[2800] in BarnOwl Developers
[PATCH 2/2] Fixed :unsub to make it work if ~/.zephyr.subs is a symlink (trac 133)
daemon@ATHENA.MIT.EDU (Jason Gross)
Wed Nov 17 02:20:58 2010
From: Jason Gross <jgross@MIT.EDU>
To: barnowl-dev@mit.edu
Date: Wed, 17 Nov 2010 02:18:48 -0500
In-Reply-To: <1289978328-29504-2-git-send-email-jgross@mit.edu>
link() fails on AFS if the target is a symlink. Additionally, on
systems where link() succeeds, barnowl overwrites the symlink, instead
of the actual file. To fix this, I've changed owl_util_file_deleteline
to resolve symlinks on the passed file name first. The new (backup)
file is written in the resolved directory, not the directory where the
symlink itself is found.
A helper function, owl_util_recursive_resolve_link, is added to
recursivly resolve symlinks (if necessary).
---
util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 48 insertions(+), 8 deletions(-)
diff --git a/util.c b/util.c
index bc442cb..bd842df 100644
--- a/util.c
+++ b/util.c
@@ -6,7 +6,9 @@
#include <pwd.h>
#include <sys/stat.h>
#include <sys/types.h>
-
+#include <assert.h>
+#include <glib.h>
+#include <glib/gstdio.h>
#include <glib-object.h>
char **atokenize(const char *buffer, const char *sep, int *i)
@@ -375,6 +377,34 @@ char *owl_util_stripnewlines(const char *in)
return(out);
}
+
+/* If filename is a link, recursively resolve symlinks. Otherwise, return the filename
+ * unchanged. On error, call owl_function_error and return NULL.
+ *
+ * This function assumes that filename eventually resolves to an acutal file.
+ * If you want to check this, you should stat() the file first.
+ *
+ * The caller of this function is responsible for freeing the return value.
+ *
+ * Error conditions are the same as g_file_read_link.
+ */
+gchar *owl_util_recursive_resolve_link(const char *filename)
+{
+ gchar *last_filename = g_strdup(filename);
+ GError *err = NULL;
+ while (last_filename != NULL && g_file_test(last_filename, G_FILE_TEST_IS_SYMLINK)) {
+ gchar *cur_filename = g_file_read_link(last_filename, &err);
+ g_free(last_filename);
+ last_filename = cur_filename;
+ }
+ if (last_filename == NULL) {
+ owl_function_error("Cannot resolve symlinked file %s: %s",
+ filename, err->message);
+ g_error_free(err);
+ }
+ return last_filename;
+}
+
/* Delete all lines matching "line" from the named file. If no such
* line is found the file is left intact. If backup==1 then leave a
* backup file containing the original contents. The match is
@@ -385,6 +415,7 @@ char *owl_util_stripnewlines(const char *in)
int owl_util_file_deleteline(const char *filename, const char *line, int backup)
{
char *backupfile, *newfile, *buf = NULL;
+ gchar *actual_filename; /* gchar; we need to g_free it */
FILE *old, *new;
struct stat st;
int numremoved = 0;
@@ -400,22 +431,29 @@ int owl_util_file_deleteline(const char *filename, const char *line, int backup)
return -1;
}
- newfile = owl_sprintf("%s.new", filename);
+ /* resolve symlinks, because link() fails on symlinks, at least on AFS */
+ actual_filename = owl_util_recursive_resolve_link(filename);
+ if (actual_filename == NULL)
+ return -1; /* resolving the symlink failed, but we already logged this error */
+
+ newfile = owl_sprintf("%s.new", actual_filename);
if ((new = fopen(newfile, "w")) == NULL) {
owl_function_error("Cannot open %s (for writing): %s",
- filename, strerror(errno));
+ actual_filename, strerror(errno));
owl_free(newfile);
fclose(old);
+ free(actual_filename);
return -1;
}
if (fchmod(fileno(new), st.st_mode & 0777) != 0) {
owl_function_error("Cannot set permissions on %s: %s",
- filename, strerror(errno));
+ actual_filename, strerror(errno));
unlink(newfile);
fclose(new);
owl_free(newfile);
fclose(old);
+ free(actual_filename);
return -1;
}
@@ -430,9 +468,9 @@ int owl_util_file_deleteline(const char *filename, const char *line, int backup)
fclose(old);
if (backup) {
- backupfile = owl_sprintf("%s.backup", filename);
+ backupfile = owl_sprintf("%s.backup", actual_filename);
unlink(backupfile);
- if (link(filename, backupfile) != 0) {
+ if (link(actual_filename, backupfile) != 0) {
owl_function_error("Cannot link %s: %s", backupfile, strerror(errno));
owl_free(backupfile);
unlink(newfile);
@@ -442,15 +480,17 @@ int owl_util_file_deleteline(const char *filename, const char *line, int backup)
owl_free(backupfile);
}
- if (rename(newfile, filename) != 0) {
+ if (rename(newfile, actual_filename) != 0) {
owl_function_error("Cannot move %s to %s: %s",
- newfile, filename, strerror(errno));
+ newfile, actual_filename, strerror(errno));
numremoved = -1;
}
unlink(newfile);
owl_free(newfile);
+ g_free(actual_filename);
+
return numremoved;
}
--
1.7.1
