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_immune_read(int fd, void *buf, size_t count, int loop_on_EINTR)
64 n = loop_on_EINTR ? safe_read(fd, buf, count) : 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 /* note: safe_poll pulls in printf */
71 loop_on_EINTR ? safe_poll(pfd, 1, -1) : poll(pfd, 1, -1);
75 // Reads one line a-la fgets (but doesn't save terminating '\n').
76 // Reads byte-by-byte. Useful when it is important to not read ahead.
77 // Bytes are appended to pfx (which must be malloced, or NULL).
78 char* FAST_FUNC xmalloc_reads(int fd, size_t *maxsz_p)
83 size_t maxsz = maxsz_p ? *maxsz_p : (INT_MAX - 4095);
88 if ((size_t)(p - buf) == sz) {
90 buf = xrealloc(buf, sz + 128);
94 if (nonblock_immune_read(fd, p, 1, /*loop_on_EINTR:*/ 1) != 1) {
96 if (p == buf) { /* we read nothing */
110 return xrealloc(buf, p - buf);
113 // Read (potentially big) files in one go. File size is estimated
114 // by stat. Extra '\0' byte is appended.
115 void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
118 size_t size, rd_size, total;
122 to_read = maxsz_p ? *maxsz_p : (INT_MAX - 4095); /* max to read */
124 /* Estimate file size */
125 st.st_size = 0; /* in case fstat fails, assume 0 */
127 /* /proc/N/stat files report st_size 0 */
128 /* In order to make such files readable, we add small const */
129 size = (st.st_size | 0x3ff) + 1;
136 buf = xrealloc(buf, total + size + 1);
137 rd_size = full_read(fd, buf + total, size);
138 if ((ssize_t)rd_size == (ssize_t)(-1)) { /* error */
143 if (rd_size < size) /* EOF */
145 if (to_read <= rd_size)
148 /* grow by 1/8, but in [1k..64k] bounds */
149 size = ((total / 8) | 0x3ff) + 1;
153 buf = xrealloc(buf, total + 1);
161 #ifdef USING_LSEEK_TO_GET_SIZE
162 /* Alternatively, file size can be obtained by lseek to the end.
163 * The code is slightly bigger. Retained in case fstat approach
164 * will not work for some weird cases (/proc, block devices, etc).
165 * (NB: lseek also can fail to work for some weird files) */
167 // Read (potentially big) files in one go. File size is estimated by
169 void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
176 fd = open(filename, O_RDONLY);
180 /* /proc/N/stat files report len 0 here */
181 /* In order to make such files readable, we add small const */
182 size = 0x3ff; /* read only 1k on unseekable files */
183 len = lseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
184 if (len != (off_t)-1) {
185 xlseek(fd, 0, SEEK_SET);
186 size = maxsz_p ? *maxsz_p : (INT_MAX - 4095);
191 buf = xmalloc(size + 1);
192 size = read_close(fd, buf, size);
193 if ((ssize_t)size < 0) {
197 buf = xrealloc(buf, size + 1);
206 // Read (potentially big) files in one go. File size is estimated
208 void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
213 fd = open(filename, O_RDONLY);
217 buf = xmalloc_read(fd, maxsz_p);
222 /* Die with an error message if we can't read the entire buffer. */
223 void FAST_FUNC xread(int fd, void *buf, size_t count)
226 ssize_t size = full_read(fd, buf, count);
227 if ((size_t)size != count)
228 bb_error_msg_and_die("short read");
232 /* Die with an error message if we can't read one character. */
233 unsigned char FAST_FUNC xread_char(int fd)
240 void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
242 void *buf = xmalloc_open_read_close(filename, maxsz_p);
244 bb_perror_msg_and_die("can't read '%s'", filename);
248 /* Used by e.g. rpm which gives us a fd without filename,
249 * thus we can't guess the format from filename's extension.
252 void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
254 const int fail_if_not_detected = 1;
262 IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd);
263 enum { xformer_prog = 0 };
265 enum { xformer = 0 };
266 const char *xformer_prog;
269 /* .gz and .bz2 both have 2-byte signature, and their
270 * unpack_XXX_stream wants this header skipped. */
271 xread(fd, magic.b16, sizeof(magic.b16[0]));
272 if (ENABLE_FEATURE_SEAMLESS_GZ
273 && magic.b16[0] == GZIP_MAGIC
276 xformer = unpack_gz_stream;
278 xformer_prog = "gunzip";
282 if (ENABLE_FEATURE_SEAMLESS_BZ2
283 && magic.b16[0] == BZIP2_MAGIC
286 xformer = unpack_bz2_stream;
288 xformer_prog = "bunzip2";
292 if (ENABLE_FEATURE_SEAMLESS_XZ
293 && magic.b16[0] == XZ_MAGIC1
296 xread(fd, magic.b32, sizeof(magic.b32[0]));
297 if (magic.b32[0] == XZ_MAGIC2) {
299 xformer = unpack_xz_stream;
300 /* unpack_xz_stream wants fd at position 6, no need to seek */
301 //xlseek(fd, offset, SEEK_CUR);
303 xformer_prog = "unxz";
309 /* No known magic seen */
310 if (fail_if_not_detected)
311 bb_error_msg_and_die("no gzip"
312 IF_FEATURE_SEAMLESS_BZ2("/bzip2")
313 IF_FEATURE_SEAMLESS_XZ("/xz")
315 xlseek(fd, offset, SEEK_CUR);
320 /* NOMMU version of open_transformer execs
321 * an external unzipper that wants
322 * file position at the start of the file */
323 xlseek(fd, offset, SEEK_CUR);
325 open_transformer(fd, xformer, xformer_prog);
329 int FAST_FUNC open_zipped(const char *fname)
332 return open(fname, O_RDONLY);
337 fd = open(fname, O_RDONLY);
341 sfx = strrchr(fname, '.');
344 if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0)
345 /* .lzma has no header/signature, just trust it */
346 open_transformer(fd, unpack_lzma_stream, "unlzma");
348 if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0)
349 || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0)
350 || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0)
352 setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/);
360 void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
365 fd = open_zipped(fname);
369 image = xmalloc_read(fd, maxsz_p);
371 bb_perror_msg("read error from '%s'", fname);