/*
* A command server client that uses Unix domain socket
*
* Copyright (c) 2011 Yuya Nishihara <yuya@tcha.org>
*
* This software may be used and distributed according to the terms of the
* GNU General Public License version 2 or any later version.
*/
#include <arpa/inet.h> /* for ntohl(), htonl() */
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
#include "hgclient.h"
#include "util.h"
enum {
CAP_GETENCODING = 0x0001,
CAP_RUNCOMMAND = 0x0002,
/* cHg extension: */
CAP_ATTACHIO = 0x0100,
CAP_CHDIR = 0x0200,
CAP_GETPAGER = 0x0400,
CAP_SETENV = 0x0800,
CAP_SETUMASK = 0x1000,
CAP_VALIDATE = 0x2000,
};
typedef struct {
const char *name;
unsigned int flag;
} cappair_t;
static const cappair_t captable[] = {
{"getencoding", CAP_GETENCODING},
{"runcommand", CAP_RUNCOMMAND},
{"attachio", CAP_ATTACHIO},
{"chdir", CAP_CHDIR},
{"getpager", CAP_GETPAGER},
{"setenv", CAP_SETENV},
{"setumask", CAP_SETUMASK},
{"validate", CAP_VALIDATE},
{NULL, 0}, /* terminator */
};
typedef struct {
char ch;
char *data;
size_t maxdatasize;
size_t datasize;
} context_t;
struct hgclient_tag_ {
int sockfd;
pid_t pgid;
pid_t pid;
context_t ctx;
unsigned int capflags;
};
static const size_t defaultdatasize = 4096;
static void initcontext(context_t *ctx)
{
ctx->ch = '\0';
ctx->data = malloc(defaultdatasize);
ctx->maxdatasize = (ctx->data) ? defaultdatasize : 0;
ctx->datasize = 0;
debugmsg("initialize context buffer with size %zu", ctx->maxdatasize);
}
static void enlargecontext(context_t *ctx, size_t newsize)
{
if (newsize <= ctx->maxdatasize)
return;
newsize = defaultdatasize
* ((newsize + defaultdatasize - 1) / defaultdatasize);
ctx->data = reallocx(ctx->data, newsize);
ctx->maxdatasize = newsize;
debugmsg("enlarge context buffer to %zu", ctx->maxdatasize);
}
static void freecontext(context_t *ctx)
{
debugmsg("free context buffer");
free(ctx->data);
ctx->data = NULL;
ctx->maxdatasize = 0;
ctx->datasize = 0;
}
/* Read channeled response from cmdserver */
static void readchannel(hgclient_t *hgc)
{
assert(hgc);
ssize_t rsize = recv(hgc->sockfd, &hgc->ctx.ch, sizeof(hgc->ctx.ch), 0);
if (rsize != sizeof(hgc->ctx.ch)) {
/* server would have exception and traceback would be printed */
debugmsg("failed to read channel");
exit(255);
}
uint32_t datasize_n;
rsize = recv(hgc->sockfd, &datasize_n, sizeof(datasize_n), 0);
if (rsize != sizeof(datasize_n))
abortmsg("failed to read data size");
/* datasize denotes the maximum size to write if input request */
hgc->ctx.datasize = ntohl(datasize_n);
enlargecontext(&hgc->ctx, hgc->ctx.datasize);
if (isupper(hgc->ctx.ch) && hgc->ctx.ch != 'S')
return; /* assumes input request */
size_t cursize = 0;
int emptycount = 0;
while (cursize < hgc->ctx.datasize) {
rsize = recv(hgc->sockfd, hgc->ctx.data + cursize,
hgc->ctx.datasize - cursize, 0);
/* rsize == 0 normally indicates EOF, while it's also a valid
* packet size for unix socket. treat it as EOF and abort if
* we get many empty responses in a row. */
emptycount = (rsize == 0 ? emptycount + 1 : 0);
if (rsize < 0 || emptycount > 20)
abortmsg("failed to read data block");
cursize += rsize;
}
}
static void sendall(int sockfd, const void *data, size_t datasize)
{
const char *p = data;
const char *const endp = p + datasize;
while (p < endp) {
ssize_t r = send(sockfd, p, endp - p, 0);
if (r < 0)
abortmsgerrno("cannot communicate");
p += r;
}
}
/* Write lengh-data block to cmdserver */
static void writeblock(const hgclient_t *hgc)
{
assert(hgc);
const uint32_t datasize_n = htonl(hgc->ctx.datasize);
sendall(hgc->sockfd, &datasize_n, sizeof(datasize_n));
sendall(hgc->sockfd, hgc->ctx.data, hgc->ctx.datasize);
}
static void writeblockrequest(const hgclient_t *hgc, const char *chcmd)
{
debugmsg("request %s, block size %zu", chcmd, hgc->ctx.datasize);
char buf[strlen(chcmd) + 1];
memcpy(buf, chcmd, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = '\n';
sendall(hgc->sockfd, buf, sizeof(buf));
writeblock(hgc);
}
/* Build '\0'-separated list of args. argsize < 0 denotes that args are
* terminated by NULL. */
static void packcmdargs(context_t *ctx, const char *const args[],
ssize_t argsize)
{
ctx->datasize = 0;
const char *const *const end = (argsize >= 0) ? args + argsize : NULL;
for (const char *const *it = args; it != end && *it; ++it) {
const size_t n = strlen(*it) + 1; /* include '\0' */
enlargecontext(ctx, ctx->datasize + n);
memcpy(ctx->data + ctx->datasize, *it, n);
ctx->datasize += n;
}
if (ctx->datasize > 0)
--ctx->datasize; /* strip last '\0' */
}
/* Extract '\0'-separated list of args to new buffer, terminated by NULL */
static const char **unpackcmdargsnul(const context_t *ctx)
{
const char **args = NULL;
size_t nargs = 0, maxnargs = 0;
const char *s = ctx->data;
const char *e = ctx->data + ctx->datasize;
for (;;) {
if (nargs + 1 >= maxnargs) { /* including last NULL */
maxnargs += 256;
args = reallocx(args, maxnargs * sizeof(args[0]));
}
args[nargs] = s;
nargs++;
s = memchr(s, '\0', e - s);
if (!s)
break;
s++;
}
args[nargs] = NULL;
return args;
}
static void handlereadrequest(hgclient_t *hgc)
{
context_t *ctx = &hgc->ctx;
size_t r = fread(ctx->data, sizeof(ctx->data[0]), ctx->datasize, stdin);
ctx->datasize = r;
writeblock(hgc);
}
/* Read single-line */
static void handlereadlinerequest(hgclient_t *hgc)
{
context_t *ctx = &hgc->ctx;
if (!fgets(ctx->data, ctx->datasize, stdin))
ctx->data[0] = '\0';
ctx->datasize = strlen(ctx->data);
writeblock(hgc);
}
/* Execute the requested command and write exit code */
static void handlesystemrequest(hgclient_t *hgc)
{
context_t *ctx = &hgc->ctx;
enlargecontext(ctx, ctx->datasize + 1);
ctx->data[ctx->datasize] = '\0'; /* terminate last string */
const char **args = unpackcmdargsnul(ctx);
if (!args[0] || !args[1])
abortmsg("missing command or cwd in system request");
debugmsg("run '%s' at '%s'", args[0], args[1]);
int32_t r = runshellcmd(args[0], args + 2, args[1]);
free(args);
uint32_t r_n = htonl(r);
memcpy(ctx->data, &r_n, sizeof(r_n));
ctx->datasize = sizeof(r_n);
writeblock(hgc);
}
/* Read response of command execution until receiving 'r'-esult */
static void handleresponse(hgclient_t *hgc)
{
for (;;) {
readchannel(hgc);
context_t *ctx = &hgc->ctx;
debugmsg("response read from channel %c, size %zu",
ctx->ch, ctx->datasize);
switch (ctx->ch) {
case 'o':
fwrite(ctx->data, sizeof(ctx->data[0]), ctx->datasize,
stdout);
break;
case 'e':
fwrite(ctx->data, sizeof(ctx->data[0]), ctx->datasize,
stderr);
break;
case 'd':
/* assumes last char is '\n' */
ctx->data[ctx->datasize - 1] = '\0';
debugmsg("server: %s", ctx->data);
break;
case 'r':
return;
case 'I':
handlereadrequest(hgc);
break;
case 'L':
handlereadlinerequest(hgc);
break;
case 'S':
handlesystemrequest(hgc);
break;
default:
if (isupper(ctx->ch))
abortmsg("cannot handle response (ch = %c)",
ctx->ch);
}
}
}
static unsigned int parsecapabilities(const char *s, const char *e)
{
unsigned int flags = 0;
while (s < e) {
const char *t = strchr(s, ' ');
if (!t || t > e)
t = e;
const cappair_t *cap;
for (cap = captable; cap->flag; ++cap) {
size_t n = t - s;
if (strncmp(s, cap->name, n) == 0 &&
strlen(cap->name) == n) {
flags |= cap->flag;
break;
}
}
s = t + 1;
}
return flags;
}
static void readhello(hgclient_t *hgc)
{
readchannel(hgc);
context_t *ctx = &hgc->ctx;
if (ctx->ch != 'o') {
char ch = ctx->ch;
if (ch == 'e') {
/* write early error and will exit */
fwrite(ctx->data, sizeof(ctx->data[0]), ctx->datasize,
stderr);
handleresponse(hgc);
}
abortmsg("unexpected channel of hello message (ch = %c)", ch);
}
enlargecontext(ctx, ctx->datasize + 1);
ctx->data[ctx->datasize] = '\0';
debugmsg("hello received: %s (size = %zu)", ctx->data, ctx->datasize);
const char *s = ctx->data;
const char *const dataend = ctx->data + ctx->datasize;
while (s < dataend) {
const char *t = strchr(s, ':');
if (!t || t[1] != ' ')
break;
const char *u = strchr(t + 2, '\n');
if (!u)
u = dataend;
if (strncmp(s, "capabilities:", t - s + 1) == 0) {
hgc->capflags = parsecapabilities(t + 2, u);
} else if (strncmp(s, "pgid:", t - s + 1) == 0) {
hgc->pgid = strtol(t + 2, NULL, 10);
} else if (strncmp(s, "pid:", t - s + 1) == 0) {
hgc->pid = strtol(t + 2, NULL, 10);
}
s = u + 1;
}
debugmsg("capflags=0x%04x, pid=%d", hgc->capflags, hgc->pid);
}
static void attachio(hgclient_t *hgc)
{
debugmsg("request attachio");
static const char chcmd[] = "attachio\n";
sendall(hgc->sockfd, chcmd, sizeof(chcmd) - 1);
readchannel(hgc);
context_t *ctx = &hgc->ctx;
if (ctx->ch != 'I')
abortmsg("unexpected response for attachio (ch = %c)", ctx->ch);
static const int fds[3] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};
struct msghdr msgh;
memset(&msgh, 0, sizeof(msgh));
struct iovec iov = {ctx->data, ctx->datasize}; /* dummy payload */
msgh.msg_iov = &iov;
msgh.msg_iovlen = 1;
char fdbuf[CMSG_SPACE(sizeof(fds))];
msgh.msg_control = fdbuf;
msgh.msg_controllen = sizeof(fdbuf);
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msgh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(fds));
memcpy(CMSG_DATA(cmsg), fds, sizeof(fds));
msgh.msg_controllen = cmsg->cmsg_len;
ssize_t r = sendmsg(hgc->sockfd, &msgh, 0);
if (r < 0)
abortmsgerrno("sendmsg failed");
handleresponse(hgc);
int32_t n;
if (ctx->datasize != sizeof(n))
abortmsg("unexpected size of attachio result");
memcpy(&n, ctx->data, sizeof(n));
n = ntohl(n);
if (n != sizeof(fds) / sizeof(fds[0]))
abortmsg("failed to send fds (n = %d)", n);
}
static void chdirtocwd(hgclient_t *hgc)
{
if (!getcwd(hgc->ctx.data, hgc->ctx.maxdatasize))
abortmsgerrno("failed to getcwd");
hgc->ctx.datasize = strlen(hgc->ctx.data);
writeblockrequest(hgc, "chdir");
}
static void forwardumask(hgclient_t *hgc)
{
mode_t mask = umask(0);
umask(mask);
static const char command[] = "setumask\n";
sendall(hgc->sockfd, command, sizeof(command) - 1);
uint32_t data = htonl(mask);
sendall(hgc->sockfd, &data, sizeof(data));
}
/*!
* Open connection to per-user cmdserver
*
* If no background server running, returns NULL.
*/
hgclient_t *hgc_open(const char *sockname)
{
int fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0)
abortmsgerrno("cannot create socket");
/* don't keep fd on fork(), so that it can be closed when the parent
* process get terminated. */
fsetcloexec(fd);
struct sockaddr_un addr;
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, sockname, sizeof(addr.sun_path));
addr.sun_path[sizeof(addr.sun_path) - 1] = '\0';
int r = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
if (r < 0) {
close(fd);
if (errno == ENOENT || errno == ECONNREFUSED)
return NULL;
abortmsgerrno("cannot connect to %s", addr.sun_path);
}
debugmsg("connected to %s", addr.sun_path);
hgclient_t *hgc = mallocx(sizeof(hgclient_t));
memset(hgc, 0, sizeof(*hgc));
hgc->sockfd = fd;
initcontext(&hgc->ctx);
readhello(hgc);
if (!(hgc->capflags & CAP_RUNCOMMAND))
abortmsg("insufficient capability: runcommand");
if (hgc->capflags & CAP_ATTACHIO)
attachio(hgc);
if (hgc->capflags & CAP_CHDIR)
chdirtocwd(hgc);
if (hgc->capflags & CAP_SETUMASK)
forwardumask(hgc);
return hgc;
}
/*!
* Close connection and free allocated memory
*/
void hgc_close(hgclient_t *hgc)
{
assert(hgc);
freecontext(&hgc->ctx);
close(hgc->sockfd);
free(hgc);
}
pid_t hgc_peerpgid(const hgclient_t *hgc)
{
assert(hgc);
return hgc->pgid;
}
pid_t hgc_peerpid(const hgclient_t *hgc)
{
assert(hgc);
return hgc->pid;
}
/*!
* Send command line arguments to let the server load the repo config and check
* whether it can process our request directly or not.
* Make sure hgc_setenv is called before calling this.
*
* @return - NULL, the server believes it can handle our request, or does not
* support "validate" command.
* - a list of strings, the server probably cannot handle our request
* and it sent instructions telling us what to do next. See
* chgserver.py for possible instruction formats.
* the list should be freed by the caller.
* the last string is guaranteed to be NULL.
*/
const char **hgc_validate(hgclient_t *hgc, const char *const args[],
size_t argsize)
{
assert(hgc);
if (!(hgc->capflags & CAP_VALIDATE))
return NULL;
packcmdargs(&hgc->ctx, args, argsize);
writeblockrequest(hgc, "validate");
handleresponse(hgc);
/* the server returns '\0' if it can handle our request */
if (hgc->ctx.datasize <= 1)
return NULL;
/* make sure the buffer is '\0' terminated */
enlargecontext(&hgc->ctx, hgc->ctx.datasize + 1);
hgc->ctx.data[hgc->ctx.datasize] = '\0';
return unpackcmdargsnul(&hgc->ctx);
}
/*!
* Execute the specified Mercurial command
*
* @return result code
*/
int hgc_runcommand(hgclient_t *hgc, const char *const args[], size_t argsize)
{
assert(hgc);
packcmdargs(&hgc->ctx, args, argsize);
writeblockrequest(hgc, "runcommand");
handleresponse(hgc);
int32_t exitcode_n;
if (hgc->ctx.datasize != sizeof(exitcode_n)) {
abortmsg("unexpected size of exitcode");
}
memcpy(&exitcode_n, hgc->ctx.data, sizeof(exitcode_n));
return ntohl(exitcode_n);
}
/*!
* (Re-)send client's stdio channels so that the server can access to tty
*/
void hgc_attachio(hgclient_t *hgc)
{
assert(hgc);
if (!(hgc->capflags & CAP_ATTACHIO))
return;
attachio(hgc);
}
/*!
* Get pager command for the given Mercurial command args
*
* If no pager enabled, returns NULL. The return value becomes invalid
* once you run another request to hgc.
*/
const char *hgc_getpager(hgclient_t *hgc, const char *const args[],
size_t argsize)
{
assert(hgc);
if (!(hgc->capflags & CAP_GETPAGER))
return NULL;
packcmdargs(&hgc->ctx, args, argsize);
writeblockrequest(hgc, "getpager");
handleresponse(hgc);
if (hgc->ctx.datasize < 1 || hgc->ctx.data[0] == '\0')
return NULL;
enlargecontext(&hgc->ctx, hgc->ctx.datasize + 1);
hgc->ctx.data[hgc->ctx.datasize] = '\0';
return hgc->ctx.data;
}
/*!
* Update server's environment variables
*
* @param envp list of environment variables in "NAME=VALUE" format,
* terminated by NULL.
*/
void hgc_setenv(hgclient_t *hgc, const char *const envp[])
{
assert(hgc && envp);
if (!(hgc->capflags & CAP_SETENV))
return;
packcmdargs(&hgc->ctx, envp, /*argsize*/ -1);
writeblockrequest(hgc, "setenv");
}