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From: Georges Khaznadar <georgesk@debian.org>
Date: Wed, 22 Nov 2023 17:10:27 +0100
Subject: Wrap long lines
To avoid loosing cronjob mails with a "line too long" error
(exim4, for example) cron will wrap very long lines. The default encoding is
set to QUOTED-PRINTABLE
A new test is provided for autopkgtests
Contributed by Frank Heckenbach <f.heckenbach@fh-soft.de>
Bug-Debian: https://bugs.debian.org/777584
Forwarded: no
Last-Update: 2023-11-22
---
config.h | 17 +++++++++++++++++
do_command.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 65 insertions(+), 5 deletions(-)
diff --git a/config.h b/config.h
index b7f4340..dd1a495 100644
--- a/config.h
+++ b/config.h
@@ -70,6 +70,23 @@
* generate the Date: header.
*/
+ /* Content-Transfer-Encoding used in mail sent
+ * if CONTENT_TRANSFER_ENCODING is not set.
+ *
+ * "8bit", the previous default, does not do
+ * any encoding and will fail with long lines
+ * (> 998 characters according to RFC 5322).
+ *
+ * "auto" means some suitable encoding (currently
+ * quoted-printable) which cron will do internally.
+ *
+ * In contrast, setting this define or
+ * CONTENT_TRANSFER_ENCODING to quoted-printable means
+ * the command output must be encoded already.
+ */
+/*#define DEFAULT_CONTENT_TRANSFER_ENCODING "8bit" /*-*/
+#define DEFAULT_CONTENT_TRANSFER_ENCODING "auto" /*-*/
+
/* if ALLOW_FILE and DENY_FILE are not defined or are
* defined but neither exists, should crontab(1) be
* usable only by root?
diff --git a/do_command.c b/do_command.c
index 43054ee..eb70b8a 100644
--- a/do_command.c
+++ b/do_command.c
@@ -543,6 +543,7 @@ child_process(e, u)
auto char hostname[MAXHOSTNAMELEN];
char *content_type = env_get("CONTENT_TYPE",jobenv),
*content_transfer_encoding = env_get("CONTENT_TRANSFER_ENCODING",jobenv);
+ int encoding_auto = 0;
(void) gethostname(hostname, MAXHOSTNAMELEN);
(void) snprintf(mailcmd, sizeof(mailcmd),
@@ -590,12 +591,13 @@ child_process(e, u)
(nl < (content_transfer_encoding+ctlen))) {
*nl = ' ';
}
-
- fprintf(mail,"Content-Transfer-Encoding: %s\n",
- content_transfer_encoding);
} else {
- fprintf(mail,"Content-Transfer-Encoding: 8bit\n");
+ content_transfer_encoding = DEFAULT_CONTENT_TRANSFER_ENCODING;
}
+ encoding_auto = strcmp (content_transfer_encoding,"auto") == 0;
+ fprintf(mail,"Content-Transfer-Encoding: %s\n",
+ encoding_auto ? "quoted-printable"
+ : content_transfer_encoding);
for (env = e->envp; *env; env++)
fprintf(mail, "X-Cron-Env: <%s>\n",
@@ -606,12 +608,53 @@ child_process(e, u)
char buf[4096];
int ret, remain;
+ /* A QP character results in 3 characters. Inserted soft line breaks
+ * may need a bit more. 4 is more than enough over the whole buffer.
+ */
+ char buf_encoded[4 * sizeof(buf)];
+ char *buf_out = buf;
+ int qp_line_length = 0;
while(1) {
if ((ret = fread(buf, 1, sizeof(buf), tmpout)) == 0)
break;
+
+ if (encoding_auto) {
+ // Quoted-printable encoding according to RFC 2045, 6.7
+ char *in, *out = buf_encoded;
+ for (in = buf; in < buf + ret; in++) {
+ // maximum output line width is 76 characters
+ if (qp_line_length > 72) {
+ *out++ = '=';
+ *out++ = '\n';
+ qp_line_length = 0;
+ }
+ if (*in == '\n') {
+ // encoded lines may not end with SPACE or TAB
+ if (out > buf_encoded
+ && (out[-1] == ' ' || out[-1] == '\t')) {
+ *out++ = '=';
+ *out++ = '\n';
+ }
+ *out++ = *in;
+ qp_line_length = 0;
+ } else if ((*in >= 33 && *in <= 126 && *in != '=')
+ || ((*in == ' ' || *in == '\t')
+ && in + 1 < buf + ret)) {
+ *out++ = *in;
+ qp_line_length++;
+ } else {
+ int r = sprintf(out, "=%02X", (unsigned char)*in);
+ out += r;
+ qp_line_length += r;
+ }
+ }
+ buf_out = buf_encoded;
+ ret = out - buf_encoded;
+ }
+
for (remain = ret; remain != 0; ) {
- ret = fwrite(buf, 1, remain, mail);
+ ret = fwrite(buf_out, 1, remain, mail);
if (ret > 0) {
remain -= ret;
bytes += ret;
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