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/*
This file is part of libextractor.
Copyright (C) 2016 Christian Grothoff
libextractor 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, or (at your
option) any later version.
libextractor 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 libextractor; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
/**
* @file plugins/pdf_extractor.c
* @brief plugin to support PDF files
* @author Christian Grothoff
*
* PDF libraries today are a nightmare (TM). So instead of doing the
* fast thing and calling some library functions to parse the PDF,
* we execute 'pdfinfo' and parse the output. Because that's 21st
* century plumbing: nobody writes reasonable code anymore.
*/
#include "platform.h"
#include <extractor.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <unistd.h>
/**
* Entry in the mapping from control data to LE types.
*/
struct Matches
{
/**
* Key in the Pdfian control file.
*/
const char *text;
/**
* Corresponding type in LE.
*/
enum EXTRACTOR_MetaType type;
};
/**
* Map from pdf-control entries to LE types.
*
* See output of 'pdfinfo'.
*/
static struct Matches tmap[] = {
{"Title", EXTRACTOR_METATYPE_TITLE},
{"Subject", EXTRACTOR_METATYPE_SUBJECT},
{"Keywords", EXTRACTOR_METATYPE_KEYWORDS},
{"Author", EXTRACTOR_METATYPE_AUTHOR_NAME},
{"Creator", EXTRACTOR_METATYPE_CREATOR},
{"Producer", EXTRACTOR_METATYPE_PRODUCED_BY_SOFTWARE},
{"CreationDate", EXTRACTOR_METATYPE_CREATION_DATE},
{"ModDate", EXTRACTOR_METATYPE_MODIFICATION_DATE},
{"PDF version", EXTRACTOR_METATYPE_ENCODER_VERSION},
{"Pages", EXTRACTOR_METATYPE_PAGE_COUNT},
{NULL, 0}
};
/**
* Process the "stdout" file from pdfinfo.
*
* @param fout stdout of pdfinfo
* @param proc function to call with meta data
* @param proc_cls closure for @e proc
*/
static void
process_stdout (FILE *fout,
EXTRACTOR_MetaDataProcessor proc,
void *proc_cls)
{
unsigned int i;
char line[1025];
const char *psuffix;
const char *colon;
while (! feof (fout))
{
if (NULL == fgets (line, sizeof (line) - 1, fout))
break;
if (0 == strlen (line))
continue;
if ('\n' == line[strlen(line)-1])
line[strlen(line)-1] = '\0';
colon = strchr (line, (int) ':');
if (NULL == colon)
break;
psuffix = colon + 1;
while (isblank ((unsigned char) psuffix[0]))
psuffix++;
if (0 == strlen (psuffix))
continue;
for (i = 0; NULL != tmap[i].text; i++)
{
if (0 != strncasecmp (line,
tmap[i].text,
colon - line))
continue;
if (0 != proc (proc_cls,
"pdf",
tmap[i].type,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
psuffix,
strlen(psuffix) + 1))
return;
break;
}
}
}
/**
* Main entry method for the PDF extraction plugin.
*
* @param ec extraction context provided to the plugin
*/
void
EXTRACTOR_pdf_extract_method (struct EXTRACTOR_ExtractContext *ec)
{
uint64_t fsize;
void *data;
pid_t pid;
int in[2];
int out[2];
FILE *fout;
uint64_t pos;
fsize = ec->get_size (ec->cls);
if (fsize < 128)
return;
if (4 !=
ec->read (ec->cls, &data, 4))
return;
if (0 != strncmp ("%PDF", data, 4))
return;
if (0 !=
ec->seek (ec->cls, 0, SEEK_SET))
return;
if (0 != pipe (in))
return;
if (0 != pipe (out))
{
close (in[0]);
close (in[1]);
return;
}
pid = fork ();
if (-1 == pid)
{
close (in[0]);
close (in[1]);
close (out[0]);
close (out[1]);
return;
}
if (0 == pid)
{
char *const args[] = {
"pdfinfo",
"-",
NULL
};
/* am child, exec 'pdfinfo' */
close (0);
close (1);
if ( (-1 == dup2 (in[0], 0)) ||
(-1 == dup2 (out[1], 1)) )
exit (1);
close (in[0]);
close (in[1]);
close (out[0]);
close (out[1]);
execvp ("pdfinfo", args);
exit (1);
}
/* am parent, send file */
close (in[0]);
close (out[1]);
fout = fdopen (out[0], "r");
if (NULL == fout)
{
close (in[1]);
close (out[0]);
kill (pid, SIGKILL);
waitpid (pid, NULL, 0);
return;
}
pos = 0;
while (pos < fsize)
{
ssize_t got;
size_t wpos;
data = NULL;
got = ec->read (ec->cls,
&data,
fsize - pos);
if ( (-1 == got) ||
(NULL == data) )
break;
wpos = 0;
while (wpos < got)
{
ssize_t out;
out = write (in[1], data + wpos, got - wpos);
if (out <= 0)
break;
wpos += out;
}
if (wpos < got)
break;
pos += got;
}
close (in[1]);
process_stdout (fout, ec->proc, ec->cls);
fclose (fout);
kill (pid, SIGKILL);
waitpid (pid, NULL, 0);
}
/* end of pdf_extractor.c */
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