src/test/examples/testlo.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * testlo.c
   4  *        test using large objects with libpq
   5  *
   6  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  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
  34 importFile(PGconn *conn, char *filename)
  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
 150 exportFile(PGconn *conn, Oid lobjId, char *filename)
 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
 195 exit_nicely(PGconn *conn)
 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))
 255                         fprintf(stderr, "%s\n", PQerrorMessage(conn));
 256         }
 257
 258         res = PQexec(conn, "end");
 259         PQclear(res);
 260         PQfinish(conn);
 261         return 0;
 262 }