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authorJeremy Kerr <jk@ozlabs.org>2013-08-08 15:25:24 +0800
committerJeremy Kerr <jk@ozlabs.org>2013-08-08 16:30:00 +0800
commit6557f07325409d769f414035cca05a563418e729 (patch)
treee817fabedfd85b0584089fe2f476189d7ccdc41d /discover
parenta70807730ef59efc4116556ecabe1b9f70ce605b (diff)
downloadtalos-petitboot-6557f07325409d769f414035cca05a563418e729.tar.gz
talos-petitboot-6557f07325409d769f414035cca05a563418e729.zip
discover/file: Add replace_file()
Add a function to atomically replace a file. Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Diffstat (limited to 'discover')
-rw-r--r--discover/file.c43
-rw-r--r--discover/file.h1
2 files changed, 44 insertions, 0 deletions
diff --git a/discover/file.c b/discover/file.c
index 269421c..1ebfe43 100644
--- a/discover/file.c
+++ b/discover/file.c
@@ -17,6 +17,8 @@
#include <fcntl.h>
#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
@@ -75,3 +77,44 @@ err_close:
close(fd);
return -1;
}
+
+static int write_fd(int fd, char *buf, int len)
+{
+ int i, rc;
+
+ for (i = 0; i < len; i += rc) {
+ rc = write(fd, buf + i, len - i);
+ if (rc < 0 && errno != -EINTR)
+ return rc;
+ }
+
+ return 0;
+}
+
+int replace_file(const char *filename, char *buf, int len)
+{
+ char *tempfile;
+ mode_t oldmask;
+ int rc, fd;
+
+ tempfile = talloc_asprintf(NULL, "%s.XXXXXX", filename);
+
+ oldmask = umask(0644);
+ fd = mkstemp(tempfile);
+ umask(oldmask);
+ if (fd < 0) {
+ free(tempfile);
+ return fd;
+ }
+
+ rc = write_fd(fd, buf, len);
+ if (rc) {
+ unlink(tempfile);
+ } else {
+ rc = rename(tempfile, filename);
+ }
+
+ free(tempfile);
+ close(fd);
+ return rc;
+}
diff --git a/discover/file.h b/discover/file.h
index 1997eca..8aa7d3c 100644
--- a/discover/file.h
+++ b/discover/file.h
@@ -18,6 +18,7 @@
#define FILE_H
int read_file(void *ctx, const char *filename, char **bufp, int *lenp);
+int replace_file(const char *filename, char *buf, int len);
#endif /* FILE_H */
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