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gnupg/common/ksba-io-support.c
Werner Koch 2a13f7f9dc
gpgsm: Strip trailing zeroes from detached signatures. 
* common/ksba-io-support.c: Include tlv.h
(struct reader_cb_parm_s): Add new fields.
(starts_with_sequence): New.
(simple_reader_cb): Handle stripping.
* common/ksba-io-support.h (GNUPG_KSBA_IO_STRIP): New.
(gnupg_ksba_create_reader): Handle the new flag.
* sm/verify.c (gpgsm_verify): Use the new flag for detached
signatures.
--

Note that this works only if --assume-binary is given.  The use case
for the feature is PDF signature checking where the PDF specs require
that the detached signature is padded with zeroes.
2023-03-08 11:00:00 +01:00

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/* kska-io-support.c - Supporting functions for ksba reader and writer
* Copyright (C) 2001-2005, 2007, 2010-2011, 2017 Werner Koch
* Copyright (C) 2006 g10 Code GmbH
*
* This file is part of GnuPG.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of either
*
* - the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* or
*
* - the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* or both in parallel, as here.
*
* This file 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 <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include <ksba.h>
#include "util.h"
#include "i18n.h"
#include "tlv.h"
#include "ksba-io-support.h"
#ifdef HAVE_DOSISH_SYSTEM
#define LF "\r\n"
#else
#define LF "\n"
#endif
/* Data used by the reader callbacks. */
struct reader_cb_parm_s
{
estream_t fp;
unsigned char line[1024];
int linelen;
int readpos;
int have_lf;
unsigned long line_counter;
int allow_multi_pem; /* Allow processing of multiple PEM objects. */
int autodetect; /* Try to detect the input encoding. */
int assume_pem; /* Assume input encoding is PEM. */
int assume_base64; /* Assume input is base64 encoded. */
int strip_zeroes; /* Expect a SEQUENCE followed by zero padding. */
/* 1 = check state; 2 = reading; 3 = checking */
/* for zeroes. */
int use_maxread; /* If true read not more than MAXREAD. */
unsigned int maxread; /* # of bytes left to read. */
off_t nzeroes; /* Number of padding zeroes red. */
int identified;
int is_pem;
int is_base64;
int stop_seen;
int might_be_smime;
int eof_seen;
struct {
int idx;
unsigned char val;
int stop_seen;
} base64;
};
/* Data used by the writer callbacks. */
struct writer_cb_parm_s
{
estream_t stream; /* Output stream. */
char *pem_name; /* Malloced. */
int wrote_begin;
int did_finish;
struct {
int idx;
int quad_count;
unsigned char radbuf[4];
} base64;
};
/* Context for this module's functions. */
struct gnupg_ksba_io_s {
union {
struct reader_cb_parm_s rparm;
struct writer_cb_parm_s wparm;
} u;
union {
ksba_reader_t reader;
ksba_writer_t writer;
} u2;
};
/* The base-64 character list */
static char bintoasc[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
/* The reverse base-64 list */
static unsigned char asctobin[256] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12,
0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24,
0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff
};
static int
has_only_base64 (const unsigned char *line, int linelen)
{
if (linelen < 20)
return 0;
for (; linelen; line++, linelen--)
{
if (*line == '\n' || (linelen > 1 && *line == '\r' && line[1] == '\n'))
break;
if ( !strchr (bintoasc, *line) )
return 0;
}
return 1; /* yes */
}
static int
is_empty_line (const unsigned char *line, int linelen)
{
if (linelen >= 2 && *line == '\r' && line[1] == '\n')
return 1;
if (linelen >= 1 && *line == '\n')
return 1;
return 0;
}
static int
base64_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread)
{
struct reader_cb_parm_s *parm = cb_value;
size_t n;
int c, c2;
*nread = 0;
if (!buffer)
return -1; /* not supported */
next:
if (!parm->linelen)
{
/* read an entire line or up to the size of the buffer */
parm->line_counter++;
parm->have_lf = 0;
for (n=0; n < DIM(parm->line);)
{
c = es_getc (parm->fp);
if (c == EOF)
{
parm->eof_seen = 1;
if (es_ferror (parm->fp))
return -1;
break;
}
parm->line[n++] = c;
if (c == '\n')
{
parm->have_lf = 1;
/* Fixme: we need to skip overlong lines while detecting
the dashed lines */
break;
}
}
parm->linelen = n;
if (!n)
return -1; /* eof */
parm->readpos = 0;
}
if (!parm->identified)
{
if (!parm->autodetect)
{
if (parm->assume_pem)
{
/* wait for the header line */
parm->linelen = parm->readpos = 0;
if (!parm->have_lf
|| strncmp ((char*)parm->line, "-----BEGIN ", 11)
|| !strncmp ((char*)parm->line+11, "PGP ", 4))
goto next;
parm->is_pem = 1;
}
else if (parm->assume_base64)
parm->is_base64 = 1;
}
else if (parm->line_counter == 1 && !parm->have_lf)
{
/* first line too long - assume DER encoding */
parm->is_pem = 0;
}
else if (parm->line_counter == 1 && parm->linelen && *parm->line == 0x30)
{
/* the very first byte does pretty much look like a SEQUENCE tag*/
parm->is_pem = 0;
}
else if ( parm->have_lf
&& !strncmp ((char*)parm->line, "-----BEGIN ", 11)
&& strncmp ((char *)parm->line+11, "PGP ", 4) )
{
/* Fixme: we must only compare if the line really starts at
the beginning */
parm->is_pem = 1;
parm->linelen = parm->readpos = 0;
}
else if ( parm->have_lf && parm->line_counter == 1
&& parm->linelen >= 13
&& !ascii_memcasecmp (parm->line, "Content-Type:", 13))
{ /* might be a S/MIME body */
parm->might_be_smime = 1;
parm->linelen = parm->readpos = 0;
goto next;
}
else if (parm->might_be_smime == 1
&& is_empty_line (parm->line, parm->linelen))
{
parm->might_be_smime = 2;
parm->linelen = parm->readpos = 0;
goto next;
}
else if (parm->might_be_smime == 2)
{
parm->might_be_smime = 0;
if ( !has_only_base64 (parm->line, parm->linelen))
{
parm->linelen = parm->readpos = 0;
goto next;
}
parm->is_pem = 1;
}
else
{
parm->linelen = parm->readpos = 0;
goto next;
}
parm->identified = 1;
parm->base64.stop_seen = 0;
parm->base64.idx = 0;
}
n = 0;
if (parm->is_pem || parm->is_base64)
{
if (parm->is_pem && parm->have_lf
&& !strncmp ((char*)parm->line, "-----END ", 9))
{
parm->identified = 0;
parm->linelen = parm->readpos = 0;
/* If the caller want to read multiple PEM objects from one
file, we have to reset our internal state and return a
EOF immediately. The caller is the expected to use
ksba_reader_clear to clear the EOF condition and continue
to read. If we don't want to do that we just return 0
bytes which will force the ksba_reader to skip until
EOF. */
if (parm->allow_multi_pem)
{
parm->identified = 0;
parm->autodetect = 0;
parm->assume_pem = 1;
parm->stop_seen = 0;
return -1; /* Send EOF now. */
}
}
else if (parm->stop_seen)
{ /* skip the rest of the line */
parm->linelen = parm->readpos = 0;
}
else
{
int idx = parm->base64.idx;
unsigned char val = parm->base64.val;
while (n < count && parm->readpos < parm->linelen )
{
c = parm->line[parm->readpos++];
if (c == '\n' || c == ' ' || c == '\r' || c == '\t')
continue;
if ((c = asctobin[(c2=c)]) == 255)
{
if (c2 == '=')
{ /* pad character: stop */
if (idx == 1)
buffer[n++] = val;
parm->stop_seen = 1;
break;
}
else if (c2 == '-'
&& parm->readpos == 1
&& parm->readpos-1+9 < parm->linelen
&& !strncmp ((char*)parm->line + parm->readpos-1,
"-----END ", 9))
{ /* END line seen (padding was not needed). */
parm->stop_seen = 1;
break;
}
log_error (_("invalid radix64 character %02x skipped\n"),
c2);
continue;
}
switch (idx)
{
case 0:
val = c << 2;
break;
case 1:
val |= (c>>4)&3;
buffer[n++] = val;
val = (c<<4)&0xf0;
break;
case 2:
val |= (c>>2)&15;
buffer[n++] = val;
val = (c<<6)&0xc0;
break;
case 3:
val |= c&0x3f;
buffer[n++] = val;
break;
}
idx = (idx+1) % 4;
}
if (parm->readpos == parm->linelen)
parm->linelen = parm->readpos = 0;
parm->base64.idx = idx;
parm->base64.val = val;
}
}
else
{ /* DER encoded */
while (n < count && parm->readpos < parm->linelen)
buffer[n++] = parm->line[parm->readpos++];
if (parm->readpos == parm->linelen)
parm->linelen = parm->readpos = 0;
}
*nread = n;
return 0;
}
/* Read up to 10 bytes to test whether the data consist of a sequence;
* if that is true, set the limited flag and record the length of the
* entire sequence in PARM. Unget everything then. Return true if we
* have a sequence with a fixed length. */
static int
starts_with_sequence (struct reader_cb_parm_s *parm)
{
gpg_error_t err;
unsigned char peekbuf[10];
int npeeked, c;
int found = 0;
const unsigned char *p;
size_t n, objlen, hdrlen;
int class, tag, constructed, ndef;
for (npeeked=0; npeeked < sizeof peekbuf; npeeked++)
{
c = es_getc (parm->fp);
if (c == EOF)
goto leave;
peekbuf[npeeked] = c;
}
/* Enough to check for a sequence. */
p = peekbuf;
n = npeeked;
err = parse_ber_header (&p, &n, &class, &tag, &constructed,
&ndef, &objlen, &hdrlen);
if (err)
{
log_debug ("%s: error parsing data: %s\n", __func__, gpg_strerror (err));
goto leave;
}
if (class == CLASS_UNIVERSAL && constructed && tag == TAG_SEQUENCE && !ndef)
{
/* We need to add 1 due to the way we implement the limit. */
parm->maxread = objlen + hdrlen + 1;
if (!(parm->maxread < objlen + hdrlen) && parm->maxread)
parm->use_maxread = 1;
found = 1;
}
leave:
while (npeeked)
es_ungetc (peekbuf[--npeeked], parm->fp);
return found;
}
static int
simple_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread)
{
struct reader_cb_parm_s *parm = cb_value;
size_t n;
int c = 0;
*nread = 0;
if (!buffer)
return -1; /* not supported */
restart:
if (parm->strip_zeroes)
{
if (parm->strip_zeroes == 1)
{
if (starts_with_sequence (parm))
parm->strip_zeroes = 2; /* Found fixed length sequence. */
else
parm->strip_zeroes = 0; /* Disable zero padding check. */
}
else if (parm->strip_zeroes == 3)
{
/* Limit reached - check that only zeroes follow. */
while (!(c = es_getc (parm->fp)))
parm->nzeroes++;
if (c == EOF)
{ /* only zeroes found. Reset zero padding engine and
* return EOF. */
parm->strip_zeroes = 0;
parm->eof_seen = 1;
return -1;
}
/* Not only zeroes. Reset engine and continue. */
parm->strip_zeroes = 0;
}
}
for (n=0; n < count; n++)
{
if (parm->use_maxread && !--parm->maxread)
{
parm->use_maxread = 0;
if (parm->strip_zeroes)
{
parm->strip_zeroes = 3;
parm->nzeroes = 0;
if (n)
goto leave; /* Return what we already got. */
goto restart; /* Immediately check for trailing zeroes. */
}
}
if (parm->nzeroes)
{
parm->nzeroes--;
c = 0;
}
else
c = es_getc (parm->fp);
if (c == EOF)
{
parm->eof_seen = 1;
if (es_ferror (parm->fp))
return -1;
if (n)
break; /* Return what we have before an EOF. */
return -1;
}
*(byte *)buffer++ = c;
}
leave:
*nread = n;
return 0;
}
static int
base64_writer_cb (void *cb_value, const void *buffer, size_t count)
{
struct writer_cb_parm_s *parm = cb_value;
unsigned char radbuf[4];
int i, c, idx, quad_count;
const unsigned char *p;
estream_t stream = parm->stream;
if (!count)
return 0;
if (!parm->wrote_begin)
{
if (parm->pem_name)
{
es_fputs ("-----BEGIN ", stream);
es_fputs (parm->pem_name, stream);
es_fputs ("-----\n", stream);
}
parm->wrote_begin = 1;
parm->base64.idx = 0;
parm->base64.quad_count = 0;
}
idx = parm->base64.idx;
quad_count = parm->base64.quad_count;
for (i=0; i < idx; i++)
radbuf[i] = parm->base64.radbuf[i];
for (p=buffer; count; p++, count--)
{
radbuf[idx++] = *p;
if (idx > 2)
{
idx = 0;
c = bintoasc[(*radbuf >> 2) & 077];
es_putc (c, stream);
c = bintoasc[(((*radbuf<<4)&060)|((radbuf[1] >> 4)&017))&077];
es_putc (c, stream);
c = bintoasc[(((radbuf[1]<<2)&074)|((radbuf[2]>>6)&03))&077];
es_putc (c, stream);
c = bintoasc[radbuf[2]&077];
es_putc (c, stream);
if (++quad_count >= (64/4))
{
es_fputs (LF, stream);
quad_count = 0;
}
}
}
for (i=0; i < idx; i++)
parm->base64.radbuf[i] = radbuf[i];
parm->base64.idx = idx;
parm->base64.quad_count = quad_count;
return es_ferror (stream)? gpg_error_from_syserror () : 0;
}
/* This callback is only used in stream mode. However, we don't
restrict it to this. */
static int
plain_writer_cb (void *cb_value, const void *buffer, size_t count)
{
struct writer_cb_parm_s *parm = cb_value;
estream_t stream = parm->stream;
if (!count)
return 0;
es_write (stream, buffer, count, NULL);
return es_ferror (stream)? gpg_error_from_syserror () : 0;
}
static int
base64_finish_write (struct writer_cb_parm_s *parm)
{
unsigned char *radbuf;
int c, idx, quad_count;
estream_t stream = parm->stream;
if (!parm->wrote_begin)
return 0; /* Nothing written or we are not called in base-64 mode. */
/* flush the base64 encoding */
idx = parm->base64.idx;
quad_count = parm->base64.quad_count;
if (idx)
{
radbuf = parm->base64.radbuf;
c = bintoasc[(*radbuf>>2)&077];
es_putc (c, stream);
if (idx == 1)
{
c = bintoasc[((*radbuf << 4) & 060) & 077];
es_putc (c, stream);
es_putc ('=', stream);
es_putc ('=', stream);
}
else
{
c = bintoasc[(((*radbuf<<4)&060)|((radbuf[1]>>4)&017))&077];
es_putc (c, stream);
c = bintoasc[((radbuf[1] << 2) & 074) & 077];
es_putc (c, stream);
es_putc ('=', stream);
}
if (++quad_count >= (64/4))
{
es_fputs (LF, stream);
quad_count = 0;
}
}
if (quad_count)
es_fputs (LF, stream);
if (parm->pem_name)
{
es_fputs ("-----END ", stream);
es_fputs (parm->pem_name, stream);
es_fputs ("-----\n", stream);
}
return es_ferror (stream)? gpg_error_from_syserror () : 0;
}
/* Create a reader for the stream FP. FLAGS can be used to specify
* the expected input encoding.
*
* The function returns a gnupg_ksba_io_t object which must be passed to
* the gpgme_destroy_reader function. The created ksba_reader_t
* object is stored at R_READER - the caller must not call the
* ksba_reader_release function on.
*
* The supported flags are:
*
* GNUPG_KSBA_IO_PEM - Assume the input is PEM encoded
* GNUPG_KSBA_IO_BASE64 - Assume the input is Base64 encoded.
* GNUPG_KSBA_IO_AUTODETECT - The reader tries to detect the encoding.
* GNUPG_KSBA_IO_MULTIPEM - The reader expects that the caller uses
* ksba_reader_clear after EOF until no more
* objects were found.
* GNUPG_KSBA_IO_STRIP - Strip zero padding from some CMS objects.
*
* Note that the PEM flag has a higher priority than the BASE64 flag
* which in turn has a gight priority than the AUTODETECT flag.
*/
gpg_error_t
gnupg_ksba_create_reader (gnupg_ksba_io_t *ctx,
unsigned int flags, estream_t fp,
ksba_reader_t *r_reader)
{
int rc;
ksba_reader_t r;
*r_reader = NULL;
*ctx = xtrycalloc (1, sizeof **ctx);
if (!*ctx)
return out_of_core ();
(*ctx)->u.rparm.allow_multi_pem = !!(flags & GNUPG_KSBA_IO_MULTIPEM);
(*ctx)->u.rparm.strip_zeroes = !!(flags & GNUPG_KSBA_IO_STRIP);
rc = ksba_reader_new (&r);
if (rc)
{
xfree (*ctx); *ctx = NULL;
return rc;
}
(*ctx)->u.rparm.fp = fp;
if ((flags & GNUPG_KSBA_IO_PEM))
{
(*ctx)->u.rparm.assume_pem = 1;
(*ctx)->u.rparm.assume_base64 = 1;
rc = ksba_reader_set_cb (r, base64_reader_cb, &(*ctx)->u.rparm);
}
else if ((flags & GNUPG_KSBA_IO_BASE64))
{
(*ctx)->u.rparm.assume_base64 = 1;
rc = ksba_reader_set_cb (r, base64_reader_cb, &(*ctx)->u.rparm);
}
else if ((flags & GNUPG_KSBA_IO_AUTODETECT))
{
(*ctx)->u.rparm.autodetect = 1;
rc = ksba_reader_set_cb (r, base64_reader_cb, &(*ctx)->u.rparm);
}
else
rc = ksba_reader_set_cb (r, simple_reader_cb, &(*ctx)->u.rparm);
if (rc)
{
ksba_reader_release (r);
xfree (*ctx); *ctx = NULL;
return rc;
}
(*ctx)->u2.reader = r;
*r_reader = r;
return 0;
}
/* Return True if an EOF as been seen. */
int
gnupg_ksba_reader_eof_seen (gnupg_ksba_io_t ctx)
{
return ctx && ctx->u.rparm.eof_seen;
}
/* Destroy a reader object. */
void
gnupg_ksba_destroy_reader (gnupg_ksba_io_t ctx)
{
if (!ctx)
return;
ksba_reader_release (ctx->u2.reader);
xfree (ctx);
}
/* Create a writer for the given STREAM. Depending on FLAGS an output
* encoding is chosen. In PEM mode PEM_NAME is used for the header
* and footer lines; if PEM_NAME is NULL the string "CMS OBJECT" is
* used.
*
* The function returns a gnupg_ksba_io_t object which must be passed to
* the gpgme_destroy_writer function. The created ksba_writer_t
* object is stored at R_WRITER - the caller must not call the
* ksba_reader_release function on it.
*
* The supported flags are:
*
* GNUPG_KSBA_IO_PEM - Write output as PEM
* GNUPG_KSBA_IO_BASE64 - Write output as plain Base64; note that the PEM
* flag overrides this flag.
*
*/
gpg_error_t
gnupg_ksba_create_writer (gnupg_ksba_io_t *ctx, unsigned int flags,
const char *pem_name, estream_t stream,
ksba_writer_t *r_writer)
{
int rc;
ksba_writer_t w;
*r_writer = NULL;
*ctx = xtrycalloc (1, sizeof **ctx);
if (!*ctx)
return gpg_error_from_syserror ();
rc = ksba_writer_new (&w);
if (rc)
{
xfree (*ctx); *ctx = NULL;
return rc;
}
if ((flags & GNUPG_KSBA_IO_PEM) || (flags & GNUPG_KSBA_IO_BASE64))
{
(*ctx)->u.wparm.stream = stream;
if ((flags & GNUPG_KSBA_IO_PEM))
{
(*ctx)->u.wparm.pem_name = xtrystrdup (pem_name
? pem_name
: "CMS OBJECT");
if (!(*ctx)->u.wparm.pem_name)
{
rc = gpg_error_from_syserror ();
ksba_writer_release (w);
xfree (*ctx); *ctx = NULL;
return rc;
}
}
rc = ksba_writer_set_cb (w, base64_writer_cb, &(*ctx)->u.wparm);
}
else if (stream)
{
(*ctx)->u.wparm.stream = stream;
rc = ksba_writer_set_cb (w, plain_writer_cb, &(*ctx)->u.wparm);
}
else
rc = gpg_error (GPG_ERR_INV_ARG);
if (rc)
{
ksba_writer_release (w);
xfree (*ctx); *ctx = NULL;
return rc;
}
(*ctx)->u2.writer = w;
*r_writer = w;
return 0;
}
/* Flush a writer. This is for example required to write the padding
* or the PEM footer. */
gpg_error_t
gnupg_ksba_finish_writer (gnupg_ksba_io_t ctx)
{
struct writer_cb_parm_s *parm;
if (!ctx)
return gpg_error (GPG_ERR_INV_VALUE);
parm = &ctx->u.wparm;
if (parm->did_finish)
return 0; /* Already done. */
parm->did_finish = 1;
if (!parm->stream)
return 0; /* Callback was not used. */
return base64_finish_write (parm);
}
/* Destroy a writer object. */
void
gnupg_ksba_destroy_writer (gnupg_ksba_io_t ctx)
{
if (!ctx)
return;
ksba_writer_release (ctx->u2.writer);
xfree (ctx->u.wparm.pem_name);
xfree (ctx);
}
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