xxd: fix printing of trailing spaces

function                                             old     new   delta
bb_dump_dump                                        1497    1523     +26
xxd_main                                             459     466      +7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 33/0)               Total: 33 bytes

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

4 files changed, 108 insertions, 59 deletions

diff --git a/include/dump.h b/include/dump.h
index 4c237ef05..f4759c193 100644
--- a/include/dump.h
+++ b/include/dump.h
@@ -2,50 +2,15 @@
 
 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
-#define F_IGNORE        0x01            /* %_A */
-#define F_SETREP        0x02            /* rep count set, not default */
-#define F_ADDRESS       0x001           /* print offset */
-#define F_BPAD          0x002           /* blank pad */
-#define F_C             0x004           /* %_c */
-#define F_CHAR          0x008           /* %c */
-#define F_DBL           0x010           /* %[EefGf] */
-#define F_INT           0x020           /* %[di] */
-#define F_P             0x040           /* %_p */
-#define F_STR           0x080           /* %s */
-#define F_U             0x100           /* %_u */
-#define F_UINT          0x200           /* %[ouXx] */
-#define F_TEXT          0x400           /* no conversions */
-
 enum dump_vflag_t { ALL, DUP, FIRST, WAIT };    /* -v values */
 
-typedef struct PR {
-        struct PR *nextpr;              /* next print unit */
-        unsigned flags;                 /* flag values */
-        int bcnt;                       /* byte count */
-        char *cchar;                    /* conversion character */
-        char *fmt;                      /* printf format */
-        char *nospace;                  /* no whitespace version */
-} PR;
-
-typedef struct FU {
-        struct FU *nextfu;              /* next format unit */
-        struct PR *nextpr;              /* next print unit */
-        unsigned flags;                 /* flag values */
-        int reps;                       /* repetition count */
-        int bcnt;                       /* byte count */
-        char *fmt;                      /* format string */
-} FU;
-
-typedef struct FS {                     /* format strings */
-        struct FS *nextfs;              /* linked list of format strings */
-        struct FU *nextfu;              /* linked list of format units */
-        int bcnt;
-} FS;
+typedef struct FS FS;
 
 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;
 } dumper_t;
 
diff --git a/libbb/dump.c b/libbb/dump.c
index 8029cca0e..920f003ef 100644
--- a/libbb/dump.c
+++ b/libbb/dump.c
@@ -13,13 +13,43 @@
 #include "libbb.h"
 #include "dump.h"
 
-static const char dot_flags_width_chars[] ALIGN1 = ".#-+ 0123456789";
-
-static const char size_conv_str[] ALIGN1 =
-"\x1\x4\x4\x4\x4\x4\x4\x8\x8\x8\x8\010cdiouxXeEfgG";
-
-static const char int_convs[] ALIGN1 = "diouxX";
-
+#define F_IGNORE        0x01            /* %_A */
+#define F_SETREP        0x02            /* rep count set, not default */
+#define F_ADDRESS       0x001           /* print offset */
+#define F_BPAD          0x002           /* blank pad */
+#define F_C             0x004           /* %_c */
+#define F_CHAR          0x008           /* %c */
+#define F_DBL           0x010           /* %[EefGf] */
+#define F_INT           0x020           /* %[di] */
+#define F_P             0x040           /* %_p */
+#define F_STR           0x080           /* %s */
+#define F_U             0x100           /* %_u */
+#define F_UINT          0x200           /* %[ouXx] */
+#define F_TEXT          0x400           /* no conversions */
+
+typedef struct PR {
+        struct PR *nextpr;              /* next print unit */
+        unsigned flags;                 /* flag values */
+        int bcnt;                       /* byte count */
+        char *cchar;                    /* conversion character */
+        char *fmt;                      /* printf format */
+        char *nospace;                  /* no whitespace version */
+} PR;
+
+typedef struct FU {
+        struct FU *nextfu;              /* next format unit */
+        struct PR *nextpr;              /* next print unit */
+        unsigned flags;                 /* flag values */
+        int reps;                       /* repetition count */
+        int bcnt;                       /* byte count */
+        char *fmt;                      /* format string */
+} FU;
+
+typedef struct FS {                     /* format strings */
+        struct FS *nextfs;              /* linked list of format strings */
+        struct FU *nextfu;              /* linked list of format units */
+        int bcnt;
+} FS;
 
 typedef struct priv_dumper_t {
         dumper_t pub;
@@ -39,6 +69,13 @@ typedef struct priv_dumper_t {
         unsigned char *get__savp;
 } priv_dumper_t;
 
+static const char dot_flags_width_chars[] ALIGN1 = ".#-+ 0123456789";
+
+static const char size_conv_str[] ALIGN1 =
+"\x1\x4\x4\x4\x4\x4\x4\x8\x8\x8\x8\010cdiouxXeEfgG";
+
+static const char int_convs[] ALIGN1 = "diouxX";
+
 dumper_t* FAST_FUNC alloc_dumper(void)
 {
         priv_dumper_t *dumper = xzalloc(sizeof(*dumper));
@@ -48,7 +85,6 @@ dumper_t* FAST_FUNC alloc_dumper(void)
         return &dumper->pub;
 }
 
-
 static NOINLINE int bb_dump_size(FS *fs)
 {
         FU *fu;
@@ -284,7 +320,9 @@ static NOINLINE void rewrite(priv_dumper_t *dumper, FS *fs)
          * repeat it as necessary.
          *
          * if rep count is greater than 1, no trailing whitespace
-         * gets output from the last iteration of the format unit.
+         * gets output from the last iteration of the format unit:
+         * 2/1 "%02x " prints "XX XX", not "XX XX "
+         * 2/1 "%02x\n" prints "XX\nXX", not "XX\nXX\n"
          */
         for (fu = fs->nextfu; fu; fu = fu->nextfu) {
                 if (!fu->nextfu
@@ -453,7 +491,7 @@ static void bpad(PR *pr)
         for (p2 = ++p1; *p1 && strchr(" -0+#", *p1); ++p1)
                 if (pr->nospace)
                         pr->nospace--;
-        while ((*p2++ = *p1++) != 0)
+        while ((*p2++ = *p1++) != '\0')
                 continue;
 }
 
@@ -520,36 +558,43 @@ static void conv_u(PR *pr, unsigned char *p)
 
 static void display(priv_dumper_t* dumper)
 {
-        FS *fs;
-        FU *fu;
-        PR *pr;
-        int cnt;
-        unsigned char *bp, *savebp;
-        off_t saveaddress;
+        unsigned char *bp;
         unsigned char savech = '\0';
 
         while ((bp = get(dumper)) != NULL) {
+                FS *fs;
+                unsigned char *savebp;
+                off_t saveaddress;
+
                 fs = dumper->pub.fshead;
                 savebp = bp;
                 saveaddress = dumper->address;
                 for (; fs; fs = fs->nextfs, bp = savebp, dumper->address = saveaddress) {
+                        FU *fu;
                         for (fu = fs->nextfu; fu; fu = fu->nextfu) {
+                                int cnt;
                                 if (fu->flags & F_IGNORE) {
                                         break;
                                 }
                                 for (cnt = fu->reps; cnt; --cnt) {
+                                        PR *pr;
                                         for (pr = fu->nextpr; pr; dumper->address += pr->bcnt,
                                                                 bp += pr->bcnt, pr = pr->nextpr) {
-                                                if (dumper->eaddress && dumper->address >= dumper->eaddress
-                                                 && !(pr->flags & (F_TEXT | F_BPAD))
+                                                if (dumper->eaddress
+                                                 && dumper->address >= dumper->eaddress
                                                 ) {
-                                                        bpad(pr);
+                                                        if (dumper->pub.eofstring) {
+                                                                /* xxd support: requested to not pad incomplete blocks */
+                                                                fputs(dumper->pub.eofstring, stdout);
+                                                                return;
+                                                        }
+                                                        if (!(pr->flags & (F_TEXT | F_BPAD)))
+                                                                bpad(pr);
                                                 }
                                                 if (cnt == 1 && pr->nospace) {
                                                         savech = *pr->nospace;
                                                         *pr->nospace = '\0';
                                                 }
-/*                      PRINT; */
                                                 switch (pr->flags) {
                                                 case F_ADDRESS:
                                                         printf(pr->fmt, (unsigned) dumper->address);
@@ -638,7 +683,9 @@ static void display(priv_dumper_t* dumper)
                         }
                 }
         }
+
         if (dumper->endfu) {
+                PR *pr;
                 /*
                  * if eaddress not set, error or file size was multiple
                  * of blocksize, and no partial block ever found.
@@ -695,8 +742,7 @@ void FAST_FUNC bb_dump_add(dumper_t* pub_dumper, const char *fmt)
 {
         const char *p;
         FS *tfs;
-        FU *tfu, **nextfupp;
-        const char *savep;
+        FU **nextfupp;
 
         /* start new linked list of format units */
         tfs = xzalloc(sizeof(FS)); /*DBU:[dave@cray.com] start out NULL */
@@ -713,6 +759,9 @@ void FAST_FUNC bb_dump_add(dumper_t* pub_dumper, const char *fmt)
         /* take the format string and break it up into format units */
         p = fmt;
         for (;;) {
+                FU *tfu;
+                const char *savep;
+
                 p = skip_whitespace(p);
                 if (*p == '\0') {
                         break;
diff --git a/testsuite/xxd.tests b/testsuite/xxd.tests
new file mode 100755
index 000000000..2e80be5fe
--- /dev/null
+++ b/testsuite/xxd.tests
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+# Copyright 2020 by Denys Vlasenko <vda.linux@googlemail.com>
+# Licensed under GPLv2, see file LICENSE in this source tree.
+
+. ./testing.sh
+
+# testing "description" "command" "result" "infile" "stdin"
+testing 'xxd -p with one NUL' \
+        'xxd -p' \
+        "\
+00
+" \
+        '' \
+        '\0'
+
+testing 'xxd -p with 30 NULs' \
+        'xxd -p' \
+        "\
+000000000000000000000000000000000000000000000000000000000000
+" \
+        '' \
+        '\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 with 31 NULs' \
+        'xxd -p' \
+        "\
+000000000000000000000000000000000000000000000000000000000000
+00
+" \
+        '' \
+        '\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'
+
+exit $FAILCOUNT
diff --git a/util-linux/hexdump_xxd.c b/util-linux/hexdump_xxd.c
index 6cf6d0297..f2d1ecb2c 100644
--- a/util-linux/hexdump_xxd.c
+++ b/util-linux/hexdump_xxd.c
@@ -141,6 +141,7 @@ int xxd_main(int argc UNUSED_PARAM, char **argv)
                 bb_dump_add(dumper, buf);
         } else {
                 bb_dump_add(dumper, "\"\n\"");
+                dumper->eofstring = "\n";
         }
 
         return bb_dump_dump(dumper, argv);