Contents of /trunk/mkinitrd-magellan/busybox/libbb/read_printf.c
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Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
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Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
File MIME type: text/plain
File size: 9192 byte(s)
-updated to busybox-1.17.1
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Utility routines. |
4 | * |
5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> |
6 | * |
7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
8 | */ |
9 | #include "libbb.h" |
10 | |
11 | #define ZIPPED (ENABLE_FEATURE_SEAMLESS_LZMA \ |
12 | || ENABLE_FEATURE_SEAMLESS_BZ2 \ |
13 | || ENABLE_FEATURE_SEAMLESS_GZ \ |
14 | /* || ENABLE_FEATURE_SEAMLESS_Z */ \ |
15 | ) |
16 | |
17 | #if ZIPPED |
18 | # include "unarchive.h" |
19 | #endif |
20 | |
21 | |
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? |
26 | * |
27 | * *** SURPRISE! It will affect the parent too! *** |
28 | * *** BIG SURPRISE! It stays even after child exits! *** |
29 | * |
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. |
34 | * |
35 | * In general, |
36 | * fd2 = dup(fd1); |
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. |
40 | * |
41 | * We need |
42 | * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD) | O_NONBLOCK); |
43 | * (note SETFD, not SETFL!) but such thing doesn't exist. |
44 | * |
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); |
48 | * "MSG_DONTWAIT: |
49 | * Enables non-blocking operation; if the operation |
50 | * would block, EAGAIN is returned." |
51 | * but recv() works only for sockets! |
52 | * |
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. |
57 | */ |
58 | ssize_t FAST_FUNC nonblock_safe_read(int fd, void *buf, size_t count) |
59 | { |
60 | struct pollfd pfd[1]; |
61 | ssize_t n; |
62 | |
63 | while (1) { |
64 | n = safe_read(fd, buf, count); |
65 | if (n >= 0 || errno != EAGAIN) |
66 | return n; |
67 | /* fd is in O_NONBLOCK mode. Wait using poll and repeat */ |
68 | pfd[0].fd = fd; |
69 | pfd[0].events = POLLIN; |
70 | safe_poll(pfd, 1, -1); /* note: this pulls in printf */ |
71 | } |
72 | } |
73 | |
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) |
78 | { |
79 | char *p; |
80 | size_t sz = buf ? strlen(buf) : 0; |
81 | size_t maxsz = maxsz_p ? *maxsz_p : (INT_MAX - 4095); |
82 | |
83 | goto jump_in; |
84 | while (sz < maxsz) { |
85 | if ((size_t)(p - buf) == sz) { |
86 | jump_in: |
87 | buf = xrealloc(buf, sz + 128); |
88 | p = buf + sz; |
89 | sz += 128; |
90 | } |
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 */ |
94 | free(buf); |
95 | return NULL; |
96 | } |
97 | break; |
98 | } |
99 | if (*p == '\n') |
100 | break; |
101 | p++; |
102 | } |
103 | *p = '\0'; |
104 | if (maxsz_p) |
105 | *maxsz_p = p - buf; |
106 | p++; |
107 | return xrealloc(buf, p - buf); |
108 | } |
109 | |
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) |
113 | { |
114 | char *buf; |
115 | size_t size, rd_size, total; |
116 | size_t to_read; |
117 | struct stat st; |
118 | |
119 | to_read = maxsz_p ? *maxsz_p : (INT_MAX - 4095); /* max to read */ |
120 | |
121 | /* Estimate file size */ |
122 | st.st_size = 0; /* in case fstat fails, assume 0 */ |
123 | fstat(fd, &st); |
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; |
127 | |
128 | total = 0; |
129 | buf = NULL; |
130 | while (1) { |
131 | if (to_read < size) |
132 | size = to_read; |
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 */ |
136 | free(buf); |
137 | return NULL; |
138 | } |
139 | total += rd_size; |
140 | if (rd_size < size) /* EOF */ |
141 | break; |
142 | if (to_read <= rd_size) |
143 | break; |
144 | to_read -= rd_size; |
145 | /* grow by 1/8, but in [1k..64k] bounds */ |
146 | size = ((total / 8) | 0x3ff) + 1; |
147 | if (size > 64*1024) |
148 | size = 64*1024; |
149 | } |
150 | buf = xrealloc(buf, total + 1); |
151 | buf[total] = '\0'; |
152 | |
153 | if (maxsz_p) |
154 | *maxsz_p = total; |
155 | return buf; |
156 | } |
157 | |
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) */ |
163 | |
164 | // Read (potentially big) files in one go. File size is estimated by |
165 | // lseek to end. |
166 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p) |
167 | { |
168 | char *buf; |
169 | size_t size; |
170 | int fd; |
171 | off_t len; |
172 | |
173 | fd = open(filename, O_RDONLY); |
174 | if (fd < 0) |
175 | return NULL; |
176 | |
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); |
184 | if (len < size) |
185 | size = len; |
186 | } |
187 | |
188 | buf = xmalloc(size + 1); |
189 | size = read_close(fd, buf, size); |
190 | if ((ssize_t)size < 0) { |
191 | free(buf); |
192 | return NULL; |
193 | } |
194 | buf = xrealloc(buf, size + 1); |
195 | buf[size] = '\0'; |
196 | |
197 | if (maxsz_p) |
198 | *maxsz_p = size; |
199 | return buf; |
200 | } |
201 | #endif |
202 | |
203 | // Read (potentially big) files in one go. File size is estimated |
204 | // by stat. |
205 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p) |
206 | { |
207 | char *buf; |
208 | int fd; |
209 | |
210 | fd = open(filename, O_RDONLY); |
211 | if (fd < 0) |
212 | return NULL; |
213 | |
214 | buf = xmalloc_read(fd, maxsz_p); |
215 | close(fd); |
216 | return buf; |
217 | } |
218 | |
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) |
221 | { |
222 | if (count) { |
223 | ssize_t size = full_read(fd, buf, count); |
224 | if ((size_t)size != count) |
225 | bb_error_msg_and_die("short read"); |
226 | } |
227 | } |
228 | |
229 | /* Die with an error message if we can't read one character. */ |
230 | unsigned char FAST_FUNC xread_char(int fd) |
231 | { |
232 | char tmp; |
233 | xread(fd, &tmp, 1); |
234 | return tmp; |
235 | } |
236 | |
237 | void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p) |
238 | { |
239 | void *buf = xmalloc_open_read_close(filename, maxsz_p); |
240 | if (!buf) |
241 | bb_perror_msg_and_die("can't read '%s'", filename); |
242 | return buf; |
243 | } |
244 | |
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. |
247 | */ |
248 | #if ZIPPED |
249 | void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/) |
250 | { |
251 | const int fail_if_not_detected = 1; |
252 | union { |
253 | uint8_t b[4]; |
254 | uint16_t b16[2]; |
255 | uint32_t b32[1]; |
256 | } magic; |
257 | int offset = -2; |
258 | # if BB_MMU |
259 | IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd); |
260 | enum { xformer_prog = 0 }; |
261 | # else |
262 | enum { xformer = 0 }; |
263 | const char *xformer_prog; |
264 | # endif |
265 | |
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 |
271 | ) { |
272 | # if BB_MMU |
273 | xformer = unpack_gz_stream; |
274 | # else |
275 | xformer_prog = "gunzip"; |
276 | # endif |
277 | goto found_magic; |
278 | } |
279 | if (ENABLE_FEATURE_SEAMLESS_BZ2 |
280 | && magic.b16[0] == BZIP2_MAGIC |
281 | ) { |
282 | # if BB_MMU |
283 | xformer = unpack_bz2_stream; |
284 | # else |
285 | xformer_prog = "bunzip2"; |
286 | # endif |
287 | goto found_magic; |
288 | } |
289 | if (ENABLE_FEATURE_SEAMLESS_XZ |
290 | && magic.b16[0] == XZ_MAGIC1 |
291 | ) { |
292 | offset = -6; |
293 | xread(fd, magic.b32, sizeof(magic.b32[0])); |
294 | if (magic.b32[0] == XZ_MAGIC2) { |
295 | # if BB_MMU |
296 | xformer = unpack_xz_stream; |
297 | /* unpack_xz_stream wants fd at position 6, no need to seek */ |
298 | //xlseek(fd, offset, SEEK_CUR); |
299 | # else |
300 | xformer_prog = "unxz"; |
301 | # endif |
302 | goto found_magic; |
303 | } |
304 | } |
305 | |
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") |
311 | " magic"); |
312 | xlseek(fd, offset, SEEK_CUR); |
313 | return; |
314 | |
315 | found_magic: |
316 | # if !BB_MMU |
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); |
321 | # endif |
322 | open_transformer(fd, xformer, xformer_prog); |
323 | } |
324 | #endif /* ZIPPED */ |
325 | |
326 | int FAST_FUNC open_zipped(const char *fname) |
327 | { |
328 | #if !ZIPPED |
329 | return open(fname, O_RDONLY); |
330 | #else |
331 | char *sfx; |
332 | int fd; |
333 | |
334 | fd = open(fname, O_RDONLY); |
335 | if (fd < 0) |
336 | return fd; |
337 | |
338 | sfx = strrchr(fname, '.'); |
339 | if (sfx) { |
340 | sfx++; |
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"); |
344 | else |
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) |
348 | ) { |
349 | setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/); |
350 | } |
351 | } |
352 | |
353 | return fd; |
354 | #endif |
355 | } |
356 | |
357 | void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p) |
358 | { |
359 | int fd; |
360 | char *image; |
361 | |
362 | fd = open_zipped(fname); |
363 | if (fd < 0) |
364 | return NULL; |
365 | |
366 | image = xmalloc_read(fd, maxsz_p); |
367 | if (!image) |
368 | bb_perror_msg("read error from '%s'", fname); |
369 | close(fd); |
370 | |
371 | return image; |
372 | } |