Change ps_status.c to explicitly track the current logical length of ps_buffer.
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
parent
2175d4fa59
commit
ede5072676
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@ -5,7 +5,7 @@
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* to contain some useful information. Mechanism differs wildly across
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* platforms.
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*
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* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.40 2010/01/02 16:57:58 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.41 2010/05/27 19:19:38 tgl Exp $
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*
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* Copyright (c) 2000-2010, PostgreSQL Global Development Group
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* various details abducted from various places
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@ -51,7 +51,7 @@ bool update_process_title = true;
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* (some other BSD systems)
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* PS_USE_CLOBBER_ARGV
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* write over the argv and environment area
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* (most SysV-like systems)
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* (Linux and most SysV-like systems)
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* PS_USE_WIN32
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* push the string out as the name of a Windows event
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* PS_USE_NONE
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@ -84,7 +84,7 @@ bool update_process_title = true;
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#ifndef PS_USE_CLOBBER_ARGV
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/* all but one options need a buffer to write their ps line in */
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/* all but one option need a buffer to write their ps line in */
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#define PS_BUFFER_SIZE 256
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static char ps_buffer[PS_BUFFER_SIZE];
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static const size_t ps_buffer_size = PS_BUFFER_SIZE;
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@ -94,6 +94,8 @@ static size_t ps_buffer_size; /* space determined at run time */
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static size_t last_status_len; /* use to minimize length of clobber */
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#endif /* PS_USE_CLOBBER_ARGV */
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static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
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static size_t ps_buffer_fixed_size; /* size of the constant prefix */
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/* save the original argv[] location here */
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@ -226,6 +228,7 @@ init_ps_display(const char *username, const char *dbname,
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/* no ps display if you didn't call save_ps_display_args() */
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if (!save_argv)
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return;
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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@ -270,7 +273,7 @@ init_ps_display(const char *username, const char *dbname,
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username, dbname, host_info);
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#endif
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ps_buffer_fixed_size = strlen(ps_buffer);
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ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
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set_ps_display(initial_str, true);
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#endif /* not PS_USE_NONE */
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@ -285,11 +288,11 @@ init_ps_display(const char *username, const char *dbname,
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void
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set_ps_display(const char *activity, bool force)
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{
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#ifndef PS_USE_NONE
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/* update_process_title=off disables updates, unless force = true */
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if (!force && !update_process_title)
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return;
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#ifndef PS_USE_NONE
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/* no ps display for stand-alone backend */
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if (!IsUnderPostmaster)
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return;
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@ -303,6 +306,7 @@ set_ps_display(const char *activity, bool force)
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/* Update ps_buffer to contain both fixed part and activity */
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strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
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ps_buffer_size - ps_buffer_fixed_size);
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ps_buffer_cur_len = strlen(ps_buffer);
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/* Transmit new setting to kernel, if necessary */
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@ -315,7 +319,7 @@ set_ps_display(const char *activity, bool force)
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union pstun pst;
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pst.pst_command = ps_buffer;
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pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
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pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
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}
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#endif /* PS_USE_PSTAT */
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@ -325,16 +329,11 @@ set_ps_display(const char *activity, bool force)
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#endif /* PS_USE_PS_STRINGS */
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#ifdef PS_USE_CLOBBER_ARGV
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{
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int buflen;
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/* pad unused memory */
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buflen = strlen(ps_buffer);
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/* clobber remainder of old status string */
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if (last_status_len > buflen)
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MemSet(ps_buffer + buflen, PS_PADDING, last_status_len - buflen);
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last_status_len = buflen;
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}
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/* pad unused memory; need only clobber remainder of old status string */
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if (last_status_len > ps_buffer_cur_len)
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MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
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last_status_len - ps_buffer_cur_len);
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last_status_len = ps_buffer_cur_len;
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#endif /* PS_USE_CLOBBER_ARGV */
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#ifdef PS_USE_WIN32
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@ -369,24 +368,15 @@ const char *
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get_ps_display(int *displen)
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{
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#ifdef PS_USE_CLOBBER_ARGV
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size_t offset;
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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{
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*displen = 0;
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return "";
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}
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/* Remove any trailing spaces to offset the effect of PS_PADDING */
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offset = ps_buffer_size;
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while (offset > ps_buffer_fixed_size && ps_buffer[offset - 1] == PS_PADDING)
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offset--;
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*displen = offset - ps_buffer_fixed_size;
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#else
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*displen = strlen(ps_buffer + ps_buffer_fixed_size);
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#endif
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*displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
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return ps_buffer + ps_buffer_fixed_size;
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}
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