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-rw-r--r--mysys/my_pread.c200
1 files changed, 200 insertions, 0 deletions
diff --git a/mysys/my_pread.c b/mysys/my_pread.c
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+++ b/mysys/my_pread.c
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+/* Copyright (c) 2000, 2011, Oracle and/or its affiliates.
+ Copyright (c) 2011, Monty Program Ab
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
+
+#include "mysys_priv.h"
+#include "mysys_err.h"
+#include "my_base.h"
+#include <m_string.h>
+#include <errno.h>
+#ifndef _WIN32
+#include <unistd.h>
+#endif
+
+/*
+ Read a chunk of bytes from a file from a given position
+
+ SYNOPSIOS
+ my_pread()
+ Filedes File descriptor
+ Buffer Buffer to read data into
+ Count Number of bytes to read
+ offset Position to read from
+ MyFlags Flags
+
+ NOTES
+ This differs from the normal pread() call in that we don't care
+ to set the position in the file back to the original position
+ if the system doesn't support pread().
+
+ RETURN
+ (size_t) -1 Error
+ # Number of bytes read
+*/
+
+size_t my_pread(File Filedes, uchar *Buffer, size_t Count, my_off_t offset,
+ myf MyFlags)
+{
+ size_t readbytes, save_count= 0;
+
+ DBUG_ENTER("my_pread");
+
+ DBUG_PRINT("my",("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %lu",
+ Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags));
+
+ if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP)))
+ MyFlags|= my_global_flags;
+
+ for (;;)
+ {
+ errno= 0; /* Linux, Windows don't reset this on EOF/success */
+#ifdef _WIN32
+ readbytes= my_win_pread(Filedes, Buffer, Count, offset);
+#else
+ readbytes= pread(Filedes, Buffer, Count, offset);
+#endif
+
+ if (readbytes != Count)
+ {
+ /* We should never read with wrong file descriptor! */
+ DBUG_ASSERT(readbytes != (size_t)-1 || errno != EBADF);
+ my_errno= errno;
+ if (errno == 0 || (readbytes != (size_t) -1 &&
+ (MyFlags & (MY_NABP | MY_FNABP))))
+ my_errno= HA_ERR_FILE_TOO_SHORT;
+ DBUG_PRINT("warning",("Read only %d bytes off %u from %d, errno: %d",
+ (int) readbytes, (uint) Count,Filedes,my_errno));
+ if ((readbytes == 0 || readbytes == (size_t) -1) && errno == EINTR)
+ {
+ DBUG_PRINT("debug", ("my_pread() was interrupted and returned %d",
+ (int) readbytes));
+ continue; /* Interrupted */
+ }
+
+ /* Do a read retry if we didn't get enough data on first read */
+ if (readbytes != (size_t) -1 && readbytes != 0 &&
+ (MyFlags & MY_FULL_IO))
+ {
+ Buffer+= readbytes;
+ Count-= readbytes;
+ save_count+= readbytes;
+ offset+= readbytes;
+ continue;
+ }
+
+ if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
+ {
+ if (readbytes == (size_t) -1)
+ my_error(EE_READ,
+ MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))),
+ my_filename(Filedes),my_errno);
+ else if (MyFlags & (MY_NABP | MY_FNABP))
+ my_error(EE_EOFERR,
+ MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))),
+ my_filename(Filedes),my_errno);
+ }
+ if (readbytes == (size_t) -1 || (MyFlags & (MY_FNABP | MY_NABP)))
+ DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
+ }
+ if (MyFlags & (MY_NABP | MY_FNABP))
+ readbytes= 0; /* Read went ok; Return 0 */
+ else
+ readbytes+= save_count;
+ DBUG_RETURN(readbytes);
+ }
+} /* my_pread */
+
+
+/*
+ Write a chunk of bytes to a file at a given position
+
+ SYNOPSIOS
+ my_pwrite()
+ Filedes File descriptor
+ Buffer Buffer to write data from
+ Count Number of bytes to write
+ offset Position to write to
+ MyFlags Flags
+
+ NOTES
+ This differs from the normal pwrite() call in that we don't care
+ to set the position in the file back to the original position
+ if the system doesn't support pwrite()
+
+ RETURN
+ (size_t) -1 Error
+ # Number of bytes read
+*/
+
+size_t my_pwrite(int Filedes, const uchar *Buffer, size_t Count,
+ my_off_t offset, myf MyFlags)
+{
+ size_t writtenbytes, written;
+ uint errors;
+ DBUG_ENTER("my_pwrite");
+ DBUG_PRINT("my",("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %lu",
+ Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags));
+ errors= 0;
+ written= 0;
+ if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP)))
+ MyFlags|= my_global_flags;
+
+ for (;;)
+ {
+#ifdef _WIN32
+ writtenbytes= my_win_pwrite(Filedes, Buffer, Count,offset);
+#else
+ writtenbytes= pwrite(Filedes, Buffer, Count, offset);
+#endif
+ if (writtenbytes == Count)
+ break;
+ my_errno= errno;
+ if (writtenbytes != (size_t) -1)
+ { /* Safegueard */
+ written+=writtenbytes;
+ Buffer+=writtenbytes;
+ Count-=writtenbytes;
+ offset+=writtenbytes;
+ }
+ DBUG_PRINT("error",("Write only %u bytes", (uint) writtenbytes));
+#ifndef NO_BACKGROUND
+ if (my_thread_var->abort)
+ MyFlags&= ~ MY_WAIT_IF_FULL; /* End if aborted by user */
+ if ((my_errno == ENOSPC || my_errno == EDQUOT) &&
+ (MyFlags & MY_WAIT_IF_FULL))
+ {
+ wait_for_free_space(my_filename(Filedes), errors);
+ errors++;
+ continue;
+ }
+ if ((writtenbytes && writtenbytes != (size_t) -1) || my_errno == EINTR)
+ continue; /* Retry */
+#endif
+
+ /* Don't give a warning if it's ok that we only write part of the data */
+ if (MyFlags & (MY_NABP | MY_FNABP))
+ {
+ if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
+ my_error(EE_WRITE, MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))),
+ my_filename(Filedes),my_errno);
+ DBUG_RETURN(MY_FILE_ERROR); /* Error on write */
+ }
+ break; /* Return bytes written */
+ }
+ DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0)););
+ if (MyFlags & (MY_NABP | MY_FNABP))
+ DBUG_RETURN(0); /* Want only errors */
+ DBUG_RETURN(writtenbytes+written); /* purecov: inspected */
+} /* my_pwrite */