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Code and docs review for multiple -c and -f options in psql. 

Commit d5563d7df9 drew complaints from Coverity, which quite
correctly complained that one copy of each -c or -f string was being
leaked.  What's more, simple_action_list_append was allocating enough space
for still a third copy of each string as part of the SimpleActionListCell,
even though that coding method had been superseded by a separate strdup
operation.  There were some other minor coding infelicities too.  The
documentation needed more work as well, eg it forgot to explain that -c
causes psql not to accept any interactive input.
This commit is contained in:
Tom Lane 2015-12-13 14:52:07 -05:00
parent a91bdf67c4
commit fcbbf82d2b
2 changed files with 121 additions and 112 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

140
doc/src/sgml/ref/psql-ref.sgml
View File

@ -39,9 +39,9 @@ PostgreSQL documentation
queries interactively, issue them to
<productname>PostgreSQL</productname>, and see the query results.
Alternatively, input can be from a file or from command line
arguments. In addition, it provides a number of meta-commands and various
shell-like features to facilitate writing scripts and automating a wide
variety of tasks.
arguments. In addition, <application>psql</application> provides a
number of meta-commands and various shell-like features to
facilitate writing scripts and automating a wide variety of tasks.
</para>
</refsect1>
@ -90,42 +90,50 @@ PostgreSQL documentation
<term><option>--command=<replaceable class="parameter">command</replaceable></></term>
<listitem>
<para>
Specifies that <application>psql</application> is to execute the given
command string, <replaceable class="parameter">command</replaceable>.
This option can be repeated and combined in any order with
the <option>-f</option> option.
Specifies that <application>psql</application> is to execute the given
command string, <replaceable class="parameter">command</replaceable>.
This option can be repeated and combined in any order with
the <option>-f</option> option. When either <option>-c</option>
or <option>-f</option> is specified, <application>psql</application>
does not read commands from standard input; instead it terminates
after processing all the <option>-c</option> and <option>-f</option>
options in sequence.
</para>
<para>
<replaceable class="parameter">command</replaceable> must be either
a command string that is completely parsable by the server (i.e.,
it contains no <application>psql</application>-specific features),
or a single backslash command. Thus you cannot mix
<acronym>SQL</acronym> and <application>psql</application>
meta-commands with this option. To achieve that, you could
use repeated <option>-c</option> options or pipe the string
into <application>psql</application>, for example:
<literal>psql -c '\x' -c 'SELECT * FROM foo;'</literal> or
<literal>echo '\x \\ SELECT * FROM foo;' | psql</literal>.
(<literal>\\</> is the separator meta-command.)
<replaceable class="parameter">command</replaceable> must be either
a command string that is completely parsable by the server (i.e.,
it contains no <application>psql</application>-specific features),
or a single backslash command. Thus you cannot mix
<acronym>SQL</acronym> and <application>psql</application>
meta-commands within a <option>-c</option> option. To achieve that,
you could use repeated <option>-c</option> options or pipe the string
into <application>psql</application>, for example:
<programlisting>
psql -c '\x' -c 'SELECT * FROM foo;'
</programlisting>
or
<programlisting>
echo '\x \\ SELECT * FROM foo;' | psql
</programlisting>
(<literal>\\</> is the separator meta-command.)
</para>
<para>
Each command string passed to <option>-c</option> is sent to the server
as a single query. Because of this, the server executes it as a single
transaction, even if a command string contains
multiple <acronym>SQL</acronym> commands, unless there are
explicit <command>BEGIN</>/<command>COMMIT</> commands included in the
string to divide it into multiple transactions. Also, the server only
returns the result of the last <acronym>SQL</acronym> command to the
client. This is different from the behavior when the same string with
multiple <acronym>SQL</acronym> commands is fed
to <application>psql</application>'s standard input because
then <application>psql</application> sends each <acronym>SQL</acronym>
command separately.
Each <acronym>SQL</acronym> command string passed
to <option>-c</option> is sent to the server as a single query.
Because of this, the server executes it as a single transaction even
if the string contains multiple <acronym>SQL</acronym> commands,
unless there are explicit <command>BEGIN</>/<command>COMMIT</>
commands included in the string to divide it into multiple
transactions. Also, <application>psql</application> only prints the
result of the last <acronym>SQL</acronym> command in the string.
This is different from the behavior when the same string is read from
a file or fed to <application>psql</application>'s standard input,
because then <application>psql</application> sends
each <acronym>SQL</acronym> command separately.
</para>
<para>
Putting more than one command in the <option>-c</option> string often
has unexpected results. This is a result of the fact that the whole
string is sent to the server as a single query.
Because of this behavior, putting more than one command in a
single <option>-c</option> string often has unexpected results.
It's better to use repeated <option>-c</option> commands or feed
multiple commands to <application>psql</application>'s standard input,
either using <application>echo</application> as illustrated above, or
@ -192,18 +200,26 @@ EOF
<term><option>--file=<replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Use the file <replaceable class="parameter">filename</replaceable>
as the source of commands instead of reading commands interactively.
This option can be repeated and combined in any order with
the <option>-c</option> option. After the commands in
every <option>-c</option> command string and <option>-f</option> file
are processed, <application>psql</application> terminates. This option
is in many ways equivalent to the meta-command <command>\i</command>.
Read commands from the
file <replaceable class="parameter">filename</replaceable>,
rather than standard input.
This option can be repeated and combined in any order with
the <option>-c</option> option. When either <option>-c</option>
or <option>-f</option> is specified, <application>psql</application>
does not read commands from standard input; instead it terminates
after processing all the <option>-c</option> and <option>-f</option>
options in sequence.
Except for that, this option is largely equivalent to the
meta-command <command>\i</command>.
</para>
<para>
If <replaceable>filename</replaceable> is <literal>-</literal>
(hyphen), then standard input is read.
(hyphen), then standard input is read until an EOF indication
or <command>\q</> meta-command. This can be used to intersperse
interactive input with input from files. Note however that Readline
is not used in this case (much as if <option>-n</option> had been
specified).
</para>
<para>
@ -550,12 +566,13 @@ EOF
<term><option>--single-transaction</option></term>
<listitem>
<para>
When <application>psql</application> executes commands from a script
and/or a <option>-c</option> option, adding this option
wraps <command>BEGIN</>/<command>COMMIT</> around all of those
commands as a whole to execute them as a single transaction. This
ensures that either all the commands complete successfully, or no
changes are applied.
This option can only be used in combination with one or more
<option>-c</option> and/or <option>-f</option> options. It causes
<application>psql</application> to issue a <command>BEGIN</> command
before the first such option and a <command>COMMIT</> command after
the last one, thereby wrapping all the commands into a single
transaction. This ensures that either all the commands complete
successfully, or no changes are applied.
</para>
<para>
@ -3799,16 +3816,6 @@ PSQL_EDITOR_LINENUMBER_ARG='--line '
<title>Notes</title>
<itemizedlist>
<listitem>
<para>
In an earlier life <application>psql</application> allowed the
first argument of a single-letter backslash command to start
directly after the command, without intervening whitespace.
As of <productname>PostgreSQL</productname> 8.4 this is no
longer allowed.
</para>
</listitem>
<listitem>
<para><application>psql</application> works best with servers of the same
or an older major version. Backslash commands are particularly likely
@ -3824,8 +3831,8 @@ PSQL_EDITOR_LINENUMBER_ARG='--line '
If you want to use <application>psql</application> to connect to several
servers of different major versions, it is recommended that you use the
newest version of <application>psql</application>. Alternatively, you
can keep a copy of <application>psql</application> from each major
version around and be sure to use the version that matches the
can keep around a copy of <application>psql</application> from each
major version and be sure to use the version that matches the
respective server. But in practice, this additional complication should
not be necessary.
</para>
@ -3833,8 +3840,19 @@ PSQL_EDITOR_LINENUMBER_ARG='--line '
<listitem>
<para>
Before <productname>PostgreSQL</productname> 9.6, <option>-c</option>
implied <option>-X</option>; this is no longer the case.
Before <productname>PostgreSQL</productname> 9.6,
the <option>-c</option> option implied <option>-X</option>
(<option>--no-psqlrc</>); this is no longer the case.
</para>
</listitem>
<listitem>
<para>
Before <productname>PostgreSQL</productname> 8.4,
<application>psql</application> allowed the
first argument of a single-letter backslash command to start
directly after the command, without intervening whitespace.
Now, some whitespace is required.
</para>
</listitem>
</itemizedlist>

93
src/bin/psql/startup.c
View File

@ -58,8 +58,8 @@ enum _actions
typedef struct SimpleActionListCell
{
struct SimpleActionListCell *next;
int action;
char *val;
enum _actions action;
char *val;
} SimpleActionListCell;
typedef struct SimpleActionList
@ -84,11 +84,11 @@ struct adhoc_opts
static void parse_psql_options(int argc, char *argv[],
struct adhoc_opts * options);
static void simple_action_list_append(SimpleActionList *list,
enum _actions action, const char *val);
static void process_psqlrc(char *argv0);
static void process_psqlrc_file(char *filename);
static void showVersion(void);
static void simple_action_list_append(SimpleActionList *list,
int action, const char *val);
static void EstablishVariableSpace(void);
#define NOPAGER 0
@ -172,9 +172,6 @@ main(int argc, char *argv[])
SetVariable(pset.vars, "PROMPT2", DEFAULT_PROMPT2);
SetVariable(pset.vars, "PROMPT3", DEFAULT_PROMPT3);
options.actions.head = NULL;
options.actions.tail = NULL;
parse_psql_options(argc, argv, &options);
/*
@ -298,13 +295,13 @@ main(int argc, char *argv[])
process_psqlrc(argv[0]);
/*
* If any actions were given by caller, process them in the order in
* which they were specified.
* If any actions were given by user, process them in the order in which
* they were specified. Note single_txn is only effective in this mode.
*/
if (options.actions.head != NULL)
{
PGresult *res;
SimpleActionListCell *cell;
PGresult *res;
SimpleActionListCell *cell;
successResult = EXIT_SUCCESS; /* silence compiler */
@ -341,8 +338,8 @@ main(int argc, char *argv[])
scan_state = psql_scan_create();
psql_scan_setup(scan_state,
cell->val,
strlen(cell->val));
cell->val,
strlen(cell->val));
successResult = HandleSlashCmds(scan_state, NULL) != PSQL_CMD_ERROR
? EXIT_SUCCESS : EXIT_FAILURE;
@ -356,7 +353,7 @@ main(int argc, char *argv[])
else
{
/* should never come here */
Assert(0);
Assert(false);
}
if (successResult != EXIT_SUCCESS && pset.on_error_stop)
@ -473,11 +470,11 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts * options)
if (optarg[0] == '\\')
simple_action_list_append(&options->actions,
ACT_SINGLE_SLASH,
pstrdup(optarg + 1));
optarg + 1);
else
simple_action_list_append(&options->actions,
ACT_SINGLE_QUERY,
pstrdup(optarg));
optarg);
break;
case 'd':
options->dbname = pg_strdup(optarg);
@ -490,8 +487,8 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts * options)
break;
case 'f':
simple_action_list_append(&options->actions,
ACT_FILE,
pg_strdup(optarg));
ACT_FILE,
optarg);
break;
case 'F':
pset.popt.topt.fieldSep.separator = pg_strdup(optarg);
@ -672,6 +669,33 @@ parse_psql_options(int argc, char *argv[], struct adhoc_opts * options)
}
/*
* Append a new item to the end of the SimpleActionList.
* Note that "val" is copied if it's not NULL.
*/
static void
simple_action_list_append(SimpleActionList *list,
enum _actions action, const char *val)
{
SimpleActionListCell *cell;
cell = (SimpleActionListCell *) pg_malloc(sizeof(SimpleActionListCell));
cell->next = NULL;
cell->action = action;
if (val)
cell->val = pg_strdup(val);
else
cell->val = NULL;
if (list->tail)
list->tail->next = cell;
else
list->head = cell;
list->tail = cell;
}
/*
* Load .psqlrc file, if found.
*/
@ -945,39 +969,6 @@ show_context_hook(const char *newval)
}
/*
* Support for list of actions. SimpleStringList cannot be used due possible
* combination different actions with the requirement to save the order.
*/
static void
simple_action_list_append(SimpleActionList *list, int action, const char *val)
{
SimpleActionListCell *cell;
size_t vallen = 0;
if (val)
vallen = strlen(val);
cell = (SimpleActionListCell *)
pg_malloc(offsetof(SimpleActionListCell, val) + vallen + 1);
cell->next = NULL;
cell->action = action;
if (val)
{
cell->val = pg_malloc(vallen + 1);
strcpy(cell->val, val);
}
else
cell->val = NULL;
if (list->tail)
list->tail->next = cell;
else
list->head = cell;
list->tail = cell;
}
static void
EstablishVariableSpace(void)
{