1 files changed, 19 insertions, 15 deletions

diff --git a/coreutils/cut.c b/coreutils/cut.c
index 3abebe7ad..20138075c 100644
--- a/coreutils/cut.c
+++ b/coreutils/cut.c
@@ -85,8 +85,8 @@
 #define opt_REGEX (option_mask32 & OPT_REGEX)
 
 struct cut_list {
-        int startpos;
-        int endpos;
+        unsigned startpos;
+        unsigned endpos;
 };
 
 static int cmpfunc(const void *a, const void *b)
@@ -116,7 +116,7 @@ static void cut_file(FILE *file, const char *delim, const char *odelim,
 
                         /* print the chars specified in each cut list */
                         for (; cl_pos < nlists; cl_pos++) {
-                                int spos;
+                                unsigned spos;
                                 for (spos = cut_list[cl_pos].startpos; spos < linelen;) {
                                         if (!printed[spos]) {
                                                 printed[spos] = 'X';
@@ -171,7 +171,7 @@ static void cut_file(FILE *file, const char *delim, const char *odelim,
                 /* Cut by fields */
                 } else {
                         unsigned next = 0, start = 0, end = 0;
-                        int dcount = 0; /* we saw Nth delimiter (0 - didn't see any yet) */
+                        unsigned dcount = 0; /* we saw Nth delimiter (0 - didn't see any yet) */
 
                         /* Blank line? Check -s (later check for -s does not catch empty lines) */
                         if (linelen == 0) {
@@ -340,10 +340,10 @@ int cut_main(int argc UNUSED_PARAM, char **argv)
 
         /*
          * parse list and put values into startpos and endpos.
-         * valid list formats: N, N-, N-M, -M
-         * more than one list can be separated by commas
+         * valid range formats: N, N-, N-M, -M
+         * more than one range can be separated by commas
          */
-        /* take apart the lists, one by one (they are separated with commas) */
+        /* take apart the ranges, one by one (separated with commas) */
         while ((ltok = strsep(&sopt, ",")) != NULL) {
                 char *ntok;
                 int s, e;
@@ -356,22 +356,26 @@ int cut_main(int argc UNUSED_PARAM, char **argv)
                 /* get the start pos */
                 ntok = strsep(&ltok, "-");
                 if (!ntok[0]) {
-                        s = 0;
+                        if (!ltok) /* testcase: -f '' */
+                                bb_show_usage();
+                        if (!ltok[0]) /* testcase: -f - */
+                                bb_show_usage();
+                        s = 0; /* "-M" means "1-M" */
                 } else {
-                        /* account for the fact that arrays are zero based, while
-                         * the user expects the first char on the line to be char #1 */
+                        /* "N" or "N-[M]" */
+                        /* arrays are zero based, while the user expects
+                         * the first field/char on the line to be char #1 */
                         s = xatoi_positive(ntok) - 1;
                 }
 
                 /* get the end pos */
-                if (ltok == NULL) {
-                        e = s;
+                if (!ltok) {
+                        e = s; /* "N" means "N-N" */
                 } else if (!ltok[0]) {
-                        /* if the user specified no end position,
-                         * that means "til the end of the line" */
+                        /* "N-" means "until the end of the line" */
                         e = INT_MAX;
                 } else {
-                        /* again, arrays are zero based, lines are 1 based */
+                        /* again, arrays are zero based, fields are 1 based */
                         e = xatoi_positive(ltok) - 1;
                 }