[PATCH] imap-send: use xsnprintf to format command

René Scharfe
2024-04-02T14:56:29Z

nfsnprintf() wraps vsnprintf(3) and reports attempts to use too small a
buffer using BUG(), just like xsnprintf().

It has an extra check that makes sure the buffer size (converted to int)
is positive. vsnprintf(3) is supposed to handle a buffer size of zero
or bigger than INT_MAX just fine, so this extra comparison doesn't make
us any safer. If a platform has a broken implementation, we'd need to
work around it in our compat code.

Call xsnprintf() instead to reduce code duplication and make the caller
slightly more readable by using this more common helper.

Signed-off-by: René Scharfe <l.s.r@web.de>
---
Uploaded this message using the patched command, but that's all the
testing I did.

imap-send.c | 24 ++++--------------------
1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index f2e1947e63..4caa8668e6 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -68,9 +68,6 @@ static void imap_warn(const char *, ...);

static char *next_arg(char **);

-__attribute__((format (printf, 3, 4)))
-static int nfsnprintf(char *buf, int blen, const char *fmt, ...);
-
static int nfvasprintf(char **strp, const char *fmt, va_list ap)
{
int len;
@@ -500,19 +497,6 @@ static char *next_arg(char **s)
return ret;
}

-__attribute__((format (printf, 3, 4)))
-static int nfsnprintf(char *buf, int blen, const char *fmt, ...)
-{
- int ret;
- va_list va;
-
- va_start(va, fmt);
- if (blen <= 0 || (unsigned)(ret = vsnprintf(buf, blen, fmt, va)) >= (unsigned)blen)
- BUG("buffer too small. Please report a bug.");
- va_end(va);
- return ret;
-}
-
static struct imap_cmd *issue_imap_cmd(struct imap_store *ctx,
struct imap_cmd_cb *cb,
const char *fmt, va_list ap)
@@ -535,11 +519,11 @@ static struct imap_cmd *issue_imap_cmd(struct imap_store *ctx,
get_cmd_result(ctx, NULL);

if (!cmd->cb.data)
- bufl = nfsnprintf(buf, sizeof(buf), "%d %s\r\n", cmd->tag, cmd->cmd);
+ bufl = xsnprintf(buf, sizeof(buf), "%d %s\r\n", cmd->tag, cmd->cmd);
else
- bufl = nfsnprintf(buf, sizeof(buf), "%d %s{%d%s}\r\n",
- cmd->tag, cmd->cmd, cmd->cb.dlen,
- CAP(LITERALPLUS) ? "+" : "");
+ bufl = xsnprintf(buf, sizeof(buf), "%d %s{%d%s}\r\n",
+ cmd->tag, cmd->cmd, cmd->cb.dlen,
+ CAP(LITERALPLUS) ? "+" : "");

if (0 < verbosity) {
if (imap->num_in_progress)
--
2.44.0