1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 #define ZIPPED (ENABLE_FEATURE_SEAMLESS_LZMA \
12 || ENABLE_FEATURE_SEAMLESS_BZ2 \
13 || ENABLE_FEATURE_SEAMLESS_GZ \
14 /* || ENABLE_FEATURE_SEAMLESS_Z */ \
22 /* Suppose that you are a shell. You start child processes.
23 * They work and eventually exit. You want to get user input.
24 * You read stdin. But what happens if last child switched
25 * its stdin into O_NONBLOCK mode?
27 * *** SURPRISE! It will affect the parent too! ***
28 * *** BIG SURPRISE! It stays even after child exits! ***
30 * This is a design bug in UNIX API.
31 * fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK);
32 * will set nonblocking mode not only on _your_ stdin, but
33 * also on stdin of your parent, etc.
37 * fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL) | O_NONBLOCK);
38 * sets both fd1 and fd2 to O_NONBLOCK. This includes cases
39 * where duping is done implicitly by fork() etc.
42 * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD) | O_NONBLOCK);
43 * (note SETFD, not SETFL!) but such thing doesn't exist.
45 * Alternatively, we need nonblocking_read(fd, ...) which doesn't
46 * require O_NONBLOCK dance at all. Actually, it exists:
47 * n = recv(fd, buf, len, MSG_DONTWAIT);
49 * Enables non-blocking operation; if the operation
50 * would block, EAGAIN is returned."
51 * but recv() works only for sockets!
53 * So far I don't see any good solution, I can only propose
54 * that affected readers should be careful and use this routine,
55 * which detects EAGAIN and uses poll() to wait on the fd.
56 * Thankfully, poll() doesn't care about O_NONBLOCK flag.
58 ssize_t FAST_FUNC
nonblock_safe_read(int fd
, void *buf
, size_t count
)
64 n
= safe_read(fd
, buf
, count
);
65 if (n
>= 0 || errno
!= EAGAIN
)
67 /* fd is in O_NONBLOCK mode. Wait using poll and repeat */
69 pfd
[0].events
= POLLIN
;
70 safe_poll(pfd
, 1, -1); /* note: this pulls in printf */
74 // Reads one line a-la fgets (but doesn't save terminating '\n').
75 // Reads byte-by-byte. Useful when it is important to not read ahead.
76 // Bytes are appended to pfx (which must be malloced, or NULL).
77 char* FAST_FUNC
xmalloc_reads(int fd
, char *buf
, size_t *maxsz_p
)
80 size_t sz
= buf
? strlen(buf
) : 0;
81 size_t maxsz
= maxsz_p
? *maxsz_p
: (INT_MAX
- 4095);
85 if ((size_t)(p
- buf
) == sz
) {
87 buf
= xrealloc(buf
, sz
+ 128);
91 /* nonblock_safe_read() because we are used by e.g. shells */
92 if (nonblock_safe_read(fd
, p
, 1) != 1) { /* EOF/error */
93 if (p
== buf
) { /* we read nothing */
107 return xrealloc(buf
, p
- buf
);
110 // Read (potentially big) files in one go. File size is estimated
111 // by stat. Extra '\0' byte is appended.
112 void* FAST_FUNC
xmalloc_read(int fd
, size_t *maxsz_p
)
115 size_t size
, rd_size
, total
;
119 to_read
= maxsz_p
? *maxsz_p
: (INT_MAX
- 4095); /* max to read */
121 /* Estimate file size */
122 st
.st_size
= 0; /* in case fstat fails, assume 0 */
124 /* /proc/N/stat files report st_size 0 */
125 /* In order to make such files readable, we add small const */
126 size
= (st
.st_size
| 0x3ff) + 1;
133 buf
= xrealloc(buf
, total
+ size
+ 1);
134 rd_size
= full_read(fd
, buf
+ total
, size
);
135 if ((ssize_t
)rd_size
== (ssize_t
)(-1)) { /* error */
140 if (rd_size
< size
) /* EOF */
142 if (to_read
<= rd_size
)
145 /* grow by 1/8, but in [1k..64k] bounds */
146 size
= ((total
/ 8) | 0x3ff) + 1;
150 buf
= xrealloc(buf
, total
+ 1);
158 #ifdef USING_LSEEK_TO_GET_SIZE
159 /* Alternatively, file size can be obtained by lseek to the end.
160 * The code is slightly bigger. Retained in case fstat approach
161 * will not work for some weird cases (/proc, block devices, etc).
162 * (NB: lseek also can fail to work for some weird files) */
164 // Read (potentially big) files in one go. File size is estimated by
166 void* FAST_FUNC
xmalloc_open_read_close(const char *filename
, size_t *maxsz_p
)
173 fd
= open(filename
, O_RDONLY
);
177 /* /proc/N/stat files report len 0 here */
178 /* In order to make such files readable, we add small const */
179 size
= 0x3ff; /* read only 1k on unseekable files */
180 len
= lseek(fd
, 0, SEEK_END
) | 0x3ff; /* + up to 1k */
181 if (len
!= (off_t
)-1) {
182 xlseek(fd
, 0, SEEK_SET
);
183 size
= maxsz_p
? *maxsz_p
: (INT_MAX
- 4095);
188 buf
= xmalloc(size
+ 1);
189 size
= read_close(fd
, buf
, size
);
190 if ((ssize_t
)size
< 0) {
194 buf
= xrealloc(buf
, size
+ 1);
203 // Read (potentially big) files in one go. File size is estimated
205 void* FAST_FUNC
xmalloc_open_read_close(const char *filename
, size_t *maxsz_p
)
210 fd
= open(filename
, O_RDONLY
);
214 buf
= xmalloc_read(fd
, maxsz_p
);
219 /* Die with an error message if we can't read the entire buffer. */
220 void FAST_FUNC
xread(int fd
, void *buf
, size_t count
)
223 ssize_t size
= full_read(fd
, buf
, count
);
224 if ((size_t)size
!= count
)
225 bb_error_msg_and_die("short read");
229 /* Die with an error message if we can't read one character. */
230 unsigned char FAST_FUNC
xread_char(int fd
)
237 void* FAST_FUNC
xmalloc_xopen_read_close(const char *filename
, size_t *maxsz_p
)
239 void *buf
= xmalloc_open_read_close(filename
, maxsz_p
);
241 bb_perror_msg_and_die("can't read '%s'", filename
);
245 /* Used by e.g. rpm which gives us a fd without filename,
246 * thus we can't guess the format from filename's extension.
249 void FAST_FUNC
setup_unzip_on_fd(int fd
/*, int fail_if_not_detected*/)
251 const int fail_if_not_detected
= 1;
259 IF_DESKTOP(long long) int FAST_FUNC (*xformer
)(int src_fd
, int dst_fd
);
260 enum { xformer_prog
= 0 };
262 enum { xformer
= 0 };
263 const char *xformer_prog
;
266 /* .gz and .bz2 both have 2-byte signature, and their
267 * unpack_XXX_stream wants this header skipped. */
268 xread(fd
, magic
.b16
, sizeof(magic
.b16
[0]));
269 if (ENABLE_FEATURE_SEAMLESS_GZ
270 && magic
.b16
[0] == GZIP_MAGIC
273 xformer
= unpack_gz_stream
;
275 xformer_prog
= "gunzip";
279 if (ENABLE_FEATURE_SEAMLESS_BZ2
280 && magic
.b16
[0] == BZIP2_MAGIC
283 xformer
= unpack_bz2_stream
;
285 xformer_prog
= "bunzip2";
289 if (ENABLE_FEATURE_SEAMLESS_XZ
290 && magic
.b16
[0] == XZ_MAGIC1
293 xread(fd
, magic
.b32
, sizeof(magic
.b32
[0]));
294 if (magic
.b32
[0] == XZ_MAGIC2
) {
296 xformer
= unpack_xz_stream
;
297 /* unpack_xz_stream wants fd at position 6, no need to seek */
298 //xlseek(fd, offset, SEEK_CUR);
300 xformer_prog
= "unxz";
306 /* No known magic seen */
307 if (fail_if_not_detected
)
308 bb_error_msg_and_die("no gzip"
309 IF_FEATURE_SEAMLESS_BZ2("/bzip2")
310 IF_FEATURE_SEAMLESS_XZ("/xz")
312 xlseek(fd
, offset
, SEEK_CUR
);
317 /* NOMMU version of open_transformer execs
318 * an external unzipper that wants
319 * file position at the start of the file */
320 xlseek(fd
, offset
, SEEK_CUR
);
322 open_transformer(fd
, xformer
, xformer_prog
);
326 int FAST_FUNC
open_zipped(const char *fname
)
329 return open(fname
, O_RDONLY
);
334 fd
= open(fname
, O_RDONLY
);
338 sfx
= strrchr(fname
, '.');
341 if (ENABLE_FEATURE_SEAMLESS_LZMA
&& strcmp(sfx
, "lzma") == 0)
342 /* .lzma has no header/signature, just trust it */
343 open_transformer(fd
, unpack_lzma_stream
, "unlzma");
345 if ((ENABLE_FEATURE_SEAMLESS_GZ
&& strcmp(sfx
, "gz") == 0)
346 || (ENABLE_FEATURE_SEAMLESS_BZ2
&& strcmp(sfx
, "bz2") == 0)
347 || (ENABLE_FEATURE_SEAMLESS_XZ
&& strcmp(sfx
, "xz") == 0)
349 setup_unzip_on_fd(fd
/*, fail_if_not_detected: 1*/);
357 void* FAST_FUNC
xmalloc_open_zipped_read_close(const char *fname
, size_t *maxsz_p
)
362 fd
= open_zipped(fname
);
366 image
= xmalloc_read(fd
, maxsz_p
);
368 bb_perror_msg("read error from '%s'", fname
);