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

tglsfdc · tglsfdc · commit fcbbf82d2b6c · 2015-12-13T14:52:07.000-05:00
Commit d5563d7 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for still a third copy of each string as part of the SimpleActionListCell, even though that coding method had been superseded by a separate strdup operation.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.
diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
@@ -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
@@ -3824,17 +3831,28 @@ 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>
       </listitem>
 
       <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>
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
@@ -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)
 {
