From 93c301fc4ff7d4f06bff98fea8db47ce67f28155 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 8 Apr 2016 12:31:42 -0400
Subject: [PATCH] Fix multiple bugs in tablespace symlink removal.
Don't try to examine S_ISLNK(st.st_mode) after a failed lstat().
It's undefined.
Also, if the lstat() reported ENOENT, we do not wish that to be a hard
error, but the code might nonetheless treat it as one (giving an entirely
misleading error message, too) depending on luck-of-the-draw as to what
S_ISLNK() returned.
Don't throw error for ENOENT from rmdir(), either. (We're not really
expecting ENOENT because we just stat'd the file successfully; but
if we're going to allow ENOENT in the symlink code path, surely the
directory code path should too.)
Generate an appropriate errcode for its-the-wrong-type-of-file complaints.
(ERRCODE_SYSTEM_ERROR doesn't seem appropriate, and failing to write
errcode() around it certainly doesn't work, and not writing an errcode
at all is not per project policy.)
Valgrind noticed the undefined S_ISLNK result; the other problems emerged
while reading the code in the area.
All of this appears to have been introduced in 8f15f74a44f68f9c.
Back-patch to 9.5 where that commit appeared.
---
src/backend/commands/tablespace.c | 32 ++++++++++++++++++++++---------
1 file changed, 23 insertions(+), 9 deletions(-)
diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index 1ff57285e59..7902d433d55 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -773,13 +773,26 @@ destroy_tablespace_directories(Oid tablespaceoid, bool redo)
remove_symlink:
linkloc = pstrdup(linkloc_with_version_dir);
get_parent_directory(linkloc);
- if (lstat(linkloc, &st) == 0 && S_ISDIR(st.st_mode))
+ if (lstat(linkloc, &st) < 0)
+ {
+ int saved_errno = errno;
+
+ ereport(redo ? LOG : (saved_errno == ENOENT ? WARNING : ERROR),
+ (errcode_for_file_access(),
+ errmsg("could not stat file \"%s\": %m",
+ linkloc)));
+ }
+ else if (S_ISDIR(st.st_mode))
{
if (rmdir(linkloc) < 0)
- ereport(redo ? LOG : ERROR,
+ {
+ int saved_errno = errno;
+
+ ereport(redo ? LOG : (saved_errno == ENOENT ? WARNING : ERROR),
(errcode_for_file_access(),
errmsg("could not remove directory \"%s\": %m",
linkloc)));
+ }
}
#ifdef S_ISLNK
else if (S_ISLNK(st.st_mode))
@@ -799,7 +812,7 @@ remove_symlink:
{
/* Refuse to remove anything that's not a directory or symlink */
ereport(redo ? LOG : ERROR,
- (ERRCODE_SYSTEM_ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("\"%s\" is not a directory or symbolic link",
linkloc)));
}
@@ -851,7 +864,7 @@ remove_tablespace_symlink(const char *linkloc)
{
struct stat st;
- if (lstat(linkloc, &st) != 0)
+ if (lstat(linkloc, &st) < 0)
{
if (errno == ENOENT)
return;
@@ -863,10 +876,10 @@ remove_tablespace_symlink(const char *linkloc)
if (S_ISDIR(st.st_mode))
{
/*
- * This will fail if the directory isn't empty, but not
- * if it's a junction point.
+ * This will fail if the directory isn't empty, but not if it's a
+ * junction point.
*/
- if (rmdir(linkloc) < 0)
+ if (rmdir(linkloc) < 0 && errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not remove directory \"%s\": %m",
@@ -878,7 +891,7 @@ remove_tablespace_symlink(const char *linkloc)
if (unlink(linkloc) < 0 && errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
- errmsg("could not remove symbolic link \"%s\": %m",
+ errmsg("could not remove symbolic link \"%s\": %m",
linkloc)));
}
#endif
@@ -886,7 +899,8 @@ remove_tablespace_symlink(const char *linkloc)
{
/* Refuse to remove anything that's not a directory or symlink */
ereport(ERROR,
- (errmsg("\"%s\" is not a directory or symbolic link",
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("\"%s\" is not a directory or symbolic link",
linkloc)));
}
}
--
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