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synced 2025-08-01 03:47:19 +03:00
Bug#51023: Mysql server crashes on SIGHUP and destroys InnoDB files
From a user perspective, the problem is that a FLUSH LOGS or SIGHUP signal could end up associating the stdout and stderr to random files. In the case of this bug report, the streams would end up associated to InnoDB ibd files. The freopen(3) function is not thread-safe on FreeBSD. What this means is that if another thread calls open(2) during freopen() is executing that another thread's fd returned by open(2) may get re-associated with the file being passed to freopen(3). See FreeBSD PR number 79887 for reference: http://www.freebsd.org/cgi/query-pr.cgi?pr=79887 This problem is worked around by substituting a internal hook within the FILE structure. This avoids the loss of atomicity by not having the original fd closed before its duplicated. Patch based on the original work by Vasil Dimov.
This commit is contained in:
@ -664,6 +664,7 @@ extern void init_glob_errs(void);
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extern void wait_for_free_space(const char *filename, int errors);
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extern void wait_for_free_space(const char *filename, int errors);
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extern FILE *my_fopen(const char *FileName,int Flags,myf MyFlags);
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extern FILE *my_fopen(const char *FileName,int Flags,myf MyFlags);
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extern FILE *my_fdopen(File Filedes,const char *name, int Flags,myf MyFlags);
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extern FILE *my_fdopen(File Filedes,const char *name, int Flags,myf MyFlags);
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extern FILE *my_freopen(const char *path, const char *mode, FILE *stream);
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extern int my_fclose(FILE *fd,myf MyFlags);
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extern int my_fclose(FILE *fd,myf MyFlags);
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extern int my_chsize(File fd,my_off_t newlength, int filler, myf MyFlags);
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extern int my_chsize(File fd,my_off_t newlength, int filler, myf MyFlags);
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extern int my_sync(File fd, myf my_flags);
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extern int my_sync(File fd, myf my_flags);
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135
mysys/my_fopen.c
135
mysys/my_fopen.c
@ -18,6 +18,10 @@
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#include <errno.h>
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#include <errno.h>
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#include "mysys_err.h"
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#include "mysys_err.h"
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#if defined(__FreeBSD__)
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extern int getosreldate(void);
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#endif
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static void make_ftype(char * to,int flag);
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static void make_ftype(char * to,int flag);
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/*
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/*
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@ -97,8 +101,137 @@ FILE *my_fopen(const char *filename, int flags, myf MyFlags)
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} /* my_fopen */
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} /* my_fopen */
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/* Close a stream */
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#if defined(_WIN32)
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static FILE *my_win_freopen(const char *path, FILE *stream)
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{
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int handle_fd, fd= _fileno(stream);
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HANDLE osfh;
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DBUG_ASSERT(filename && stream);
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/* Services don't have stdout/stderr on Windows, so _fileno returns -1. */
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if (fd < 0)
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{
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if (!freopen(filename, mode, stream))
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return NULL;
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fd= _fileno(stream);
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}
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if ((osfh= CreateFile(path, GENERIC_READ | GENERIC_WRITE,
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FILE_SHARE_READ | FILE_SHARE_WRITE |
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FILE_SHARE_DELETE, NULL,
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OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL,
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NULL)) == INVALID_HANDLE_VALUE)
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return NULL;
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if ((handle_fd= _open_osfhandle((intptr_t)osfh,
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_O_APPEND | _O_TEXT)) == -1)
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{
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CloseHandle(osfh);
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return NULL;
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}
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if (_dup2(handle_fd, fd) < 0)
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{
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CloseHandle(osfh);
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return NULL;
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}
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_close(handle_fd);
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return stream;
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}
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#elif defined(__FreeBSD__)
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/* No close operation hook. */
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static int no_close(void *cookie __attribute__((unused)))
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{
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return 0;
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}
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/*
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A hack around a race condition in the implementation of freopen.
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The race condition steams from the fact that the current fd of
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the stream is closed before its number is used to duplicate the
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new file descriptor. This defeats the desired atomicity of the
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close and duplicate of dup2().
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See PR number 79887 for reference:
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http://www.freebsd.org/cgi/query-pr.cgi?pr=79887
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*/
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static FILE *my_freebsd_freopen(const char *path, const char *mode, FILE *stream)
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{
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int old_fd;
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FILE *result;
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flockfile(stream);
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old_fd= fileno(stream);
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/* Use a no operation close hook to avoid having the fd closed. */
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stream->_close= no_close;
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/* Relies on the implicit dup2 to close old_fd. */
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result= freopen(path, mode, stream);
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/* If successful, the _close hook was replaced. */
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if (result == NULL)
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close(old_fd);
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else
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funlockfile(result);
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return result;
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}
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#endif
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/**
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Change the file associated with a file stream.
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@param path Path to file.
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@param mode Mode of the stream.
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@param stream File stream.
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@note
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This function is used to redirect stdout and stderr to a file and
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subsequently to close and reopen that file for log rotation.
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@retval A FILE pointer on success. Otherwise, NULL.
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*/
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FILE *my_freopen(const char *path, const char *mode, FILE *stream)
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{
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FILE *result;
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#if defined(_WIN32)
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result= my_win_freopen(path, mode, stream);
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#elif defined(__FreeBSD__)
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/*
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XXX: Once the fix is ported to the stable releases, this should
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be dependent upon the specific FreeBSD versions. Check at:
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http://www.freebsd.org/cgi/query-pr.cgi?pr=79887
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*/
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if (getosreldate() > 900027)
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result= freopen(path, mode, stream);
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else
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result= my_freebsd_freopen(path, mode, stream);
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#else
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result= freopen(path, mode, stream);
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#endif
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return result;
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}
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/* Close a stream */
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int my_fclose(FILE *fd, myf MyFlags)
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int my_fclose(FILE *fd, myf MyFlags)
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{
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{
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int err,file;
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int err,file;
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76
sql/log.cc
76
sql/log.cc
@ -5171,80 +5171,26 @@ void sql_perror(const char *message)
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}
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}
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#ifdef __WIN__
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/*
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Change the file associated with two output streams. Used to
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redirect stdout and stderr to a file. The streams are reopened
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only for appending (writing at end of file).
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*/
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extern "C" my_bool reopen_fstreams(const char *filename,
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extern "C" my_bool reopen_fstreams(const char *filename,
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FILE *outstream, FILE *errstream)
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FILE *outstream, FILE *errstream)
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{
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{
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int handle_fd;
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if (outstream && !my_freopen(filename, "a", outstream))
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int err_fd, out_fd;
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return TRUE;
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HANDLE osfh;
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DBUG_ASSERT(filename && errstream);
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if (errstream && !my_freopen(filename, "a", errstream))
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return TRUE;
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// Services don't have stdout/stderr on Windows, so _fileno returns -1.
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err_fd= _fileno(errstream);
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if (err_fd < 0)
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{
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if (!freopen(filename, "a+", errstream))
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return TRUE;
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/* The error stream must be unbuffered. */
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if (errstream)
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setbuf(errstream, NULL);
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setbuf(errstream, NULL);
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err_fd= _fileno(errstream);
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}
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if (outstream)
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{
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out_fd= _fileno(outstream);
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if (out_fd < 0)
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{
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if (!freopen(filename, "a+", outstream))
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return TRUE;
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out_fd= _fileno(outstream);
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}
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}
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if ((osfh= CreateFile(filename, GENERIC_READ | GENERIC_WRITE,
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FILE_SHARE_READ | FILE_SHARE_WRITE |
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FILE_SHARE_DELETE, NULL,
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OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL,
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NULL)) == INVALID_HANDLE_VALUE)
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return TRUE;
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if ((handle_fd= _open_osfhandle((intptr_t)osfh,
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_O_APPEND | _O_TEXT)) == -1)
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{
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CloseHandle(osfh);
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return TRUE;
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}
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if (_dup2(handle_fd, err_fd) < 0)
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{
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CloseHandle(osfh);
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return TRUE;
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}
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if (outstream && _dup2(handle_fd, out_fd) < 0)
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{
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CloseHandle(osfh);
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return TRUE;
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}
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_close(handle_fd);
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return FALSE;
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}
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#else
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extern "C" my_bool reopen_fstreams(const char *filename,
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FILE *outstream, FILE *errstream)
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{
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if (outstream && !freopen(filename, "a+", outstream))
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return TRUE;
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if (errstream && !freopen(filename, "a+", errstream))
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return TRUE;
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return FALSE;
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return FALSE;
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}
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}
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#endif
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/*
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/*
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Reference in New Issue
Block a user