Move export code to export.c

1 files changed, 271 insertions, 0 deletions

diff --git a/export.c b/export.c
new file mode 100644
index 0000000..3e87521
--- /dev/null
+++ b/export.c
@@ -0,0 +1,271 @@
+/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "archive.h"
+#include "imap.h"
+
+static const char *uidPath(uint32_t uid, const char *type) {
+	static char buf[PATH_MAX];
+	snprintf(buf, sizeof(buf), "UID/%" PRIu32 ".%s", uid, type);
+	return buf;
+}
+
+static void flatten(struct List *flat, struct List nested) {
+	for (size_t i = 0; i < nested.len; ++i) {
+		if (nested.ptr[i].type == List) {
+			flatten(flat, nested.ptr[i].list);
+		} else {
+			listPush(flat, nested.ptr[i]);
+		}
+	}
+}
+
+enum Atom exportThreads(FILE *imap, struct List threads) {
+	struct List uids = {0};
+	flatten(&uids, threads);
+	for (size_t i = uids.len - 1; i < uids.len; --i) {
+		if (uids.ptr[i].type != Number) {
+			errx(EX_PROTOCOL, "invalid thread UID");
+		}
+		uint32_t uid = uids.ptr[i].number;
+		int error = 0;
+		if (!error) error = access(uidPath(uid, "atom"), F_OK);
+		if (!error) error = access(uidPath(uid, "html"), F_OK);
+		if (!error) error = access(uidPath(uid, "mbox"), F_OK);
+		if (!error) {
+			uids.ptr[i] = uids.ptr[--uids.len];
+		}
+	}
+	enum Atom tag = 0;
+	if (!uids.len) goto done;
+
+	tag = atom("exportThreads");
+	fprintf(imap, "%s UID FETCH ", Atoms[tag]);
+	for (size_t i = 0; i < uids.len; ++i) {
+		fprintf(imap, "%s%" PRIu32, (i ? "," : ""), uids.ptr[i].number);
+	}
+	fprintf(
+		imap,
+		" ("
+		"UID ENVELOPE "
+		"BODY[HEADER.FIELDS (" MBOX_HEADERS ")] BODY[TEXT]"
+		")\r\n"
+	);
+
+done:
+	listFree(uids);
+	return tag;
+}
+
+static struct Address parseAddress(struct List list) {
+	if (list.len < 4) {
+		errx(EX_PROTOCOL, "missing address structure fields");
+	}
+	struct Address addr = {0};
+	if (list.ptr[0].type == String) {
+		// TODO: Decode UTF-8 in name.
+		addr.name = strdup(list.ptr[0].string);
+		if (!addr.name) err(EX_OSERR, "strdup");
+	}
+	if (list.ptr[2].type == String) addr.mailbox = list.ptr[2].string;
+	if (list.ptr[3].type == String) addr.host = list.ptr[3].string;
+	return addr;
+}
+
+static struct AddressList parseAddressList(struct List list) {
+	struct Address *addrs = calloc(list.len, sizeof(*addrs));
+	if (!addrs) err(EX_OSERR, "calloc");
+	for (size_t i = 0; i < list.len; ++i) {
+		if (list.ptr[i].type != List) {
+			errx(EX_PROTOCOL, "invalid address field");
+		}
+		addrs[i] = parseAddress(list.ptr[i].list);
+	}
+	return (struct AddressList) { list.len, addrs };
+}
+
+static char *parseID(char *id) {
+	size_t len = strlen(id);
+	if (id[0] != '<' || !len || id[len - 1] != '>') {
+		errx(EX_PROTOCOL, "invalid message ID");
+	}
+	id[len - 1] = '\0';
+	return &id[1];
+}
+
+static struct Envelope parseEnvelope(struct List list) {
+	enum {
+		Date, Subject, From, Sender, ReplyTo,
+		To, Cc, Bcc, InReplyTo, MessageID,
+		EnvelopeLen,
+	};
+	if (list.len < EnvelopeLen) {
+		errx(EX_PROTOCOL, "missing envelope structure fields");
+	}
+	struct Envelope envelope = {0};
+
+	if (list.ptr[Date].type != String) {
+		errx(EX_PROTOCOL, "invalid envelope date field");
+	}
+	const char *date = list.ptr[Date].string;
+	date = strptime(date, "%a, %e %b %Y %H:%M:%S %z", &envelope.date);
+	if (!date) errx(EX_PROTOCOL, "invalid envelope date format");
+
+	envelope.date.tm_isdst = -1;
+	envelope.utc = mktime(&envelope.date);
+
+	if (list.ptr[Subject].type != String) {
+		errx(EX_PROTOCOL, "invalid envelope subject field");
+	}
+	// TODO: Decode UTF-8 in subject.
+	envelope.subject = strdup(list.ptr[Subject].string);
+	if (!envelope.subject) err(EX_OSERR, "strdup");
+
+	for (size_t i = From; i <= Bcc; ++i) {
+		if (list.ptr[i].type == List) continue;
+		if (list.ptr[i].type == Atom && list.ptr[i].atom == AtomNil) {
+			list.ptr[i].type = List;
+			list.ptr[i].list = (struct List) {0};
+			continue;
+		}
+		errx(EX_PROTOCOL, "invalid envelope address field");
+	}
+	for (size_t i = From; i <= ReplyTo; ++i) {
+		if (!list.ptr[i].list.len || list.ptr[i].list.ptr[0].type != List) {
+			errx(EX_PROTOCOL, "invalid envelope address field");
+		}
+	}
+	envelope.from = parseAddress(list.ptr[From].list.ptr[0].list);
+	envelope.sender = parseAddress(list.ptr[Sender].list.ptr[0].list);
+	envelope.replyTo = parseAddress(list.ptr[ReplyTo].list.ptr[0].list);
+	envelope.to = parseAddressList(list.ptr[To].list);
+	envelope.cc = parseAddressList(list.ptr[Cc].list);
+	envelope.bcc = parseAddressList(list.ptr[Bcc].list);
+
+	if (list.ptr[InReplyTo].type == String) {
+		envelope.inReplyTo = parseID(list.ptr[InReplyTo].string);
+	}
+	if (list.ptr[MessageID].type != String) {
+		errx(EX_PROTOCOL, "invalid envelope message-id field");
+	}
+	envelope.messageID = parseID(list.ptr[MessageID].string);
+
+	return envelope;
+}
+
+static enum Atom AtomBody;
+static enum Atom AtomEnvelope;
+static enum Atom AtomHeaderFields;
+static enum Atom AtomText;
+static enum Atom AtomUID;
+
+void exportData(struct List items) {
+	if (!AtomBody) AtomBody = atom("BODY");
+	if (!AtomEnvelope) AtomEnvelope = atom("ENVELOPE");
+	if (!AtomHeaderFields) AtomHeaderFields = atom("HEADER.FIELDS");
+	if (!AtomText) AtomText = atom("TEXT");
+	if (!AtomUID) AtomUID = atom("UID");
+
+	uint32_t uid = 0;
+	struct Envelope envelope = {0};
+	char *header = NULL;
+	char *body = NULL;
+
+	for (size_t i = 0; i + 1 < items.len; i += 2) {
+		enum Atom name;
+		if (items.ptr[i].type == Atom) {
+			name = items.ptr[i].atom;
+		} else if (
+			items.ptr[i].type == List &&
+			items.ptr[i].list.len &&
+			items.ptr[i].list.ptr[0].type == Atom
+		) {
+			name = items.ptr[i].list.ptr[0].atom;
+		} else {
+			errx(EX_PROTOCOL, "invalid data item name");
+		}
+
+		if (name == AtomBody) {
+			i--;
+			continue;
+		} else if (name == AtomUID) {
+			if (items.ptr[i + 1].type != Number) {
+				errx(EX_PROTOCOL, "invalid UID data item value");
+			}
+			uid = items.ptr[i + 1].number;
+		} else if (name == AtomEnvelope) {
+			if (items.ptr[i + 1].type != List) {
+				errx(EX_PROTOCOL, "invalid ENVELOPE data item value");
+			}
+			envelope = parseEnvelope(items.ptr[i + 1].list);
+		} else if (name == AtomHeaderFields) {
+			if (items.ptr[i + 1].type != String) {
+				errx(EX_PROTOCOL, "invalid BODY[HEADER.FIELDS] data item value");
+			}
+			header = items.ptr[i + 1].string;
+		} else if (name == AtomText) {
+			if (items.ptr[i + 1].type != String) {
+				errx(EX_PROTOCOL, "invalid BODY[TEXT] data item value");
+			}
+			body = items.ptr[i + 1].string;
+		}
+	}
+
+	if (!uid) errx(EX_PROTOCOL, "missing UID data item");
+	if (!envelope.subject) errx(EX_PROTOCOL, "missing ENVELOPE data item");
+	if (!header) errx(EX_PROTOCOL, "missing BODY[HEADER.FIELDS] data item");
+	if (!body) errx(EX_PROTOCOL, "missing BODY[TEXT] data item");
+
+	const char *path;
+	FILE *file;
+	int error;
+
+	path = uidPath(uid, "mbox");
+	file = fopen(path, "w");
+	if (!file) err(EX_CANTCREAT, "%s", path);
+	error = mboxFrom(file)
+		|| mboxHeader(file, header)
+		|| mboxBody(file, body)
+		|| fclose(file);
+	if (error) err(EX_IOERR, "%s", path);
+
+	path = uidPath(uid, "html");
+	file = fopen(path, "w");
+	if (!file) err(EX_CANTCREAT, "%s", path);
+	error = htmlEnvelope(file, &envelope)
+		|| fclose(file);
+	if (error) err(EX_IOERR, "%s", path);
+
+	path = uidPath(uid, "atom");
+	file = fopen(path, "w");
+	if (!file) err(EX_CANTCREAT, "%s", path);
+	error = atomEnvelope(file, &envelope)
+		|| fclose(file);
+	if (error) err(EX_IOERR, "%s", path);
+
+	envelopeFree(envelope);
+}