xxd: implement -o DISPLAYOFFSET

function                                             old     new   delta
xxd_main                                             680     710     +30
xstrtoll                                               -      30     +30
bb_dump_dump                                        1511    1531     +20
rewrite                                              941     951     +10
packed_usage                                       33629   33639     +10
.rodata                                           103250  103252      +2
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 5/0 up/down: 102/0)             Total: 102 bytes

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

3 files changed, 22 insertions, 11 deletions

diff --git a/include/dump.h b/include/dump.h
index 9193a6925..54f5629a7 100644
--- a/include/dump.h
+++ b/include/dump.h
@@ -32,8 +32,9 @@ typedef struct dumper_t {
         off_t dump_skip;                /* bytes to skip */
         int dump_length;                /* max bytes to read */
         smallint dump_vflag;            /*enum dump_vflag_t*/
-        const char *eofstring;
         FS *fshead;
+        const char *xxd_eofstring;
+        long long xxd_displayoff;
 } dumper_t;
 
 dumper_t* alloc_dumper(void) FAST_FUNC;
diff --git a/libbb/dump.c b/libbb/dump.c
index e83633c1d..8c2a370d0 100644
--- a/libbb/dump.c
+++ b/libbb/dump.c
@@ -228,7 +228,8 @@ static NOINLINE void rewrite(priv_dumper_t *dumper, FS *fs)
                                         if ((p1[2] != 'd') && (p1[2] != 'o') && (p1[2] != 'x')) {
                                                 goto DO_BAD_CONV_CHAR;
                                         }
-                                        *p1 = p1[2];
+                                        *p1++ = 'l';
+                                        *p1++ = 'l';
                                         break;
                                 case 'c':       /* %_c: chars, \ooo, \n \r \t etc */
                                         pr->flags = F_C;
@@ -558,9 +559,9 @@ static void display(priv_dumper_t* dumper)
                                                 if (dumper->eaddress
                                                  && dumper->address >= dumper->eaddress
                                                 ) {
-                                                        if (dumper->pub.eofstring) {
+                                                        if (dumper->pub.xxd_eofstring) {
                                                                 /* xxd support: requested to not pad incomplete blocks */
-                                                                fputs_stdout(dumper->pub.eofstring);
+                                                                fputs_stdout(dumper->pub.xxd_eofstring);
                                                                 return;
                                                         }
                                                         if (!(pr->flags & (F_TEXT | F_BPAD)))
@@ -572,7 +573,7 @@ static void display(priv_dumper_t* dumper)
                                                 }
                                                 switch (pr->flags) {
                                                 case F_ADDRESS:
-                                                        printf(pr->fmt, (unsigned) dumper->address);
+                                                        printf(pr->fmt, (unsigned long long) dumper->address + dumper->pub.xxd_displayoff);
                                                         break;
                                                 case F_BPAD:
                                                         printf(pr->fmt, "");
@@ -674,7 +675,7 @@ static void display(priv_dumper_t* dumper)
                 for (pr = dumper->endfu->nextpr; pr; pr = pr->nextpr) {
                         switch (pr->flags) {
                         case F_ADDRESS:
-                                printf(pr->fmt, (unsigned) dumper->eaddress);
+                                printf(pr->fmt, (unsigned long long) dumper->eaddress + dumper->pub.xxd_displayoff);
                                 break;
                         case F_TEXT:
                                 printf(pr->fmt);
diff --git a/util-linux/hexdump_xxd.c b/util-linux/hexdump_xxd.c
index 29bbc6633..817250c69 100644
--- a/util-linux/hexdump_xxd.c
+++ b/util-linux/hexdump_xxd.c
@@ -41,7 +41,7 @@
 //    -u          use upper case hex letters.
 
 //usage:#define xxd_trivial_usage
-//usage:       "[-pr] [-g N] [-c N] [-n LEN] [-s OFS] [FILE]"
+//usage:       "[-pr] [-g N] [-c N] [-n LEN] [-s OFS] [-o OFS] [FILE]"
 //usage:#define xxd_full_usage "\n\n"
 //usage:       "Hex dump FILE (or stdin)\n"
 //usage:     "\n        -g N            Bytes per group"
@@ -50,6 +50,7 @@
 // exactly the same help text lines in hexdump and xxd:
 //usage:     "\n        -l LENGTH       Show only first LENGTH bytes"
 //usage:     "\n        -s OFFSET       Skip OFFSET bytes"
+//usage:     "\n        -o OFFSET       Add OFFSET to displayed offset"
 //usage:     "\n        -r              Reverse (with -p, assumes no offsets in input)"
 
 #include "libbb.h"
@@ -62,6 +63,9 @@
 #define OPT_a (1 << 2)
 #define OPT_p (1 << 3)
 #define OPT_r (1 << 4)
+#define OPT_g (1 << 5)
+#define OPT_c (1 << 6)
+#define OPT_o (1 << 7)
 
 static void reverse(unsigned opt, unsigned cols, const char *filename)
 {
@@ -127,15 +131,15 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
 {
         char buf[80];
         dumper_t *dumper;
-        char *opt_l, *opt_s;
+        char *opt_l, *opt_s, *opt_o;
         unsigned bytes = 2;
         unsigned cols = 0;
         unsigned opt;
 
         dumper = alloc_dumper();
 
-        opt = getopt32(argv, "^" "l:s:aprg:+c:+" "\0" "?1" /* 1 argument max */,
-                        &opt_l, &opt_s, &bytes, &cols
+        opt = getopt32(argv, "^" "l:s:aprg:+c:+o:" "\0" "?1" /* 1 argument max */,
+                        &opt_l, &opt_s, &bytes, &cols, &opt_o
         );
         argv += optind;
 
@@ -158,6 +162,11 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
                 //BUGGY for /proc/version (unseekable?)
         }
 
+        if (opt & OPT_o) {
+                /* -o accepts negative numbers too */
+                dumper->xxd_displayoff = xstrtoll(opt_o, /*base:*/ 0);
+        }
+
         if (opt & OPT_p) {
                 if (cols == 0)
                         cols = 30;
@@ -206,7 +215,7 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
                 bb_dump_add(dumper, buf);
         } else {
                 bb_dump_add(dumper, "\"\n\"");
-                dumper->eofstring = "\n";
+                dumper->xxd_eofstring = "\n";
         }
 
         return bb_dump_dump(dumper, argv);