[dpkg] 170/187: dpkg: Do not fail when removing non-existent files on read-only filesystems

[Reiner Herrmann]

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deki-guest pushed a commit to branch master
in repository dpkg.

commit 4daaec6bb83c65bc7b83022dd241b5d6bbf83b86
Author: Guillem Jover <guillem at debian.org>
Date:   Fri Nov 4 05:28:26 2016 +0100

    dpkg: Do not fail when removing non-existent files on read-only filesystems
    
    Trying to rmdir(2) or unlink(2) a non-existent pathname on at least
    Linux returns with EROFS. Handle this case specifically to check if
    the pathname exists with access(2).
    
    Closes: #838877
---
 debian/changelog       | 2 ++
 lib/dpkg/path-remove.c | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index dbc88ce..6fcc881 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -67,6 +67,8 @@ dpkg (1.18.11) UNRELEASED; urgency=medium
     - Hook it into the dpkg-buildpackage machinery.
     Based on a patch by Jérémy Bobbio <lunar at debian.org>. Closes: #138409
   * Enable dpkg-buildpackage -Jauto by default. Closes: #842845
+  * Fix dpkg to not fail when removing non-existent backup files on read-only
+    filesystems. Closes: #838877
   * Architecture support:
     - Add support for AIX operating system.
     - Add a version pseudo-field to the arch tables.
diff --git a/lib/dpkg/path-remove.c b/lib/dpkg/path-remove.c
index 3086408..ab26b4a 100644
--- a/lib/dpkg/path-remove.c
+++ b/lib/dpkg/path-remove.c
@@ -137,6 +137,13 @@ path_remove_tree(const char *pathname)
 		if (errno == ENOTDIR)
 			return;
 	}
+	/* Trying to remove a directory or a file on a read-only filesystem,
+	 * even if non-existent, always returns EROFS. */
+	if (errno == EROFS) {
+		if (access(pathname, F_OK) < 0 && errno == ENOENT)
+			return;
+		errno = EROFS;
+	}
 	if (errno != ENOTEMPTY && errno != EEXIST) /* Huh? */
 		ohshite(_("unable to securely remove '%.255s'"), pathname);
 

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