archive: refactor file extension format-guessing
[git/git.git] / archive-tar.c
CommitLineData
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1/*
2 * Copyright (c) 2005, 2006 Rene Scharfe
3 */
3d74982f 4#include "cache.h"
3d74982f 5#include "tar.h"
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6#include "archive.h"
7
8#define RECORDSIZE (512)
9#define BLOCKSIZE (RECORDSIZE * 20)
10
11static char block[BLOCKSIZE];
12static unsigned long offset;
13
f08b3b0e 14static int tar_umask = 002;
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15
16/* writes out the whole block, but only if it is full */
17static void write_if_needed(void)
18{
19 if (offset == BLOCKSIZE) {
20 write_or_die(1, block, BLOCKSIZE);
21 offset = 0;
22 }
23}
24
25/*
26 * queues up writes, so that all our write(2) calls write exactly one
27 * full block; pads writes to RECORDSIZE
28 */
29static void write_blocked(const void *data, unsigned long size)
30{
31 const char *buf = data;
32 unsigned long tail;
33
34 if (offset) {
35 unsigned long chunk = BLOCKSIZE - offset;
36 if (size < chunk)
37 chunk = size;
38 memcpy(block + offset, buf, chunk);
39 size -= chunk;
40 offset += chunk;
41 buf += chunk;
42 write_if_needed();
43 }
44 while (size >= BLOCKSIZE) {
45 write_or_die(1, buf, BLOCKSIZE);
46 size -= BLOCKSIZE;
47 buf += BLOCKSIZE;
48 }
49 if (size) {
50 memcpy(block + offset, buf, size);
51 offset += size;
52 }
53 tail = offset % RECORDSIZE;
54 if (tail) {
55 memset(block + offset, 0, RECORDSIZE - tail);
56 offset += RECORDSIZE - tail;
57 }
58 write_if_needed();
59}
60
61/*
62 * The end of tar archives is marked by 2*512 nul bytes and after that
63 * follows the rest of the block (if any).
64 */
65static void write_trailer(void)
66{
67 int tail = BLOCKSIZE - offset;
68 memset(block + offset, 0, tail);
69 write_or_die(1, block, BLOCKSIZE);
70 if (tail < 2 * RECORDSIZE) {
71 memset(block, 0, offset);
72 write_or_die(1, block, BLOCKSIZE);
73 }
74}
75
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76/*
77 * pax extended header records have the format "%u %s=%s\n". %u contains
78 * the size of the whole string (including the %u), the first %s is the
79 * keyword, the second one is the value. This function constructs such a
80 * string and appends it to a struct strbuf.
81 */
82static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
83 const char *value, unsigned int valuelen)
84{
7a604f16 85 int len, tmp;
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86
87 /* "%u %s=%s\n" */
88 len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
89 for (tmp = len; tmp > 9; tmp /= 10)
90 len++;
91
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92 strbuf_grow(sb, len);
93 strbuf_addf(sb, "%u %s=", len, keyword);
94 strbuf_add(sb, value, valuelen);
95 strbuf_addch(sb, '\n');
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96}
97
98static unsigned int ustar_header_chksum(const struct ustar_header *header)
99{
100 char *p = (char *)header;
101 unsigned int chksum = 0;
102 while (p < header->chksum)
103 chksum += *p++;
104 chksum += sizeof(header->chksum) * ' ';
105 p += sizeof(header->chksum);
106 while (p < (char *)header + sizeof(struct ustar_header))
107 chksum += *p++;
108 return chksum;
109}
110
562e25ab 111static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
3d74982f 112{
562e25ab 113 size_t i = pathlen;
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114 if (i > maxlen)
115 i = maxlen;
116 do {
117 i--;
562e25ab 118 } while (i > 0 && path[i] != '/');
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119 return i;
120}
121
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122static int write_tar_entry(struct archiver_args *args,
123 const unsigned char *sha1, const char *path, size_t pathlen,
124 unsigned int mode, void *buffer, unsigned long size)
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125{
126 struct ustar_header header;
f285a2d7 127 struct strbuf ext_header = STRBUF_INIT;
562e25ab 128 int err = 0;
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129
130 memset(&header, 0, sizeof(header));
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131
132 if (!sha1) {
133 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
134 mode = 0100666;
135 strcpy(header.name, "pax_global_header");
136 } else if (!path) {
137 *header.typeflag = TYPEFLAG_EXT_HEADER;
138 mode = 0100666;
139 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
140 } else {
302b9282 141 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
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142 *header.typeflag = TYPEFLAG_DIR;
143 mode = (mode | 0777) & ~tar_umask;
144 } else if (S_ISLNK(mode)) {
145 *header.typeflag = TYPEFLAG_LNK;
146 mode |= 0777;
147 } else if (S_ISREG(mode)) {
148 *header.typeflag = TYPEFLAG_REG;
149 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
150 } else {
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151 return error("unsupported file mode: 0%o (SHA1: %s)",
152 mode, sha1_to_hex(sha1));
3d74982f 153 }
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154 if (pathlen > sizeof(header.name)) {
155 size_t plen = get_path_prefix(path, pathlen,
156 sizeof(header.prefix));
157 size_t rest = pathlen - plen - 1;
3d74982f 158 if (plen > 0 && rest <= sizeof(header.name)) {
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159 memcpy(header.prefix, path, plen);
160 memcpy(header.name, path + plen + 1, rest);
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161 } else {
162 sprintf(header.name, "%s.data",
163 sha1_to_hex(sha1));
164 strbuf_append_ext_header(&ext_header, "path",
562e25ab 165 path, pathlen);
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166 }
167 } else
562e25ab 168 memcpy(header.name, path, pathlen);
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169 }
170
171 if (S_ISLNK(mode) && buffer) {
172 if (size > sizeof(header.linkname)) {
173 sprintf(header.linkname, "see %s.paxheader",
174 sha1_to_hex(sha1));
175 strbuf_append_ext_header(&ext_header, "linkpath",
176 buffer, size);
177 } else
178 memcpy(header.linkname, buffer, size);
179 }
180
181 sprintf(header.mode, "%07o", mode & 07777);
182 sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
3e1629f5 183 sprintf(header.mtime, "%011lo", (unsigned long) args->time);
3d74982f 184
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185 sprintf(header.uid, "%07o", 0);
186 sprintf(header.gid, "%07o", 0);
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187 strlcpy(header.uname, "root", sizeof(header.uname));
188 strlcpy(header.gname, "root", sizeof(header.gname));
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189 sprintf(header.devmajor, "%07o", 0);
190 sprintf(header.devminor, "%07o", 0);
191
192 memcpy(header.magic, "ustar", 6);
193 memcpy(header.version, "00", 2);
194
195 sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
196
197 if (ext_header.len > 0) {
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198 err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
199 ext_header.len);
200 if (err)
201 return err;
3d74982f 202 }
7a604f16 203 strbuf_release(&ext_header);
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204 write_blocked(&header, sizeof(header));
205 if (S_ISREG(mode) && buffer && size > 0)
206 write_blocked(buffer, size);
562e25ab 207 return err;
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208}
209
562e25ab 210static int write_global_extended_header(struct archiver_args *args)
3d74982f 211{
562e25ab 212 const unsigned char *sha1 = args->commit_sha1;
f285a2d7 213 struct strbuf ext_header = STRBUF_INIT;
562e25ab 214 int err;
7a604f16 215
3d74982f 216 strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
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217 err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
218 ext_header.len);
7a604f16 219 strbuf_release(&ext_header);
562e25ab 220 return err;
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221}
222
ef90d6d4 223static int git_tar_config(const char *var, const char *value, void *cb)
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224{
225 if (!strcmp(var, "tar.umask")) {
cc1816b0 226 if (value && !strcmp(value, "user")) {
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227 tar_umask = umask(0);
228 umask(tar_umask);
229 } else {
230 tar_umask = git_config_int(var, value);
231 }
232 return 0;
233 }
40e76291 234 return 0;
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235}
236
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237static int write_tar_archive(const struct archiver *ar,
238 struct archiver_args *args)
3d74982f 239{
562e25ab 240 int err = 0;
3d74982f 241
3d74982f 242 if (args->commit_sha1)
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243 err = write_global_extended_header(args);
244 if (!err)
245 err = write_archive_entries(args, write_tar_entry);
246 if (!err)
247 write_trailer();
248 return err;
3d74982f 249}
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250
251static struct archiver tar_archiver = {
252 "tar",
253 write_tar_archive,
254 0
255};
256
257void init_tar_archiver(void)
258{
259 register_archiver(&tar_archiver);
260 git_config(git_tar_config, NULL);
261}