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testlo.c
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1 /*-------------------------------------------------------------------------
2  *
3  * testlo.c
4  * test using large objects with libpq
5  *
6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/test/examples/testlo.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include <stdio.h>
16 #include <stdlib.h>
17 
18 #include <sys/types.h>
19 #include <sys/stat.h>
20 #include <fcntl.h>
21 #include <unistd.h>
22 
23 #include "libpq-fe.h"
24 #include "libpq/libpq-fs.h"
25 
26 #define BUFSIZE 1024
27 
28 /*
29  * importFile -
30  * import file "in_filename" into database as large object "lobjOid"
31  *
32  */
33 static Oid
35 {
36  Oid lobjId;
37  int lobj_fd;
38  char buf[BUFSIZE];
39  int nbytes,
40  tmp;
41  int fd;
42 
43  /*
44  * open the file to be read in
45  */
46  fd = open(filename, O_RDONLY, 0666);
47  if (fd < 0)
48  { /* error */
49  fprintf(stderr, "cannot open unix file\"%s\"\n", filename);
50  }
51 
52  /*
53  * create the large object
54  */
55  lobjId = lo_creat(conn, INV_READ | INV_WRITE);
56  if (lobjId == 0)
57  fprintf(stderr, "cannot create large object");
58 
59  lobj_fd = lo_open(conn, lobjId, INV_WRITE);
60 
61  /*
62  * read in from the Unix file and write to the inversion file
63  */
64  while ((nbytes = read(fd, buf, BUFSIZE)) > 0)
65  {
66  tmp = lo_write(conn, lobj_fd, buf, nbytes);
67  if (tmp < nbytes)
68  fprintf(stderr, "error while reading \"%s\"", filename);
69  }
70 
71  close(fd);
72  lo_close(conn, lobj_fd);
73 
74  return lobjId;
75 }
76 
77 static void
78 pickout(PGconn *conn, Oid lobjId, int start, int len)
79 {
80  int lobj_fd;
81  char *buf;
82  int nbytes;
83  int nread;
84 
85  lobj_fd = lo_open(conn, lobjId, INV_READ);
86  if (lobj_fd < 0)
87  fprintf(stderr, "cannot open large object %u", lobjId);
88 
89  lo_lseek(conn, lobj_fd, start, SEEK_SET);
90  buf = malloc(len + 1);
91 
92  nread = 0;
93  while (len - nread > 0)
94  {
95  nbytes = lo_read(conn, lobj_fd, buf, len - nread);
96  buf[nbytes] = '\0';
97  fprintf(stderr, ">>> %s", buf);
98  nread += nbytes;
99  if (nbytes <= 0)
100  break; /* no more data? */
101  }
102  free(buf);
103  fprintf(stderr, "\n");
104  lo_close(conn, lobj_fd);
105 }
106 
107 static void
108 overwrite(PGconn *conn, Oid lobjId, int start, int len)
109 {
110  int lobj_fd;
111  char *buf;
112  int nbytes;
113  int nwritten;
114  int i;
115 
116  lobj_fd = lo_open(conn, lobjId, INV_WRITE);
117  if (lobj_fd < 0)
118  fprintf(stderr, "cannot open large object %u", lobjId);
119 
120  lo_lseek(conn, lobj_fd, start, SEEK_SET);
121  buf = malloc(len + 1);
122 
123  for (i = 0; i < len; i++)
124  buf[i] = 'X';
125  buf[i] = '\0';
126 
127  nwritten = 0;
128  while (len - nwritten > 0)
129  {
130  nbytes = lo_write(conn, lobj_fd, buf + nwritten, len - nwritten);
131  nwritten += nbytes;
132  if (nbytes <= 0)
133  {
134  fprintf(stderr, "\nWRITE FAILED!\n");
135  break;
136  }
137  }
138  free(buf);
139  fprintf(stderr, "\n");
140  lo_close(conn, lobj_fd);
141 }
142 
143 
144 /*
145  * exportFile -
146  * export large object "lobjOid" to file "out_filename"
147  *
148  */
149 static void
151 {
152  int lobj_fd;
153  char buf[BUFSIZE];
154  int nbytes,
155  tmp;
156  int fd;
157 
158  /*
159  * open the large object
160  */
161  lobj_fd = lo_open(conn, lobjId, INV_READ);
162  if (lobj_fd < 0)
163  fprintf(stderr, "cannot open large object %u", lobjId);
164 
165  /*
166  * open the file to be written to
167  */
168  fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
169  if (fd < 0)
170  { /* error */
171  fprintf(stderr, "cannot open unix file\"%s\"",
172  filename);
173  }
174 
175  /*
176  * read in from the inversion file and write to the Unix file
177  */
178  while ((nbytes = lo_read(conn, lobj_fd, buf, BUFSIZE)) > 0)
179  {
180  tmp = write(fd, buf, nbytes);
181  if (tmp < nbytes)
182  {
183  fprintf(stderr, "error while writing \"%s\"",
184  filename);
185  }
186  }
187 
188  lo_close(conn, lobj_fd);
189  close(fd);
190 
191  return;
192 }
193 
194 static void
196 {
197  PQfinish(conn);
198  exit(1);
199 }
200 
201 int
202 main(int argc, char **argv)
203 {
204  char *in_filename,
205  *out_filename;
206  char *database;
207  Oid lobjOid;
208  PGconn *conn;
209  PGresult *res;
210 
211  if (argc != 4)
212  {
213  fprintf(stderr, "Usage: %s database_name in_filename out_filename\n",
214  argv[0]);
215  exit(1);
216  }
217 
218  database = argv[1];
219  in_filename = argv[2];
220  out_filename = argv[3];
221 
222  /*
223  * set up the connection
224  */
225  conn = PQsetdb(NULL, NULL, NULL, NULL, database);
226 
227  /* check to see that the backend connection was successfully made */
228  if (PQstatus(conn) != CONNECTION_OK)
229  {
230  fprintf(stderr, "Connection to database failed: %s",
231  PQerrorMessage(conn));
232  exit_nicely(conn);
233  }
234 
235  res = PQexec(conn, "begin");
236  PQclear(res);
237  printf("importing file \"%s\" ...\n", in_filename);
238 /* lobjOid = importFile(conn, in_filename); */
239  lobjOid = lo_import(conn, in_filename);
240  if (lobjOid == 0)
241  fprintf(stderr, "%s\n", PQerrorMessage(conn));
242  else
243  {
244  printf("\tas large object %u.\n", lobjOid);
245 
246  printf("picking out bytes 1000-2000 of the large object\n");
247  pickout(conn, lobjOid, 1000, 1000);
248 
249  printf("overwriting bytes 1000-2000 of the large object with X's\n");
250  overwrite(conn, lobjOid, 1000, 1000);
251 
252  printf("exporting large object to file \"%s\" ...\n", out_filename);
253 /* exportFile(conn, lobjOid, out_filename); */
254  if (lo_export(conn, lobjOid, out_filename) < 0)
255  fprintf(stderr, "%s\n", PQerrorMessage(conn));
256  }
257 
258  res = PQexec(conn, "end");
259  PQclear(res);
260  PQfinish(conn);
261  return 0;
262 }
char * PQerrorMessage(const PGconn *conn)
Definition: fe-connect.c:6014
#define write(a, b, c)
Definition: win32.h:14
int lo_lseek(PGconn *conn, int fd, int offset, int whence)
Definition: fe-lobj.c:366
int main(int argc, char **argv)
Definition: testlo.c:202
void PQfinish(PGconn *conn)
Definition: fe-connect.c:3547
static void exit_nicely(PGconn *conn)
Definition: testlo.c:195
unsigned int Oid
Definition: postgres_ext.h:31
static int fd(const char *x, int i)
Definition: preproc-init.c:105
#define malloc(a)
Definition: header.h:50
#define INV_READ
Definition: libpq-fs.h:22
int lo_close(PGconn *conn, int fd)
Definition: fe-lobj.c:100
PGconn * conn
Definition: streamutil.c:42
int lo_export(PGconn *conn, Oid lobjId, const char *filename)
Definition: fe-lobj.c:785
static char * buf
Definition: pg_test_fsync.c:66
int lo_read(int fd, char *buf, int len)
Definition: be-fsstubs.c:155
int lo_open(PGconn *conn, Oid lobjId, int mode)
Definition: fe-lobj.c:58
int lo_write(int fd, const char *buf, int len)
Definition: be-fsstubs.c:189
#define PQsetdb(M_PGHOST, M_PGPORT, M_PGOPT, M_PGTTY, M_DBNAME)
Definition: libpq-fe.h:269
static void exportFile(PGconn *conn, Oid lobjId, char *filename)
Definition: testlo.c:150
static void overwrite(PGconn *conn, Oid lobjId, int start, int len)
Definition: testlo.c:108
void PQclear(PGresult *res)
Definition: fe-exec.c:650
#define free(a)
Definition: header.h:65
#define NULL
Definition: c.h:229
#define INV_WRITE
Definition: libpq-fs.h:21
Oid lo_creat(PGconn *conn, int mode)
Definition: fe-lobj.c:466
static char * filename
Definition: pg_dumpall.c:89
static Oid importFile(PGconn *conn, char *filename)
Definition: testlo.c:34
int i
#define BUFSIZE
Definition: testlo.c:26
PGresult * PQexec(PGconn *conn, const char *query)
Definition: fe-exec.c:1846
static void pickout(PGconn *conn, Oid lobjId, int start, int len)
Definition: testlo.c:78
#define close(a)
Definition: win32.h:12
ConnStatusType PQstatus(const PGconn *conn)
Definition: fe-connect.c:5961
Oid lo_import(PGconn *conn, const char *filename)
Definition: fe-lobj.c:669
#define read(a, b, c)
Definition: win32.h:13