postgresql/contrib/pg_upgrade/file.c
2011-03-15 20:52:35 -04:00

381 lines
8.4 KiB
C

/*
* file.c
*
* file system operations
*
* Copyright (c) 2010-2011, PostgreSQL Global Development Group
* contrib/pg_upgrade/file.c
*/
#include "pg_upgrade.h"
#include <fcntl.h>
static int copy_file(const char *fromfile, const char *tofile, bool force);
#ifdef WIN32
static int win32_pghardlink(const char *src, const char *dst);
#endif
#ifndef HAVE_SCANDIR
static int pg_scandir_internal(const char *dirname,
struct dirent *** namelist,
int (*selector) (const struct dirent *));
#endif
/*
* copyAndUpdateFile()
*
* Copies a relation file from src to dst. If pageConverter is non-NULL, this function
* uses that pageConverter to do a page-by-page conversion.
*/
const char *
copyAndUpdateFile(pageCnvCtx *pageConverter,
const char *src, const char *dst, bool force)
{
if (pageConverter == NULL)
{
if (pg_copy_file(src, dst, force) == -1)
return getErrorText(errno);
else
return NULL;
}
else
{
/*
* We have a pageConverter object - that implies that the
* PageLayoutVersion differs between the two clusters so we have to
* perform a page-by-page conversion.
*
* If the pageConverter can convert the entire file at once, invoke
* that plugin function, otherwise, read each page in the relation
* file and call the convertPage plugin function.
*/
#ifdef PAGE_CONVERSION
if (pageConverter->convertFile)
return pageConverter->convertFile(pageConverter->pluginData,
dst, src);
else
#endif
{
int src_fd;
int dstfd;
char buf[BLCKSZ];
ssize_t bytesRead;
const char *msg = NULL;
if ((src_fd = open(src, O_RDONLY, 0)) < 0)
return "can't open source file";
if ((dstfd = open(dst, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR)) < 0)
{
close(src_fd);
return "can't create destination file";
}
while ((bytesRead = read(src_fd, buf, BLCKSZ)) == BLCKSZ)
{
#ifdef PAGE_CONVERSION
if ((msg = pageConverter->convertPage(pageConverter->pluginData, buf, buf)) != NULL)
break;
#endif
if (write(dstfd, buf, BLCKSZ) != BLCKSZ)
{
msg = "can't write new page to destination";
break;
}
}
close(src_fd);
close(dstfd);
if (msg)
return msg;
else if (bytesRead != 0)
return "found partial page in source file";
else
return NULL;
}
}
}
/*
* linkAndUpdateFile()
*
* Creates a symbolic 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 symlink each relation
* instead of copying the data from the old cluster to the new cluster.
*/
const char *
linkAndUpdateFile(pageCnvCtx *pageConverter,
const char *src, const char *dst)
{
if (pageConverter != NULL)
return "Can't in-place update this cluster, page-by-page conversion is required";
if (pg_link_file(src, dst) == -1)
return getErrorText(errno);
else
return NULL;
}
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;
if ((srcfile == NULL) || (dstfile == NULL))
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)
{
if (src_fd != 0)
close(src_fd);
return -1;
}
buffer = (char *) malloc(COPY_BUF_SIZE);
if (buffer == NULL)
{
if (src_fd != 0)
close(src_fd);
if (dest_fd != 0)
close(dest_fd);
return -1;
}
/* 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)
{
int save_errno = errno;
if (buffer != NULL)
free(buffer);
if (src_fd != 0)
close(src_fd);
if (dest_fd != 0)
close(dest_fd);
errno = save_errno;
return -1;
}
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 */
int save_errno = errno ? errno : ENOSPC;
if (buffer != NULL)
free(buffer);
if (src_fd != 0)
close(src_fd);
if (dest_fd != 0)
close(dest_fd);
errno = save_errno;
return -1;
}
}
if (buffer != NULL)
free(buffer);
if (src_fd != 0)
close(src_fd);
if (dest_fd != 0)
close(dest_fd);
return 1;
}
/*
* pg_scandir()
*
* Wrapper for portable scandir functionality
*/
int
pg_scandir(const char *dirname,
struct dirent *** namelist,
int (*selector) (const struct dirent *))
{
#ifndef HAVE_SCANDIR
return pg_scandir_internal(dirname, namelist, selector);
/*
* scandir() is originally from BSD 4.3, which had the third argument as
* non-const. Linux and other C libraries have updated it to use a const.
* http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2005-12/msg002
* 14.html
*
* Here we try to guess which libc's need const, and which don't. The net
* goal here is to try to suppress a compiler warning due to a prototype
* mismatch of const usage. Ideally we would do this via autoconf, but
* autoconf doesn't have a suitable builtin test and it seems overkill to
* add one just to avoid a warning.
*/
#elif defined(__FreeBSD__) || defined(__bsdi__) || defined(__darwin__) || defined(__OpenBSD__)
/* no const */
return scandir(dirname, namelist, (int (*) (struct dirent *)) selector, NULL);
#else
/* use const */
return scandir(dirname, namelist, selector, NULL);
#endif
}
#ifndef HAVE_SCANDIR
/*
* pg_scandir_internal()
*
* Implement our own scandir() on platforms that don't have it.
*
* Returns count of files that meet the selection criteria coded in
* the function pointed to by selector. Creates an array of pointers
* to dirent structures. Address of array returned in namelist.
*
* Note that the number of dirent structures needed is dynamically
* allocated using realloc. Realloc can be inefficient if invoked a
* large number of times. Its use in pg_upgrade is to find filesystem
* filenames that have extended beyond the initial segment (file.1,
* .2, etc.) and should therefore be invoked a small number of times.
*/
static int
pg_scandir_internal(const char *dirname,
struct dirent *** namelist, int (*selector) (const struct dirent *))
{
DIR *dirdesc;
struct dirent *direntry;
int count = 0;
int name_num = 0;
size_t entrysize;
if ((dirdesc = opendir(dirname)) == NULL)
pg_log(PG_FATAL, "Could not open directory \"%s\": %m\n", dirname);
*namelist = NULL;
while ((direntry = readdir(dirdesc)) != NULL)
{
/* Invoke the selector function to see if the direntry matches */
if ((*selector) (direntry))
{
count++;
*namelist = (struct dirent **) realloc((void *) (*namelist),
(size_t) ((name_num + 1) * sizeof(struct dirent *)));
if (*namelist == NULL)
{
closedir(dirdesc);
return -1;
}
entrysize = sizeof(struct dirent) - sizeof(direntry->d_name) +
strlen(direntry->d_name) + 1;
(*namelist)[name_num] = (struct dirent *) malloc(entrysize);
if ((*namelist)[name_num] == NULL)
{
closedir(dirdesc);
return -1;
}
memcpy((*namelist)[name_num], direntry, entrysize);
name_num++;
}
}
closedir(dirdesc);
return count;
}
#endif
/*
* dir_matching_filenames
*
* Return only matching file names during directory scan
*/
int
dir_matching_filenames(const struct dirent * scan_ent)
{
/* we only compare for string length because the number suffix varies */
if (!strncmp(scandir_file_pattern, scan_ent->d_name, strlen(scandir_file_pattern)))
return 1;
return 0;
}
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_log(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(errno));
}
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