shuf: add (disabled) code to support very long numbers in -i LO-HI

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 58 insertions, 6 deletions

diff --git a/coreutils/shuf.c b/coreutils/shuf.c
index 337366b45..fe0358e07 100644
--- a/coreutils/shuf.c
+++ b/coreutils/shuf.c
@@ -66,6 +66,12 @@ static void shuffle_lines(char **lines, unsigned numlines, unsigned outlines)
         }
 }
 
+/* We can handle insanity like this:
+ * shuf -i 3333333333333333333333333333333333333333333333333333333333333123456789001-3333333333333333333333333333333333333333333333333333333333333123456789019
+ * but do we want to have +200 bytes of code (~40% code growth)?
+ */
+#define COMMON_PREFIX_HACK 0
+
 int shuf_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int shuf_main(int argc, char **argv)
 {
@@ -76,6 +82,11 @@ int shuf_main(int argc, char **argv)
         unsigned numlines, outlines;
         unsigned i;
         char eol;
+#if COMMON_PREFIX_HACK
+        unsigned pfx_len = 0;
+        unsigned padding_width = padding_width;
+        const char *pfx = pfx;
+#endif
 
         opts = getopt32(argv, "^"
                         OPT_STR
@@ -104,10 +115,46 @@ int shuf_main(int argc, char **argv)
                 if (!dash) {
                         bb_error_msg_and_die("bad range '%s'", opt_i_str);
                 }
-                *dash = '\0';
+                *dash++ = '\0';
+#if COMMON_PREFIX_HACK
+                {
+                        const char *a = opt_i_str;
+                        const char *b = dash;
+                        /* Skip leading zeros (they may mask that common prefix does exist) */
+                        while (*a == '0') a++;
+                        while (*b == '0') b++;
+                        /* Do we have a common prefix (long enough to bother)? */
+                        padding_width = strlen(a);
+                        if (padding_width > 5 && padding_width == strlen(b)) {
+                                /* How long is it? */
+                                pfx = a;
+                                while (isdigit(*a) && *a == *b) {
+                                        a++;
+                                        b++;
+                                }
+                                if (*a == '\0') {
+                                        /* "123456-123456", and we 'ate' all of them */
+                                        /* prevent trying to xatoull("") */
+                                        a--;
+                                        b--;
+                                }
+                                pfx_len = a - opt_i_str; /* can end up being 0 */
+                                padding_width -= pfx_len;
+                                lo = xatoull(a);
+                                hi = xatoull(b);
+                        } else {
+                                /* Undo leading zero 'eating' (think "0-9") */
+                                a = opt_i_str;
+                                b = dash;
+                        }
+                        lo = xatoull(a);
+                        hi = xatoull(b);
+                }
+#else
                 lo = xatoull(opt_i_str);
-                hi = xatoull(dash + 1);
-                *dash = '-';
+                hi = xatoull(dash);
+#endif
+                dash[-1] = '-';
                 if (hi < lo)
                         bb_error_msg_and_die("bad range '%s'", opt_i_str);
                 hi -= lo;
@@ -165,9 +212,14 @@ int shuf_main(int argc, char **argv)
                 eol = '\0';
 
         for (i = numlines - outlines; i < numlines; i++) {
-                if (opts & OPT_i)
-                        printf("%llu%c", lo + (uintptr_t)lines[i], eol);
-                else
+                if (opts & OPT_i) {
+#if COMMON_PREFIX_HACK
+                        if (pfx_len != 0)
+                                printf("%.*s%0*llu%c", pfx_len, pfx, padding_width, lo + (uintptr_t)lines[i], eol);
+                        else
+#endif
+                                printf("%llu%c", lo + (uintptr_t)lines[i], eol);
+                } else
                         printf("%s%c", lines[i], eol);
         }