mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2024-12-21 08:29:39 +08:00
Code Issues Packages Projects Releases Wiki Activity

Change ps_status.c to explicitly track the current logical length of ps_buffer.

Browse Source 
This saves cycles in get_ps_display() on many popular platforms, and more
importantly ensures that get_ps_display() will correctly return an empty
string if init_ps_display() hasn't been called yet.  Per trouble report
from Ray Stell, in which log_line_prefix %i produced junk early in backend
startup.

Back-patch to 8.0.  7.4 doesn't have %i and its version of get_ps_display()
makes no pretense of avoiding pad junk anyhow.
This commit is contained in:
Tom Lane 2010-05-27 19:19:58 +00:00
parent dcb7b4a32e
commit b723b17008
1 changed files with 20 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
src/backend/utils/misc/ps_status.c
View File

@ -5,7 +5,7 @@
* to contain some useful information. Mechanism differs wildly across
* platforms.
*
* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.33.2.1 2008/01/31 09:21:22 mha Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.33.2.2 2010/05/27 19:19:58 tgl Exp $
*
* Copyright (c) 2000-2006, PostgreSQL Global Development Group
* various details abducted from various places
@ -51,7 +51,7 @@ bool update_process_title = true;
* (some other BSD systems)
* PS_USE_CLOBBER_ARGV
* write over the argv and environment area
* (most SysV-like systems)
* (Linux and most SysV-like systems)
* PS_USE_WIN32
* push the string out as the name of a Windows event
* PS_USE_NONE
@ -84,15 +84,18 @@ bool update_process_title = true;
#ifndef PS_USE_CLOBBER_ARGV
/* all but one options need a buffer to write their ps line in */
/* all but one option need a buffer to write their ps line in */
#define PS_BUFFER_SIZE 256
static char ps_buffer[PS_BUFFER_SIZE];
static const size_t ps_buffer_size = PS_BUFFER_SIZE;
#else /* PS_USE_CLOBBER_ARGV */
static char *ps_buffer; /* will point to argv area */
static size_t ps_buffer_size; /* space determined at run time */
static size_t last_status_len; /* use to minimize length of clobber */
#endif /* PS_USE_CLOBBER_ARGV */
static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
static size_t ps_buffer_fixed_size; /* size of the constant prefix */
/* save the original argv[] location here */
@ -153,7 +156,7 @@ save_ps_display_args(int argc, char **argv)
}
ps_buffer = argv[0];
ps_buffer_size = end_of_area - argv[0];
last_status_len = ps_buffer_size = end_of_area - argv[0];
/*
* move the environment out of the way
@ -225,6 +228,7 @@ init_ps_display(const char *username, const char *dbname,
/* no ps display if you didn't call save_ps_display_args() */
if (!save_argv)
return;
#ifdef PS_USE_CLOBBER_ARGV
/* If ps_buffer is a pointer, it might still be null */
if (!ps_buffer)
@ -269,7 +273,7 @@ init_ps_display(const char *username, const char *dbname,
username, dbname, host_info);
#endif
ps_buffer_fixed_size = strlen(ps_buffer);
ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
set_ps_display(initial_str, true);
#endif /* not PS_USE_NONE */
@ -284,11 +288,11 @@ init_ps_display(const char *username, const char *dbname,
void
set_ps_display(const char *activity, bool force)
{
#ifndef PS_USE_NONE
/* update_process_title=off disables updates, unless force = true */
if (!force && !update_process_title)
return;
#ifndef PS_USE_NONE
/* no ps display for stand-alone backend */
if (!IsUnderPostmaster)
return;
@ -302,6 +306,7 @@ set_ps_display(const char *activity, bool force)
/* Update ps_buffer to contain both fixed part and activity */
strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
ps_buffer_size - ps_buffer_fixed_size);
ps_buffer_cur_len = strlen(ps_buffer);
/* Transmit new setting to kernel, if necessary */
@ -314,7 +319,7 @@ set_ps_display(const char *activity, bool force)
union pstun pst;
pst.pst_command = ps_buffer;
pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
}
#endif /* PS_USE_PSTAT */
@ -324,13 +329,11 @@ set_ps_display(const char *activity, bool force)
#endif /* PS_USE_PS_STRINGS */
#ifdef PS_USE_CLOBBER_ARGV
{
int buflen;
/* pad unused memory */
buflen = strlen(ps_buffer);
MemSet(ps_buffer + buflen, PS_PADDING, ps_buffer_size - buflen);
}
/* pad unused memory; need only clobber remainder of old status string */
if (last_status_len > ps_buffer_cur_len)
MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
last_status_len - ps_buffer_cur_len);
last_status_len = ps_buffer_cur_len;
#endif /* PS_USE_CLOBBER_ARGV */
#ifdef PS_USE_WIN32
@ -365,24 +368,15 @@ const char *
get_ps_display(int *displen)
{
#ifdef PS_USE_CLOBBER_ARGV
size_t offset;
/* If ps_buffer is a pointer, it might still be null */
if (!ps_buffer)
{
*displen = 0;
return "";
}
/* Remove any trailing spaces to offset the effect of PS_PADDING */
offset = ps_buffer_size;
while (offset > ps_buffer_fixed_size && ps_buffer[offset - 1] == PS_PADDING)
offset--;
*displen = offset - ps_buffer_fixed_size;
#else
*displen = strlen(ps_buffer + ps_buffer_fixed_size);
#endif
*displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
return ps_buffer + ps_buffer_fixed_size;
}