sfeed

commit ced0dd7f8a01dedad3ba16c4cf209aea673c3e82
parent 3f1d323497e5aefce65a3758d1bc408130d9bbe0
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
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 interface.
 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 hiltjo@codemadness.org
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", tm)) {
+			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 : argv[i];
+			printfeed(fp, name);
+			checkfileerror(fp, argv[i], 'r');
+			checkfileerror(stdout, "<stdout>", 'w');
+			fclose(fp);
+		}
+	}
+	fputs("]\n}\n", stdout);
+
+	checkfileerror(stdout, "<stdout>", 'w');
+
+	return 0;
+}