--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/chg/hgclient.c	Sun Jan 03 12:39:27 2016 +0900
@@ -0,0 +1,527 @@
+/*
+ * 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,
+};
+
+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},
+	{NULL, 0},  /* terminator */
+};
+
+typedef struct {
+	char ch;
+	char *data;
+	size_t maxdatasize;
+	size_t datasize;
+} context_t;
+
+struct hgclient_tag_ {
+	int sockfd;
+	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);
+	char *p = realloc(ctx->data, newsize);
+	if (!p)
+		abortmsg("failed to allocate buffer");
+	ctx->data = p;
+	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))
+		abortmsg("failed to read channel");
+
+	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;
+	while (cursize < hgc->ctx.datasize) {
+		rsize = recv(hgc->sockfd, hgc->ctx.data + cursize,
+			     hgc->ctx.datasize - cursize, 0);
+		if (rsize < 0)
+			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)
+			abortmsg("cannot communicate (errno = %d)", errno);
+		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 = realloc(args, maxnargs * sizeof(args[0]));
+			if (!args)
+				abortmsg("failed to allocate args buffer");
+		}
+		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')
+		abortmsg("unexpected channel of hello message (ch = %c)",
+			 ctx->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, "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)
+		abortmsg("sendmsg failed (errno = %d)", errno);
+
+	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))
+		abortmsg("failed to getcwd (errno = %d)", errno);
+	hgc->ctx.datasize = strlen(hgc->ctx.data);
+	writeblockrequest(hgc, "chdir");
+}
+
+/*!
+ * 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)
+		abortmsg("cannot create socket (errno = %d)", errno);
+
+	/* don't keep fd on fork(), so that it can be closed when the parent
+	 * process get terminated. */
+	int flags = fcntl(fd, F_GETFD);
+	if (flags < 0)
+		abortmsg("cannot get flags of socket (errno = %d)", errno);
+	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)
+		abortmsg("cannot set flags of socket (errno = %d)", errno);
+
+	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';
+
+	debugmsg("connect to %s", addr.sun_path);
+	int r = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
+	if (r < 0) {
+		close(fd);
+		if (errno == ENOENT || errno == ECONNREFUSED)
+			return NULL;
+		abortmsg("cannot connect to %s (errno = %d)",
+			 addr.sun_path, errno);
+	}
+
+	hgclient_t *hgc = malloc(sizeof(hgclient_t));
+	if (!hgc)
+		abortmsg("failed to allocate hgclient object");
+	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);
+
+	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_peerpid(const hgclient_t *hgc)
+{
+	assert(hgc);
+	return hgc->pid;
+}
+
+/*!
+ * 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");
+}