diff --git a/src/backend/libpq/hba.c b/src/backend/libpq/hba.c
index 5991a21cf2..9f106653f3 100644
--- a/src/backend/libpq/hba.c
+++ b/src/backend/libpq/hba.c
@@ -502,33 +502,8 @@ tokenize_file(const char *filename, FILE *file, List **tok_lines, int elevel)
 		/* Collect the next input line, handling backslash continuations */
 		resetStringInfo(&buf);
 
-		while (!feof(file) && !ferror(file))
+		while (pg_get_line_append(file, &buf))
 		{
-			/* Make sure there's a reasonable amount of room in the buffer */
-			enlargeStringInfo(&buf, 128);
-
-			/* Read some data, appending it to what we already have */
-			if (fgets(buf.data + buf.len, buf.maxlen - buf.len, file) == NULL)
-			{
-				int			save_errno = errno;
-
-				if (!ferror(file))
-					break;		/* normal EOF */
-				/* I/O error! */
-				ereport(elevel,
-						(errcode_for_file_access(),
-						 errmsg("could not read file \"%s\": %m", filename)));
-				err_msg = psprintf("could not read file \"%s\": %s",
-								   filename, strerror(save_errno));
-				resetStringInfo(&buf);
-				break;
-			}
-			buf.len += strlen(buf.data + buf.len);
-
-			/* If we haven't got a whole line, loop to read more */
-			if (!(buf.len > 0 && buf.data[buf.len - 1] == '\n'))
-				continue;
-
 			/* Strip trailing newline, including \r in case we're on Windows */
 			buf.len = pg_strip_crlf(buf.data);
 
@@ -551,6 +526,19 @@ tokenize_file(const char *filename, FILE *file, List **tok_lines, int elevel)
 			break;
 		}
 
+		if (ferror(file))
+		{
+			/* I/O error! */
+			int			save_errno = errno;
+
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not read file \"%s\": %m", filename)));
+			err_msg = psprintf("could not read file \"%s\": %s",
+							   filename, strerror(save_errno));
+			break;
+		}
+
 		/* Parse fields */
 		lineptr = buf.data;
 		while (*lineptr && err_msg == NULL)
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 861b8817b9..37e0d7ceab 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -470,9 +470,9 @@ readfile(const char *path)
 {
 	char	  **result;
 	FILE	   *infile;
+	StringInfoData line;
 	int			maxlines;
 	int			n;
-	char	   *ln;
 
 	if ((infile = fopen(path, "r")) == NULL)
 	{
@@ -480,11 +480,13 @@ readfile(const char *path)
 		exit(1);
 	}
 
+	initStringInfo(&line);
+
 	maxlines = 1024;
 	result = (char **) pg_malloc(maxlines * sizeof(char *));
 
 	n = 0;
-	while ((ln = pg_get_line(infile)) != NULL)
+	while (pg_get_line_append(infile, &line))
 	{
 		/* make sure there will be room for a trailing NULL pointer */
 		if (n >= maxlines - 1)
@@ -493,10 +495,14 @@ readfile(const char *path)
 			result = (char **) pg_realloc(result, maxlines * sizeof(char *));
 		}
 
-		result[n++] = ln;
+		result[n++] = pg_strdup(line.data);
+
+		resetStringInfo(&line);
 	}
 	result[n] = NULL;
 
+	pfree(line.data);
+
 	fclose(infile);
 
 	return result;
diff --git a/src/common/pg_get_line.c b/src/common/pg_get_line.c
index 38433675d4..2fb8e19893 100644
--- a/src/common/pg_get_line.c
+++ b/src/common/pg_get_line.c
@@ -41,6 +41,11 @@
  * Note that while I/O errors are reflected back to the caller to be
  * dealt with, an OOM condition for the palloc'd buffer will not be;
  * there'll be an ereport(ERROR) or exit(1) inside stringinfo.c.
+ *
+ * Also note that the palloc'd buffer is usually a lot longer than
+ * strictly necessary, so it may be inadvisable to use this function
+ * to collect lots of long-lived data.  A less memory-hungry option
+ * is to use pg_get_line_append() in a loop, then pstrdup() each line.
  */
 char *
 pg_get_line(FILE *stream)
@@ -49,21 +54,7 @@ pg_get_line(FILE *stream)
 
 	initStringInfo(&buf);
 
-	/* Read some data, appending it to whatever we already have */
-	while (fgets(buf.data + buf.len, buf.maxlen - buf.len, stream) != NULL)
-	{
-		buf.len += strlen(buf.data + buf.len);
-
-		/* Done if we have collected a newline */
-		if (buf.len > 0 && buf.data[buf.len - 1] == '\n')
-			return buf.data;
-
-		/* Make some more room in the buffer, and loop to read more data */
-		enlargeStringInfo(&buf, 128);
-	}
-
-	/* Did fgets() fail because of an I/O error? */
-	if (ferror(stream))
+	if (!pg_get_line_append(stream, &buf))
 	{
 		/* ensure that free() doesn't mess up errno */
 		int			save_errno = errno;
@@ -73,13 +64,50 @@ pg_get_line(FILE *stream)
 		return NULL;
 	}
 
-	/* If we read no data before reaching EOF, we should return NULL */
-	if (buf.len == 0)
-	{
-		pfree(buf.data);
-		return NULL;
-	}
-
-	/* No newline at EOF ... so return what we have */
 	return buf.data;
 }
+
+/*
+ * pg_get_line_append()
+ *
+ * This has similar behavior to pg_get_line(), and thence to fgets(),
+ * except that the collected data is appended to whatever is in *buf.
+ *
+ * Returns true if a line was successfully collected (including the
+ * case of a non-newline-terminated line at EOF).  Returns false if
+ * there was an I/O error or no data was available before EOF.
+ * (Check ferror(stream) to distinguish these cases.)
+ *
+ * In the false-result case, the contents of *buf are logically unmodified,
+ * though it's possible that the buffer has been resized.
+ */
+bool
+pg_get_line_append(FILE *stream, StringInfo buf)
+{
+	int			orig_len = buf->len;
+
+	/* Read some data, appending it to whatever we already have */
+	while (fgets(buf->data + buf->len, buf->maxlen - buf->len, stream) != NULL)
+	{
+		buf->len += strlen(buf->data + buf->len);
+
+		/* Done if we have collected a newline */
+		if (buf->len > orig_len && buf->data[buf->len - 1] == '\n')
+			return true;
+
+		/* Make some more room in the buffer, and loop to read more data */
+		enlargeStringInfo(buf, 128);
+	}
+
+	/* Check for I/O errors and EOF */
+	if (ferror(stream) || buf->len == orig_len)
+	{
+		/* Discard any data we collected before detecting error */
+		buf->len = orig_len;
+		buf->data[orig_len] = '\0';
+		return false;
+	}
+
+	/* No newline at EOF, but we did collect some data */
+	return true;
+}
diff --git a/src/include/common/string.h b/src/include/common/string.h
index 18aa1dc5aa..50c241a811 100644
--- a/src/include/common/string.h
+++ b/src/include/common/string.h
@@ -10,6 +10,8 @@
 #ifndef COMMON_STRING_H
 #define COMMON_STRING_H
 
+struct StringInfoData;			/* avoid including stringinfo.h here */
+
 /* functions in src/common/string.c */
 extern bool pg_str_endswith(const char *str, const char *end);
 extern int	strtoint(const char *pg_restrict str, char **pg_restrict endptr,
@@ -19,6 +21,7 @@ extern int	pg_strip_crlf(char *str);
 
 /* functions in src/common/pg_get_line.c */
 extern char *pg_get_line(FILE *stream);
+extern bool pg_get_line_append(FILE *stream, struct StringInfoData *buf);
 
 /* functions in src/common/sprompt.c */
 extern char *simple_prompt(const char *prompt, bool echo);