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	sfeed_json: add JSON output format tool - sfeed - RSS and Atom parser
	git clone git://git.codemadness.org/sfeed
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	---
	commit ced0dd7f8a01dedad3ba16c4cf209aea673c3e82
	parent 3f1d323497e5aefce65a3758d1bc408130d9bbe0
	Author: Hiltjo Posthuma <[email protected]>
	Date: Mon, 10 Apr 2023 17:03:57 +0200

	sfeed_json: add JSON output format tool

	This outputs the TSV data to JSON.

	It uses a subset of JSON Feed 1.1:

	https://www.jsonfeed.org/version/1.1/

	Diffstat:
	M Makefile \| 1 +
	M README \| 1 +
	A sfeed_json.1 \| 48 +++++++++++++++++++++++++++++…
	A sfeed_json.c \| 171 +++++++++++++++++++++++++++++…

	4 files changed, 221 insertions(+), 0 deletions(-)
	---
	diff --git a/Makefile b/Makefile
	@@ -51,6 +51,7 @@ BIN = \
	sfeed_frames\
	sfeed_gopher\
	sfeed_html\
	+ sfeed_json\
	sfeed_mbox\
	sfeed_opml_import\
	sfeed_plain\
	diff --git a/README b/README
	@@ -186,6 +186,7 @@ sfeed_curses - Format feed data (TSV) to a curses inte…
	sfeed_frames - Format feed data (TSV) to HTML file(s) with frames.
	sfeed_gopher - Format feed data (TSV) to Gopher files.
	sfeed_html - Format feed data (TSV) to HTML.
	+sfeed_json - Format feed data (TSV) to JSON Feed.
	sfeed_opml_export - Generate an OPML XML file from a sfeedrc config file.
	sfeed_opml_import - Generate a sfeedrc config file from an OPML XML file.
	sfeed_markread - Mark items as read/unread, for use with sfeed_curses.
	diff --git a/sfeed_json.1 b/sfeed_json.1
	@@ -0,0 +1,48 @@
	+.Dd March 8, 2023
	+.Dt SFEED_JSON 1
	+.Os
	+.Sh NAME
	+.Nm sfeed_json
	+.Nd format feed data to JSON Feed
	+.Sh SYNOPSIS
	+.Nm
	+.Op Ar
	+.Sh DESCRIPTION
	+.Nm
	+formats feed data (TSV) from
	+.Xr sfeed 1
	+from stdin or for each
	+.Ar file
	+to stdout as JSON Feed data.
	+If one or more
	+.Ar file
	+arguments are specified then the basename of the
	+.Ar file
	+is used as the feed name in the output.
	+If no
	+.Ar file
	+arguments are specified and so the data is read from stdin then the feed name
	+is empty.
	+If
	+.Nm
	+is reading from one or more
	+.Ar file
	+arguments it will prefix the entry title with "[feed name] ".
	+.Sh EXIT STATUS
	+.Ex -std
	+.Sh EXAMPLES
	+.Bd -literal
	+curl -s 'https://codemadness.org/atom.xml' \| sfeed \| sfeed_json
	+.Ed
	+.Sh SEE ALSO
	+.Xr sfeed 1 ,
	+.Xr sfeed_atom 1 ,
	+.Xr sfeed 5
	+.Sh STANDARDS
	+.Rs
	+.%T JSON Feed Version 1.1
	+.%U https://www.jsonfeed.org/version/1.1/
	+.%D Nov, 2022
	+.Re
	+.Sh AUTHORS
	+.An Hiltjo Posthuma Aq Mt [email protected]
	diff --git a/sfeed_json.c b/sfeed_json.c
	@@ -0,0 +1,171 @@
	+#include <stdio.h>
	+#include <stdlib.h>
	+#include <string.h>
	+#include <unistd.h>
	+
	+#include "util.h"
	+
	+static char *line;
	+static size_t linesize;
	+static int firstitem = 1;
	+
	+/* Unescape / decode fields printed by string_print_encoded() */
	+static void
	+printcontent(const char *s)
	+{
	+ for (; *s; s++) {
	+ switch (*s) {
	+ case '\\':
	+ s++;
	+ switch (*s) {
	+ case 'n': fputs("\\n", stdout); break;
	+ case '\\': fputs("\\\\", stdout); break;
	+ case 't': fputs("\\t", stdout); break;
	+ }
	+ break; /* ignore invalid escape sequence */
	+ case '"': fputs("\\\"", stdout); break;
	+ default:
	+ putchar(*s);
	+ break;
	+ }
	+ }
	+}
	+
	+static void
	+printfield(const char *s)
	+{
	+ for (; *s; s++) {
	+ if (*s == '\\')
	+ fputs("\\\\", stdout);
	+ else if (*s == '"')
	+ fputs("\\\"", stdout);
	+ else
	+ putchar(*s);
	+ }
	+}
	+
	+static void
	+printfeed(FILE fp, const char feedname)
	+{
	+ char *fields[FieldLast], timebuf[32];
	+ struct tm parsedtm, *tm;
	+ time_t parsedtime;
	+ ssize_t linelen;
	+ int ch;
	+ char p, s;
	+
	+ while ((linelen = getline(&line, &linesize, fp)) > 0 &&
	+ !ferror(stdout)) {
	+ if (line[linelen - 1] == '\n')
	+ line[--linelen] = '\0';
	+ parseline(line, fields);
	+
	+ if (!firstitem)
	+ fputs(",\n", stdout);
	+ firstitem = 0;
	+
	+ fputs("{\n\t\"id\": \"", stdout);
	+ printfield(fields[FieldId]);
	+ fputs("\"", stdout);
	+
	+ parsedtime = 0;
	+ if (!strtotime(fields[FieldUnixTimestamp], &parsedtime) &&
	+ (tm = gmtime_r(&parsedtime, &parsedtm)) &&
	+ strftime(timebuf, sizeof(timebuf), "%Y-%m-%dT%H:%M:%SZ", t…
	+ fputs(",\n\t\"date_published\": \"", stdout);
	+ fputs(timebuf, stdout);
	+ fputs("\"", stdout);
	+ }
	+
	+ fputs(",\n\t\"title\": \"", stdout);
	+ if (feedname[0]) {
	+ fputs("[", stdout);
	+ printfield(feedname);
	+ fputs("] ", stdout);
	+ }
	+ printfield(fields[FieldTitle]);
	+ fputs("\"", stdout);
	+
	+ if (fields[FieldLink][0]) {
	+ fputs(",\n\t\"url\": \"", stdout);
	+ printfield(fields[FieldLink]);
	+ fputs("\"", stdout);
	+ }
	+
	+ if (fields[FieldAuthor][0]) {
	+ fputs(",\n\t\"authors\": [{\"name\": \"", stdout);
	+ printfield(fields[FieldAuthor]);
	+ fputs("\"}]", stdout);
	+ }
	+
	+ if (fields[FieldCategory][0]) {
	+ fputs(",\n\t\"tags\": [", stdout);
	+
	+ for (p = s = fields[FieldCategory]; ; s++) {
	+ if (s == '\|' \|\| s == '\0') {
	+ if (p != fields[FieldCategory])
	+ fputs(", ", stdout);
	+ ch = *s;
	+ s = '\0'; / temporary NUL terminate …
	+ fputs("\"", stdout);
	+ printfield(p);
	+ fputs("\"", stdout);
	+ s = ch; / restore */
	+ p = s + 1;
	+ }
	+ if (*s == '\0')
	+ break;
	+ }
	+ fputs("]", stdout);
	+ }
	+
	+ if (fields[FieldEnclosure][0]) {
	+ fputs(",\n\t\"attachments\": [{\"url:\": \"", stdout);
	+ printfield(fields[FieldEnclosure]);
	+ fputs("\"}]", stdout);
	+ }
	+
	+ if (!strcmp(fields[FieldContentType], "html"))
	+ fputs(",\n\t\"content_html\": \"", stdout);
	+ else
	+ fputs(",\n\t\"content_text\": \"", stdout);
	+ printcontent(fields[FieldContent]);
	+ fputs("\"\n}", stdout);
	+ }
	+}
	+
	+int
	+main(int argc, char *argv[])
	+{
	+ FILE *fp;
	+ char *name;
	+ int i;
	+
	+ if (pledge(argc == 1 ? "stdio" : "stdio rpath", NULL) == -1)
	+ err(1, "pledge");
	+
	+ fputs("{\n"
	+ "\"version\": \"https://jsonfeed.org/version/1.1\",\n"
	+ "\"title\": \"Newsfeed\",\n"
	+ "\"items\": [\n", stdout);
	+
	+ if (argc == 1) {
	+ printfeed(stdin, "");
	+ checkfileerror(stdin, "<stdin>", 'r');
	+ } else {
	+ for (i = 1; i < argc; i++) {
	+ if (!(fp = fopen(argv[i], "r")))
	+ err(1, "fopen: %s", argv[i]);
	+ name = ((name = strrchr(argv[i], '/'))) ? name + 1 : a…
	+ printfeed(fp, name);
	+ checkfileerror(fp, argv[i], 'r');
	+ checkfileerror(stdout, "<stdout>", 'w');
	+ fclose(fp);
	+ }
	+ }
	+ fputs("]\n}\n", stdout);
	+
	+ checkfileerror(stdout, "<stdout>", 'w');
	+
	+ return 0;
	+}