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MDEV-38494 .mariadb_history rename race condition #4699

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Merged
vuvova merged 1 commit into from
Mar 18, 2026
Merged

MDEV-38494 .mariadb_history rename race condition #4699

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22 changes: 17 additions & 5 deletions client/mysql.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1441,13 +1441,25 @@ int main(int argc,char *argv[])
if (verbose)
tee_fprintf(stdout, "Reading history-file %s\n",histfile);
read_history(histfile);
if (!(histfile_tmp= (char*) my_malloc(PSI_NOT_INSTRUMENTED,
strlen(histfile) + 5, MYF(MY_WME))))
{
fprintf(stderr, "Couldn't allocate memory for temp histfile!\n");
exit(1);
/* Extra space for the suffix appended to histfile:
"." - separator (sizeof = 2, includes NUL)
+ PID - up to 20 digits (ULONG_MAX = 18446744073709551615)
+ ".TMP"- extension (sizeof = 5, includes NUL, doubles
as the string NUL terminator)
sizeof(".") and sizeof(".TMP") each carry a NUL, so the sum
over-allocates by one byte, which is intentional. */
size_t hlen= strlen(histfile) + sizeof(".") + 20 + sizeof(".TMP");
if (!(histfile_tmp= (char*) my_malloc(PSI_NOT_INSTRUMENTED, hlen, MYF(MY_WME))))
{
fprintf(stderr, "Couldn't allocate memory for temp histfile!\n");
exit(1);
}
/* Include PID in name to avoid rename collision when concurrent sessions exit. */
/* pid_t is signed but getpid() always returns a non-negative value (POSIX). */
snprintf(histfile_tmp, hlen, "%s.%lu.TMP", histfile,
(unsigned long) getpid());
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@grooverdan grooverdan Mar 18, 2026

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Need windows. From another area of code:

IF_WIN(GetCurrentProcessId(), getpid()))

create_temp_file (from mysys/mf_tempfile.c) might be a more portable way.

}
sprintf(histfile_tmp, "%s.TMP", histfile);
}
}

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