Thread-safe xmalloc and xrealloc needs a recursive mutex
[git/dscho.git] / archive-tar.c
blobcee06ce3cbc1819008337633ed0753638c423ac5
1 /*
2  * Copyright (c) 2005, 2006 Rene Scharfe
3  */
4 #include "cache.h"
5 #include "tar.h"
6 #include "archive.h"
8 #define RECORDSIZE      (512)
9 #define BLOCKSIZE       (RECORDSIZE * 20)
11 static char block[BLOCKSIZE];
12 static unsigned long offset;
14 static int tar_umask = 002;
16 /* writes out the whole block, but only if it is full */
17 static void write_if_needed(void)
19         if (offset == BLOCKSIZE) {
20                 write_or_die(1, block, BLOCKSIZE);
21                 offset = 0;
22         }
26  * queues up writes, so that all our write(2) calls write exactly one
27  * full block; pads writes to RECORDSIZE
28  */
29 static void write_blocked(const void *data, unsigned long size)
31         const char *buf = data;
32         unsigned long tail;
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();
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  */
65 static void write_trailer(void)
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         }
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  */
82 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
83                                      const char *value, unsigned int valuelen)
85         int len, tmp;
87         /* "%u %s=%s\n" */
88         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
89         for (tmp = len; tmp > 9; tmp /= 10)
90                 len++;
92         strbuf_grow(sb, len);
93         strbuf_addf(sb, "%u %s=", len, keyword);
94         strbuf_add(sb, value, valuelen);
95         strbuf_addch(sb, '\n');
98 static unsigned int ustar_header_chksum(const struct ustar_header *header)
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;
111 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
113         size_t i = pathlen;
114         if (i > maxlen)
115                 i = maxlen;
116         do {
117                 i--;
118         } while (i > 0 && path[i] != '/');
119         return i;
122 static 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)
126         struct ustar_header header;
127         struct strbuf ext_header = STRBUF_INIT;
128         int err = 0;
130         memset(&header, 0, sizeof(header));
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 {
141                 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
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 {
151                         return error("unsupported file mode: 0%o (SHA1: %s)",
152                                         mode, sha1_to_hex(sha1));
153                 }
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;
158                         if (plen > 0 && rest <= sizeof(header.name)) {
159                                 memcpy(header.prefix, path, plen);
160                                 memcpy(header.name, path + plen + 1, rest);
161                         } else {
162                                 sprintf(header.name, "%s.data",
163                                         sha1_to_hex(sha1));
164                                 strbuf_append_ext_header(&ext_header, "path",
165                                                 path, pathlen);
166                         }
167                 } else
168                         memcpy(header.name, path, pathlen);
169         }
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         }
181         sprintf(header.mode, "%07o", mode & 07777);
182         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
183         sprintf(header.mtime, "%011lo", (unsigned long) args->time);
185         sprintf(header.uid, "%07o", 0);
186         sprintf(header.gid, "%07o", 0);
187         strlcpy(header.uname, "root", sizeof(header.uname));
188         strlcpy(header.gname, "root", sizeof(header.gname));
189         sprintf(header.devmajor, "%07o", 0);
190         sprintf(header.devminor, "%07o", 0);
192         memcpy(header.magic, "ustar", 6);
193         memcpy(header.version, "00", 2);
195         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
197         if (ext_header.len > 0) {
198                 err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
199                                 ext_header.len);
200                 if (err)
201                         return err;
202         }
203         strbuf_release(&ext_header);
204         write_blocked(&header, sizeof(header));
205         if (S_ISREG(mode) && buffer && size > 0)
206                 write_blocked(buffer, size);
207         return err;
210 static int write_global_extended_header(struct archiver_args *args)
212         const unsigned char *sha1 = args->commit_sha1;
213         struct strbuf ext_header = STRBUF_INIT;
214         int err;
216         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
217         err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
218                         ext_header.len);
219         strbuf_release(&ext_header);
220         return err;
223 static int git_tar_config(const char *var, const char *value, void *cb)
225         if (!strcmp(var, "tar.umask")) {
226                 if (value && !strcmp(value, "user")) {
227                         tar_umask = umask(0);
228                         umask(tar_umask);
229                 } else {
230                         tar_umask = git_config_int(var, value);
231                 }
232                 return 0;
233         }
234         return git_default_config(var, value, cb);
237 int write_tar_archive(struct archiver_args *args)
239         int err = 0;
241         git_config(git_tar_config, NULL);
243         if (args->commit_sha1)
244                 err = write_global_extended_header(args);
245         if (!err)
246                 err = write_archive_entries(args, write_tar_entry);
247         if (!err)
248                 write_trailer();
249         return err;