97d21c886d
Some Exchange systems wrap lines over 75 characters long while converting messages to quoted-printable, preventing ctm_rmail from reassembling emailed deltas. For a negligible loss of encoding efficiency, this change allows ctm deltas to once more pass through Exchange undamaged.
498 lines
12 KiB
C
498 lines
12 KiB
C
/*
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* Send a compressed CTM delta to a recipient mailing list by encoding it
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* in safe ASCII characters, in mailer-friendly chunks, and passing them
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* to sendmail. Optionally, the chunks can be queued to be sent later by
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* ctm_dequeue in controlled bursts. The encoding is almost the same as
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* MIME BASE64, and is protected by a simple checksum.
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*
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* Author: Stephen McKay
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*
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* NOTICE: This is free software. I hope you get some use from this program.
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* In return you should think about all the nice people who give away software.
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* Maybe you should write some free software too.
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*
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* $FreeBSD$
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <paths.h>
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#include <limits.h>
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#include "error.h"
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#include "options.h"
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#define DEF_MAX_MSG 64000 /* Default maximum mail msg minus headers. */
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#define LINE_LENGTH 72 /* Chars per encoded line. Divisible by 4. */
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int chop_and_send_or_queue(FILE *dfp, char *delta, off_t ctm_size,
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long max_msg_size, char *mail_alias, char *queue_dir);
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int chop_and_send(FILE *dfp, char *delta, long msg_size, int npieces,
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char *mail_alias);
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int chop_and_queue(FILE *dfp, char *delta, long msg_size, int npieces,
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char *mail_alias, char *queue_dir);
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void clean_up_queue(char *queue_dir);
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int encode_body(FILE *sm_fp, FILE *delta_fp, long msg_size, unsigned *sum);
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void write_header(FILE *sfp, char *mail_alias, char *delta, int pce,
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int npieces);
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void write_trailer(FILE *sfp, unsigned sum);
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int apologise(char *delta, off_t ctm_size, long max_ctm_size,
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char *mail_alias, char *queue_dir);
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FILE *open_sendmail(void);
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int close_sendmail(FILE *fp);
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int
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main(int argc, char **argv)
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{
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int status = 0;
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char *delta_file;
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char *mail_alias;
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long max_msg_size = DEF_MAX_MSG;
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long max_ctm_size = 0;
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char *log_file = NULL;
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char *queue_dir = NULL;
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char *delta;
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FILE *dfp;
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struct stat sb;
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err_prog_name(argv[0]);
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OPTIONS("[-l log] [-m maxmsgsize] [-c maxctmsize] [-q queuedir] ctm-delta mail-alias")
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NUMBER('m', max_msg_size)
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NUMBER('c', max_ctm_size)
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STRING('l', log_file)
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STRING('q', queue_dir)
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ENDOPTS
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if (argc != 3)
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usage();
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if (log_file != NULL)
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err_set_log(log_file);
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delta_file = argv[1];
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mail_alias = argv[2];
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if ((delta = strrchr(delta_file, '/')) == NULL)
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delta = delta_file;
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else
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delta++;
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if ((dfp = fopen(delta_file, "r")) == NULL || fstat(fileno(dfp), &sb) < 0)
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{
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err("*%s", delta_file);
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exit(1);
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}
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if (max_ctm_size != 0 && sb.st_size > max_ctm_size)
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status = apologise(delta, sb.st_size, max_ctm_size, mail_alias,
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queue_dir);
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else
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status = chop_and_send_or_queue(dfp, delta, sb.st_size, max_msg_size,
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mail_alias, queue_dir);
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fclose(dfp);
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return status;
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}
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/*
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* Carve our CTM delta into pieces, encode them, and send or queue them.
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* Returns 0 on success, and 1 on failure.
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*/
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int
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chop_and_send_or_queue(FILE *dfp, char *delta, off_t ctm_size,
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long max_msg_size, char *mail_alias, char *queue_dir)
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{
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int npieces;
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long msg_size;
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long exp_size;
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int status;
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#undef howmany
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#define howmany(x,y) (((x)+((y)-1)) / (y))
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/*
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* Work out how many pieces we need, bearing in mind that each piece
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* grows by 4/3 when encoded. We count the newlines too, but ignore
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* all mail headers and piece headers. They are a "small" (almost
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* constant) per message overhead that we make the user worry about. :-)
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*/
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exp_size = ctm_size * 4 / 3;
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exp_size += howmany(exp_size, LINE_LENGTH);
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npieces = howmany(exp_size, max_msg_size);
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msg_size = howmany(ctm_size, npieces);
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#undef howmany
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if (queue_dir == NULL)
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status = chop_and_send(dfp, delta, msg_size, npieces, mail_alias);
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else
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{
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status = chop_and_queue(dfp, delta, msg_size, npieces, mail_alias,
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queue_dir);
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if (status)
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clean_up_queue(queue_dir);
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}
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return status;
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}
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/*
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* Carve our CTM delta into pieces, encode them, and send them.
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* Returns 0 on success, and 1 on failure.
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*/
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int
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chop_and_send(FILE *dfp, char *delta, long msg_size, int npieces,
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char *mail_alias)
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{
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int pce;
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FILE *sfp;
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unsigned sum;
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/*
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* Send each chunk directly to sendmail as it is generated.
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* No temporary files necessary. If things turn ugly, we just
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* have to live with the fact the we have sent only part of
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* the delta.
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*/
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for (pce = 1; pce <= npieces; pce++)
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{
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int read_error;
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if ((sfp = open_sendmail()) == NULL)
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return 1;
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write_header(sfp, mail_alias, delta, pce, npieces);
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read_error = encode_body(sfp, dfp, msg_size, &sum);
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if (!read_error)
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write_trailer(sfp, sum);
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if (!close_sendmail(sfp) || read_error)
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return 1;
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err("%s %d/%d sent to %s", delta, pce, npieces, mail_alias);
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}
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return 0;
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}
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/*
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* Construct the tmp queue file name of a delta piece.
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*/
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#define mk_tmp_name(fn,qd,p) \
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sprintf((fn), "%s/.%08ld.%03d", (qd), (long)getpid(), (p))
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/*
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* Construct the final queue file name of a delta piece.
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*/
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#define mk_queue_name(fn,qd,d,p,n) \
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sprintf((fn), "%s/%s+%03d-%03d", (qd), (d), (p), (n))
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/*
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* Carve our CTM delta into pieces, encode them, and queue them.
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* Returns 0 on success, and 1 on failure.
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*/
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int
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chop_and_queue(FILE *dfp, char *delta, long msg_size, int npieces,
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char *mail_alias, char *queue_dir)
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{
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int pce;
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FILE *qfp;
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unsigned sum;
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char tname[PATH_MAX];
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char qname[PATH_MAX];
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/*
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* Store each piece in the queue directory, but under temporary names,
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* so that they can be deleted without unpleasant consequences if
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* anything goes wrong. We could easily fill up a disk, for example.
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*/
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for (pce = 1; pce <= npieces; pce++)
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{
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int write_error;
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mk_tmp_name(tname, queue_dir, pce);
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if ((qfp = fopen(tname, "w")) == NULL)
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{
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err("cannot open '%s' for writing", tname);
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return 1;
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}
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write_header(qfp, mail_alias, delta, pce, npieces);
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if (encode_body(qfp, dfp, msg_size, &sum))
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return 1;
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write_trailer(qfp, sum);
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fflush(qfp);
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write_error = ferror(qfp);
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fclose(qfp);
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if (write_error)
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{
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err("error writing '%s'", tname);
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return 1;
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}
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/*
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* Give the warm success message now, instead of all in a rush
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* during the rename phase.
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*/
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err("%s %d/%d queued for %s", delta, pce, npieces, mail_alias);
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}
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/*
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* Rename the pieces into place. If an error occurs now, we are
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* stuffed, but there is no neat way to back out. rename() should
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* only fail now under extreme circumstances.
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*/
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for (pce = 1; pce <= npieces; pce++)
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{
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mk_tmp_name(tname, queue_dir, pce);
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mk_queue_name(qname, queue_dir, delta, pce, npieces);
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if (rename(tname, qname) < 0)
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{
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err("*rename: '%s' to '%s'", tname, qname);
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unlink(tname);
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}
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}
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return 0;
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}
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/*
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* There may be temporary files cluttering up the queue directory.
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*/
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void
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clean_up_queue(char *queue_dir)
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{
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int pce;
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char tname[PATH_MAX];
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err("discarding queued delta pieces");
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for (pce = 1; ; pce++)
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{
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mk_tmp_name(tname, queue_dir, pce);
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if (unlink(tname) < 0)
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break;
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}
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}
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/*
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* MIME BASE64 encode table.
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*/
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static char to_b64[0x40] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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/*
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* This cheap plastic checksum effectively rotates our checksum-so-far
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* left one, then adds the character. We only want 16 bits of it, and
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* don't care what happens to the rest. It ain't much, but it's small.
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*/
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#define add_ck(sum,x) \
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((sum) += ((x)&0xff) + (sum) + (((sum)&0x8000) ? 1 : 0))
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/*
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* Encode the body. Use an encoding almost the same as MIME BASE64.
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*
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* Characters are read from delta_fp and encoded characters are written
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* to sm_fp. At most 'msg_size' characters should be read from delta_fp.
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*
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* The body consists of lines of up to LINE_LENGTH characters. Each group
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* of 4 characters encodes 3 input characters. Each output character encodes
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* 6 bits. Thus 64 different characters are needed in this representation.
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*/
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int
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encode_body(FILE *sm_fp, FILE *delta_fp, long msg_size, unsigned *sum)
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{
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unsigned short cksum = 0xffff;
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unsigned char *ip;
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char *op;
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int want, n, i;
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unsigned char inbuf[LINE_LENGTH*3/4];
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char outbuf[LINE_LENGTH+1];
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/*
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* Round up to the nearest line boundary, for the tiniest of gains,
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* and lots of neatness. :-)
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*/
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msg_size += (LINE_LENGTH*3/4) - 1;
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msg_size -= msg_size % (LINE_LENGTH*3/4);
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while (msg_size > 0)
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{
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want = (msg_size < sizeof(inbuf)) ? msg_size : sizeof(inbuf);
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if ((n = fread(inbuf, sizeof(char), want, delta_fp)) == 0)
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break;
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msg_size -= n;
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for (i = 0; i < n; i++)
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add_ck(cksum, inbuf[i]);
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/*
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* Produce a line of encoded data. Every line length will be a
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* multiple of 4, except for, perhaps, the last line.
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*/
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ip = inbuf;
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op = outbuf;
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while (n >= 3)
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{
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*op++ = to_b64[ip[0] >> 2];
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*op++ = to_b64[(ip[0] << 4 & 0x3f) | ip[1] >> 4];
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*op++ = to_b64[(ip[1] << 2 & 0x3f) | ip[2] >> 6];
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*op++ = to_b64[ip[2] & 0x3f];
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ip += 3;
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n -= 3;
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}
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if (n > 0)
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{
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*op++ = to_b64[ip[0] >> 2];
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*op++ = to_b64[(ip[0] << 4 & 0x3f) | ip[1] >> 4];
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if (n >= 2)
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*op++ = to_b64[ip[1] << 2 & 0x3f];
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}
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*op++ = '\n';
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fwrite(outbuf, sizeof(char), op - outbuf, sm_fp);
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}
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if (ferror(delta_fp))
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{
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err("error reading input file.");
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return 1;
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}
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*sum = cksum;
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return 0;
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}
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/*
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* Write the mail header and data header.
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*/
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void
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write_header(FILE *sfp, char *mail_alias, char *delta, int pce, int npieces)
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{
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fprintf(sfp, "From: owner-%s\n", mail_alias);
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fprintf(sfp, "To: %s\n", mail_alias);
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fprintf(sfp, "Subject: ctm-mail %s %d/%d\n\n", delta, pce, npieces);
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fprintf(sfp, "CTM_MAIL BEGIN %s %d %d\n", delta, pce, npieces);
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}
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/*
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* Write the data trailer.
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*/
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void
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write_trailer(FILE *sfp, unsigned sum)
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{
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fprintf(sfp, "CTM_MAIL END %ld\n", (long)sum);
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}
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/*
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* We're terribly sorry, but the delta is too big to send.
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* Returns 0 on success, 1 on failure.
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*/
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int
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apologise(char *delta, off_t ctm_size, long max_ctm_size, char *mail_alias,
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char *queue_dir)
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{
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FILE *sfp;
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char qname[PATH_MAX];
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if (queue_dir == NULL)
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{
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sfp = open_sendmail();
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if (sfp == NULL)
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return 1;
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}
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else
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{
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mk_queue_name(qname, queue_dir, delta, 1, 1);
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sfp = fopen(qname, "w");
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if (sfp == NULL)
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{
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err("cannot open '%s' for writing", qname);
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return 1;
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}
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}
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fprintf(sfp, "From: owner-%s\n", mail_alias);
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fprintf(sfp, "To: %s\n", mail_alias);
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fprintf(sfp, "Subject: ctm-notice %s\n\n", delta);
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fprintf(sfp, "%s is %ld bytes. The limit is %ld bytes.\n\n", delta,
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(long)ctm_size, max_ctm_size);
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fprintf(sfp, "You can retrieve this delta via ftp.\n");
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if (queue_dir == NULL)
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{
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if (!close_sendmail(sfp))
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return 1;
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}
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else
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{
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if (fclose(sfp)!=0)
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{
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err("error writing '%s'", qname);
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unlink(qname);
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return 1;
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}
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}
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return 0;
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}
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/*
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* Start a pipe to sendmail. Sendmail will decode the destination
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* from the message contents.
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*/
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FILE *
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open_sendmail()
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{
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FILE *fp;
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char buf[100];
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sprintf(buf, "%s -odq -t", _PATH_SENDMAIL);
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if ((fp = popen(buf, "w")) == NULL)
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err("cannot start sendmail");
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return fp;
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}
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/*
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* Close a pipe to sendmail. Sendmail will then do its bit.
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* Return 1 on success, 0 on failure.
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*/
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int
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close_sendmail(FILE *fp)
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{
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int status;
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fflush(fp);
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if (ferror(fp))
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{
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err("error writing to sendmail");
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return 0;
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}
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if ((status = pclose(fp)) != 0)
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err("sendmail failed with status %d", status);
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return (status == 0);
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}
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