xxd: fix -p -r, closes 13881

function                                             old     new   delta
xxd_main                                             893     890      -3

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

2 files changed, 44 insertions, 13 deletions

diff --git a/testsuite/xxd.tests b/testsuite/xxd.tests
index 2e80be5fe..76fa96af9 100755
--- a/testsuite/xxd.tests
+++ b/testsuite/xxd.tests
@@ -31,4 +31,10 @@ testing 'xxd -p with 31 NULs' \
         '' \
         '\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0'
 
+testing 'xxd -p -r' \
+        'xxd -p -r' \
+        '01234567765432100123456776543210' \
+        '' \
+        '30313233343536373736353433323130 30313233343536373736353433323130'
+
 exit $FAILCOUNT
diff --git a/util-linux/hexdump_xxd.c b/util-linux/hexdump_xxd.c
index fe78f6242..76dada983 100644
--- a/util-linux/hexdump_xxd.c
+++ b/util-linux/hexdump_xxd.c
@@ -69,7 +69,7 @@
 #define OPT_c (1 << 7)
 #define OPT_o (1 << 8)
 
-static void reverse(unsigned opt, unsigned cols, const char *filename)
+static void reverse(unsigned opt, const char *filename)
 {
         FILE *fp;
         char *buf;
@@ -77,9 +77,9 @@ static void reverse(unsigned opt, unsigned cols, const char *filename)
         fp = filename ? xfopen_for_read(filename) : stdin;
 
         while ((buf = xmalloc_fgetline(fp)) != NULL) {
-                char *p = buf;
-                unsigned cnt = cols;
+                char *p;
 
+                p = buf;
                 if (!(opt & OPT_p)) {
                         /* skip address */
                         while (isxdigit(*p)) p++;
@@ -92,9 +92,9 @@ static void reverse(unsigned opt, unsigned cols, const char *filename)
                 }
 
                 /* Process hex bytes optionally separated by whitespace */
-                do {
+                for (;;) {
                         uint8_t val, c;
-
+ nibble1:
                         p = skip_whitespace(p);
 
                         c = *p++;
@@ -102,8 +102,19 @@ static void reverse(unsigned opt, unsigned cols, const char *filename)
                                 val = c - '0';
                         else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
                                 val = (c|0x20) - ('a' - 10);
-                        else
+                        else {
+                                /* xxd V1.10 is inconsistent here.
+                                 *  echo -e "31 !3 0a 0a" | xxd -r -p
+                                 * is "10<a0>" (no <cr>) - "!" is ignored,
+                                 * but
+                                 *  echo -e "31 !!343434\n30 0a" | xxd -r -p
+                                 * is "10<cr>" - "!!" drops rest of the line.
+                                 * We will ignore all invalid chars:
+                                 */
+                                if (c != '\0')
+                                        goto nibble1;
                                 break;
+                        }
                         val <<= 4;
 
                         /* Works the same with xxd V1.10:
@@ -111,6 +122,7 @@ static void reverse(unsigned opt, unsigned cols, const char *filename)
                          *  echo "31 0 9 32 0a" | xxd -r -p
                          * thus allow whitespace even within the byte:
                          */
+ nibble2:
                         p = skip_whitespace(p);
 
                         c = *p++;
@@ -118,10 +130,23 @@ static void reverse(unsigned opt, unsigned cols, const char *filename)
                                 val |= c - '0';
                         else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
                                 val |= (c|0x20) - ('a' - 10);
-                        else
-                                break;
+                        else {
+                                if (c != '\0') {
+                                        /* "...3<not_hex_char>..." ignores both chars */
+                                        goto nibble1;
+                                }
+                                /* Nibbles can join even through newline:
+                                 * echo -e "31 3\n2 0a" | xxd -r -p
+                                 * is "12<cr>".
+                                 */
+                                free(buf);
+                                p = buf = xmalloc_fgetline(fp);
+                                if (!buf)
+                                        break;
+                                goto nibble2;
+                        }
                         putchar(val);
-                } while (!(opt & OPT_p) || --cnt != 0);
+                }
                 free(buf);
         }
         //fclose(fp);
@@ -174,6 +199,10 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
                 //BUGGY for /proc/version (unseekable?)
         }
 
+        if (opt & OPT_r) {
+                reverse(opt, argv[0]);
+        }
+
         if (opt & OPT_o) {
                 /* -o accepts negative numbers too */
                 dumper->xxd_displayoff = xstrtoll(opt_o, /*base:*/ 0);
@@ -194,10 +223,6 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
                         bb_dump_add(dumper, "\"%08.8_ax: \""); // "address: "
         }
 
-        if (opt & OPT_r) {
-                reverse(opt, cols, argv[0]);
-        }
-
         if (bytes < 1 || bytes >= cols) {
                 sprintf(buf, "%u/1 \"%%02x\"", cols); // cols * "XX"
                 bb_dump_add(dumper, buf);