* block size */
+	ssize_t		dbcnt;		/* current buffer byte count */
+	ssize_t		dbrcnt;		/* last read byte count */
+	ssize_t		dbsz;		/* block size */
 
 #define	ISCHR		0x01		/* character device (warn on short) */
 #define	ISPIPE		0x02		/* pipe-like (see position.c) */

bin/dd/position.c

@@ -207,7 +207,7 @@ pos_out(void)
 			n = write(out.fd, out.db, out.dbsz);
 			if (n == -1)
 				err(1, "%s", out.name);
-			if ((size_t)n != out.dbsz)
+			if (n != out.dbsz)
 				errx(1, "%s: write failure", out.name);
 		}
 		break;