patch 8.2.4088: xxd cannot output everything in one line

Problem:    Xxd cannot output everything in one line.
Solution:   Make zero columns mean infinite columns. (Erik Auerswald,
            closes #9524)
diff --git a/src/testdir/test_xxd.vim b/src/testdir/test_xxd.vim
index 7d0cbab..bdcbd08 100644
--- a/src/testdir/test_xxd.vim
+++ b/src/testdir/test_xxd.vim
@@ -320,10 +320,11 @@
 endfunc
 
 " -c0 selects the format specific default column value, as if no -c was given
+" except for -ps, where it disables extra newlines
 func Test_xxd_c0_is_def_cols()
   call writefile(["abcdefghijklmnopqrstuvwxyz0123456789"], 'Xxdin')
   for cols in ['-c0', '-c 0', '-cols 0']
-    for fmt in ['', '-b', '-e', '-i', '-p', ]
+    for fmt in ['', '-b', '-e', '-i']
       exe 'r! ' . s:xxd_cmd . ' ' . fmt ' Xxdin > Xxdout1'
       exe 'r! ' . s:xxd_cmd . ' ' . cols . ' ' . fmt ' Xxdin > Xxdout2'
       call assert_equalfile('Xxdout1', 'Xxdout2')
@@ -334,4 +335,27 @@
   call delete('Xxdout2')
 endfunc
 
+" all output in a single line for -c0 -ps
+func Test_xxd_plain_one_line()
+  call writefile([
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+        \ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"],
+        \ 'Xxdin')
+  for cols in ['-c0', '-c 0', '-cols 0']
+    exe 'r! ' . s:xxd_cmd . ' -ps ' . cols ' Xxdin'
+    " output seems to start in line 2
+    let out = join(getline(2, '$'))
+    bwipe!
+    " newlines in xxd output result in spaces in the string variable out
+    call assert_notmatch(" ", out)
+    " xxd output must be non-empty and comprise only lower case hex digits
+    call assert_match("^[0-9a-f][0-9a-f]*$", out)
+  endfor
+  call delete('Xxdin')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 782a64a..b55bdda 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4088,
+/**/
     4087,
 /**/
     4086,
diff --git a/src/xxd/xxd.c b/src/xxd/xxd.c
index c32b9b8..0e056c9 100644
--- a/src/xxd/xxd.c
+++ b/src/xxd/xxd.c
@@ -54,6 +54,7 @@
  * 08.06.2013  Little-endian hexdump (-e) and offset (-o) by Vadim Vygonets.
  * 11.01.2019  Add full 64/32 bit range to -o and output by Christer Jensen.
  * 04.02.2020  Add -d for decimal offsets by Aapo Rantalainen
+ * 14.01.2022  Disable extra newlines with -c0 -p by Erik Auerswald.
  *
  * (c) 1990-1998 by Juergen Weigert (jnweiger@gmail.com)
  *
@@ -135,7 +136,7 @@
 extern long int strtol();
 extern long int ftell();
 
-char version[] = "xxd 2021-10-22 by Juergen Weigert et al.";
+char version[] = "xxd 2022-01-14 by Juergen Weigert et al.";
 #ifdef WIN32
 char osver[] = " (Win32)";
 #else
@@ -487,7 +488,7 @@
 {
   FILE *fp, *fpo;
   int c, e, p = 0, relseek = 1, negseek = 0, revert = 0;
-  int cols = 0, nonzero = 0, autoskip = 0, hextype = HEX_NORMAL;
+  int cols = 0, colsgiven = 0, nonzero = 0, autoskip = 0, hextype = HEX_NORMAL;
   int capitalize = 0, decimal_offset = 0;
   int ebcdic = 0;
   int octspergrp = -1;	/* number of octets grouped in output */
@@ -540,11 +541,15 @@
 	  if (pp[2] && !STRNCMP("apitalize", pp + 2, 9))
 	    capitalize = 1;
 	  else if (pp[2] && STRNCMP("ols", pp + 2, 3))
-	    cols = (int)strtol(pp + 2, NULL, 0);
+	    {
+	      colsgiven = 1;
+	      cols = (int)strtol(pp + 2, NULL, 0);
+	    }
 	  else
 	    {
 	      if (!argv[2])
 		exit_with_usage();
+	      colsgiven = 1;
 	      cols = (int)strtol(argv[2], NULL, 0);
 	      argv++;
 	      argc--;
@@ -645,7 +650,7 @@
       argc--;
     }
 
-  if (!cols)
+  if (!colsgiven || (!cols && hextype != HEX_POSTSCRIPT))
     switch (hextype)
       {
       case HEX_POSTSCRIPT:	cols = 30; break;
@@ -667,7 +672,9 @@
       default:			octspergrp = 0; break;
       }
 
-  if (cols < 1 || ((hextype == HEX_NORMAL || hextype == HEX_BITS || hextype == HEX_LITTLEENDIAN)
+  if ((hextype == HEX_POSTSCRIPT && cols < 0) ||
+      (hextype != HEX_POSTSCRIPT && cols < 1) ||
+      ((hextype == HEX_NORMAL || hextype == HEX_BITS || hextype == HEX_LITTLEENDIAN)
 							    && (cols > COLS)))
     {
       fprintf(stderr, "%s: invalid number of columns (max. %d).\n", pname, COLS);
@@ -787,13 +794,13 @@
 	  putc_or_die(hexx[(e >> 4) & 0xf], fpo);
 	  putc_or_die(hexx[e & 0xf], fpo);
 	  n++;
-	  if (!--p)
+	  if (cols > 0 && !--p)
 	    {
 	      putc_or_die('\n', fpo);
 	      p = cols;
 	    }
 	}
-      if (p < cols)
+      if (cols == 0 || p < cols)
 	putc_or_die('\n', fpo);
       fclose_or_die(fp, fpo);
       return 0;