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/*
* file.c
*
* file system operations
*
* Copyright (c) 2010-2016, PostgreSQL Global Development Group
* src/bin/pg_upgrade/file.c
*/
#include "postgres_fe.h"
#include "pg_upgrade.h"
#include <fcntl.h>
#ifndef WIN32
static int copy_file(const char *fromfile, const char *tofile, bool force);
#else
static int win32_pghardlink(const char *src, const char *dst);
#endif
/*
* copyFile()
*
* Copies a relation file from src to dst.
*/
const char *
copyFile(const char *src, const char *dst, bool force)
{
#ifndef WIN32
if (copy_file(src, dst, force) == -1)
#else
if (CopyFile(src, dst, !force) == 0)
#endif
return getErrorText();
else
return NULL;
}
/*
* linkFile()
*
* Creates a hard link between the given relation files. We use
* this function to perform a true in-place update. If the on-disk
* format of the new cluster is bit-for-bit compatible with the on-disk
* format of the old cluster, we can simply link each relation
* instead of copying the data from the old cluster to the new cluster.
*/
const char *
linkFile(const char *src, const char *dst)
{
if (pg_link_file(src, dst) == -1)
return getErrorText();
else
return NULL;
}
#ifndef WIN32
static int
copy_file(const char *srcfile, const char *dstfile, bool force)
{
#define COPY_BUF_SIZE (50 * BLCKSZ)
int src_fd;
int dest_fd;
char *buffer;
int ret = 0;
int save_errno = 0;
if ((srcfile == NULL) || (dstfile == NULL))
{
errno = EINVAL;
return -1;
}
if ((src_fd = open(srcfile, O_RDONLY, 0)) < 0)
return -1;
if ((dest_fd = open(dstfile, O_RDWR | O_CREAT | (force ? 0 : O_EXCL), S_IRUSR | S_IWUSR)) < 0)
{
save_errno = errno;
if (src_fd != 0)
close(src_fd);
errno = save_errno;
return -1;
}
buffer = (char *) pg_malloc(COPY_BUF_SIZE);
/* perform data copying i.e read src source, write to destination */
while (true)
{
ssize_t nbytes = read(src_fd, buffer, COPY_BUF_SIZE);
if (nbytes < 0)
{
save_errno = errno;
ret = -1;
break;
}
if (nbytes == 0)
break;
errno = 0;
if (write(dest_fd, buffer, nbytes) != nbytes)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
save_errno = errno;
ret = -1;
break;
}
}
pg_free(buffer);
if (src_fd != 0)
close(src_fd);
if (dest_fd != 0)
close(dest_fd);
if (save_errno != 0)
errno = save_errno;
return ret;
}
#endif
void
check_hard_link(void)
{
char existing_file[MAXPGPATH];
char new_link_file[MAXPGPATH];
snprintf(existing_file, sizeof(existing_file), "%s/PG_VERSION", old_cluster.pgdata);
snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.linktest", new_cluster.pgdata);
unlink(new_link_file); /* might fail */
if (pg_link_file(existing_file, new_link_file) == -1)
{
pg_fatal("Could not create hard link between old and new data directories: %s\n"
"In link mode the old and new data directories must be on the same file system volume.\n",
getErrorText());
}
unlink(new_link_file);
}
#ifdef WIN32
static int
win32_pghardlink(const char *src, const char *dst)
{
/*
* CreateHardLinkA returns zero for failure
* http://msdn.microsoft.com/en-us/library/aa363860(VS.85).aspx
*/
if (CreateHardLinkA(dst, src, NULL) == 0)
return -1;
else
return 0;
}
#endif
/* fopen() file with no group/other permissions */
FILE *
fopen_priv(const char *path, const char *mode)
{
mode_t old_umask = umask(S_IRWXG | S_IRWXO);
FILE *fp;
fp = fopen(path, mode);
umask(old_umask);
return fp;
}
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