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From 2dfa73cf8b3be174696423996c17e4b30b4f1487 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sat, 1 May 2021 00:23:39 -0700
Subject: [PATCH] Fix fread error checking
fread returns size_t, an unsigned type, so the error check and
TEMP_FAILURE_RETRY had no effect.
Instead, errors can be detected when fread returns a partial amount
and the ferror flag is set.
---
libnetlink.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/libnetlink.c b/libnetlink.c
index b1760ba..5546ccb 100644
--- a/libnetlink.c
+++ b/libnetlink.c
@@ -425,7 +425,7 @@ int rtnl_listen(struct rtnl_handle *rtnl,
int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
void *jarg)
{
- int status;
+ size_t status;
struct sockaddr_nl nladdr;
char buf[8192];
struct nlmsghdr *h = (void*)buf;
@@ -435,18 +435,19 @@ int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
nladdr.nl_pid = 0;
nladdr.nl_groups = 0;
- while (1) {
+ while (!feof(rtnl)) {
int err, len;
int l;
- status = TEMP_FAILURE_RETRY ( fread(&buf, 1, sizeof(*h), rtnl) );
+ status = fread(&buf, 1, sizeof(*h), rtnl);
- if (status < 0) {
- perror("rtnl_from_file: fread");
+ if (status < sizeof(*h)) {
+ if (ferror(rtnl))
+ perror("rtnl_from_file: fread");
+ else
+ fprintf(stderr, "rtnl_from_file: truncated message\n");
return -1;
}
- if (status == 0)
- return 0;
len = h->nlmsg_len;
l = len - sizeof(*h);
@@ -459,12 +460,11 @@ int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);
- if (status < 0) {
- perror("rtnl_from_file: fread");
- return -1;
- }
- if (status < l) {
- fprintf(stderr, "rtnl-from_file: truncated message\n");
+ if (status < NLMSG_ALIGN(l)) {
+ if (ferror(rtnl))
+ perror("rtnl_from_file: fread");
+ else
+ fprintf(stderr, "rtnl_from_file: truncated message\n");
return -1;
}
@@ -472,6 +472,7 @@ int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
if (err < 0)
return err;
}
+ return 0;
}
int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
--
2.31.1
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