Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * local_source.c
       4             :  *    Functions for using a local data directory as the source.
       5             :  *
       6             :  * Portions Copyright (c) 2013-2024, PostgreSQL Global Development Group
       7             :  *
       8             :  *-------------------------------------------------------------------------
       9             :  */
      10             : #include "postgres_fe.h"
      11             : 
      12             : #include <fcntl.h>
      13             : #include <unistd.h>
      14             : 
      15             : #include "datapagemap.h"
      16             : #include "file_ops.h"
      17             : #include "filemap.h"
      18             : #include "pg_rewind.h"
      19             : #include "rewind_source.h"
      20             : 
      21             : typedef struct
      22             : {
      23             :     rewind_source common;       /* common interface functions */
      24             : 
      25             :     const char *datadir;        /* path to the source data directory */
      26             : } local_source;
      27             : 
      28             : static void local_traverse_files(rewind_source *source,
      29             :                                  process_file_callback_t callback);
      30             : static char *local_fetch_file(rewind_source *source, const char *path,
      31             :                               size_t *filesize);
      32             : static void local_queue_fetch_file(rewind_source *source, const char *path,
      33             :                                    size_t len);
      34             : static void local_queue_fetch_range(rewind_source *source, const char *path,
      35             :                                     off_t off, size_t len);
      36             : static void local_finish_fetch(rewind_source *source);
      37             : static void local_destroy(rewind_source *source);
      38             : 
      39             : rewind_source *
      40          22 : init_local_source(const char *datadir)
      41             : {
      42             :     local_source *src;
      43             : 
      44          22 :     src = pg_malloc0(sizeof(local_source));
      45             : 
      46          22 :     src->common.traverse_files = local_traverse_files;
      47          22 :     src->common.fetch_file = local_fetch_file;
      48          22 :     src->common.queue_fetch_file = local_queue_fetch_file;
      49          22 :     src->common.queue_fetch_range = local_queue_fetch_range;
      50          22 :     src->common.finish_fetch = local_finish_fetch;
      51          22 :     src->common.get_current_wal_insert_lsn = NULL;
      52          22 :     src->common.destroy = local_destroy;
      53             : 
      54          22 :     src->datadir = datadir;
      55             : 
      56          22 :     return &src->common;
      57             : }
      58             : 
      59             : static void
      60          14 : local_traverse_files(rewind_source *source, process_file_callback_t callback)
      61             : {
      62          14 :     traverse_datadir(((local_source *) source)->datadir, callback);
      63          14 : }
      64             : 
      65             : static char *
      66          46 : local_fetch_file(rewind_source *source, const char *path, size_t *filesize)
      67             : {
      68          46 :     return slurpFile(((local_source *) source)->datadir, path, filesize);
      69             : }
      70             : 
      71             : /*
      72             :  * Copy a file from source to target.
      73             :  *
      74             :  * 'len' is the expected length of the file.
      75             :  */
      76             : static void
      77        4438 : local_queue_fetch_file(rewind_source *source, const char *path, size_t len)
      78             : {
      79        4438 :     const char *datadir = ((local_source *) source)->datadir;
      80             :     PGIOAlignedBlock buf;
      81             :     char        srcpath[MAXPGPATH];
      82             :     int         srcfd;
      83             :     size_t      written_len;
      84             : 
      85        4438 :     snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir, path);
      86             : 
      87             :     /* Open source file for reading */
      88        4438 :     srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
      89        4438 :     if (srcfd < 0)
      90           0 :         pg_fatal("could not open source file \"%s\": %m",
      91             :                  srcpath);
      92             : 
      93             :     /* Truncate and open the target file for writing */
      94        4438 :     open_target_file(path, true);
      95             : 
      96        4438 :     written_len = 0;
      97             :     for (;;)
      98       95276 :     {
      99             :         ssize_t     read_len;
     100             : 
     101       99714 :         read_len = read(srcfd, buf.data, sizeof(buf));
     102             : 
     103       99714 :         if (read_len < 0)
     104           0 :             pg_fatal("could not read file \"%s\": %m", srcpath);
     105       99714 :         else if (read_len == 0)
     106        4438 :             break;              /* EOF reached */
     107             : 
     108       95276 :         write_target_range(buf.data, written_len, read_len);
     109       95276 :         written_len += read_len;
     110             :     }
     111             : 
     112             :     /*
     113             :      * A local source is not expected to change while we're rewinding, so
     114             :      * check that the size of the file matches our earlier expectation.
     115             :      */
     116        4438 :     if (written_len != len)
     117           2 :         pg_fatal("size of source file \"%s\" changed concurrently: %d bytes expected, %d copied",
     118             :                  srcpath, (int) len, (int) written_len);
     119             : 
     120        4436 :     if (close(srcfd) != 0)
     121           0 :         pg_fatal("could not close file \"%s\": %m", srcpath);
     122        4436 : }
     123             : 
     124             : /*
     125             :  * Copy a file from source to target, starting at 'off', for 'len' bytes.
     126             :  */
     127             : static void
     128        1644 : local_queue_fetch_range(rewind_source *source, const char *path, off_t off,
     129             :                         size_t len)
     130             : {
     131        1644 :     const char *datadir = ((local_source *) source)->datadir;
     132             :     PGIOAlignedBlock buf;
     133             :     char        srcpath[MAXPGPATH];
     134             :     int         srcfd;
     135        1644 :     off_t       begin = off;
     136        1644 :     off_t       end = off + len;
     137             : 
     138        1644 :     snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir, path);
     139             : 
     140        1644 :     srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
     141        1644 :     if (srcfd < 0)
     142           0 :         pg_fatal("could not open source file \"%s\": %m",
     143             :                  srcpath);
     144             : 
     145        1644 :     if (lseek(srcfd, begin, SEEK_SET) == -1)
     146           0 :         pg_fatal("could not seek in source file: %m");
     147             : 
     148        1644 :     open_target_file(path, false);
     149             : 
     150        3780 :     while (end - begin > 0)
     151             :     {
     152             :         ssize_t     readlen;
     153             :         size_t      thislen;
     154             : 
     155        2136 :         if (end - begin > sizeof(buf))
     156         492 :             thislen = sizeof(buf);
     157             :         else
     158        1644 :             thislen = end - begin;
     159             : 
     160        2136 :         readlen = read(srcfd, buf.data, thislen);
     161             : 
     162        2136 :         if (readlen < 0)
     163           0 :             pg_fatal("could not read file \"%s\": %m", srcpath);
     164        2136 :         else if (readlen == 0)
     165           0 :             pg_fatal("unexpected EOF while reading file \"%s\"", srcpath);
     166             : 
     167        2136 :         write_target_range(buf.data, begin, readlen);
     168        2136 :         begin += readlen;
     169             :     }
     170             : 
     171        1644 :     if (close(srcfd) != 0)
     172           0 :         pg_fatal("could not close file \"%s\": %m", srcpath);
     173        1644 : }
     174             : 
     175             : static void
     176          12 : local_finish_fetch(rewind_source *source)
     177             : {
     178             :     /*
     179             :      * Nothing to do, local_queue_fetch_range() copies the ranges immediately.
     180             :      */
     181          12 : }
     182             : 
     183             : static void
     184          12 : local_destroy(rewind_source *source)
     185             : {
     186          12 :     pfree(source);
     187          12 : }