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emacsclient receiving long-line fixes

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Do not mishandle long lines, or lines containing NUL,
when receiving data.
* lib-src/emacsclient.c (check_socket_timeout, main):
Use ssize_t for return values from recv,
since in theory the value could exceed INT_MAX now.
(main): Do not use a fixed-size buffer for receiving data;
instead, grow the buffer as needed (admittedly unlikely).
When a partial line is received via recv, do not discard its data;
instead, keep reading, possibly with a grown buffer.
Do not ignore received data after a null byte is received.
Add a comment about when received data is ignored due to a goto.
This commit is contained in:
Paul Eggert
2026-04-12 22:56:16 -07:00
parent 46c08d8574
commit 7d07690e5d
1 changed files with 26 additions and 10 deletions
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36
lib-src/emacsclient.c
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@@ -1975,7 +1975,7 @@ set_socket_timeout (HSOCKET socket, int seconds)
} }
static bool static bool
check_socket_timeout (int rl) check_socket_timeout (ssize_t rl)
{ {
#ifndef WINDOWSNT #ifndef WINDOWSNT
return (rl == -1) return (rl == -1)
@@ -1994,9 +1994,11 @@ main (int argc, char **argv)
main_argv = argv; main_argv = argv;
progname = argv[0] ? argv[0] : "emacsclient"; progname = argv[0] ? argv[0] : "emacsclient";
int rl = 0; ssize_t rl = 0;
bool skiplf = true; bool skiplf = true;
char string[BUFSIZ + 1]; char *recv_buf = NULL;
ptrdiff_t recv_bufsize = 0;
int exit_status = EXIT_SUCCESS; int exit_status = EXIT_SUCCESS;
#ifdef HAVE_NTGUI #ifdef HAVE_NTGUI
@@ -2208,6 +2210,8 @@ main (int argc, char **argv)
set_socket_timeout (emacs_socket, timeout > 0 ? timeout : DEFAULT_TIMEOUT); set_socket_timeout (emacs_socket, timeout > 0 ? timeout : DEFAULT_TIMEOUT);
bool saw_response = false; bool saw_response = false;
ptrdiff_t nrecv = 0;
/* Now, wait for an answer and print any messages. */ /* Now, wait for an answer and print any messages. */
while (exit_status == EXIT_SUCCESS) while (exit_status == EXIT_SUCCESS)
{ {
@@ -2216,7 +2220,14 @@ main (int argc, char **argv)
do do
{ {
act_on_signals (emacs_socket); act_on_signals (emacs_socket);
rl = recv (emacs_socket, string, BUFSIZ, 0); if (nrecv == recv_bufsize)
{
enum { DEFAULT_RECV_BUFSIZE = 4096 };
recv_bufsize = (recv_bufsize + (recv_bufsize >> 1)
+ DEFAULT_RECV_BUFSIZE);
recv_buf = xrealloc (recv_buf, recv_bufsize);
}
rl = recv (emacs_socket, recv_buf + nrecv, recv_bufsize - nrecv, 0);
retry = check_socket_timeout (rl); retry = check_socket_timeout (rl);
if (retry && !saw_response) if (retry && !saw_response)
{ {
@@ -2239,16 +2250,17 @@ main (int argc, char **argv)
if (rl <= 0) if (rl <= 0)
break; break;
nrecv += rl;
saw_response = true; saw_response = true;
string[rl] = '\0';
/* Loop over all NL-terminated messages. */ /* Loop over all NL-terminated messages. */
char *p = string; char *p = recv_buf;
for (char *end_p = p; end_p && *end_p != '\0'; p = end_p) for (char *end_p = p; end_p < recv_buf + nrecv; p = end_p)
{ {
end_p = strchr (p, '\n'); end_p = memchr (p, '\n', recv_buf + nrecv - p);
if (end_p != NULL) if (!end_p)
*end_p++ = '\0'; break;
*end_p++ = '\0';
if (strprefix ("-emacs-pid ", p)) if (strprefix ("-emacs-pid ", p))
{ {
@@ -2271,6 +2283,7 @@ main (int argc, char **argv)
tty = true; tty = true;
} }
/* This discards any remaining data in recv_buf. */
goto retry; goto retry;
} }
else if (strprefix ("-print ", p)) else if (strprefix ("-print ", p))
@@ -2324,6 +2337,9 @@ main (int argc, char **argv)
skiplf = true; skiplf = true;
} }
} }
nrecv -= p - recv_buf;
memmove (recv_buf, p, nrecv);
} }
if (!skiplf && 0 <= process_grouping ()) if (!skiplf && 0 <= process_grouping ())