PYTHON
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Contents
1 Introduction
A priori, il n'y a pas de page de manuel, il faut utiliser la doc file:///usr/share/doc/db5.3-doc/api_reference/C/index.html
# apt-get install libdb-dev db5.3-doc db-util $ ls /usr/share/doc/db5.3-doc/index.html
Makefile
CFLAGS=-Wall -O0 -g LDFLAGS=-ldb test%: test%.o gcc $(LDFLAGS) $^ -o $@ test%.o: test%.c gcc -c $(CFLAGS) $< -o $@ all: test1 test2 clean: rm -f *.o test?
The valgrind errors are expected unless you configure Berkeley DB with the '-enable-umrw' flag, which ensures that all bytes are initialized with zeros, even if they are never read by Berkeley DB (e.g., padding bytes in data structures).
==25180== Syscall param pwrite64(buf) points to uninitialised byte(s) ==25180== at 0x4C13BDC: pwrite64 (pwrite64.c:29) ==25180== by 0x49AADD8: __os_io (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x499665E: ??? (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x4996B79: __memp_bhwrite (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x49A6BF8: __memp_sync_int (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x49A7393: __memp_fsync (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x493E218: __db_sync (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x493BA85: __db_refresh (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x493C2A1: __db_close (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x494E07C: __db_close_pp (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x10887D: bdbClose (test1.c:87) ==25180== by 0x108D0F: main (test1.c:237) ==25180== Address 0x4c28cd8 is 3,944 bytes inside a block of size 4,156 alloc'd ==25180== at 0x482E27C: malloc (vg_replace_malloc.c:299) ==25180== by 0x49A8048: __os_malloc (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x497360F: __env_alloc (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x4994748: __memp_alloc (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x4998544: __memp_fget (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x489B2A4: __bam_get_root (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x489BB48: __bam_search (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x488727C: ??? (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x488B8B4: ??? (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x49428C9: __dbc_iput (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x4943E66: __dbc_put (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== by 0x493D805: __db_put (in /usr/lib/i386-linux-gnu/libdb-5.3.so) ==25180== Uninitialised value was created by a stack allocation ==25180== at 0x108B21: main (test1.c:192)
2 Taille fixe
test1.c : enregistrements de taille fixe
#include <stdio.h>
#include <string.h> // memset
#include <db.h>
#define TRUE 1
#define FALSE 0
typedef struct MyRecord
{
char id[10];
char label1[10];
char label2[10];
} MyRecord;
/*=======================================================================
* Function : bdbOpen
* Description: open a Berkeley database
* Synopsis : int bdbOpen(DB **dbp, char* path)
* Input : char* path: path of the database file
* Output : DB **dbp: database pointer
* TRUE on success
=======================================================================*/
int bdbOpen(DB **dbp, char* path)
{
int rc = FALSE;
u_int32_t flags = 0; /* database open flags */
int err = 0; /* function return value */
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* Initialize the structure. This
* database is not opened in an environment,
* so the environment pointer is NULL. */
if ((err = db_create(dbp, NULL, 0))) {
printf("db_create fails: %s\n", db_strerror(err));
goto error;
}
/* Database open flags */
flags = DB_CREATE; /* If the database does not exist,
* create it.*/
/* open the database */
if ((err = (*dbp)->open(*dbp, /* DB structure pointer */
NULL, /* Transaction pointer */
path, /* On-disk file that holds the database. */
NULL, /* Optional logical database name */
DB_BTREE, /* Database access method */
flags, /* Open flags */
0))) { /* File mode (using defaults) */
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
rc = TRUE;
error:
if (!rc) {
printf("bdbOpen fails\n");
}
return rc;
}
/*=======================================================================
* Function : bdbClose
* Description: close a Berkeley database
* Synopsis : int bdbClose(DB **dbp)
* Input : DB **dbp: database pointer
* Output : DB **dbp: database pointer is unset to NULL
* TRUE on success
=======================================================================*/
int bdbClose(DB **dbp)
{
int rc = FALSE;
int err = 0;
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* When we're done with the database, close it. */
if (!(*dbp)) goto end;
if ((err = (*dbp)->close(*dbp, 0))) {
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
*dbp = 0;
end:
rc = TRUE;
error:
if (!rc) {
printf("bdbClose fails\n");
}
return rc;
}
/**************************************/
int addMyRecord(DB *dbp, MyRecord* record)
{
int rc = FALSE;
int err = 0;
DBT key;
DBT data;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = record->id;
key.size = strlen(record->id) + 1;
data.data = record;
data.size = sizeof(MyRecord);
if ((err = dbp->put(dbp, NULL, &key, &data, DB_NOOVERWRITE))) {
if (err == DB_KEYEXIST) {
printf("addMyRecord fails: key '%s' already there\n", record->id);
}
else {
printf("sbp->put fails: %s\n", db_strerror(err));
}
goto error;
}
rc = TRUE;
error:
if (!rc) {
printf("addMyRecord fails\n");
}
return rc;
}
int getMyRecord(DB *dbp, char* id, MyRecord* record)
{
int rc = FALSE;
int err = 0;
DBT key;
DBT data;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
memset(record, 0, sizeof(MyRecord));
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = id;
key.size = strlen(id) + 1;
/* Use our memory to retrieve the structure */
data.data = record;
data.ulen = sizeof(MyRecord);
data.flags = DB_DBT_USERMEM;
if ((err = dbp->get(dbp, NULL, &key, &data, 0))) {
if (err == DB_NOTFOUND) {
printf("getMyRecord fails: no '%s' key there\n", id);
goto end;
}
printf("sbp->put fails: %s\n", db_strerror(err));
goto error;
}
end:
rc = TRUE;
error:
if (!rc) {
printf("getMyRecord fails\n");
}
return rc;
}
int main(int argc, char** argv)
{
int rc = 0;
DB *dbp; /* DB structure handle */
char id[10] = "";
MyRecord record;
int i;
if (argc < 2) {
printf("please provide ORDER arcument (get or put)\n");
goto error;
}
if (!bdbOpen(&dbp, "my_db.db")) goto error;
if (!strcmp(argv[1], "put")) {
printf("do put\n");
for (i=0; i<5; ++i) {
sprintf(record.id, "id_%i", i);
sprintf(record.label1, "label1_%i", i);
sprintf(record.label2, "label2_%i", i);
if (!addMyRecord(dbp, &record)) goto error;
}
goto end;
}
if (!strcmp(argv[1], "get")) {
printf("do get\n");
for (i=0; i<6; ++i) {
sprintf(id, "id_%i", i);
if (!getMyRecord(dbp, id, &record)) continue;
printf("get %s %s %s\n", record.id, record.label1, record.label2);
}
goto end;
}
printf("bad ORDER argument '%s', get or put was expected\n", argv[1]);
goto error;
end:
rc = 0;
error:
if (!bdbClose(&dbp)) rc = 1;
printf("%s\n", rc?"failure":"success");
return rc;
}
3 Taille variable
test2.c : enregistrements de taille variable
#include <stdio.h>
#include <string.h> // memset
#include <stdlib.h> // malloc
#include <db.h>
#define TRUE 1
#define FALSE 0
typedef struct MyRecord
{
char* id;
char* label1;
char* label2;
} MyRecord;
/*=======================================================================
* Function : bdbOpen
* Description: open a Berkeley database
* Synopsis : int bdbOpen(DB **dbp, char* path)
* Input : char* path: path of the database file
* Output : DB **dbp: database pointer
* TRUE on success
=======================================================================*/
int
bdbOpen(DB **dbp, char* path)
{
int rc = FALSE;
u_int32_t flags = 0; /* database open flags */
int err = 0; /* function return value */
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* Initialize the structure. This
* database is not opened in an environment,
* so the environment pointer is NULL. */
if ((err = db_create(dbp, NULL, 0))) {
printf("db_create fails: %s\n", db_strerror(err));
goto error;
}
/* Database open flags */
flags = DB_CREATE; /* If the database does not exist,
* create it.*/
/* open the database */
if ((err = (*dbp)->open(*dbp, /* DB structure pointer */
NULL, /* Transaction pointer */
path, /* On-disk file that holds the database. */
NULL, /* Optional logical database name */
DB_BTREE, /* Database access method */
flags, /* Open flags */
0))) { /* File mode (using defaults) */
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
rc = TRUE;
error:
if (!rc) {
printf("bdbOpen fails\n");
}
return rc;
}
/*=======================================================================
* Function : bdbClose
* Description: close a Berkeley database
* Synopsis : int bdbClose(DB **dbp)
* Input : DB **dbp: database pointer
* Output : DB **dbp: database pointer is unset to NULL
* TRUE on success
=======================================================================*/
int
bdbClose(DB **dbp)
{
int rc = FALSE;
int err = 0;
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* When we're done with the database, close it. */
if (!(*dbp)) goto end;
if ((err = (*dbp)->close(*dbp, 0))) {
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
*dbp = 0;
end:
rc = TRUE;
error:
if (!rc) {
printf("bdbClose fails\n");
}
return rc;
}
/**************************************/
char*
packString(char *buffer, char *string)
{
int len = 0;
len = strlen(string);
strncpy(buffer, string, len+1);
return(buffer + len + 1);
}
char*
unpackString(char *buffer, char **string)
{
int len = 0;
*string = buffer;
len = strlen(*string);
return(buffer + len + 1);
}
int
addMyRecord(DB *dbp, MyRecord* record)
{
int rc = FALSE;
char *buffer = 0;
char* ptr = 0;
int len = 0;
int err = 0;
DBT key;
DBT data;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
len = strlen(record->id) + strlen(record->label1) + strlen(record->label2) +3;
if (!(buffer = malloc(len))) {
printf("malloc fails\n");
goto error;
}
ptr = packString(buffer, record->id);
ptr = packString(ptr, record->label1);
ptr = packString(ptr, record->label2);
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = record->id;
key.size = strlen(record->id) + 1;
data.data = buffer;
data.size = len;
if ((err = dbp->put(dbp, NULL, &key, &data, DB_NOOVERWRITE))) {
if (err == DB_KEYEXIST) {
printf("addMyRecord fails: key '%s' already there\n", record->id);
}
else {
printf("sbp->put fails: %s\n", db_strerror(err));
}
goto error;
}
rc = TRUE;
error:
if (buffer) free(buffer);
if (!rc) {
printf("addMyRecord fails\n");
}
return rc;
}
int
getMyRecord(DB *dbp, char* id, MyRecord* record)
{
int rc = FALSE;
int err = 0;
DBT key;
DBT data;
//char buffer[128];
char* ptr = 0;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
memset(record, 0, sizeof(MyRecord));
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = id;
key.size = strlen(id) + 1;
if ((err = dbp->get(dbp, NULL, &key, &data, 0))) {
if (err == DB_NOTFOUND) {
printf("getMyRecord fails: no '%s' key there\n", id);
goto end;
}
printf("sbp->put fails: %s\n", db_strerror(err));
goto error;
}
ptr = data.data;
ptr = unpackString(ptr, &(record->id));
ptr = unpackString(ptr, &(record->label1));
ptr = unpackString(ptr, &(record->label2));
end:
rc = TRUE;
error:
if (!rc) {
printf("getMyRecord fails\n");
}
return rc;
}
int main(int argc, char** argv)
{
int rc = 0;
DB *dbp = 0; /* DB structure handle */
char id[10] = "";
char label1[10];
char label2[10];
MyRecord record;
int i;
if (argc < 2) {
printf("please provide ORDER arcument (get or put)\n");
goto error;
}
if (!bdbOpen(&dbp, "my_db.db")) goto error;
if (!strcmp(argv[1], "put")) {
printf("do put\n");
record.id = id;
record.label1 = label1;
record.label2 = label2;
for (i=0; i<5; ++i) {
sprintf(record.id, "id_%i", i);
sprintf(record.label1, "label1_%i", i);
sprintf(record.label2, "label2_%i", i);
if (!addMyRecord(dbp, &record)) goto error;
}
goto end;
}
if (!strcmp(argv[1], "get")) {
printf("do get\n");
for (i=0; i<6; ++i) {
sprintf(id, "id_%i", i);
if (!getMyRecord(dbp, id, &record)) continue;
printf("get %s %s %s\n", record.id, record.label1, record.label2);
}
goto end;
}
printf("bad ORDER argument '%s', get or put was expected\n", argv[1]);
goto error;
end:
rc = 0;
error:
if (!bdbClose(&dbp)) rc = 1;
printf("%s\n", rc?"failure":"success");
return rc;
}
4 Curseurs
test3.c : on accepte les doublons sur une même clé.
#include <stdio.h>
#include <string.h> // memset
#include <stdlib.h> // malloc
#include <db.h>
#define TRUE 1
#define FALSE 0
typedef struct MyRecord
{
char* id;
char* label1;
char* label2;
} MyRecord;
/*=======================================================================
* Function : bdbOpen
* Description: open a Berkeley database
* Synopsis : int bdbOpen(DB **dbp, char* path)
* Input : char* path: path of the database file
* Output : DB **dbp: database pointer
* TRUE on success
=======================================================================*/
int
bdbOpen(DB **dbp, char* path)
{
int rc = FALSE;
u_int32_t flags = 0; /* database open flags */
int err = 0; /* function return value */
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* Initialize the structure. This
* database is not opened in an environment,
* so the environment pointer is NULL. */
if ((err = db_create(dbp, NULL, 0))) {
printf("db_create fails: %s\n", db_strerror(err));
goto error;
}
if ((err = (*dbp)->set_flags(*dbp, DB_DUP))) {
printf("dbp->set_flags fails: %s\n", db_strerror(err));
goto error;
}
/* Database open flags */
flags = DB_CREATE; /* If the database does not exist,
* create it.*/
/* open the database */
if ((err = (*dbp)->open(*dbp, /* DB structure pointer */
NULL, /* Transaction pointer */
path, /* On-disk file that holds the database. */
NULL, /* Optional logical database name */
DB_BTREE, /* Database access method */
flags, /* Open flags */
0))) { /* File mode (using defaults) */
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
rc = TRUE;
error:
if (!rc) {
printf("bdbOpen fails\n");
}
return rc;
}
/*=======================================================================
* Function : bdbClose
* Description: close a Berkeley database
* Synopsis : int bdbClose(DB **dbp)
* Input : DB **dbp: database pointer
* Output : DB **dbp: database pointer is unset to NULL
* TRUE on success
=======================================================================*/
int
bdbClose(DB **dbp)
{
int rc = FALSE;
int err = 0;
if (!dbp) {
printf("please provide a DB** pointer");
goto error;
}
/* When we're done with the database, close it. */
if (!(*dbp)) goto end;
if ((err = (*dbp)->close(*dbp, 0))) {
printf("dbp->open fails: %s\n", db_strerror(err));
goto error;
}
*dbp = 0;
end:
rc = TRUE;
error:
if (!rc) {
printf("bdbClose fails\n");
}
return rc;
}
/**************************************/
char*
packString(char *buffer, char *string)
{
int len = 0;
len = strlen(string);
strncpy(buffer, string, len+1);
return(buffer + len + 1);
}
char*
unpackString(char *buffer, char **string)
{
int len = 0;
*string = buffer;
len = strlen(*string);
return(buffer + len + 1);
}
int
addMyRecord(DB *dbp, MyRecord* record)
{
int rc = FALSE;
char *buffer = 0;
char* ptr = 0;
int len = 0;
int err = 0;
DBT key;
DBT data;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
len = strlen(record->id) + strlen(record->label1) + strlen(record->label2) +3;
if (!(buffer = malloc(len))) {
printf("malloc fails\n");
goto error;
}
ptr = packString(buffer, record->id);
ptr = packString(ptr, record->label1);
ptr = packString(ptr, record->label2);
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = record->id;
key.size = strlen(record->id) + 1;
data.data = buffer;
data.size = len;
if ((err = dbp->put(dbp, NULL, &key, &data, 0/*DB_NOOVERWRITE*/))) {
if (err == DB_KEYEXIST) {
printf("addMyRecord fails: key '%s' already there\n", record->id);
}
else {
printf("sbp->put fails: %s\n", db_strerror(err));
}
goto error;
}
rc = TRUE;
error:
if (buffer) free(buffer);
if (!rc) {
printf("addMyRecord fails\n");
}
return rc;
}
int
getMyRecords(DB *dbp, char* id, MyRecord* record)
{
int rc = FALSE;
int err = 0;
DBC *cursorp = 0;
DBT key;
DBT data;
//char buffer[128];
char* ptr = 0;
if (!dbp) {
printf("please provide a DB* pointer");
goto error;
}
memset(record, 0, sizeof(MyRecord));
/* Get a cursor */
if ((err = dbp->cursor(dbp, NULL, &cursorp, 0))) {
printf("dbp->cursor fails: %s\n", db_strerror(err));
goto error;
}
/* Zero out the DBTs before using them. */
memset(&key, 0, sizeof(DBT));
memset(&data, 0, sizeof(DBT));
key.data = id;
key.size = strlen(id) + 1;
err = cursorp->get(cursorp, &key, &data, DB_SET);
while (!err && !strcmp(key.data, id)) {
ptr = data.data;
ptr = unpackString(ptr, &(record->id));
ptr = unpackString(ptr, &(record->label1));
ptr = unpackString(ptr, &(record->label2));
printf("get %s %s %s\n", record->id, record->label1, record->label2);
err = cursorp->get(cursorp, &key, &data, DB_NEXT);
}
if (err && err != DB_NOTFOUND) {
printf("cursorp->get fails: %s\n", db_strerror(err));
goto error;
}
if ((err = cursorp->close(cursorp))) {
printf("cursorp->close fails: %s\n", db_strerror(err));
goto error;
}
rc = TRUE;
error:
if (!rc) {
printf("getMyRecord fails\n");
}
return rc;
}
int main(int argc, char** argv)
{
int rc = 0;
DB *dbp = 0; /* DB structure handle */
char id[10] = "";
char label1[10];
char label2[10];
MyRecord record;
int i;
if (argc < 2) {
printf("please provide ORDER arcument (get or put)\n");
goto error;
}
if (!bdbOpen(&dbp, "my_db.db")) goto error;
if (!strcmp(argv[1], "put")) {
printf("do put\n");
record.id = id;
record.label1 = label1;
record.label2 = label2;
for (i=0; i<5; ++i) {
sprintf(record.id, "id_%i", i);
sprintf(record.label1, "label1_%i", i);
sprintf(record.label2, "label2_%i", i);
if (!addMyRecord(dbp, &record)) goto error;
}
goto end;
}
if (!strcmp(argv[1], "get")) {
printf("do get\n");
for (i=0; i<6; ++i) {
sprintf(id, "id_%i", i);
printf("-- %s --\n", id);
if (!getMyRecords(dbp, id, &record)) continue;
}
goto end;
}
printf("bad ORDER argument '%s', get or put was expected\n", argv[1]);
goto error;
end:
rc = 0;
error:
if (!bdbClose(&dbp)) rc = 1;
printf("%s\n", rc?"failure":"success");
return rc;
}
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