Clean up psql's control-C handling to avoid longjmp'ing out of random

places --- that risks corrupting data structures, losing sync with the
backend, etc.  We now longjmp only from calls to readline, fgets, and
fread, which we assume are coded to protect themselves against interrupts
at undesirable times.  This requires adding explicit tests for
cancel_pressed in long-running loops, but on the whole it's far cleaner.
Martijn van Oosterhout and Tom Lane.

src/bin/psql/input.c

@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2000-2006, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/psql/input.c,v 1.54 2006/06/11 23:06:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/bin/psql/input.c,v 1.55 2006/06/14 16:49:02 tgl Exp $
  */
 #include "postgres_fe.h"
 
@@ -82,7 +82,9 @@ GetHistControlConfig(void)
  * gets_interactive()
  *
  * Gets a line of interactive input, using readline if desired.
- * The result is malloc'ed.
+ * The result is a malloc'd string.
+ *
+ * Caller *must* have set up sigint_interrupt_jmp before calling.
  */
 char *
 gets_interactive(const char *prompt)
@@ -90,8 +92,18 @@ gets_interactive(const char *prompt)
 #ifdef USE_READLINE
 	if (useReadline)
 	{
+		char   *result;
+
+		/* Enable SIGINT to longjmp to sigint_interrupt_jmp */
+		sigint_interrupt_enabled = true;
+
 		/* On some platforms, readline is declared as readline(char *) */
-		return readline((char *) prompt);
+		result = readline((char *) prompt);
+
+		/* Disable SIGINT again */
+		sigint_interrupt_enabled = false;
+
+		return result;
 	}
 #endif
 
@@ -169,30 +181,56 @@ pg_send_history(PQExpBuffer history_buf)
  * gets_fromFile
  *
  * Gets a line of noninteractive input from a file (which could be stdin).
+ * The result is a malloc'd string.
+ *
+ * Caller *must* have set up sigint_interrupt_jmp before calling.
+ *
+ * Note: we re-use a static PQExpBuffer for each call.  This is to avoid
+ * leaking memory if interrupted by SIGINT.
  */
 char *
 gets_fromFile(FILE *source)
 {
-	PQExpBufferData buffer;
+	static PQExpBuffer buffer = NULL;
+
 	char		line[1024];
 
-	initPQExpBuffer(&buffer);
+	if (buffer == NULL)			/* first time through? */
+		buffer = createPQExpBuffer();
+	else
+		resetPQExpBuffer(buffer);
 
-	while (fgets(line, sizeof(line), source) != NULL)
+	for (;;)
 	{
-		appendPQExpBufferStr(&buffer, line);
-		if (buffer.data[buffer.len - 1] == '\n')
+		char   *result;
+
+		/* Enable SIGINT to longjmp to sigint_interrupt_jmp */
+		sigint_interrupt_enabled = true;
+
+		/* Get some data */
+		result = fgets(line, sizeof(line), source);
+
+		/* Disable SIGINT again */
+		sigint_interrupt_enabled = false;
+
+		/* EOF? */
+		if (result == NULL)
+			break;
+
+		appendPQExpBufferStr(buffer, line);
+
+		/* EOL? */
+		if (buffer->data[buffer->len - 1] == '\n')
 		{
-			buffer.data[buffer.len - 1] = '\0';
-			return buffer.data;
+			buffer->data[buffer->len - 1] = '\0';
+			return pg_strdup(buffer->data);
 		}
 	}
 
-	if (buffer.len > 0)
-		return buffer.data;		/* EOF after reading some bufferload(s) */
+	if (buffer->len > 0)		/* EOF after reading some bufferload(s) */
+		return pg_strdup(buffer->data);
 
 	/* EOF, so return null */
-	termPQExpBuffer(&buffer);
 	return NULL;
 }