summaryrefslogtreecommitdiff
path: root/csum-file.c
blob: a172199e44bf370cd66ee7073f5a2228fd9679ef (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
/*
 * csum-file.c
 *
 * Copyright (C) 2005 Linus Torvalds
 *
 * Simple file write infrastructure for writing SHA1-summed
 * files. Useful when you write a file that you want to be
 * able to verify hasn't been messed with afterwards.
 */
#include "cache.h"
#include "progress.h"
#include "csum-file.h"

static void flush(struct sha1file *f, const void *buf, unsigned int count)
{
	if (0 <= f->check_fd && count)  {
		unsigned char check_buffer[8192];
		ssize_t ret = read_in_full(f->check_fd, check_buffer, count);

		if (ret < 0)
			die_errno("%s: sha1 file read error", f->name);
		if (ret < count)
			die("%s: sha1 file truncated", f->name);
		if (memcmp(buf, check_buffer, count))
			die("sha1 file '%s' validation error", f->name);
	}

	for (;;) {
		int ret = xwrite(f->fd, buf, count);
		if (ret > 0) {
			f->total += ret;
			display_throughput(f->tp, f->total);
			buf = (char *) buf + ret;
			count -= ret;
			if (count)
				continue;
			return;
		}
		if (!ret)
			die("sha1 file '%s' write error. Out of diskspace", f->name);
		die_errno("sha1 file '%s' write error", f->name);
	}
}

void sha1flush(struct sha1file *f)
{
	unsigned offset = f->offset;

	if (offset) {
		git_SHA1_Update(&f->ctx, f->buffer, offset);
		flush(f, f->buffer, offset);
		f->offset = 0;
	}
}

int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
{
	int fd;

	sha1flush(f);
	git_SHA1_Final(f->buffer, &f->ctx);
	if (result)
		hashcpy(result, f->buffer);
	if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
		/* write checksum and close fd */
		flush(f, f->buffer, 20);
		if (flags & CSUM_FSYNC)
			fsync_or_die(f->fd, f->name);
		if (close(f->fd))
			die_errno("%s: sha1 file error on close", f->name);
		fd = 0;
	} else
		fd = f->fd;
	if (0 <= f->check_fd) {
		char discard;
		int cnt = read_in_full(f->check_fd, &discard, 1);
		if (cnt < 0)
			die_errno("%s: error when reading the tail of sha1 file",
				  f->name);
		if (cnt)
			die("%s: sha1 file has trailing garbage", f->name);
		if (close(f->check_fd))
			die_errno("%s: sha1 file error on close", f->name);
	}
	free(f);
	return fd;
}

void sha1write(struct sha1file *f, const void *buf, unsigned int count)
{
	while (count) {
		unsigned offset = f->offset;
		unsigned left = sizeof(f->buffer) - offset;
		unsigned nr = count > left ? left : count;
		const void *data;

		if (f->do_crc)
			f->crc32 = crc32(f->crc32, buf, nr);

		if (nr == sizeof(f->buffer)) {
			/* process full buffer directly without copy */
			data = buf;
		} else {
			memcpy(f->buffer + offset, buf, nr);
			data = f->buffer;
		}

		count -= nr;
		offset += nr;
		buf = (char *) buf + nr;
		left -= nr;
		if (!left) {
			git_SHA1_Update(&f->ctx, data, offset);
			flush(f, data, offset);
			offset = 0;
		}
		f->offset = offset;
	}
}

struct sha1file *sha1fd(int fd, const char *name)
{
	return sha1fd_throughput(fd, name, NULL);
}

struct sha1file *sha1fd_check(const char *name)
{
	int sink, check;
	struct sha1file *f;

	sink = open("/dev/null", O_WRONLY);
	if (sink < 0)
		die_errno("unable to open /dev/null");
	check = open(name, O_RDONLY);
	if (check < 0)
		die_errno("unable to open '%s'", name);
	f = sha1fd(sink, name);
	f->check_fd = check;
	return f;
}

struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
{
	struct sha1file *f = xmalloc(sizeof(*f));
	f->fd = fd;
	f->check_fd = -1;
	f->offset = 0;
	f->total = 0;
	f->tp = tp;
	f->name = name;
	f->do_crc = 0;
	git_SHA1_Init(&f->ctx);
	return f;
}

void sha1file_checkpoint(struct sha1file *f, struct sha1file_checkpoint *checkpoint)
{
	sha1flush(f);
	checkpoint->offset = f->total;
	checkpoint->ctx = f->ctx;
}

int sha1file_truncate(struct sha1file *f, struct sha1file_checkpoint *checkpoint)
{
	off_t offset = checkpoint->offset;

	if (ftruncate(f->fd, offset) ||
	    lseek(f->fd, offset, SEEK_SET) != offset)
		return -1;
	f->total = offset;
	f->ctx = checkpoint->ctx;
	f->offset = 0; /* sha1flush() was called in checkpoint */
	return 0;
}

void crc32_begin(struct sha1file *f)
{
	f->crc32 = crc32(0, NULL, 0);
	f->do_crc = 1;
}

uint32_t crc32_end(struct sha1file *f)
{
	f->do_crc = 0;
	return f->crc32;
}