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blockresolver.c
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blockresolver.c
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/**
* @file
*
* @brief Source for blockresolver plugin
*
* @copyright BSD License (see LICENSE.md or https://www.libelektra.org)
*
*/
#include "blockresolver.h"
#include <kdberrors.h>
#include <kdbhelper.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include "../resolver/shared.h"
#include <kdbinvoke.h>
#define TV_MAX_DIGITS 26
#define BUFSIZE_MAX 1024
typedef struct
{
char * tmpFile;
char * realFile;
char * identifier;
time_t mtime;
long startPos;
long endPos;
unsigned short getPass;
unsigned short setPass;
} BlockData;
static int elektraResolveFilename (Key * parentKey, ElektraResolveTempfile tmpFile)
{
int rc = 0;
ElektraInvokeHandle * handle = elektraInvokeOpen ("resolver", 0, 0);
if (!handle)
{
rc = -1;
goto RESOLVE_FAILED;
}
ElektraResolved * resolved = NULL;
typedef ElektraResolved * (*resolveFileFunc) (elektraNamespace, const char *, ElektraResolveTempfile, Key *);
resolveFileFunc resolveFunc = *(resolveFileFunc *) elektraInvokeGetFunction (handle, "filename");
if (!resolveFunc)
{
rc = -1;
goto RESOLVE_FAILED;
}
typedef void (*freeHandleFunc) (ElektraResolved *);
freeHandleFunc freeHandle = *(freeHandleFunc *) elektraInvokeGetFunction (handle, "freeHandle");
if (!freeHandle)
{
rc = -1;
goto RESOLVE_FAILED;
}
resolved = resolveFunc (keyGetNamespace (parentKey), keyString (parentKey), tmpFile, parentKey);
if (!resolved)
{
rc = -1;
goto RESOLVE_FAILED;
}
else
{
keySetString (parentKey, resolved->fullPath);
freeHandle (resolved);
}
RESOLVE_FAILED:
elektraInvokeClose (handle, 0);
return rc;
}
int elektraBlockresolverCheckFile (const char * filename ELEKTRA_UNUSED)
{
return 1;
}
static const char * genTempFilename (void)
{
struct timeval tv;
gettimeofday (&tv, 0);
const char * tmpFilePrefix = "/tmp/elektra_blockresolver_";
char * tmpFile = elektraMalloc (strlen (tmpFilePrefix) + TV_MAX_DIGITS + 2);
snprintf (tmpFile, strlen (tmpFilePrefix) + TV_MAX_DIGITS + 2, "%s%lu:" ELEKTRA_TIME_USEC_F, tmpFilePrefix, tv.tv_sec, tv.tv_usec);
return tmpFile;
}
static int initData (Plugin * handle, Key * parentKey)
{
BlockData * data = elektraPluginGetData (handle);
if (!data)
{
data = elektraCalloc (sizeof (BlockData));
elektraPluginSetData (handle, data);
KeySet * config = elektraPluginGetConfig (handle);
Key * key = ksLookupByName (config, "/identifier", KDB_O_NONE);
if (!key) return -1;
data->identifier = (char *) keyString (key);
if (elektraResolveFilename (parentKey, ELEKTRA_RESOLVER_TEMPFILE_NONE) == -1)
{
return -1;
}
data->realFile = elektraStrDup (keyString (parentKey));
struct stat buf;
if (stat (data->realFile, &buf))
{
return -1;
}
data->mtime = buf.st_mtime;
data->tmpFile = (char *) genTempFilename ();
data->startPos = -1;
data->endPos = -1;
data->getPass = 0;
data->setPass = 0;
}
return 0;
}
int elektraBlockresolverClose (Plugin * handle ELEKTRA_UNUSED, Key * errorKey ELEKTRA_UNUSED)
{
// free all plugin resources and shut it down
// this function is optional
BlockData * data = elektraPluginGetData (handle);
if (data)
{
if (data->tmpFile)
{
unlink (data->tmpFile);
elektraFree (data->tmpFile);
}
if (data->realFile) elektraFree (data->realFile);
elektraFree (data);
}
elektraPluginSetData (handle, 0);
return 1; // success
}
static long getBlockStart (FILE * fp, const char * identifier)
{
long position = -1;
char buffer[BUFSIZE_MAX];
fseek (fp, 0, SEEK_SET);
while (fgets (buffer, sizeof (buffer), fp))
{
if (!strncmp (buffer, identifier, strlen (identifier)))
{
if (!strcmp (buffer + strlen (identifier) + 1, "start\n"))
{
position = ftell (fp);
break;
}
else
{
break;
}
}
}
return position;
}
static long getBlockEnd (FILE * fp, const char * identifier, long offset)
{
if (offset < 0) return -1;
long position = -1;
char buffer[BUFSIZE_MAX];
fseek (fp, offset, 0);
while (fgets (buffer, sizeof (buffer), fp))
{
if (!strncmp (buffer, identifier, strlen (identifier)))
{
if (!strcmp (buffer + strlen (identifier) + 1, "stop\n"))
{
position = ftell (fp) - (long) strlen (buffer);
break;
}
else
{
break;
}
}
}
return position;
}
static const char * getBlock (FILE * fp, const long startPos, const long endPos)
{
fseek (fp, startPos, SEEK_SET);
if (endPos <= startPos) return NULL;
size_t blockSize = (size_t) (endPos - startPos);
if (blockSize <= 0) return NULL;
char * block = elektraMalloc (blockSize + 1);
if (!block) return NULL;
size_t read = fread (block, 1, blockSize, fp);
if (read != blockSize)
{
elektraFree (block);
return NULL;
}
block[read] = '\0';
return block;
}
int elektraBlockresolverGet (Plugin * handle ELEKTRA_UNUSED, KeySet * returned ELEKTRA_UNUSED, Key * parentKey ELEKTRA_UNUSED)
{
if (!elektraStrCmp (keyName (parentKey), "system:/elektra/modules/blockresolver"))
{
KeySet * contract = ksNew (
30,
keyNew ("system:/elektra/modules/blockresolver", KEY_VALUE, "blockresolver plugin waits for your orders", KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports", KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/close", KEY_FUNC, elektraBlockresolverClose, KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/error", KEY_FUNC, elektraBlockresolverError, KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/get", KEY_FUNC, elektraBlockresolverGet, KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/set", KEY_FUNC, elektraBlockresolverSet, KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/commit", KEY_FUNC, elektraBlockresolverCommit, KEY_END),
keyNew ("system:/elektra/modules/blockresolver/exports/checkfile", KEY_FUNC, elektraBlockresolverCheckFile,
KEY_END),
#include ELEKTRA_README
keyNew ("system:/elektra/modules/blockresolver/infos/version", KEY_VALUE, PLUGINVERSION, KEY_END), KS_END);
ksAppend (returned, contract);
ksDel (contract);
return 1; // success
}
int rc = initData (handle, parentKey);
if (rc) return -1;
int retVal = 0;
BlockData * data = elektraPluginGetData (handle);
keySetString (parentKey, data->tmpFile);
FILE * fin = NULL;
FILE * fout = NULL;
char * block = NULL;
if (data->getPass > 0)
{
struct stat buf;
if (stat (data->realFile, &buf))
{
ELEKTRA_ADD_RESOURCE_WARNINGF (parentKey, "Failed to stat file %s\n. Reason: %s", data->realFile, strerror (errno));
return -1;
}
if (buf.st_mtime == data->mtime) return 0;
}
fin = fopen (data->realFile, "r");
if (!fin)
{
ELEKTRA_SET_RESOURCE_ERRORF (parentKey, "Couldn't open %s for reading. Reason: %s", data->realFile, strerror (errno));
goto GET_CLEANUP;
}
data->startPos = getBlockStart (fin, data->identifier);
if (data->startPos == -1) goto GET_CLEANUP;
data->endPos = getBlockEnd (fin, data->identifier, data->startPos);
if (data->endPos == -1)
{
ELEKTRA_SET_VALIDATION_SYNTACTIC_ERRORF (parentKey, "Couldn't find end of block %s", data->identifier);
retVal = -1;
goto GET_CLEANUP;
}
block = (char *) getBlock (fin, data->startPos, data->endPos);
if (!block)
{
ELEKTRA_SET_VALIDATION_SYNTACTIC_ERRORF (parentKey, "Failed to extract block %s\n", data->identifier);
retVal = -1;
goto GET_CLEANUP;
}
fclose (fin);
fin = NULL;
fout = fopen (data->tmpFile, "w");
if (!fout)
{
ELEKTRA_SET_RESOURCE_ERRORF (parentKey, "Couldn't open %s for writing. Reason: %s", data->tmpFile, strerror (errno));
retVal = -1;
goto GET_CLEANUP;
}
size_t blockSize = (size_t) (data->endPos - data->startPos);
fwrite (block, 1, blockSize, fout);
retVal = 1;
++(data->getPass);
GET_CLEANUP:
if (fin) fclose (fin);
if (fout) fclose (fout);
if (block) elektraFree (block);
return retVal; // success
}
int elektraBlockresolverSet (Plugin * handle ELEKTRA_UNUSED, KeySet * returned ELEKTRA_UNUSED, Key * parentKey ELEKTRA_UNUSED)
{
BlockData * data = elektraPluginGetData (handle);
if (!data) return -1;
keySetString (parentKey, data->tmpFile);
struct stat buf;
if (stat (data->realFile, &buf))
{
ELEKTRA_ADD_RESOURCE_WARNINGF (parentKey, "Failed to stat file %s\n. Reason: %s", data->realFile, strerror (errno));
return -1;
}
if (buf.st_mtime > data->mtime)
{
ELEKTRA_SET_CONFLICTING_STATE_ERRORF (parentKey, "File '%s' has been modified", data->realFile);
return -1;
}
FILE * fout = NULL;
FILE * fin = NULL;
char * block = NULL;
char * mergeFile = NULL;
int retVal = -1;
if (!data->setPass)
{
++(data->setPass);
return 1;
}
else if (data->setPass == 1)
{
// commit phase
mergeFile = (char *) genTempFilename ();
fout = fopen (mergeFile, "w");
if (!fout)
{
ELEKTRA_SET_RESOURCE_ERRORF (parentKey, "Couldn't open %s for writing. Reason: %s", data->realFile,
strerror (errno));
goto SET_CLEANUP;
}
fin = fopen (data->realFile, "r");
if (!fin)
{
ELEKTRA_SET_RESOURCE_ERRORF (parentKey, "Couldn't open %s for reading. Reason: %s", data->realFile,
strerror (errno));
goto SET_CLEANUP;
}
block = (char *) getBlock (fin, 0, data->startPos);
if (!block)
{
ELEKTRA_SET_VALIDATION_SYNTACTIC_ERRORF (parentKey, "Failed to extract block before %s\n", data->identifier);
goto SET_CLEANUP;
}
fwrite (block, 1, (size_t) data->startPos, fout);
fseek (fin, 0, SEEK_END);
elektraFree (block);
block = NULL;
size_t blockSize = (size_t) (ftell (fin) - data->endPos);
block = (char *) getBlock (fin, data->endPos, ftell (fin));
if (!block)
{
ELEKTRA_SET_VALIDATION_SYNTACTIC_ERRORF (parentKey, "Failed to extract block after %s\n", data->identifier);
goto SET_CLEANUP;
}
fclose (fin);
fin = fopen (data->tmpFile, "r");
if (!fin)
{
ELEKTRA_SET_RESOURCE_ERRORF (parentKey, "Couldn't open %s for reading Reason: %s", data->tmpFile, strerror (errno));
goto SET_CLEANUP;
}
char buffer[BUFSIZE_MAX];
size_t read = 0;
while ((read = fread (buffer, 1, sizeof (buffer), fin)) > 0)
{
fwrite (buffer, 1, read, fout);
}
fwrite (block, 1, blockSize, fout);
retVal = 1;
}
SET_CLEANUP:
if (fin) fclose (fin);
if (fout) fclose (fout);
if (block) elektraFree (block);
if (retVal == 1)
{
if (rename (mergeFile, data->realFile) == -1) retVal = -1;
elektraFree (mergeFile);
mergeFile = NULL;
}
if (mergeFile) elektraFree (mergeFile);
return retVal; // success
}
int elektraBlockresolverError (Plugin * handle ELEKTRA_UNUSED, KeySet * returned ELEKTRA_UNUSED, Key * parentKey ELEKTRA_UNUSED)
{
// set all keys
// this function is optional
return 1; // success
}
int elektraBlockresolverCommit (Plugin * handle ELEKTRA_UNUSED, KeySet * returned ELEKTRA_UNUSED, Key * parentKey ELEKTRA_UNUSED)
{
return elektraBlockresolverSet (handle, returned, parentKey);
}
Plugin * ELEKTRA_PLUGIN_EXPORT
{
// clang-format off
return elektraPluginExport ("blockresolver",
ELEKTRA_PLUGIN_CLOSE, &elektraBlockresolverClose,
ELEKTRA_PLUGIN_ERROR, &elektraBlockresolverError,
ELEKTRA_PLUGIN_GET, &elektraBlockresolverGet,
ELEKTRA_PLUGIN_SET, &elektraBlockresolverSet,
ELEKTRA_PLUGIN_COMMIT, &elektraBlockresolverCommit,
ELEKTRA_PLUGIN_END);
}