sqlcipher/tool/getlock.c at Xcode5 · sqlcipher/sqlcipher · GitHub

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** This utility program looks at an SQLite database and determines whether

** or not it is locked, the kind of lock, and who is holding this lock.

** This only works on unix when the posix advisory locking method is used

** (which is the default on unix) and when the PENDING_BYTE is in its

** usual place.

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <fcntl.h>

#include <string.h>

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

static void usage(const char *argv0){

fprintf(stderr, "Usage: %s database\n", argv0);

exit(1);

}

/* Check for a conflicting lock. If one is found, print an this

** on standard output using the format string given and return 1.

** If there are no conflicting locks, return 0.

static int isLocked(

int h, /* File descriptor to check */

int type, /* F_RDLCK or F_WRLCK */

unsigned int iOfst, /* First byte of the lock */

unsigned int iCnt, /* Number of bytes in the lock range */

const char *zType /* Type of lock */

){

struct flock lk;

memset(&lk, 0, sizeof(lk));

lk.l_type = type;

lk.l_whence = SEEK_SET;

lk.l_start = iOfst;

lk.l_len = iCnt;

if( fcntl(h, F_GETLK, &lk)==(-1) ){

fprintf(stderr, "fcntl(%d) failed: errno=%d\n", h, errno);

exit(1);

}

if( lk.l_type==F_UNLCK ) return 0;

printf("%s lock held by %d\n", zType, (int)lk.l_pid);

return 1;

}

** Location of locking bytes in the database file

#define PENDING_BYTE (0x40000000)

#define RESERVED_BYTE (PENDING_BYTE+1)

#define SHARED_FIRST (PENDING_BYTE+2)

#define SHARED_SIZE 510

** Lock locations for shared-memory locks used by WAL mode.

#define SHM_BASE 120

#define SHM_WRITE SHM_BASE

#define SHM_CHECKPOINT (SHM_BASE+1)

#define SHM_RECOVER (SHM_BASE+2)

#define SHM_READ_FIRST (SHM_BASE+3)

#define SHM_READ_SIZE 5

int main(int argc, char **argv){

int hDb; /* File descriptor for the open database file */

int hShm; /* File descriptor for WAL shared-memory file */

char *zShm; /* Name of the shared-memory file for WAL mode */

ssize_t got; /* Bytes read from header */

int isWal; /* True if in WAL mode */

int nName; /* Length of filename */

unsigned char aHdr[100]; /* Database header */

int nLock = 0; /* Number of locks held */

int i; /* Loop counter */

if( argc!=2 ) usage(argv[0]);

hDb = open(argv[1], O_RDONLY, 0);

if( hDb<0 ){

fprintf(stderr, "cannot open %s\n", argv[1]);

return 1;

}

/* Make sure we are dealing with an database file */

got = read(hDb, aHdr, 100);

if( got!=100 || memcmp(aHdr, "SQLite format 3",16)!=0 ){

fprintf(stderr, "not an SQLite database: %s\n", argv[1]);

exit(1);

}

/* First check for an exclusive lock */

if( isLocked(hDb, F_RDLCK, SHARED_FIRST, SHARED_SIZE, "EXCLUSIVE") ){

return 0;

}

isWal = aHdr[18]==2;

if( isWal==0 ){

/* Rollback mode */

if( isLocked(hDb, F_RDLCK, PENDING_BYTE, 1, "PENDING") ) return 0;

if( isLocked(hDb, F_RDLCK, RESERVED_BYTE, 1, "RESERVED") ) return 0;

if( isLocked(hDb, F_WRLCK, SHARED_FIRST, SHARED_SIZE, "SHARED") ){

return 0;

}

}else{

/* WAL mode */

nName = (int)strlen(argv[1]);

zShm = malloc( nName + 100 );

if( zShm==0 ){

fprintf(stderr, "out of memory\n");

exit(1);

}

memcpy(zShm, argv[1], nName);

memcpy(&zShm[nName], "-shm", 5);

hShm = open(zShm, O_RDONLY, 0);

if( hShm<0 ){

fprintf(stderr, "cannot open %s\n", zShm);

return 1;

}

if( isLocked(hShm, F_RDLCK, SHM_RECOVER, 1, "WAL-RECOVERY") ){

return 0;

}

nLock += isLocked(hShm, F_RDLCK, SHM_CHECKPOINT, 1, "WAL-CHECKPOINT");

nLock += isLocked(hShm, F_RDLCK, SHM_WRITE, 1, "WAL-WRITE");

for(i=0; i<SHM_READ_SIZE; i++){

nLock += isLocked(hShm, F_WRLCK, SHM_READ_FIRST+i, 1, "WAL-READ");

}

if( nLock==0 ){

printf("file is not locked\n");

}

return 0;

}

sqlcipher/tool/getlock.c at Xcode5 · sqlcipher/sqlcipher · GitHub

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