btrfs-progs: Improve the parse_size() error message

When using parse_size(), even non-numeric value is passed, it will only
give error message "ERROR: size value is empty", which is quite
confusing for end users.

This patch will introduce more meaningful error message for the
following new cases
1) Invalid size string (non-numeric string)
2) Minus size value (like "-1K")

Also this patch will take full use of endptr returned by strtoll() to
reduce unneeded loop.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/utils.c b/utils.c
index c718d0f..46c3a43 100644 (file)
--- a/utils.c
+++ b/utils.c
@@ -1638,20 +1638,57 @@ scan_again:
        return 0;
 }
 
-u64 parse_size(char *s)
+/*
+ * A not-so-good version fls64. No fascinating optimization since
+ * no one except parse_size use it
+ */
+static int fls64(u64 x)
 {
        int i;
+
+       for (i = 0; i <64; i++)
+               if (x << i & (1UL << 63))
+                       return 64 - i;
+       return 64 - i;
+}
+
+u64 parse_size(char *s)
+{
        char c;
+       char *endptr;
        u64 mult = 1;
+       u64 ret;
 
-       for (i = 0; s && s[i] && isdigit(s[i]); i++) ;
-       if (!i) {
-               fprintf(stderr, "ERROR: size value is empty\n");
-               exit(50);
+       if (!s) {
+               fprintf(stderr, "ERROR: Size value is empty\n");
+               exit(1);
        }
-
-       if (s[i]) {
-               c = tolower(s[i]);
+       if (s[0] == '-') {
+               fprintf(stderr,
+                       "ERROR: Size value '%s' is less equal than 0\n", s);
+               exit(1);
+       }
+       ret = strtoull(s, &endptr, 10);
+       if (endptr == s) {
+               fprintf(stderr, "ERROR: Size value '%s' is invalid\n", s);
+               exit(1);
+       }
+       if (endptr[0] && endptr[1]) {
+               fprintf(stderr, "ERROR: Illegal suffix contains character '%c' in wrong position\n",
+                       endptr[1]);
+               exit(1);
+       }
+       /*
+        * strtoll returns LLONG_MAX when overflow, if this happens,
+        * need to call strtoull to get the real size
+        */
+       if (errno == ERANGE && ret == ULLONG_MAX) {
+               fprintf(stderr,
+                       "ERROR: Size value '%s' is too large for u64\n", s);
+               exit(1);
+       }
+       if (endptr[0]) {
+               c = tolower(endptr[0]);
                switch (c) {
                case 'e':
                        mult *= 1024;
@@ -1674,18 +1711,19 @@ u64 parse_size(char *s)
                case 'b':
                        break;
                default:
-                       fprintf(stderr, "ERROR: Unknown size descriptor "
-                               "'%c'\n", c);
+                       fprintf(stderr, "ERROR: Unknown size descriptor '%c'\n",
+                               c);
                        exit(1);
                }
        }
-       if (s[i] && s[i+1]) {
-               fprintf(stderr, "ERROR: Illegal suffix contains "
-                       "character '%c' in wrong position\n",
-                       s[i+1]);
-               exit(51);
+       /* Check whether ret * mult overflow */
+       if (fls64(ret) + fls64(mult) - 1 > 64) {
+               fprintf(stderr,
+                       "ERROR: Size value '%s' is too large for u64\n", s);
+               exit(1);
        }
-       return strtoull(s, NULL, 10) * mult;
+       ret *= mult;
+       return ret;
 }
 
 int open_file_or_dir3(const char *fname, DIR **dirstream, int open_flags)