logsave: Fix warn_unused_result warnings from gcc
Fixed a potential bug where by partial returns from the write(2)
system call could some bytes to be lost when writing to the log file.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/misc/logsave.c b/misc/logsave.c
index f0011f8..81ac9f6 100644
--- a/misc/logsave.c
+++ b/misc/logsave.c
@@ -49,6 +49,29 @@
#define SEND_CONSOLE 0x02
#define SEND_BOTH 0x03
+/*
+ * Helper function that does the right thing if write returns a
+ * partial write, or an EGAIN/EINTR error.
+ */
+static int write_all(int fd, const char *buf, size_t count)
+{
+ ssize_t ret;
+ int c = 0;
+
+ while (count > 0) {
+ ret = write(fd, buf, count);
+ if (ret < 0) {
+ if ((errno == EAGAIN) || (errno == EINTR))
+ continue;
+ return -1;
+ }
+ count -= ret;
+ buf += ret;
+ c += ret;
+ }
+ return c;
+}
+
static void send_output(const char *buffer, int c, int flag)
{
char *n;
@@ -57,11 +80,11 @@
c = strlen(buffer);
if (flag & SEND_CONSOLE)
- write(1, buffer, c);
+ write_all(1, buffer, c);
if (!(flag & SEND_LOG))
return;
if (outfd > 0)
- write(outfd, buffer, c);
+ write_all(outfd, buffer, c);
else {
n = realloc(outbuf, outbufsize + c);
if (n) {
@@ -280,7 +303,7 @@
outfd = open(outfn, openflags, 0644);
sleep(1);
}
- write(outfd, outbuf, outbufsize);
+ write_all(outfd, outbuf, outbufsize);
free(outbuf);
}
close(outfd);