mirror of
https://git.postgresql.org/git/postgresql.git
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244 lines
5.0 KiB
C
244 lines
5.0 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) 2010-2012, PostgreSQL Global Development Group
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* contrib/pg_upgrade/file.c
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*/
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#include "postgres.h"
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#include "pg_upgrade.h"
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#include <fcntl.h>
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#ifndef WIN32
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static int copy_file(const char *fromfile, const char *tofile, bool force);
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#else
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static int win32_pghardlink(const char *src, const char *dst);
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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(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 "could not 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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{
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close(src_fd);
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return "could not create destination file";
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}
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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 = "could not 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 hard 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 link 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(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 "Cannot 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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#ifndef WIN32
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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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int ret = 0;
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int save_errno = 0;
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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 *) pg_malloc(COPY_BUF_SIZE);
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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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save_errno = errno;
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ret = -1;
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break;
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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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save_errno = errno;
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ret = -1;
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break;
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}
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}
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pg_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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if (save_errno != 0)
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errno = save_errno;
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return ret;
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}
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#endif
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void
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check_hard_link(void)
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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", old_cluster.pgdata);
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snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.linktest", new_cluster.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(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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/* fopen() file with no group/other permissions */
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FILE *
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fopen_priv(const char *path, const char *mode)
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{
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mode_t old_umask = umask(S_IRWXG | S_IRWXO);
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FILE *fp;
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fp = fopen(path, mode);
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umask(old_umask);
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return fp;
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}
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