Author: jilles
Date: Sat Jan 8 00:03:18 2011
New Revision: 217133
URL: http://svn.freebsd.org/changeset/base/217133
Log:
sed: Try hard links to make -i target available continually.
When creating a backup file, sed renamed the original before renaming the
changed copy into place, leading to a short time when no file with the
original name was present (usually only visible on SMP systems). Try
creating the backup file using a hard link instead, avoiding this problem.
If creating the hard link fails for any reason, fall back to the old rename
method.
When not creating a backup file, sed already renamed the changed copy onto
the original. This remains unchanged.
I am not adding the suppression of redundant fchown/fchmod to this commit,
because FreeBSD appears to check this in the kernel (for msdosfs at least).
PR: bin/153261
Submitted by: Pedro F. Giffuni
Reviewed by: dds (older version)
Obtained from: Illumos
MFC after: 2 weeks
Modified:
head/usr.bin/sed/main.c
Modified: head/usr.bin/sed/main.c
==============================================================================
--- head/usr.bin/sed/main.c Fri Jan 7 23:39:41 2011 (r217132)
+++ head/usr.bin/sed/main.c Sat Jan 8 00:03:18 2011 (r217133)
@@ -338,18 +338,35 @@ mf_fgets(SPACE *sp, enum e_spflag spflag
if (infile != NULL) {
fclose(infile);
if (*oldfname != '\0') {
- if (rename(fname, oldfname) != 0) {
+ /* if there was a backup file, remove it */
+ unlink(oldfname);
+ /*
+ * Backup the original. Note that hard links
+ * are not supported on all filesystems.
+ */
+ if ((link(fname, oldfname) != 0) &&
+ (rename(fname, oldfname) != 0)) {
warn("rename()");
- unlink(tmpfname);
+ if (*tmpfname)
+ unlink(tmpfname);
exit(1);
}
*oldfname = '\0';
}
if (*tmpfname != '\0') {
if (outfile != NULL && outfile != stdout)
- fclose(outfile);
+ if (fclose(outfile) != 0) {
+ warn("fclose()");
+ unlink(tmpfname);
+ exit(1);
+ }
outfile = NULL;
- rename(tmpfname, fname);
+ if (rename(tmpfname, fname) != 0) {
+ /* this should not happen really! */
+ warn("rename()");
+ unlink(tmpfname);
+ exit(1);
+ }
*tmpfname = '\0';
}
outfname = NULL;
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