summaryrefslogtreecommitdiff
path: root/receive-pack.c
blob: d05f7d5ec42a088b29d3cac14d42b416013aedf7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include <sys/wait.h>
 
static const char receive_pack_usage[] = "git-receive-pack <git-dir>";
 
static const char *unpacker = "git-unpack-objects";
 
static int show_ref(const char *path, const unsigned char *sha1)
{
	packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
	return 0;
}
 
static void write_head_info(void)
{
	for_each_ref(show_ref);
}
 
struct command {
	struct command *next;
	unsigned char old_sha1[20];
	unsigned char new_sha1[20];
	char ref_name[0];
};
 
struct command *commands = NULL;
 
static int is_all_zeroes(const char *hex)
{
	int i;
	for (i = 0; i < 40; i++)
		if (*hex++ != '0')
			return 0;
	return 1;
}
 
static int verify_old_ref(const char *name, char *hex_contents)
{
	int fd, ret;
	char buffer[60];
 
	if (is_all_zeroes(hex_contents))
		return 0;
	fd = open(name, O_RDONLY);
	if (fd < 0)
		return -1;
	ret = read(fd, buffer, 40);
	close(fd);
	if (ret != 40)
		return -1;
	if (memcmp(buffer, hex_contents, 40))
		return -1;
	return 0;
}
 
static void update(const char *name, unsigned char *old_sha1, unsigned char *new_sha1)
{
	char new_hex[60], *old_hex, *lock_name;
	int newfd, namelen, written;
 
	namelen = strlen(name);
	lock_name = xmalloc(namelen + 10);
	memcpy(lock_name, name, namelen);
	memcpy(lock_name + namelen, ".lock", 6);
 
	strcpy(new_hex, sha1_to_hex(new_sha1));
	old_hex = sha1_to_hex(old_sha1);
	if (!has_sha1_file(new_sha1))
		die("unpack should have generated %s, but I can't find it!", new_hex);
 
	newfd = open(lock_name, O_CREAT | O_EXCL | O_WRONLY, 0644);
	if (newfd < 0)
		die("unable to create %s (%s)", lock_name, strerror(errno));
 
	/* Write the ref with an ending '\n' */
	new_hex[40] = '\n';
	new_hex[41] = 0;
	written = write(newfd, new_hex, 41);
	/* Remove the '\n' again */
	new_hex[40] = 0;
 
	close(newfd);
	if (written != 41) {
		unlink(lock_name);
		die("unable to write %s", lock_name);
	}
	if (verify_old_ref(name, old_hex) < 0) {
		unlink(lock_name);
		die("%s changed during push", name);
	}
	if (rename(lock_name, name) < 0) {
		unlink(lock_name);
		die("unable to replace %s", name);
	}
	fprintf(stderr, "%s: %s -> %s\n", name, old_hex, new_hex);
}
 
 
/*
 * This gets called after(if) we've successfully
 * unpacked the data payload.
 */
static void execute_commands(void)
{
	struct command *cmd = commands;
 
	while (cmd) {
		update(cmd->ref_name, cmd->old_sha1, cmd->new_sha1);
		cmd = cmd->next;
	}
}
 
static void read_head_info(void)
{
	struct command **p = &commands;
	for (;;) {
		static char line[1000];
		unsigned char old_sha1[20], new_sha1[20];
		struct command *cmd;
		int len;
 
		len = packet_read_line(0, line, sizeof(line));
		if (!len)
			break;
		if (line[len-1] == '\n')
			line[--len] = 0;
		if (len < 83 ||
		    line[40] != ' ' ||
		    line[81] != ' ' ||
		    get_sha1_hex(line, old_sha1) ||
		    get_sha1_hex(line + 41, new_sha1))
			die("protocol error: expected old/new/ref, got '%s'", line);
		cmd = xmalloc(sizeof(struct command) + len - 80);
		memcpy(cmd->old_sha1, old_sha1, 20);
		memcpy(cmd->new_sha1, new_sha1, 20);
		memcpy(cmd->ref_name, line + 82, len - 81);
		cmd->next = NULL;
		*p = cmd;
		p = &cmd->next;
	}
}
 
static void unpack(void)
{
	pid_t pid = fork();
 
	if (pid < 0)
		die("unpack fork failed");
	if (!pid) {
		execlp(unpacker, unpacker, NULL);
		die("unpack execute failed");
	}
 
	for (;;) {
		int status, code;
		int retval = waitpid(pid, &status, 0);
 
		if (retval < 0) {
			if (errno == EINTR)
				continue;
			die("waitpid failed (%s)", strerror(retval));
		}
		if (retval != pid)
			die("waitpid is confused");
		if (WIFSIGNALED(status))
			die("%s died of signal %d", unpacker, WTERMSIG(status));
		if (!WIFEXITED(status))
			die("%s died out of really strange complications", unpacker);
		code = WEXITSTATUS(status);
		if (code)
			die("%s exited with error code %d", unpacker, code);
		return;
	}
}
 
int main(int argc, char **argv)
{
	int i;
	const char *dir = NULL;
 
	argv++;
	for (i = 1; i < argc; i++) {
		const char *arg = *argv++;
 
		if (*arg == '-') {
			/* Do flag handling here */
			usage(receive_pack_usage);
		}
		if (dir)
			usage(receive_pack_usage);
		dir = arg;
	}
	if (!dir)
		usage(receive_pack_usage);
 
	/* chdir to the directory. If that fails, try appending ".git" */
	if (chdir(dir) < 0) {
		static char path[PATH_MAX];
		snprintf(path, sizeof(path), "%s.git", dir);
		if (chdir(path) < 0)
			die("unable to cd to %s", dir);
	}
 
	/* If we have a ".git" directory, chdir to it */
	chdir(".git");
	setenv("GIT_DIR", ".", 1);
 
	if (access("objects", X_OK) < 0 || access("refs/heads", X_OK) < 0)
		die("%s doesn't appear to be a git directory", dir);
	write_head_info();
 
	/* EOF */
	packet_flush(1);
 
	read_head_info();
	if (commands) {
		unpack();
		execute_commands();
	}
	return 0;
}