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ipc_send_message: use stack frame with fixed size

This commit is contained in:
Michael Stapelberg 2013-01-11 19:09:41 +01:00
parent fc0e80ee7f
commit 7b0d75ee0a
3 changed files with 38 additions and 20 deletions
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9
include/i3/ipc.h
View File

@ -2,7 +2,7 @@
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009-2012 Michael Stapelberg and contributors (see also: LICENSE)
* © 2009-2013 Michael Stapelberg and contributors (see also: LICENSE)
*
* This public header defines the different constants and message types to use
* for the IPC interface to i3 (see docs/ipc for more information).
@ -11,6 +11,13 @@
#ifndef I3_I3_IPC_H
#define I3_I3_IPC_H
typedef struct i3_ipc_header {
/* 6 = strlen(I3_IPC_MAGIC) */
char magic[6];
uint32_t size;
uint32_t type;
} __attribute__ ((packed)) i3_ipc_header_t;
/*
* Messages from clients to i3
*

4
include/libi3.h
View File

@ -202,8 +202,8 @@ int ipc_connect(const char *socket_path);
* Returns 0 on success.
*
*/
int ipc_send_message(int sockfd, uint32_t message_size,
uint32_t message_type, const uint8_t *payload);
int ipc_send_message(int sockfd, const uint32_t message_size,
const uint32_t message_type, const uint8_t *payload);
/**
* Reads a message from the given socket file descriptor and stores its length

45
libi3/ipc_send_message.c
View File

@ -2,7 +2,7 @@
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
* © 2009-2013 Michael Stapelberg and contributors (see also: LICENSE)
*
*/
#include <string.h>
@ -24,24 +24,35 @@
* Returns 0 on success.
*
*/
int ipc_send_message(int sockfd, uint32_t message_size,
uint32_t message_type, const uint8_t *payload) {
int buffer_size = strlen(I3_IPC_MAGIC) + sizeof(uint32_t) + sizeof(uint32_t) + message_size;
char msg[buffer_size];
char *walk = msg;
strncpy(walk, I3_IPC_MAGIC, buffer_size - 1);
walk += strlen(I3_IPC_MAGIC);
memcpy(walk, &message_size, sizeof(uint32_t));
walk += sizeof(uint32_t);
memcpy(walk, &message_type, sizeof(uint32_t));
walk += sizeof(uint32_t);
memcpy(walk, payload, message_size);
int ipc_send_message(int sockfd, const uint32_t message_size,
const uint32_t message_type, const uint8_t *payload) {
const i3_ipc_header_t header = {
/* We don’t use I3_IPC_MAGIC because it’s a 0-terminated C string. */
.magic = { 'i', '3', '-', 'i', 'p', 'c' },
.size = message_size,
.type = message_type
};
int sent_bytes = 0;
while (sent_bytes < buffer_size) {
int n = write(sockfd, msg + sent_bytes, buffer_size - sent_bytes);
if (n == -1) {
int n = 0;
/* This first loop is basically unnecessary. No operating system has
* buffers which cannot fit 14 bytes into them, so the write() will only be
* called once. */
while (sent_bytes < sizeof(i3_ipc_header_t)) {
if ((n = write(sockfd, ((void*)&header) + sent_bytes, sizeof(i3_ipc_header_t) - sent_bytes)) == -1) {
if (errno == EAGAIN)
continue;
return -1;
}
sent_bytes += n;
}
sent_bytes = 0;
while (sent_bytes < message_size) {
if ((n = write(sockfd, payload + sent_bytes, message_size - sent_bytes)) == -1) {
if (errno == EAGAIN)
continue;
return -1;