Avoid zero-length iowrite - sacc - sacc(omys), simple console gopher client
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---
DIR commit 20a51bafd3906aa0337fe221d0981293d94370a5
DIR parent 21d46d603a3697f04072e4c0edb0076b4a215a2e
HTML Author: Michael Forney <mforney@mforney.org>
Date: Tue, 19 Mar 2024 14:52:09 -0700
Avoid zero-length iowrite
iowrite with bs==0 results in either a zero-length write() or
tls_write().
The former is unspecified by POSIX[0]:
> If nbyte is zero and the file is not a regular file, the results
> are unspecified.
The latter is not explicitly disallowed by tls_write(3), but libressl
implements tls_write with a call to SSL_write, which is documented
to have undefined behavior[1]:
> When calling SSL_write() with num=0 bytes to be sent, the behaviour
> is undefined.
[0] https://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html
[1] https://man.openbsd.org/SSL_write.3
Diffstat:
M sacc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
---
DIR diff --git a/sacc.c b/sacc.c
@@ -535,10 +535,10 @@ sendselector(struct cnx *c, const char *selector)
msg = p = xmalloc(ln);
snprintf(msg, ln--, "%s\r\n", selector);
- while ((n = iowrite(c, p, ln)) > 0) {
+ while (ln && (n = iowrite(c, p, ln)) > 0) {
ln -= n;
p += n;
- };
+ }
free(msg);
if (n == -1)