Replace FWRITE with a function

In a few places we use the FWRITE() macro to open a file, replace it's
contents with a given string and close it again.  There's no real
reason this needs to be a macro rather than just a function though.
Turn it into a function 'write_file()' and make some ancillary
cleanups while we're there:
  - Add a return code so the caller can handle giving a useful error message
  - Handle the case of short write()s (unlikely, but possible)
  - Add O_TRUNC, to make sure we replace the existing contents entirely

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/pasta.c b/pasta.c
index a6e49eb..d135f1b 100644
--- a/pasta.c
+++ b/pasta.c
@@ -167,8 +167,8 @@ static int pasta_setup_ns(void *arg)
 {
 	const struct pasta_setup_ns_arg *a;
 
-	FWRITE("/proc/sys/net/ipv4/ping_group_range", "0 0",
-	       "Cannot set ping_group_range, ICMP requests might fail");
+	if (write_file("/proc/sys/net/ipv4/ping_group_range", "0 0"))
+		warn("Cannot set ping_group_range, ICMP requests might fail");
 
 	a = (const struct pasta_setup_ns_arg *)arg;
 	execvp(a->exe, a->argv);