date: make DATE_MODE thread-safe
[git.git] / csum-file.c
blob870748e01695f865e1e4d587cdb38f769367a5c6
1 /*
2 * csum-file.c
4 * Copyright (C) 2005 Linus Torvalds
6 * Simple file write infrastructure for writing SHA1-summed
7 * files. Useful when you write a file that you want to be
8 * able to verify hasn't been messed with afterwards.
9 */
10 #include "git-compat-util.h"
11 #include "progress.h"
12 #include "csum-file.h"
13 #include "hash.h"
15 static void verify_buffer_or_die(struct hashfile *f,
16 const void *buf,
17 unsigned int count)
19 ssize_t ret = read_in_full(f->check_fd, f->check_buffer, count);
21 if (ret < 0)
22 die_errno("%s: sha1 file read error", f->name);
23 if (ret != count)
24 die("%s: sha1 file truncated", f->name);
25 if (memcmp(buf, f->check_buffer, count))
26 die("sha1 file '%s' validation error", f->name);
29 static void flush(struct hashfile *f, const void *buf, unsigned int count)
31 if (0 <= f->check_fd && count)
32 verify_buffer_or_die(f, buf, count);
34 if (write_in_full(f->fd, buf, count) < 0) {
35 if (errno == ENOSPC)
36 die("sha1 file '%s' write error. Out of diskspace", f->name);
37 die_errno("sha1 file '%s' write error", f->name);
40 f->total += count;
41 display_throughput(f->tp, f->total);
44 void hashflush(struct hashfile *f)
46 unsigned offset = f->offset;
48 if (offset) {
49 if (!f->skip_hash)
50 the_hash_algo->update_fn(&f->ctx, f->buffer, offset);
51 flush(f, f->buffer, offset);
52 f->offset = 0;
56 static void free_hashfile(struct hashfile *f)
58 free(f->buffer);
59 free(f->check_buffer);
60 free(f);
63 int finalize_hashfile(struct hashfile *f, unsigned char *result,
64 enum fsync_component component, unsigned int flags)
66 int fd;
68 hashflush(f);
70 if (f->skip_hash)
71 hashclr(f->buffer);
72 else
73 the_hash_algo->final_fn(f->buffer, &f->ctx);
75 if (result)
76 hashcpy(result, f->buffer);
77 if (flags & CSUM_HASH_IN_STREAM)
78 flush(f, f->buffer, the_hash_algo->rawsz);
79 if (flags & CSUM_FSYNC)
80 fsync_component_or_die(component, f->fd, f->name);
81 if (flags & CSUM_CLOSE) {
82 if (close(f->fd))
83 die_errno("%s: sha1 file error on close", f->name);
84 fd = 0;
85 } else
86 fd = f->fd;
87 if (0 <= f->check_fd) {
88 char discard;
89 int cnt = read_in_full(f->check_fd, &discard, 1);
90 if (cnt < 0)
91 die_errno("%s: error when reading the tail of sha1 file",
92 f->name);
93 if (cnt)
94 die("%s: sha1 file has trailing garbage", f->name);
95 if (close(f->check_fd))
96 die_errno("%s: sha1 file error on close", f->name);
98 free_hashfile(f);
99 return fd;
102 void hashwrite(struct hashfile *f, const void *buf, unsigned int count)
104 while (count) {
105 unsigned left = f->buffer_len - f->offset;
106 unsigned nr = count > left ? left : count;
108 if (f->do_crc)
109 f->crc32 = crc32(f->crc32, buf, nr);
111 if (nr == f->buffer_len) {
113 * Flush a full batch worth of data directly
114 * from the input, skipping the memcpy() to
115 * the hashfile's buffer. In this block,
116 * f->offset is necessarily zero.
118 if (!f->skip_hash)
119 the_hash_algo->update_fn(&f->ctx, buf, nr);
120 flush(f, buf, nr);
121 } else {
123 * Copy to the hashfile's buffer, flushing only
124 * if it became full.
126 memcpy(f->buffer + f->offset, buf, nr);
127 f->offset += nr;
128 left -= nr;
129 if (!left)
130 hashflush(f);
133 count -= nr;
134 buf = (char *) buf + nr;
138 struct hashfile *hashfd_check(const char *name)
140 int sink, check;
141 struct hashfile *f;
143 sink = xopen("/dev/null", O_WRONLY);
144 check = xopen(name, O_RDONLY);
145 f = hashfd(sink, name);
146 f->check_fd = check;
147 f->check_buffer = xmalloc(f->buffer_len);
149 return f;
152 static struct hashfile *hashfd_internal(int fd, const char *name,
153 struct progress *tp,
154 size_t buffer_len)
156 struct hashfile *f = xmalloc(sizeof(*f));
157 f->fd = fd;
158 f->check_fd = -1;
159 f->offset = 0;
160 f->total = 0;
161 f->tp = tp;
162 f->name = name;
163 f->do_crc = 0;
164 f->skip_hash = 0;
165 the_hash_algo->init_fn(&f->ctx);
167 f->buffer_len = buffer_len;
168 f->buffer = xmalloc(buffer_len);
169 f->check_buffer = NULL;
171 return f;
174 struct hashfile *hashfd(int fd, const char *name)
177 * Since we are not going to use a progress meter to
178 * measure the rate of data passing through this hashfile,
179 * use a larger buffer size to reduce fsync() calls.
181 return hashfd_internal(fd, name, NULL, 128 * 1024);
184 struct hashfile *hashfd_throughput(int fd, const char *name, struct progress *tp)
187 * Since we are expecting to report progress of the
188 * write into this hashfile, use a smaller buffer
189 * size so the progress indicators arrive at a more
190 * frequent rate.
192 return hashfd_internal(fd, name, tp, 8 * 1024);
195 void hashfile_checkpoint(struct hashfile *f, struct hashfile_checkpoint *checkpoint)
197 hashflush(f);
198 checkpoint->offset = f->total;
199 the_hash_algo->clone_fn(&checkpoint->ctx, &f->ctx);
202 int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint)
204 off_t offset = checkpoint->offset;
206 if (ftruncate(f->fd, offset) ||
207 lseek(f->fd, offset, SEEK_SET) != offset)
208 return -1;
209 f->total = offset;
210 the_hash_algo->clone_fn(&f->ctx, &checkpoint->ctx);
211 f->offset = 0; /* hashflush() was called in checkpoint */
212 return 0;
215 void crc32_begin(struct hashfile *f)
217 f->crc32 = crc32(0, NULL, 0);
218 f->do_crc = 1;
221 uint32_t crc32_end(struct hashfile *f)
223 f->do_crc = 0;
224 return f->crc32;
227 int hashfile_checksum_valid(const unsigned char *data, size_t total_len)
229 unsigned char got[GIT_MAX_RAWSZ];
230 git_hash_ctx ctx;
231 size_t data_len = total_len - the_hash_algo->rawsz;
233 if (total_len < the_hash_algo->rawsz)
234 return 0; /* say "too short"? */
236 the_hash_algo->init_fn(&ctx);
237 the_hash_algo->update_fn(&ctx, data, data_len);
238 the_hash_algo->final_fn(got, &ctx);
240 return hasheq(got, data + data_len);