mirror of
https://git.postgresql.org/git/postgresql.git
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469 lines
10 KiB
C
469 lines
10 KiB
C
/*
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* file.c
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*
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* file system operations
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*
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* Copyright (c) 2010, PostgreSQL Global Development Group
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* contrib/pg_upgrade/file.c
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*/
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#include "pg_upgrade.h"
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#include <fcntl.h>
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static int copy_file(const char *fromfile, const char *tofile, bool force);
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#ifdef WIN32
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static int win32_pghardlink(const char *src, const char *dst);
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#endif
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#ifdef NOT_USED
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static int copy_dir(const char *from, const char *to, bool force);
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#endif
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#ifndef HAVE_SCANDIR
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static int pg_scandir_internal(migratorContext *ctx, const char *dirname,
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struct dirent *** namelist,
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int (*selector) (const struct dirent *));
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#endif
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/*
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* copyAndUpdateFile()
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*
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* Copies a relation file from src to dst. If pageConverter is non-NULL, this function
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* uses that pageConverter to do a page-by-page conversion.
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*/
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const char *
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copyAndUpdateFile(migratorContext *ctx, pageCnvCtx *pageConverter,
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const char *src, const char *dst, bool force)
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{
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if (pageConverter == NULL)
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{
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if (pg_copy_file(src, dst, force) == -1)
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return getErrorText(errno);
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else
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return NULL;
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}
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else
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{
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/*
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* We have a pageConverter object - that implies that the
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* PageLayoutVersion differs between the two clusters so we have to
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* perform a page-by-page conversion.
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*
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* If the pageConverter can convert the entire file at once, invoke
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* that plugin function, otherwise, read each page in the relation
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* file and call the convertPage plugin function.
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*/
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#ifdef PAGE_CONVERSION
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if (pageConverter->convertFile)
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return pageConverter->convertFile(pageConverter->pluginData,
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dst, src);
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else
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#endif
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{
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int src_fd;
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int dstfd;
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char buf[BLCKSZ];
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ssize_t bytesRead;
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const char *msg = NULL;
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if ((src_fd = open(src, O_RDONLY, 0)) < 0)
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return "can't open source file";
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if ((dstfd = open(dst, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR)) < 0)
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return "can't create destination file";
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while ((bytesRead = read(src_fd, buf, BLCKSZ)) == BLCKSZ)
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{
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#ifdef PAGE_CONVERSION
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if ((msg = pageConverter->convertPage(pageConverter->pluginData, buf, buf)) != NULL)
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break;
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#endif
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if (write(dstfd, buf, BLCKSZ) != BLCKSZ)
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{
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msg = "can't write new page to destination";
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break;
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}
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}
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close(src_fd);
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close(dstfd);
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if (msg)
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return msg;
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else if (bytesRead != 0)
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return "found partial page in source file";
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else
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return NULL;
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}
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}
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}
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/*
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* linkAndUpdateFile()
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*
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* Creates a symbolic link between the given relation files. We use
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* this function to perform a true in-place update. If the on-disk
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* format of the new cluster is bit-for-bit compatible with the on-disk
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* format of the old cluster, we can simply symlink each relation
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* instead of copying the data from the old cluster to the new cluster.
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*/
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const char *
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linkAndUpdateFile(migratorContext *ctx, pageCnvCtx *pageConverter,
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const char *src, const char *dst)
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{
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if (pageConverter != NULL)
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return "Can't in-place update this cluster, page-by-page conversion is required";
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if (pg_link_file(src, dst) == -1)
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return getErrorText(errno);
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else
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return NULL;
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}
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static int
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copy_file(const char *srcfile, const char *dstfile, bool force)
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{
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#define COPY_BUF_SIZE (50 * BLCKSZ)
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int src_fd;
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int dest_fd;
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char *buffer;
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if ((srcfile == NULL) || (dstfile == NULL))
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return -1;
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if ((src_fd = open(srcfile, O_RDONLY, 0)) < 0)
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return -1;
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if ((dest_fd = open(dstfile, O_RDWR | O_CREAT | (force ? 0 : O_EXCL), S_IRUSR | S_IWUSR)) < 0)
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{
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if (src_fd != 0)
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close(src_fd);
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return -1;
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}
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buffer = (char *) malloc(COPY_BUF_SIZE);
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if (buffer == NULL)
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{
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if (src_fd != 0)
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close(src_fd);
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if (dest_fd != 0)
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close(dest_fd);
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return -1;
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}
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/* perform data copying i.e read src source, write to destination */
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while (true)
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{
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ssize_t nbytes = read(src_fd, buffer, COPY_BUF_SIZE);
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if (nbytes < 0)
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{
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int save_errno = errno;
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if (buffer != NULL)
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free(buffer);
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if (src_fd != 0)
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close(src_fd);
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if (dest_fd != 0)
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close(dest_fd);
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errno = save_errno;
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return -1;
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}
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if (nbytes == 0)
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break;
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errno = 0;
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if (write(dest_fd, buffer, nbytes) != nbytes)
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{
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/* if write didn't set errno, assume problem is no disk space */
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int save_errno = errno ? errno : ENOSPC;
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if (buffer != NULL)
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free(buffer);
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if (src_fd != 0)
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close(src_fd);
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if (dest_fd != 0)
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close(dest_fd);
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errno = save_errno;
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return -1;
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}
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}
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if (buffer != NULL)
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free(buffer);
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if (src_fd != 0)
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close(src_fd);
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if (dest_fd != 0)
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close(dest_fd);
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return 1;
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}
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/*
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* pg_scandir()
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*
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* Wrapper for portable scandir functionality
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*/
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int
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pg_scandir(migratorContext *ctx, const char *dirname,
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struct dirent *** namelist,
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int (*selector) (const struct dirent *))
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{
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#ifndef HAVE_SCANDIR
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return pg_scandir_internal(ctx, dirname, namelist, selector);
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/*
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* scandir() is originally from BSD 4.3, which had the third argument as
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* non-const. Linux and other C libraries have updated it to use a const.
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* http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2005-12/msg002
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* 14.html
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*
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* Here we try to guess which libc's need const, and which don't. The net
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* goal here is to try to suppress a compiler warning due to a prototype
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* mismatch of const usage. Ideally we would do this via autoconf, but
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* autoconf doesn't have a suitable builtin test and it seems overkill to
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* add one just to avoid a warning.
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*/
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#elif defined(__FreeBSD__) || defined(__bsdi__) || defined(__darwin__) || defined(__OpenBSD__)
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/* no const */
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return scandir(dirname, namelist, (int (*) (struct dirent *)) selector, NULL);
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#else
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/* use const */
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return scandir(dirname, namelist, selector, NULL);
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#endif
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}
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#ifndef HAVE_SCANDIR
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/*
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* pg_scandir_internal()
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*
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* Implement our own scandir() on platforms that don't have it.
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*
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* Returns count of files that meet the selection criteria coded in
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* the function pointed to by selector. Creates an array of pointers
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* to dirent structures. Address of array returned in namelist.
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*
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* Note that the number of dirent structures needed is dynamically
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* allocated using realloc. Realloc can be inefficient if invoked a
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* large number of times. Its use in pg_upgrade is to find filesystem
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* filenames that have extended beyond the initial segment (file.1,
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* .2, etc.) and should therefore be invoked a small number of times.
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*/
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static int
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pg_scandir_internal(migratorContext *ctx, const char *dirname,
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struct dirent *** namelist, int (*selector) (const struct dirent *))
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{
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DIR *dirdesc;
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struct dirent *direntry;
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int count = 0;
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int name_num = 0;
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size_t entrysize;
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if ((dirdesc = opendir(dirname)) == NULL)
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pg_log(ctx, PG_FATAL, "Could not open directory \"%s\": %m\n", dirname);
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*namelist = NULL;
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while ((direntry = readdir(dirdesc)) != NULL)
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{
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/* Invoke the selector function to see if the direntry matches */
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if ((*selector) (direntry))
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{
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count++;
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*namelist = (struct dirent **) realloc((void *) (*namelist),
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(size_t) ((name_num + 1) * sizeof(struct dirent *)));
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if (*namelist == NULL)
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return -1;
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entrysize = sizeof(struct dirent) - sizeof(direntry->d_name) +
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strlen(direntry->d_name) + 1;
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(*namelist)[name_num] = (struct dirent *) malloc(entrysize);
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if ((*namelist)[name_num] == NULL)
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return -1;
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memcpy((*namelist)[name_num], direntry, entrysize);
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name_num++;
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}
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}
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closedir(dirdesc);
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return count;
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}
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#endif
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/*
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* dir_matching_filenames
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*
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* Return only matching file names during directory scan
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*/
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int
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dir_matching_filenames(const struct dirent * scan_ent)
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{
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/* we only compare for string length because the number suffix varies */
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if (!strncmp(scandir_file_pattern, scan_ent->d_name, strlen(scandir_file_pattern)))
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return 1;
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return 0;
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}
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void
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check_hard_link(migratorContext *ctx)
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{
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char existing_file[MAXPGPATH];
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char new_link_file[MAXPGPATH];
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snprintf(existing_file, sizeof(existing_file), "%s/PG_VERSION", ctx->old.pgdata);
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snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.linktest", ctx->new.pgdata);
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unlink(new_link_file); /* might fail */
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if (pg_link_file(existing_file, new_link_file) == -1)
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{
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pg_log(ctx, PG_FATAL,
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"Could not create hard link between old and new data directories: %s\n"
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"In link mode the old and new data directories must be on the same file system volume.\n",
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getErrorText(errno));
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}
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unlink(new_link_file);
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}
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#ifdef WIN32
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static int
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win32_pghardlink(const char *src, const char *dst)
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{
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/*
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* CreateHardLinkA returns zero for failure
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* http://msdn.microsoft.com/en-us/library/aa363860(VS.85).aspx
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*/
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if (CreateHardLinkA(dst, src, NULL) == 0)
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return -1;
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else
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return 0;
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}
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#endif
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#ifdef NOT_USED
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/*
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* copy_dir()
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*
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* Copies either a directory or a single file within a directory. If the
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* source argument names a directory, we recursively copy that directory,
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* otherwise we copy a single file.
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*/
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static int
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copy_dir(const char *src, const char *dst, bool force)
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{
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DIR *srcdir;
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struct dirent *de = NULL;
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struct stat fst;
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if (src == NULL || dst == NULL)
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return -1;
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/*
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* Try to open the source directory - if it turns out not to be a
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* directory, assume that it's a file and copy that instead.
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*/
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if ((srcdir = opendir(src)) == NULL)
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{
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if (errno == ENOTDIR)
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return copy_file(src, dst, true);
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return -1;
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}
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if (mkdir(dst, S_IRWXU) != 0)
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{
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/*
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* ignore directory already exist error
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*/
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if (errno != EEXIST)
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return -1;
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}
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while ((de = readdir(srcdir)) != NULL)
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{
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char src_file[MAXPGPATH];
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char dest_file[MAXPGPATH];
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if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
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continue;
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memset(src_file, 0, sizeof(src_file));
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memset(dest_file, 0, sizeof(dest_file));
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snprintf(src_file, sizeof(src_file), "%s/%s", src, de->d_name);
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snprintf(dest_file, sizeof(dest_file), "%s/%s", dst, de->d_name);
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if (stat(src_file, &fst) < 0)
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{
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if (srcdir != NULL)
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{
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closedir(srcdir);
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srcdir = NULL;
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}
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return -1;
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}
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if (fst.st_mode & S_IFDIR)
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{
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/* recurse to handle subdirectories */
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if (force)
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copy_dir(src_file, dest_file, true);
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}
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else if (fst.st_mode & S_IFREG)
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{
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if ((copy_file(src_file, dest_file, 1)) == -1)
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{
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if (srcdir != NULL)
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{
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closedir(srcdir);
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srcdir = NULL;
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}
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return -1;
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}
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}
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}
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if (srcdir != NULL)
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{
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closedir(srcdir);
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srcdir = NULL;
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}
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return 1;
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}
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#endif
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