Add -0 / --nul-output option for processing values containing newlines

Closes: #1271

docs/content/manual/manual.yml

@@ -199,6 +199,11 @@ sections:
 
         Like `-r` but jq won't print a newline after each output.
 
+      * `--nul-output` / `-0`:
+
+        Like `-r` but jq will print NUL instead of newline after each output.
+        This can be useful when the values being output can contain newlines.
+
       * `-f filename` / `--from-file filename`:
 
         Read filter from the file rather than from a command line, like

src/main.c

@@ -130,6 +130,7 @@ enum {
   RAW_INPUT             = 2,
   PROVIDE_NULL          = 4,
   RAW_OUTPUT            = 8,
+  RAW_NUL               = 16,
   ASCII_OUTPUT          = 32,
   COLOR_OUTPUT          = 64,
   NO_COLOR_OUTPUT       = 128,
@@ -196,6 +197,8 @@ static int process(jq_state *jq, jv value, int flags, int dumpopts) {
     }
     if (!(options & RAW_NO_LF))
       priv_fwrite("\n", 1, stdout, dumpopts & JV_PRINT_ISATTY);
+    if (options & RAW_NUL)
+      priv_fwrite("\0", 1, stdout, dumpopts & JV_PRINT_ISATTY);
     if (options & UNBUFFERED_OUTPUT)
       fflush(stdout);
   }
@@ -394,6 +397,10 @@ int main(int argc, char* argv[]) {
         options |= RAW_OUTPUT | RAW_NO_LF;
         if (!short_opts) continue;
       }
+      if (isoption(argv[i], '0', "nul-output", &short_opts)) {
+        options |= RAW_OUTPUT | RAW_NO_LF | RAW_NUL;
+        if (!short_opts) continue;
+      }
       if (isoption(argv[i], 'b', "binary", &short_opts)) {
 #ifdef WIN32
         fflush(stdout);